--- /dev/null
+Contributor Acknowledgements
+============================
+
+Companies
+---------
+
+Linaro Limited
+
+NVIDIA Corporation
+
+Socionext Inc.
+
+Xilinx, Inc.
+
+Individuals
+-----------
--- /dev/null
+Contributing to ARM Trusted Firmware
+====================================
+
+Getting Started
+---------------
+
+- Make sure you have a `GitHub account`_.
+- Create an `issue`_ for your work if one does not already exist. This gives
+ everyone visibility of whether others are working on something similar. ARM
+ licensees may contact ARM directly via their partner managers instead if
+ they prefer.
+
+ - Note that the `issue`_ tracker for this project is in a separate
+ `issue tracking repository`_. Please follow the guidelines in that
+ repository.
+ - If you intend to include Third Party IP in your contribution, please
+ raise a separate `issue`_ for this and ensure that the changes that
+ include Third Party IP are made on a separate topic branch.
+
+- `Fork`_ `arm-trusted-firmware`_ on GitHub.
+- Clone the fork to your own machine.
+- Create a local topic branch based on the `arm-trusted-firmware`_ ``master``
+ branch.
+
+Making Changes
+--------------
+
+- Make commits of logical units. See these general `Git guidelines`_ for
+ contributing to a project.
+- Follow the `Linux coding style`_; this style is enforced for the ARM Trusted
+ Firmware project (style errors only, not warnings).
+
+ - Use the checkpatch.pl script provided with the Linux source tree. A
+ Makefile target is provided for convenience (see section 2 in the
+ `User Guide`_).
+
+- Keep the commits on topic. If you need to fix another bug or make another
+ enhancement, please create a separate `issue`_ and address it on a separate
+ topic branch.
+- Avoid long commit series. If you do have a long series, consider whether
+ some commits should be squashed together or addressed in a separate topic.
+- Make sure your commit messages are in the proper format. If a commit fixes
+ a GitHub `issue`_, include a reference (e.g.
+ "fixes arm-software/tf-issues#45"); this ensures the `issue`_ is
+ `automatically closed`_ when merged into the `arm-trusted-firmware`_ ``master``
+ branch.
+- Where appropriate, please update the documentation.
+
+ - Consider whether the `User Guide`_, `Porting Guide`_, `Firmware Design`_ or
+ other in-source documentation needs updating.
+ - Ensure that each changed file has the correct copyright and license
+ information. Files that entirely consist of contributions to this
+ project should have the copyright notice and BSD-3-Clause SPDX license
+ identifier as shown in `license.rst`_. Files that contain
+ changes to imported Third Party IP should contain a notice as follows,
+ with the original copyright and license text retained:
+
+ ::
+
+ Portions copyright (c) [XXXX-]YYYY, ARM Limited and Contributors. All rights reserved.
+
+ where XXXX is the year of first contribution (if different to YYYY) and
+ YYYY is the year of most recent contribution.
+ - If not done previously, you may add your name or your company name to
+ the `Acknowledgements`_ file.
+ - If you are submitting new files that you intend to be the technical
+ sub-maintainer for (for example, a new platform port), then also update
+ the `Maintainers`_ file.
+ - For topics with multiple commits, you should make all documentation
+ changes (and nothing else) in the last commit of the series. Otherwise,
+ include the documentation changes within the single commit.
+
+- Please test your changes. As a minimum, ensure UEFI boots to the shell on
+ the Foundation FVP. See `Running the software on FVP`_ for more information.
+
+Submitting Changes
+------------------
+
+- Ensure that each commit in the series has at least one ``Signed-off-by:``
+ line, using your real name and email address. The names in the
+ ``Signed-off-by:`` and ``Author:`` lines must match. If anyone else contributes
+ to the commit, they must also add their own ``Signed-off-by:`` line.
+ By adding this line the contributor certifies the contribution is made under
+ the terms of the `Developer Certificate of Origin (DCO)`_.
+- Push your local changes to your fork of the repository.
+- Submit a `pull request`_ to the `arm-trusted-firmware`_ ``integration`` branch.
+
+ - The changes in the `pull request`_ will then undergo further review and
+ testing by the `Maintainers`_. Any review comments will be made as
+ comments on the `pull request`_. This may require you to do some rework.
+
+- When the changes are accepted, the `Maintainers`_ will integrate them.
+
+ - Typically, the `Maintainers`_ will merge the `pull request`_ into the
+ ``integration`` branch within the GitHub UI, creating a merge commit.
+ - Please avoid creating merge commits in the `pull request`_ itself.
+ - If the `pull request`_ is not based on a recent commit, the `Maintainers`_
+ may rebase it onto the ``master`` branch first, or ask you to do this.
+ - If the `pull request`_ cannot be automatically merged, the `Maintainers`_
+ will ask you to rebase it onto the ``master`` branch.
+ - After final integration testing, the `Maintainers`_ will push your merge
+ commit to the ``master`` branch. If a problem is found during integration,
+ the merge commit will be removed from the ``integration`` branch and the
+ `Maintainers`_ will ask you to create a new pull request to resolve the
+ problem.
+ - Please do not delete your topic branch until it is safely merged into
+ the ``master`` branch.
+
+--------------
+
+*Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.*
+
+.. _GitHub account: https://github.com/signup/free
+.. _issue: https://github.com/ARM-software/tf-issues/issues
+.. _issue tracking repository: https://github.com/ARM-software/tf-issues
+.. _Fork: https://help.github.com/articles/fork-a-repo
+.. _arm-trusted-firmware: https://github.com/ARM-software/arm-trusted-firmware
+.. _Git guidelines: http://git-scm.com/book/ch5-2.html
+.. _Linux coding style: https://www.kernel.org/doc/Documentation/CodingStyle
+.. _User Guide: ./docs/user-guide.rst
+.. _automatically closed: https://help.github.com/articles/closing-issues-via-commit-messages
+.. _Porting Guide: ./docs/porting-guide.rst
+.. _Firmware Design: ./docs/firmware-design.rst
+.. _license.rst: ./license.rst
+.. _Acknowledgements: ./acknowledgements.rst
+.. _Maintainers: ./maintainers.rst
+.. _Running the software on FVP: ./docs/user-guide.rst#user-content-running-the-software-on-fvp
+.. _Developer Certificate of Origin (DCO): ./dco.txt
+.. _pull request: https://help.github.com/articles/using-pull-requests
--- /dev/null
+ARM SiP Service
+===============
+
+This document enumerates and describes the ARM SiP (Silicon Provider) services.
+
+SiP services are non-standard, platform-specific services offered by the silicon
+implementer or platform provider. They are accessed via. ``SMC`` ("SMC calls")
+instruction executed from Exception Levels below EL3. SMC calls for SiP
+services:
+
+- Follow `SMC Calling Convention`_;
+- Use SMC function IDs that fall in the SiP range, which are ``0xc2000000`` -
+ ``0xc200ffff`` for 64-bit calls, and ``0x82000000`` - ``0x8200ffff`` for 32-bit
+ calls.
+
+The ARM SiP implementation offers the following services:
+
+- Performance Measurement Framework (PMF)
+- Execution State Switching service
+
+Source definitions for ARM SiP service are located in the ``arm_sip_svc.h`` header
+file.
+
+Performance Measurement Framework (PMF)
+---------------------------------------
+
+The `Performance Measurement Framework`_
+allows callers to retrieve timestamps captured at various paths in ARM Trusted
+Firmware execution. It's described in detail in `Firmware Design document`_.
+
+Execution State Switching service
+---------------------------------
+
+Execution State Switching service provides a mechanism for a non-secure lower
+Exception Level (either EL2, or NS EL1 if EL2 isn't implemented) to request to
+switch its execution state (a.k.a. Register Width), either from AArch64 to
+AArch32, or from AArch32 to AArch64, for the calling CPU. This service is only
+available when ARM Trusted Firmware is built for AArch64 (i.e. when build option
+``ARCH`` is set to ``aarch64``).
+
+``ARM_SIP_SVC_EXE_STATE_SWITCH``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t Function ID
+ uint32_t PC hi
+ uint32_t PC lo
+ uint32_t Cookie hi
+ uint32_t Cookie lo
+
+ Return:
+ uint32_t
+
+The function ID parameter must be ``0x82000020``. It uniquely identifies the
+Execution State Switching service being requested.
+
+The parameters *PC hi* and *PC lo* defines upper and lower words, respectively,
+of the entry point (physical address) at which execution should start, after
+Execution State has been switched. When calling from AArch64, *PC hi* must be 0.
+
+When execution starts at the supplied entry point after Execution State has been
+switched, the parameters *Cookie hi* and *Cookie lo* are passed in CPU registers
+0 and 1, respectively. When calling from AArch64, *Cookie hi* must be 0.
+
+This call can only be made on the primary CPU, before any secondaries were
+brought up with ``CPU_ON`` PSCI call. Otherwise, the call will always fail.
+
+The effect of switching execution state is as if the Exception Level were
+entered for the first time, following power on. This means CPU registers that
+have a defined reset value by the Architecture will assume that value. Other
+registers should not be expected to hold their values before the call was made.
+CPU endianness, however, is preserved from the previous execution state. Note
+that this switches the execution state of the calling CPU only. This is not a
+substitute for PSCI ``SYSTEM_RESET``.
+
+The service may return the following error codes:
+
+- ``STATE_SW_E_PARAM``: If any of the parameters were deemed invalid for
+ a specific request.
+- ``STATE_SW_E_DENIED``: If the call is not successful, or when ARM Trusted
+ Firmware is built for AArch32.
+
+If the call is successful, the caller wouldn't observe the SMC returning.
+Instead, execution starts at the supplied entry point, with the CPU registers 0
+and 1 populated with the supplied *Cookie hi* and *Cookie lo* values,
+respectively.
+
+--------------
+
+*Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.*
+
+.. _SMC Calling Convention: http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html
+.. _Performance Measurement Framework: ./firmware-design.rst#user-content-performance-measurement-framework
+.. _Firmware Design document: ./firmware-design.rst
--- /dev/null
+Abstracting a Chain of Trust
+============================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+The aim of this document is to describe the authentication framework implemented
+in the Trusted Firmware. This framework fulfills the following requirements:
+
+#. It should be possible for a platform port to specify the Chain of Trust in
+ terms of certificate hierarchy and the mechanisms used to verify a
+ particular image/certificate.
+
+#. The framework should distinguish between:
+
+ - The mechanism used to encode and transport information, e.g. DER encoded
+ X.509v3 certificates to ferry Subject Public Keys, hashes and non-volatile
+ counters.
+
+ - The mechanism used to verify the transported information i.e. the
+ cryptographic libraries.
+
+The framework has been designed following a modular approach illustrated in the
+next diagram:
+
+::
+
+ +---------------+---------------+------------+
+ | Trusted | Trusted | Trusted |
+ | Firmware | Firmware | Firmware |
+ | Generic | IO Framework | Platform |
+ | Code i.e. | (IO) | Port |
+ | BL1/BL2 (GEN) | | (PP) |
+ +---------------+---------------+------------+
+ ^ ^ ^
+ | | |
+ v v v
+ +-----------+ +-----------+ +-----------+
+ | | | | | Image |
+ | Crypto | | Auth | | Parser |
+ | Module |<->| Module |<->| Module |
+ | (CM) | | (AM) | | (IPM) |
+ | | | | | |
+ +-----------+ +-----------+ +-----------+
+ ^ ^
+ | |
+ v v
+ +----------------+ +-----------------+
+ | Cryptographic | | Image Parser |
+ | Libraries (CL) | | Libraries (IPL) |
+ +----------------+ +-----------------+
+ | |
+ | |
+ | |
+ v v
+ +-----------------+
+ | Misc. Libs e.g. |
+ | ASN.1 decoder |
+ | |
+ +-----------------+
+
+ DIAGRAM 1.
+
+This document describes the inner details of the authentication framework and
+the abstraction mechanisms available to specify a Chain of Trust.
+
+Framework design
+----------------
+
+This section describes some aspects of the framework design and the rationale
+behind them. These aspects are key to verify a Chain of Trust.
+
+Chain of Trust
+~~~~~~~~~~~~~~
+
+A CoT is basically a sequence of authentication images which usually starts with
+a root of trust and culminates in a single data image. The following diagram
+illustrates how this maps to a CoT for the BL31 image described in the
+TBBR-Client specification.
+
+::
+
+ +------------------+ +-------------------+
+ | ROTPK/ROTPK Hash |------>| Trusted Key |
+ +------------------+ | Certificate |
+ | (Auth Image) |
+ /+-------------------+
+ / |
+ / |
+ / |
+ / |
+ L v
+ +------------------+ +-------------------+
+ | Trusted World |------>| BL31 Key |
+ | Public Key | | Certificate |
+ +------------------+ | (Auth Image) |
+ +-------------------+
+ / |
+ / |
+ / |
+ / |
+ / v
+ +------------------+ L +-------------------+
+ | BL31 Content |------>| BL31 Content |
+ | Certificate PK | | Certificate |
+ +------------------+ | (Auth Image) |
+ +-------------------+
+ / |
+ / |
+ / |
+ / |
+ / v
+ +------------------+ L +-------------------+
+ | BL31 Hash |------>| BL31 Image |
+ | | | (Data Image) |
+ +------------------+ | |
+ +-------------------+
+
+ DIAGRAM 2.
+
+The root of trust is usually a public key (ROTPK) that has been burnt in the
+platform and cannot be modified.
+
+Image types
+~~~~~~~~~~~
+
+Images in a CoT are categorised as authentication and data images. An
+authentication image contains information to authenticate a data image or
+another authentication image. A data image is usually a boot loader binary, but
+it could be any other data that requires authentication.
+
+Component responsibilities
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For every image in a Chain of Trust, the following high level operations are
+performed to verify it:
+
+#. Allocate memory for the image either statically or at runtime.
+
+#. Identify the image and load it in the allocated memory.
+
+#. Check the integrity of the image as per its type.
+
+#. Authenticate the image as per the cryptographic algorithms used.
+
+#. If the image is an authentication image, extract the information that will
+ be used to authenticate the next image in the CoT.
+
+In Diagram 1, each component is responsible for one or more of these operations.
+The responsibilities are briefly described below.
+
+TF Generic code and IO framework (GEN/IO)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These components are responsible for initiating the authentication process for a
+particular image in BL1 or BL2. For each BL image that requires authentication,
+the Generic code asks recursively the Authentication module what is the parent
+image until either an authenticated image or the ROT is reached. Then the
+Generic code calls the IO framewotk to load the image and calls the
+Authentication module to authenticate it, following the CoT from ROT to Image.
+
+TF Platform Port (PP)
+^^^^^^^^^^^^^^^^^^^^^
+
+The platform is responsible for:
+
+#. Specifying the CoT for each image that needs to be authenticated. Details of
+ how a CoT can be specified by the platform are explained later. The platform
+ also specifies the authentication methods and the parsing method used for
+ each image.
+
+#. Statically allocating memory for each parameter in each image which is
+ used for verifying the CoT, e.g. memory for public keys, hashes etc.
+
+#. Providing the ROTPK or a hash of it.
+
+#. Providing additional information to the IPM to enable it to identify and
+ extract authentication parameters contained in an image, e.g. if the
+ parameters are stored as X509v3 extensions, the corresponding OID must be
+ provided.
+
+#. Fulfill any other memory requirements of the IPM and the CM (not currently
+ described in this document).
+
+#. Export functions to verify an image which uses an authentication method that
+ cannot be interpreted by the CM, e.g. if an image has to be verified using a
+ NV counter, then the value of the counter to compare with can only be
+ provided by the platform.
+
+#. Export a custom IPM if a proprietary image format is being used (described
+ later).
+
+Authentication Module (AM)
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It is responsible for:
+
+#. Providing the necessary abstraction mechanisms to describe a CoT. Amongst
+ other things, the authentication and image parsing methods must be specified
+ by the PP in the CoT.
+
+#. Verifying the CoT passed by GEN by utilising functionality exported by the
+ PP, IPM and CM.
+
+#. Tracking which images have been verified. In case an image is a part of
+ multiple CoTs then it should be verified only once e.g. the Trusted World
+ Key Certificate in the TBBR-Client spec. contains information to verify
+ SCP\_BL2, BL31, BL32 each of which have a separate CoT. (This
+ responsibility has not been described in this document but should be
+ trivial to implement).
+
+#. Reusing memory meant for a data image to verify authentication images e.g.
+ in the CoT described in Diagram 2, each certificate can be loaded and
+ verified in the memory reserved by the platform for the BL31 image. By the
+ time BL31 (the data image) is loaded, all information to authenticate it
+ will have been extracted from the parent image i.e. BL31 content
+ certificate. It is assumed that the size of an authentication image will
+ never exceed the size of a data image. It should be possible to verify this
+ at build time using asserts.
+
+Cryptographic Module (CM)
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The CM is responsible for providing an API to:
+
+#. Verify a digital signature.
+#. Verify a hash.
+
+The CM does not include any cryptography related code, but it relies on an
+external library to perform the cryptographic operations. A Crypto-Library (CL)
+linking the CM and the external library must be implemented. The following
+functions must be provided by the CL:
+
+.. code:: c
+
+ void (*init)(void);
+ int (*verify_signature)(void *data_ptr, unsigned int data_len,
+ void *sig_ptr, unsigned int sig_len,
+ void *sig_alg, unsigned int sig_alg_len,
+ void *pk_ptr, unsigned int pk_len);
+ int (*verify_hash)(void *data_ptr, unsigned int data_len,
+ void *digest_info_ptr, unsigned int digest_info_len);
+
+These functions are registered in the CM using the macro:
+
+.. code:: c
+
+ REGISTER_CRYPTO_LIB(_name, _init, _verify_signature, _verify_hash);
+
+``_name`` must be a string containing the name of the CL. This name is used for
+debugging purposes.
+
+Image Parser Module (IPM)
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The IPM is responsible for:
+
+#. Checking the integrity of each image loaded by the IO framework.
+#. Extracting parameters used for authenticating an image based upon a
+ description provided by the platform in the CoT descriptor.
+
+Images may have different formats (for example, authentication images could be
+x509v3 certificates, signed ELF files or any other platform specific format).
+The IPM allows to register an Image Parser Library (IPL) for every image format
+used in the CoT. This library must implement the specific methods to parse the
+image. The IPM obtains the image format from the CoT and calls the right IPL to
+check the image integrity and extract the authentication parameters.
+
+See Section "Describing the image parsing methods" for more details about the
+mechanism the IPM provides to define and register IPLs.
+
+Authentication methods
+~~~~~~~~~~~~~~~~~~~~~~
+
+The AM supports the following authentication methods:
+
+#. Hash
+#. Digital signature
+
+The platform may specify these methods in the CoT in case it decides to define
+a custom CoT instead of reusing a predefined one.
+
+If a data image uses multiple methods, then all the methods must be a part of
+the same CoT. The number and type of parameters are method specific. These
+parameters should be obtained from the parent image using the IPM.
+
+#. Hash
+
+ Parameters:
+
+ #. A pointer to data to hash
+ #. Length of the data
+ #. A pointer to the hash
+ #. Length of the hash
+
+ The hash will be represented by the DER encoding of the following ASN.1
+ type:
+
+ ::
+
+ DigestInfo ::= SEQUENCE {
+ digestAlgorithm DigestAlgorithmIdentifier,
+ digest Digest
+ }
+
+ This ASN.1 structure makes it possible to remove any assumption about the
+ type of hash algorithm used as this information accompanies the hash. This
+ should allow the Cryptography Library (CL) to support multiple hash
+ algorithm implementations.
+
+#. Digital Signature
+
+ Parameters:
+
+ #. A pointer to data to sign
+ #. Length of the data
+ #. Public Key Algorithm
+ #. Public Key value
+ #. Digital Signature Algorithm
+ #. Digital Signature value
+
+ The Public Key parameters will be represented by the DER encoding of the
+ following ASN.1 type:
+
+ ::
+
+ SubjectPublicKeyInfo ::= SEQUENCE {
+ algorithm AlgorithmIdentifier{PUBLIC-KEY,{PublicKeyAlgorithms}},
+ subjectPublicKey BIT STRING }
+
+ The Digital Signature Algorithm will be represented by the DER encoding of
+ the following ASN.1 types.
+
+ ::
+
+ AlgorithmIdentifier {ALGORITHM:IOSet } ::= SEQUENCE {
+ algorithm ALGORITHM.&id({IOSet}),
+ parameters ALGORITHM.&Type({IOSet}{@algorithm}) OPTIONAL
+ }
+
+ The digital signature will be represented by:
+
+ ::
+
+ signature ::= BIT STRING
+
+The authentication framework will use the image descriptor to extract all the
+information related to authentication.
+
+Specifying a Chain of Trust
+---------------------------
+
+A CoT can be described as a set of image descriptors linked together in a
+particular order. The order dictates the sequence in which they must be
+verified. Each image has a set of properties which allow the AM to verify it.
+These properties are described below.
+
+The PP is responsible for defining a single or multiple CoTs for a data image.
+Unless otherwise specified, the data structures described in the following
+sections are populated by the PP statically.
+
+Describing the image parsing methods
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The parsing method refers to the format of a particular image. For example, an
+authentication image that represents a certificate could be in the X.509v3
+format. A data image that represents a boot loader stage could be in raw binary
+or ELF format. The IPM supports three parsing methods. An image has to use one
+of the three methods described below. An IPL is responsible for interpreting a
+single parsing method. There has to be one IPL for every method used by the
+platform.
+
+#. Raw format: This format is effectively a nop as an image using this method
+ is treated as being in raw binary format e.g. boot loader images used by ARM
+ TF. This method should only be used by data images.
+
+#. X509V3 method: This method uses industry standards like X.509 to represent
+ PKI certificates (authentication images). It is expected that open source
+ libraries will be available which can be used to parse an image represented
+ by this method. Such libraries can be used to write the corresponding IPL
+ e.g. the X.509 parsing library code in mbed TLS.
+
+#. Platform defined method: This method caters for platform specific
+ proprietary standards to represent authentication or data images. For
+ example, The signature of a data image could be appended to the data image
+ raw binary. A header could be prepended to the combined blob to specify the
+ extents of each component. The platform will have to implement the
+ corresponding IPL to interpret such a format.
+
+The following enum can be used to define these three methods.
+
+.. code:: c
+
+ typedef enum img_type_enum {
+ IMG_RAW, /* Binary image */
+ IMG_PLAT, /* Platform specific format */
+ IMG_CERT, /* X509v3 certificate */
+ IMG_MAX_TYPES,
+ } img_type_t;
+
+An IPL must provide functions with the following prototypes:
+
+.. code:: c
+
+ void init(void);
+ int check_integrity(void *img, unsigned int img_len);
+ int get_auth_param(const auth_param_type_desc_t *type_desc,
+ void *img, unsigned int img_len,
+ void **param, unsigned int *param_len);
+
+An IPL for each type must be registered using the following macro:
+
+::
+
+ REGISTER_IMG_PARSER_LIB(_type, _name, _init, _check_int, _get_param)
+
+- ``_type``: one of the types described above.
+- ``_name``: a string containing the IPL name for debugging purposes.
+- ``_init``: initialization function pointer.
+- ``_check_int``: check image integrity function pointer.
+- ``_get_param``: extract authentication parameter funcion pointer.
+
+The ``init()`` function will be used to initialize the IPL.
+
+The ``check_integrity()`` function is passed a pointer to the memory where the
+image has been loaded by the IO framework and the image length. It should ensure
+that the image is in the format corresponding to the parsing method and has not
+been tampered with. For example, RFC-2459 describes a validation sequence for an
+X.509 certificate.
+
+The ``get_auth_param()`` function is passed a parameter descriptor containing
+information about the parameter (``type_desc`` and ``cookie``) to identify and
+extract the data corresponding to that parameter from an image. This data will
+be used to verify either the current or the next image in the CoT sequence.
+
+Each image in the CoT will specify the parsing method it uses. This information
+will be used by the IPM to find the right parser descriptor for the image.
+
+Describing the authentication method(s)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+As part of the CoT, each image has to specify one or more authentication methods
+which will be used to verify it. As described in the Section "Authentication
+methods", there are three methods supported by the AM.
+
+.. code:: c
+
+ typedef enum {
+ AUTH_METHOD_NONE,
+ AUTH_METHOD_HASH,
+ AUTH_METHOD_SIG,
+ AUTH_METHOD_NUM
+ } auth_method_type_t;
+
+The AM defines the type of each parameter used by an authentication method. It
+uses this information to:
+
+#. Specify to the ``get_auth_param()`` function exported by the IPM, which
+ parameter should be extracted from an image.
+
+#. Correctly marshall the parameters while calling the verification function
+ exported by the CM and PP.
+
+#. Extract authentication parameters from a parent image in order to verify a
+ child image e.g. to verify the certificate image, the public key has to be
+ obtained from the parent image.
+
+.. code:: c
+
+ typedef enum {
+ AUTH_PARAM_NONE,
+ AUTH_PARAM_RAW_DATA, /* Raw image data */
+ AUTH_PARAM_SIG, /* The image signature */
+ AUTH_PARAM_SIG_ALG, /* The image signature algorithm */
+ AUTH_PARAM_HASH, /* A hash (including the algorithm) */
+ AUTH_PARAM_PUB_KEY, /* A public key */
+ } auth_param_type_t;
+
+The AM defines the following structure to identify an authentication parameter
+required to verify an image.
+
+.. code:: c
+
+ typedef struct auth_param_type_desc_s {
+ auth_param_type_t type;
+ void *cookie;
+ } auth_param_type_desc_t;
+
+``cookie`` is used by the platform to specify additional information to the IPM
+which enables it to uniquely identify the parameter that should be extracted
+from an image. For example, the hash of a BL3x image in its corresponding
+content certificate is stored in an X509v3 custom extension field. An extension
+field can only be identified using an OID. In this case, the ``cookie`` could
+contain the pointer to the OID defined by the platform for the hash extension
+field while the ``type`` field could be set to ``AUTH_PARAM_HASH``. A value of 0 for
+the ``cookie`` field means that it is not used.
+
+For each method, the AM defines a structure with the parameters required to
+verify the image.
+
+.. code:: c
+
+ /*
+ * Parameters for authentication by hash matching
+ */
+ typedef struct auth_method_param_hash_s {
+ auth_param_type_desc_t *data; /* Data to hash */
+ auth_param_type_desc_t *hash; /* Hash to match with */
+ } auth_method_param_hash_t;
+
+ /*
+ * Parameters for authentication by signature
+ */
+ typedef struct auth_method_param_sig_s {
+ auth_param_type_desc_t *pk; /* Public key */
+ auth_param_type_desc_t *sig; /* Signature to check */
+ auth_param_type_desc_t *alg; /* Signature algorithm */
+ auth_param_type_desc_t *tbs; /* Data signed */
+ } auth_method_param_sig_t;
+
+The AM defines the following structure to describe an authentication method for
+verifying an image
+
+.. code:: c
+
+ /*
+ * Authentication method descriptor
+ */
+ typedef struct auth_method_desc_s {
+ auth_method_type_t type;
+ union {
+ auth_method_param_hash_t hash;
+ auth_method_param_sig_t sig;
+ } param;
+ } auth_method_desc_t;
+
+Using the method type specified in the ``type`` field, the AM finds out what field
+needs to access within the ``param`` union.
+
+Storing Authentication parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A parameter described by ``auth_param_type_desc_t`` to verify an image could be
+obtained from either the image itself or its parent image. The memory allocated
+for loading the parent image will be reused for loading the child image. Hence
+parameters which are obtained from the parent for verifying a child image need
+to have memory allocated for them separately where they can be stored. This
+memory must be statically allocated by the platform port.
+
+The AM defines the following structure to store the data corresponding to an
+authentication parameter.
+
+.. code:: c
+
+ typedef struct auth_param_data_desc_s {
+ void *auth_param_ptr;
+ unsigned int auth_param_len;
+ } auth_param_data_desc_t;
+
+The ``auth_param_ptr`` field is initialized by the platform. The ``auth_param_len``
+field is used to specify the length of the data in the memory.
+
+For parameters that can be obtained from the child image itself, the IPM is
+responsible for populating the ``auth_param_ptr`` and ``auth_param_len`` fields
+while executing the ``img_get_auth_param()`` function.
+
+The AM defines the following structure to enable an image to describe the
+parameters that should be extracted from it and used to verify the next image
+(child) in a CoT.
+
+.. code:: c
+
+ typedef struct auth_param_desc_s {
+ auth_param_type_desc_t type_desc;
+ auth_param_data_desc_t data;
+ } auth_param_desc_t;
+
+Describing an image in a CoT
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+An image in a CoT is a consolidation of the following aspects of a CoT described
+above.
+
+#. A unique identifier specified by the platform which allows the IO framework
+ to locate the image in a FIP and load it in the memory reserved for the data
+ image in the CoT.
+
+#. A parsing method which is used by the AM to find the appropriate IPM.
+
+#. Authentication methods and their parameters as described in the previous
+ section. These are used to verify the current image.
+
+#. Parameters which are used to verify the next image in the current CoT. These
+ parameters are specified only by authentication images and can be extracted
+ from the current image once it has been verified.
+
+The following data structure describes an image in a CoT.
+
+.. code:: c
+
+ typedef struct auth_img_desc_s {
+ unsigned int img_id;
+ const struct auth_img_desc_s *parent;
+ img_type_t img_type;
+ auth_method_desc_t img_auth_methods[AUTH_METHOD_NUM];
+ auth_param_desc_t authenticated_data[COT_MAX_VERIFIED_PARAMS];
+ } auth_img_desc_t;
+
+A CoT is defined as an array of ``auth_image_desc_t`` structures linked together
+by the ``parent`` field. Those nodes with no parent must be authenticated using
+the ROTPK stored in the platform.
+
+Implementation example
+----------------------
+
+This section is a detailed guide explaining a trusted boot implementation using
+the authentication framework. This example corresponds to the Applicative
+Functional Mode (AFM) as specified in the TBBR-Client document. It is
+recommended to read this guide along with the source code.
+
+The TBBR CoT
+~~~~~~~~~~~~
+
+The CoT can be found in ``drivers/auth/tbbr/tbbr_cot.c``. This CoT consists of an
+array of image descriptors and it is registered in the framework using the macro
+``REGISTER_COT(cot_desc)``, where 'cot\_desc' must be the name of the array
+(passing a pointer or any other type of indirection will cause the registration
+process to fail).
+
+The number of images participating in the boot process depends on the CoT. There
+is, however, a minimum set of images that are mandatory in the Trusted Firmware
+and thus all CoTs must present:
+
+- ``BL2``
+- ``SCP_BL2`` (platform specific)
+- ``BL31``
+- ``BL32`` (optional)
+- ``BL33``
+
+The TBBR specifies the additional certificates that must accompany these images
+for a proper authentication. Details about the TBBR CoT may be found in the
+`Trusted Board Boot`_ document.
+
+Following the `Platform Porting Guide`_, a platform must provide unique
+identifiers for all the images and certificates that will be loaded during the
+boot process. If a platform is using the TBBR as a reference for trusted boot,
+these identifiers can be obtained from ``include/common/tbbr/tbbr_img_def.h``.
+ARM platforms include this file in ``include/plat/arm/common/arm_def.h``. Other
+platforms may also include this file or provide their own identifiers.
+
+**Important**: the authentication module uses these identifiers to index the
+CoT array, so the descriptors location in the array must match the identifiers.
+
+Each image descriptor must specify:
+
+- ``img_id``: the corresponding image unique identifier defined by the platform.
+- ``img_type``: the image parser module uses the image type to call the proper
+ parsing library to check the image integrity and extract the required
+ authentication parameters. Three types of images are currently supported:
+
+ - ``IMG_RAW``: image is a raw binary. No parsing functions are available,
+ other than reading the whole image.
+ - ``IMG_PLAT``: image format is platform specific. The platform may use this
+ type for custom images not directly supported by the authentication
+ framework.
+ - ``IMG_CERT``: image is an x509v3 certificate.
+
+- ``parent``: pointer to the parent image descriptor. The parent will contain
+ the information required to authenticate the current image. If the parent
+ is NULL, the authentication parameters will be obtained from the platform
+ (i.e. the BL2 and Trusted Key certificates are signed with the ROT private
+ key, whose public part is stored in the platform).
+- ``img_auth_methods``: this array defines the authentication methods that must
+ be checked to consider an image authenticated. Each method consists of a
+ type and a list of parameter descriptors. A parameter descriptor consists of
+ a type and a cookie which will point to specific information required to
+ extract that parameter from the image (i.e. if the parameter is stored in an
+ x509v3 extension, the cookie will point to the extension OID). Depending on
+ the method type, a different number of parameters must be specified.
+ Supported methods are:
+
+ - ``AUTH_METHOD_HASH``: the hash of the image must match the hash extracted
+ from the parent image. The following parameter descriptors must be
+ specified:
+
+ - ``data``: data to be hashed (obtained from current image)
+ - ``hash``: reference hash (obtained from parent image)
+
+ - ``AUTH_METHOD_SIG``: the image (usually a certificate) must be signed with
+ the private key whose public part is extracted from the parent image (or
+ the platform if the parent is NULL). The following parameter descriptors
+ must be specified:
+
+ - ``pk``: the public key (obtained from parent image)
+ - ``sig``: the digital signature (obtained from current image)
+ - ``alg``: the signature algorithm used (obtained from current image)
+ - ``data``: the data to be signed (obtained from current image)
+
+- ``authenticated_data``: this array indicates what authentication parameters
+ must be extracted from an image once it has been authenticated. Each
+ parameter consists of a parameter descriptor and the buffer address/size
+ to store the parameter. The CoT is responsible for allocating the required
+ memory to store the parameters.
+
+In the ``tbbr_cot.c`` file, a set of buffers are allocated to store the parameters
+extracted from the certificates. In the case of the TBBR CoT, these parameters
+are hashes and public keys. In DER format, an RSA-2048 public key requires 294
+bytes, and a hash requires 51 bytes. Depending on the CoT and the authentication
+process, some of the buffers may be reused at different stages during the boot.
+
+Next in that file, the parameter descriptors are defined. These descriptors will
+be used to extract the parameter data from the corresponding image.
+
+Example: the BL31 Chain of Trust
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Four image descriptors form the BL31 Chain of Trust:
+
+.. code:: asm
+
+ [TRUSTED_KEY_CERT_ID] = {
+ .img_id = TRUSTED_KEY_CERT_ID,
+ .img_type = IMG_CERT,
+ .parent = NULL,
+ .img_auth_methods = {
+ [0] = {
+ .type = AUTH_METHOD_SIG,
+ .param.sig = {
+ .pk = &subject_pk,
+ .sig = &sig,
+ .alg = &sig_alg,
+ .data = &raw_data,
+ }
+ }
+ },
+ .authenticated_data = {
+ [0] = {
+ .type_desc = &trusted_world_pk,
+ .data = {
+ .ptr = (void *)trusted_world_pk_buf,
+ .len = (unsigned int)PK_DER_LEN
+ }
+ },
+ [1] = {
+ .type_desc = &non_trusted_world_pk,
+ .data = {
+ .ptr = (void *)non_trusted_world_pk_buf,
+ .len = (unsigned int)PK_DER_LEN
+ }
+ }
+ }
+ },
+ [SOC_FW_KEY_CERT_ID] = {
+ .img_id = SOC_FW_KEY_CERT_ID,
+ .img_type = IMG_CERT,
+ .parent = &cot_desc[TRUSTED_KEY_CERT_ID],
+ .img_auth_methods = {
+ [0] = {
+ .type = AUTH_METHOD_SIG,
+ .param.sig = {
+ .pk = &trusted_world_pk,
+ .sig = &sig,
+ .alg = &sig_alg,
+ .data = &raw_data,
+ }
+ }
+ },
+ .authenticated_data = {
+ [0] = {
+ .type_desc = &soc_fw_content_pk,
+ .data = {
+ .ptr = (void *)content_pk_buf,
+ .len = (unsigned int)PK_DER_LEN
+ }
+ }
+ }
+ },
+ [SOC_FW_CONTENT_CERT_ID] = {
+ .img_id = SOC_FW_CONTENT_CERT_ID,
+ .img_type = IMG_CERT,
+ .parent = &cot_desc[SOC_FW_KEY_CERT_ID],
+ .img_auth_methods = {
+ [0] = {
+ .type = AUTH_METHOD_SIG,
+ .param.sig = {
+ .pk = &soc_fw_content_pk,
+ .sig = &sig,
+ .alg = &sig_alg,
+ .data = &raw_data,
+ }
+ }
+ },
+ .authenticated_data = {
+ [0] = {
+ .type_desc = &soc_fw_hash,
+ .data = {
+ .ptr = (void *)soc_fw_hash_buf,
+ .len = (unsigned int)HASH_DER_LEN
+ }
+ }
+ }
+ },
+ [BL31_IMAGE_ID] = {
+ .img_id = BL31_IMAGE_ID,
+ .img_type = IMG_RAW,
+ .parent = &cot_desc[SOC_FW_CONTENT_CERT_ID],
+ .img_auth_methods = {
+ [0] = {
+ .type = AUTH_METHOD_HASH,
+ .param.hash = {
+ .data = &raw_data,
+ .hash = &soc_fw_hash,
+ }
+ }
+ }
+ }
+
+The **Trusted Key certificate** is signed with the ROT private key and contains
+the Trusted World public key and the Non-Trusted World public key as x509v3
+extensions. This must be specified in the image descriptor using the
+``img_auth_methods`` and ``authenticated_data`` arrays, respectively.
+
+The Trusted Key certificate is authenticated by checking its digital signature
+using the ROTPK. Four parameters are required to check a signature: the public
+key, the algorithm, the signature and the data that has been signed. Therefore,
+four parameter descriptors must be specified with the authentication method:
+
+- ``subject_pk``: parameter descriptor of type ``AUTH_PARAM_PUB_KEY``. This type
+ is used to extract a public key from the parent image. If the cookie is an
+ OID, the key is extracted from the corresponding x509v3 extension. If the
+ cookie is NULL, the subject public key is retrieved. In this case, because
+ the parent image is NULL, the public key is obtained from the platform
+ (this key will be the ROTPK).
+- ``sig``: parameter descriptor of type ``AUTH_PARAM_SIG``. It is used to extract
+ the signature from the certificate.
+- ``sig_alg``: parameter descriptor of type ``AUTH_PARAM_SIG``. It is used to
+ extract the signature algorithm from the certificate.
+- ``raw_data``: parameter descriptor of type ``AUTH_PARAM_RAW_DATA``. It is used
+ to extract the data to be signed from the certificate.
+
+Once the signature has been checked and the certificate authenticated, the
+Trusted World public key needs to be extracted from the certificate. A new entry
+is created in the ``authenticated_data`` array for that purpose. In that entry,
+the corresponding parameter descriptor must be specified along with the buffer
+address to store the parameter value. In this case, the ``tz_world_pk`` descriptor
+is used to extract the public key from an x509v3 extension with OID
+``TRUSTED_WORLD_PK_OID``. The BL31 key certificate will use this descriptor as
+parameter in the signature authentication method. The key is stored in the
+``plat_tz_world_pk_buf`` buffer.
+
+The **BL31 Key certificate** is authenticated by checking its digital signature
+using the Trusted World public key obtained previously from the Trusted Key
+certificate. In the image descriptor, we specify a single authentication method
+by signature whose public key is the ``tz_world_pk``. Once this certificate has
+been authenticated, we have to extract the BL31 public key, stored in the
+extension specified by ``bl31_content_pk``. This key will be copied to the
+``plat_content_pk`` buffer.
+
+The **BL31 certificate** is authenticated by checking its digital signature
+using the BL31 public key obtained previously from the BL31 Key certificate.
+We specify the authentication method using ``bl31_content_pk`` as public key.
+After authentication, we need to extract the BL31 hash, stored in the extension
+specified by ``bl31_hash``. This hash will be copied to the ``plat_bl31_hash_buf``
+buffer.
+
+The **BL31 image** is authenticated by calculating its hash and matching it
+with the hash obtained from the BL31 certificate. The image descriptor contains
+a single authentication method by hash. The parameters to the hash method are
+the reference hash, ``bl31_hash``, and the data to be hashed. In this case, it is
+the whole image, so we specify ``raw_data``.
+
+The image parser library
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+The image parser module relies on libraries to check the image integrity and
+extract the authentication parameters. The number and type of parser libraries
+depend on the images used in the CoT. Raw images do not need a library, so
+only an x509v3 library is required for the TBBR CoT.
+
+ARM platforms will use an x509v3 library based on mbed TLS. This library may be
+found in ``drivers/auth/mbedtls/mbedtls_x509_parser.c``. It exports three
+functions:
+
+.. code:: c
+
+ void init(void);
+ int check_integrity(void *img, unsigned int img_len);
+ int get_auth_param(const auth_param_type_desc_t *type_desc,
+ void *img, unsigned int img_len,
+ void **param, unsigned int *param_len);
+
+The library is registered in the framework using the macro
+``REGISTER_IMG_PARSER_LIB()``. Each time the image parser module needs to access
+an image of type ``IMG_CERT``, it will call the corresponding function exported
+in this file.
+
+The build system must be updated to include the corresponding library and
+mbed TLS sources. ARM platforms use the ``arm_common.mk`` file to pull the
+sources.
+
+The cryptographic library
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The cryptographic module relies on a library to perform the required operations,
+i.e. verify a hash or a digital signature. ARM platforms will use a library
+based on mbed TLS, which can be found in
+``drivers/auth/mbedtls/mbedtls_crypto.c``. This library is registered in the
+authentication framework using the macro ``REGISTER_CRYPTO_LIB()`` and exports
+three functions:
+
+.. code:: c
+
+ void init(void);
+ int verify_signature(void *data_ptr, unsigned int data_len,
+ void *sig_ptr, unsigned int sig_len,
+ void *sig_alg, unsigned int sig_alg_len,
+ void *pk_ptr, unsigned int pk_len);
+ int verify_hash(void *data_ptr, unsigned int data_len,
+ void *digest_info_ptr, unsigned int digest_info_len);
+
+The key algorithm (rsa, ecdsa) must be specified in the build system using the
+``TF_MBEDTLS_KEY_ALG`` variable, so the Makefile can include the corresponding
+sources in the build.
+
+Note: If code size is a concern, the build option ``MBEDTLS_SHA256_SMALLER`` can
+be defined in the platform Makefile. It will make mbed TLS use an implementation
+of SHA-256 with smaller memory footprint (~1.5 KB less) but slower (~30%).
+
+--------------
+
+*Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.*
+
+.. _Trusted Board Boot: ./trusted-board-boot.rst
+.. _Platform Porting Guide: ./porting-guide.rst
--- /dev/null
+ARM Trusted Firmware - version 1.3
+==================================
+
+New features
+------------
+
+- Added support for running Trusted Firmware in AArch32 execution state.
+
+ The PSCI library has been refactored to allow integration with **EL3 Runtime
+ Software**. This is software that is executing at the highest secure
+ privilege which is EL3 in AArch64 or Secure SVC/Monitor mode in AArch32. See
+ `PSCI Integration Guide`_.
+
+ Included is a minimal AArch32 Secure Payload, **SP-MIN**, that illustrates
+ the usage and integration of the PSCI library with EL3 Runtime Software
+ running in AArch32 state.
+
+ Booting to the BL1/BL2 images as well as booting straight to the Secure
+ Payload is supported.
+
+- Improvements to the initialization framework for the PSCI service and ARM
+ Standard Services in general.
+
+ The PSCI service is now initialized as part of ARM Standard Service
+ initialization. This consolidates the initializations of any ARM Standard
+ Service that may be added in the future.
+
+ A new function ``get_arm_std_svc_args()`` is introduced to get arguments
+ corresponding to each standard service and must be implemented by the EL3
+ Runtime Software.
+
+ For PSCI, a new versioned structure ``psci_lib_args_t`` is introduced to
+ initialize the PSCI Library. **Note** this is a compatibility break due to
+ the change in the prototype of ``psci_setup()``.
+
+- To support AArch32 builds of BL1 and BL2, implemented a new, alternative
+ firmware image loading mechanism that adds flexibility.
+
+ The current mechanism has a hard-coded set of images and execution order
+ (BL31, BL32, etc). The new mechanism is data-driven by a list of image
+ descriptors provided by the platform code.
+
+ ARM platforms have been updated to support the new loading mechanism.
+
+ The new mechanism is enabled by a build flag (``LOAD_IMAGE_V2``) which is
+ currently off by default for the AArch64 build.
+
+ **Note** ``TRUSTED_BOARD_BOOT`` is currently not supported when
+ ``LOAD_IMAGE_V2`` is enabled.
+
+- Updated requirements for making contributions to ARM TF.
+
+ Commits now must have a 'Signed-off-by:' field to certify that the
+ contribution has been made under the terms of the
+ `Developer Certificate of Origin`_.
+
+ A signed CLA is no longer required.
+
+ The `Contribution Guide`_ has been updated to reflect this change.
+
+- Introduced Performance Measurement Framework (PMF) which provides support
+ for capturing, storing, dumping and retrieving time-stamps to measure the
+ execution time of critical paths in the firmware. This relies on defining
+ fixed sample points at key places in the code.
+
+- To support the QEMU platform port, imported libfdt v1.4.1 from
+ https://git.kernel.org/cgit/utils/dtc/dtc.git
+
+- Updated PSCI support:
+
+ - Added support for PSCI NODE\_HW\_STATE API for ARM platforms.
+
+ - New optional platform hook, ``pwr_domain_pwr_down_wfi()``, in
+ ``plat_psci_ops`` to enable platforms to perform platform-specific actions
+ needed to enter powerdown, including the 'wfi' invocation.
+
+ - PSCI STAT residency and count functions have been added on ARM platforms
+ by using PMF.
+
+- Enhancements to the translation table library:
+
+ - Limited memory mapping support for region overlaps to only allow regions
+ to overlap that are identity mapped or have the same virtual to physical
+ address offset, and overlap completely but must not cover the same area.
+
+ This limitation will enable future enhancements without having to
+ support complex edge cases that may not be necessary.
+
+ - The initial translation lookup level is now inferred from the virtual
+ address space size. Previously, it was hard-coded.
+
+ - Added support for mapping Normal, Inner Non-cacheable, Outer
+ Non-cacheable memory in the translation table library.
+
+ This can be useful to map a non-cacheable memory region, such as a DMA
+ buffer.
+
+ - Introduced the MT\_EXECUTE/MT\_EXECUTE\_NEVER memory mapping attributes to
+ specify the access permissions for instruction execution of a memory
+ region.
+
+- Enabled support to isolate code and read-only data on separate memory pages,
+ allowing independent access control to be applied to each.
+
+- Enabled SCR\_EL3.SIF (Secure Instruction Fetch) bit in BL1 and BL31 common
+ architectural setup code, preventing fetching instructions from non-secure
+ memory when in secure state.
+
+- Enhancements to FIP support:
+
+ - Replaced ``fip_create`` with ``fiptool`` which provides a more consistent
+ and intuitive interface as well as additional support to remove an image
+ from a FIP file.
+
+ - Enabled printing the SHA256 digest with info command, allowing quick
+ verification of an image within a FIP without having to extract the
+ image and running sha256sum on it.
+
+ - Added support for unpacking the contents of an existing FIP file into
+ the working directory.
+
+ - Aligned command line options for specifying images to use same naming
+ convention as specified by TBBR and already used in cert\_create tool.
+
+- Refactored the TZC-400 driver to also support memory controllers that
+ integrate TZC functionality, for example ARM CoreLink DMC-500. Also added
+ DMC-500 specific support.
+
+- Implemented generic delay timer based on the system generic counter and
+ migrated all platforms to use it.
+
+- Enhanced support for ARM platforms:
+
+ - Updated image loading support to make SCP images (SCP\_BL2 and SCP\_BL2U)
+ optional.
+
+ - Enhanced topology description support to allow multi-cluster topology
+ definitions.
+
+ - Added interconnect abstraction layer to help platform ports select the
+ right interconnect driver, CCI or CCN, for the platform.
+
+ - Added support to allow loading BL31 in the TZC-secured DRAM instead of
+ the default secure SRAM.
+
+ - Added support to use a System Security Control (SSC) Registers Unit
+ enabling ARM TF to be compiled to support multiple ARM platforms and
+ then select one at runtime.
+
+ - Restricted mapping of Trusted ROM in BL1 to what is actually needed by
+ BL1 rather than entire Trusted ROM region.
+
+ - Flash is now mapped as execute-never by default. This increases security
+ by restricting the executable region to what is strictly needed.
+
+- Applied following erratum workarounds for Cortex-A57: 833471, 826977,
+ 829520, 828024 and 826974.
+
+- Added support for Mediatek MT6795 platform.
+
+- Added support for QEMU virtualization ARMv8-A target.
+
+- Added support for Rockchip RK3368 and RK3399 platforms.
+
+- Added support for Xilinx Zynq UltraScale+ MPSoC platform.
+
+- Added support for ARM Cortex-A73 MPCore Processor.
+
+- Added support for ARM Cortex-A72 processor.
+
+- Added support for ARM Cortex-A35 processor.
+
+- Added support for ARM Cortex-A32 MPCore Processor.
+
+- Enabled preloaded BL33 alternative boot flow, in which BL2 does not load
+ BL33 from non-volatile storage and BL31 hands execution over to a preloaded
+ BL33. The User Guide has been updated with an example of how to use this
+ option with a bootwrapped kernel.
+
+- Added support to build ARM TF on a Windows-based host machine.
+
+- Updated Trusted Board Boot prototype implementation:
+
+ - Enabled the ability for a production ROM with TBBR enabled to boot test
+ software before a real ROTPK is deployed (e.g. manufacturing mode).
+ Added support to use ROTPK in certificate without verifying against the
+ platform value when ``ROTPK_NOT_DEPLOYED`` bit is set.
+
+ - Added support for non-volatile counter authentication to the
+ Authentication Module to protect against roll-back.
+
+- Updated GICv3 support:
+
+ - Enabled processor power-down and automatic power-on using GICv3.
+
+ - Enabled G1S or G0 interrupts to be configured independently.
+
+ - Changed FVP default interrupt driver to be the GICv3-only driver.
+ **Note** the default build of Trusted Firmware will not be able to boot
+ Linux kernel with GICv2 FDT blob.
+
+ - Enabled wake-up from CPU\_SUSPEND to stand-by by temporarily re-routing
+ interrupts and then restoring after resume.
+
+Issues resolved since last release
+----------------------------------
+
+Known issues
+------------
+
+- The version of the AEMv8 Base FVP used in this release resets the model
+ instead of terminating its execution in response to a shutdown request using
+ the PSCI ``SYSTEM_OFF`` API. This issue will be fixed in a future version of
+ the model.
+
+- Building TF with compiler optimisations disabled (``-O0``) fails.
+
+- ARM TF cannot be built with mbed TLS version v2.3.0 due to build warnings
+ that the ARM TF build system interprets as errors.
+
+- TBBR is not currently supported when running Trusted Firmware in AArch32
+ state.
+
+ARM Trusted Firmware - version 1.2
+==================================
+
+New features
+------------
+
+- The Trusted Board Boot implementation on ARM platforms now conforms to the
+ mandatory requirements of the TBBR specification.
+
+ In particular, the boot process is now guarded by a Trusted Watchdog, which
+ will reset the system in case of an authentication or loading error. On ARM
+ platforms, a secure instance of ARM SP805 is used as the Trusted Watchdog.
+
+ Also, a firmware update process has been implemented. It enables
+ authenticated firmware to update firmware images from external interfaces to
+ SoC Non-Volatile memories. This feature functions even when the current
+ firmware in the system is corrupt or missing; it therefore may be used as
+ a recovery mode.
+
+- Improvements have been made to the Certificate Generation Tool
+ (``cert_create``) as follows.
+
+ - Added support for the Firmware Update process by extending the Chain
+ of Trust definition in the tool to include the Firmware Update
+ certificate and the required extensions.
+
+ - Introduced a new API that allows one to specify command line options in
+ the Chain of Trust description. This makes the declaration of the tool's
+ arguments more flexible and easier to extend.
+
+ - The tool has been reworked to follow a data driven approach, which
+ makes it easier to maintain and extend.
+
+- Extended the FIP tool (``fip_create``) to support the new set of images
+ involved in the Firmware Update process.
+
+- Various memory footprint improvements. In particular:
+
+ - The bakery lock structure for coherent memory has been optimised.
+
+ - The mbed TLS SHA1 functions are not needed, as SHA256 is used to
+ generate the certificate signature. Therefore, they have been compiled
+ out, reducing the memory footprint of BL1 and BL2 by approximately
+ 6 KB.
+
+ - On ARM development platforms, each BL stage now individually defines
+ the number of regions that it needs to map in the MMU.
+
+- Added the following new design documents:
+
+ - `Authentication framework`_
+ - `Firmware Update`_
+ - `TF Reset Design`_
+ - `Power Domain Topology Design`_
+
+- Applied the new image terminology to the code base and documentation, as
+ described on the `TF wiki on GitHub`_.
+
+- The build system has been reworked to improve readability and facilitate
+ adding future extensions.
+
+- On ARM standard platforms, BL31 uses the boot console during cold boot
+ but switches to the runtime console for any later logs at runtime. The TSP
+ uses the runtime console for all output.
+
+- Implemented a basic NOR flash driver for ARM platforms. It programs the
+ device using CFI (Common Flash Interface) standard commands.
+
+- Implemented support for booting EL3 payloads on ARM platforms, which
+ reduces the complexity of developing EL3 baremetal code by doing essential
+ baremetal initialization.
+
+- Provided separate drivers for GICv3 and GICv2. These expect the entire
+ software stack to use either GICv2 or GICv3; hybrid GIC software systems
+ are no longer supported and the legacy ARM GIC driver has been deprecated.
+
+- Added support for Juno r1 and r2. A single set of Juno TF binaries can run
+ on Juno r0, r1 and r2 boards. Note that this TF version depends on a Linaro
+ release that does *not* contain Juno r2 support.
+
+- Added support for MediaTek mt8173 platform.
+
+- Implemented a generic driver for ARM CCN IP.
+
+- Major rework of the PSCI implementation.
+
+ - Added framework to handle composite power states.
+
+ - Decoupled the notions of affinity instances (which describes the
+ hierarchical arrangement of cores) and of power domain topology, instead
+ of assuming a one-to-one mapping.
+
+ - Better alignment with version 1.0 of the PSCI specification.
+
+- Added support for the SYSTEM\_SUSPEND PSCI API on ARM platforms. When invoked
+ on the last running core on a supported platform, this puts the system
+ into a low power mode with memory retention.
+
+- Unified the reset handling code as much as possible across BL stages.
+ Also introduced some build options to enable optimization of the reset path
+ on platforms that support it.
+
+- Added a simple delay timer API, as well as an SP804 timer driver, which is
+ enabled on FVP.
+
+- Added support for NVidia Tegra T210 and T132 SoCs.
+
+- Reorganised ARM platforms ports to greatly improve code shareability and
+ facilitate the reuse of some of this code by other platforms.
+
+- Added support for ARM Cortex-A72 processor in the CPU specific framework.
+
+- Provided better error handling. Platform ports can now define their own
+ error handling, for example to perform platform specific bookkeeping or
+ post-error actions.
+
+- Implemented a unified driver for ARM Cache Coherent Interconnects used for
+ both CCI-400 & CCI-500 IPs. ARM platforms ports have been migrated to this
+ common driver. The standalone CCI-400 driver has been deprecated.
+
+Issues resolved since last release
+----------------------------------
+
+- The Trusted Board Boot implementation has been redesigned to provide greater
+ modularity and scalability. See the `Authentication Framework`_ document.
+ All missing mandatory features are now implemented.
+
+- The FVP and Juno ports may now use the hash of the ROTPK stored in the
+ Trusted Key Storage registers to verify the ROTPK. Alternatively, a
+ development public key hash embedded in the BL1 and BL2 binaries might be
+ used instead. The location of the ROTPK is chosen at build-time using the
+ ``ARM_ROTPK_LOCATION`` build option.
+
+- GICv3 is now fully supported and stable.
+
+Known issues
+------------
+
+- The version of the AEMv8 Base FVP used in this release resets the model
+ instead of terminating its execution in response to a shutdown request using
+ the PSCI ``SYSTEM_OFF`` API. This issue will be fixed in a future version of
+ the model.
+
+- While this version has low on-chip RAM requirements, there are further
+ RAM usage enhancements that could be made.
+
+- The upstream documentation could be improved for structural consistency,
+ clarity and completeness. In particular, the design documentation is
+ incomplete for PSCI, the TSP(D) and the Juno platform.
+
+- Building TF with compiler optimisations disabled (``-O0``) fails.
+
+ARM Trusted Firmware - version 1.1
+==================================
+
+New features
+------------
+
+- A prototype implementation of Trusted Board Boot has been added. Boot
+ loader images are verified by BL1 and BL2 during the cold boot path. BL1 and
+ BL2 use the PolarSSL SSL library to verify certificates and images. The
+ OpenSSL library is used to create the X.509 certificates. Support has been
+ added to ``fip_create`` tool to package the certificates in a FIP.
+
+- Support for calling CPU and platform specific reset handlers upon entry into
+ BL3-1 during the cold and warm boot paths has been added. This happens after
+ another Boot ROM ``reset_handler()`` has already run. This enables a developer
+ to perform additional actions or undo actions already performed during the
+ first call of the reset handlers e.g. apply additional errata workarounds.
+
+- Support has been added to demonstrate routing of IRQs to EL3 instead of
+ S-EL1 when execution is in secure world.
+
+- The PSCI implementation now conforms to version 1.0 of the PSCI
+ specification. All the mandatory APIs and selected optional APIs are
+ supported. In particular, support for the ``PSCI_FEATURES`` API has been
+ added. A capability variable is constructed during initialization by
+ examining the ``plat_pm_ops`` and ``spd_pm_ops`` exported by the platform and
+ the Secure Payload Dispatcher. This is used by the PSCI FEATURES function
+ to determine which PSCI APIs are supported by the platform.
+
+- Improvements have been made to the PSCI code as follows.
+
+ - The code has been refactored to remove redundant parameters from
+ internal functions.
+
+ - Changes have been made to the code for PSCI ``CPU_SUSPEND``, ``CPU_ON`` and
+ ``CPU_OFF`` calls to facilitate an early return to the caller in case a
+ failure condition is detected. For example, a PSCI ``CPU_SUSPEND`` call
+ returns ``SUCCESS`` to the caller if a pending interrupt is detected early
+ in the code path.
+
+ - Optional platform APIs have been added to validate the ``power_state`` and
+ ``entrypoint`` parameters early in PSCI ``CPU_ON`` and ``CPU_SUSPEND`` code
+ paths.
+
+ - PSCI migrate APIs have been reworked to invoke the SPD hook to determine
+ the type of Trusted OS and the CPU it is resident on (if
+ applicable). Also, during a PSCI ``MIGRATE`` call, the SPD hook to migrate
+ the Trusted OS is invoked.
+
+- It is now possible to build Trusted Firmware without marking at least an
+ extra page of memory as coherent. The build flag ``USE_COHERENT_MEM`` can be
+ used to choose between the two implementations. This has been made possible
+ through these changes.
+
+ - An implementation of Bakery locks, where the locks are not allocated in
+ coherent memory has been added.
+
+ - Memory which was previously marked as coherent is now kept coherent
+ through the use of software cache maintenance operations.
+
+ Approximately, 4K worth of memory is saved for each boot loader stage when
+ ``USE_COHERENT_MEM=0``. Enabling this option increases the latencies
+ associated with acquire and release of locks. It also requires changes to
+ the platform ports.
+
+- It is now possible to specify the name of the FIP at build time by defining
+ the ``FIP_NAME`` variable.
+
+- Issues with depedencies on the 'fiptool' makefile target have been
+ rectified. The ``fip_create`` tool is now rebuilt whenever its source files
+ change.
+
+- The BL3-1 runtime console is now also used as the crash console. The crash
+ console is changed to SoC UART0 (UART2) from the previous FPGA UART0 (UART0)
+ on Juno. In FVP, it is changed from UART0 to UART1.
+
+- CPU errata workarounds are applied only when the revision and part number
+ match. This behaviour has been made consistent across the debug and release
+ builds. The debug build additionally prints a warning if a mismatch is
+ detected.
+
+- It is now possible to issue cache maintenance operations by set/way for a
+ particular level of data cache. Levels 1-3 are currently supported.
+
+- The following improvements have been made to the FVP port.
+
+ - The build option ``FVP_SHARED_DATA_LOCATION`` which allowed relocation of
+ shared data into the Trusted DRAM has been deprecated. Shared data is
+ now always located at the base of Trusted SRAM.
+
+ - BL2 Translation tables have been updated to map only the region of
+ DRAM which is accessible to normal world. This is the region of the 2GB
+ DDR-DRAM memory at 0x80000000 excluding the top 16MB. The top 16MB is
+ accessible to only the secure world.
+
+ - BL3-2 can now reside in the top 16MB of DRAM which is accessible only to
+ the secure world. This can be done by setting the build flag
+ ``FVP_TSP_RAM_LOCATION`` to the value ``dram``.
+
+- Separate transation tables are created for each boot loader image. The
+ ``IMAGE_BLx`` build options are used to do this. This allows each stage to
+ create mappings only for areas in the memory map that it needs.
+
+- A Secure Payload Dispatcher (OPTEED) for the OP-TEE Trusted OS has been
+ added. Details of using it with ARM Trusted Firmware can be found in
+ `OP-TEE Dispatcher`_
+
+Issues resolved since last release
+----------------------------------
+
+- The Juno port has been aligned with the FVP port as follows.
+
+ - Support for reclaiming all BL1 RW memory and BL2 memory by overlaying
+ the BL3-1/BL3-2 NOBITS sections on top of them has been added to the
+ Juno port.
+
+ - The top 16MB of the 2GB DDR-DRAM memory at 0x80000000 is configured
+ using the TZC-400 controller to be accessible only to the secure world.
+
+ - The ARM GIC driver is used to configure the GIC-400 instead of using a
+ GIC driver private to the Juno port.
+
+ - PSCI ``CPU_SUSPEND`` calls that target a standby state are now supported.
+
+ - The TZC-400 driver is used to configure the controller instead of direct
+ accesses to the registers.
+
+- The Linux kernel version referred to in the user guide has DVFS and HMP
+ support enabled.
+
+- DS-5 v5.19 did not detect Version 5.8 of the Cortex-A57-A53 Base FVPs in
+ CADI server mode. This issue is not seen with DS-5 v5.20 and Version 6.2 of
+ the Cortex-A57-A53 Base FVPs.
+
+Known issues
+------------
+
+- The Trusted Board Boot implementation is a prototype. There are issues with
+ the modularity and scalability of the design. Support for a Trusted
+ Watchdog, firmware update mechanism, recovery images and Trusted debug is
+ absent. These issues will be addressed in future releases.
+
+- The FVP and Juno ports do not use the hash of the ROTPK stored in the
+ Trusted Key Storage registers to verify the ROTPK in the
+ ``plat_match_rotpk()`` function. This prevents the correct establishment of
+ the Chain of Trust at the first step in the Trusted Board Boot process.
+
+- The version of the AEMv8 Base FVP used in this release resets the model
+ instead of terminating its execution in response to a shutdown request using
+ the PSCI ``SYSTEM_OFF`` API. This issue will be fixed in a future version of
+ the model.
+
+- GICv3 support is experimental. There are known issues with GICv3
+ initialization in the ARM Trusted Firmware.
+
+- While this version greatly reduces the on-chip RAM requirements, there are
+ further RAM usage enhancements that could be made.
+
+- The firmware design documentation for the Test Secure-EL1 Payload (TSP) and
+ its dispatcher (TSPD) is incomplete. Similarly for the PSCI section.
+
+- The Juno-specific firmware design documentation is incomplete.
+
+ARM Trusted Firmware - version 1.0
+==================================
+
+New features
+------------
+
+- It is now possible to map higher physical addresses using non-flat virtual
+ to physical address mappings in the MMU setup.
+
+- Wider use is now made of the per-CPU data cache in BL3-1 to store:
+
+ - Pointers to the non-secure and secure security state contexts.
+
+ - A pointer to the CPU-specific operations.
+
+ - A pointer to PSCI specific information (for example the current power
+ state).
+
+ - A crash reporting buffer.
+
+- The following RAM usage improvements result in a BL3-1 RAM usage reduction
+ from 96KB to 56KB (for FVP with TSPD), and a total RAM usage reduction
+ across all images from 208KB to 88KB, compared to the previous release.
+
+ - Removed the separate ``early_exception`` vectors from BL3-1 (2KB code size
+ saving).
+
+ - Removed NSRAM from the FVP memory map, allowing the removal of one
+ (4KB) translation table.
+
+ - Eliminated the internal ``psci_suspend_context`` array, saving 2KB.
+
+ - Correctly dimensioned the PSCI ``aff_map_node`` array, saving 1.5KB in the
+ FVP port.
+
+ - Removed calling CPU mpidr from the bakery lock API, saving 160 bytes.
+
+ - Removed current CPU mpidr from PSCI common code, saving 160 bytes.
+
+ - Inlined the mmio accessor functions, saving 360 bytes.
+
+ - Fully reclaimed all BL1 RW memory and BL2 memory on the FVP port by
+ overlaying the BL3-1/BL3-2 NOBITS sections on top of these at runtime.
+
+ - Made storing the FP register context optional, saving 0.5KB per context
+ (8KB on the FVP port, with TSPD enabled and running on 8 CPUs).
+
+ - Implemented a leaner ``tf_printf()`` function, allowing the stack to be
+ greatly reduced.
+
+ - Removed coherent stacks from the codebase. Stacks allocated in normal
+ memory are now used before and after the MMU is enabled. This saves 768
+ bytes per CPU in BL3-1.
+
+ - Reworked the crash reporting in BL3-1 to use less stack.
+
+ - Optimized the EL3 register state stored in the ``cpu_context`` structure
+ so that registers that do not change during normal execution are
+ re-initialized each time during cold/warm boot, rather than restored
+ from memory. This saves about 1.2KB.
+
+ - As a result of some of the above, reduced the runtime stack size in all
+ BL images. For BL3-1, this saves 1KB per CPU.
+
+- PSCI SMC handler improvements to correctly handle calls from secure states
+ and from AArch32.
+
+- CPU contexts are now initialized from the ``entry_point_info``. BL3-1 fully
+ determines the exception level to use for the non-trusted firmware (BL3-3)
+ based on the SPSR value provided by the BL2 platform code (or otherwise
+ provided to BL3-1). This allows platform code to directly run non-trusted
+ firmware payloads at either EL2 or EL1 without requiring an EL2 stub or OS
+ loader.
+
+- Code refactoring improvements:
+
+ - Refactored ``fvp_config`` into a common platform header.
+
+ - Refactored the fvp gic code to be a generic driver that no longer has an
+ explicit dependency on platform code.
+
+ - Refactored the CCI-400 driver to not have dependency on platform code.
+
+ - Simplified the IO driver so it's no longer necessary to call ``io_init()``
+ and moved all the IO storage framework code to one place.
+
+ - Simplified the interface the the TZC-400 driver.
+
+ - Clarified the platform porting interface to the TSP.
+
+ - Reworked the TSPD setup code to support the alternate BL3-2
+ intialization flow where BL3-1 generic code hands control to BL3-2,
+ rather than expecting the TSPD to hand control directly to BL3-2.
+
+ - Considerable rework to PSCI generic code to support CPU specific
+ operations.
+
+- Improved console log output, by:
+
+ - Adding the concept of debug log levels.
+
+ - Rationalizing the existing debug messages and adding new ones.
+
+ - Printing out the version of each BL stage at runtime.
+
+ - Adding support for printing console output from assembler code,
+ including when a crash occurs before the C runtime is initialized.
+
+- Moved up to the latest versions of the FVPs, toolchain, EDK2, kernel, Linaro
+ file system and DS-5.
+
+- On the FVP port, made the use of the Trusted DRAM region optional at build
+ time (off by default). Normal platforms will not have such a "ready-to-use"
+ DRAM area so it is not a good example to use it.
+
+- Added support for PSCI ``SYSTEM_OFF`` and ``SYSTEM_RESET`` APIs.
+
+- Added support for CPU specific reset sequences, power down sequences and
+ register dumping during crash reporting. The CPU specific reset sequences
+ include support for errata workarounds.
+
+- Merged the Juno port into the master branch. Added support for CPU hotplug
+ and CPU idle. Updated the user guide to describe how to build and run on the
+ Juno platform.
+
+Issues resolved since last release
+----------------------------------
+
+- Removed the concept of top/bottom image loading. The image loader now
+ automatically detects the position of the image inside the current memory
+ layout and updates the layout to minimize fragementation. This resolves the
+ image loader limitations of previously releases. There are currently no
+ plans to support dynamic image loading.
+
+- CPU idle now works on the publicized version of the Foundation FVP.
+
+- All known issues relating to the compiler version used have now been
+ resolved. This TF version uses Linaro toolchain 14.07 (based on GCC 4.9).
+
+Known issues
+------------
+
+- GICv3 support is experimental. The Linux kernel patches to support this are
+ not widely available. There are known issues with GICv3 initialization in
+ the ARM Trusted Firmware.
+
+- While this version greatly reduces the on-chip RAM requirements, there are
+ further RAM usage enhancements that could be made.
+
+- The firmware design documentation for the Test Secure-EL1 Payload (TSP) and
+ its dispatcher (TSPD) is incomplete. Similarly for the PSCI section.
+
+- The Juno-specific firmware design documentation is incomplete.
+
+- Some recent enhancements to the FVP port have not yet been translated into
+ the Juno port. These will be tracked via the tf-issues project.
+
+- The Linux kernel version referred to in the user guide has DVFS and HMP
+ support disabled due to some known instabilities at the time of this
+ release. A future kernel version will re-enable these features.
+
+- DS-5 v5.19 does not detect Version 5.8 of the Cortex-A57-A53 Base FVPs in
+ CADI server mode. This is because the ``<SimName>`` reported by the FVP in
+ this version has changed. For example, for the Cortex-A57x4-A53x4 Base FVP,
+ the ``<SimName>`` reported by the FVP is ``FVP_Base_Cortex_A57x4_A53x4``, while
+ DS-5 expects it to be ``FVP_Base_A57x4_A53x4``.
+
+ The temporary fix to this problem is to change the name of the FVP in
+ ``sw/debugger/configdb/Boards/ARM FVP/Base_A57x4_A53x4/cadi_config.xml``.
+ Change the following line:
+
+ ::
+
+ <SimName>System Generator:FVP_Base_A57x4_A53x4</SimName>
+
+ to
+ System Generator:FVP\_Base\_Cortex-A57x4\_A53x4
+
+ A similar change can be made to the other Cortex-A57-A53 Base FVP variants.
+
+ARM Trusted Firmware - version 0.4
+==================================
+
+New features
+------------
+
+- Makefile improvements:
+
+ - Improved dependency checking when building.
+
+ - Removed ``dump`` target (build now always produces dump files).
+
+ - Enabled platform ports to optionally make use of parts of the Trusted
+ Firmware (e.g. BL3-1 only), rather than being forced to use all parts.
+ Also made the ``fip`` target optional.
+
+ - Specified the full path to source files and removed use of the ``vpath``
+ keyword.
+
+- Provided translation table library code for potential re-use by platforms
+ other than the FVPs.
+
+- Moved architectural timer setup to platform-specific code.
+
+- Added standby state support to PSCI cpu\_suspend implementation.
+
+- SRAM usage improvements:
+
+ - Started using the ``-ffunction-sections``, ``-fdata-sections`` and
+ ``--gc-sections`` compiler/linker options to remove unused code and data
+ from the images. Previously, all common functions were being built into
+ all binary images, whether or not they were actually used.
+
+ - Placed all assembler functions in their own section to allow more unused
+ functions to be removed from images.
+
+ - Updated BL1 and BL2 to use a single coherent stack each, rather than one
+ per CPU.
+
+ - Changed variables that were unnecessarily declared and initialized as
+ non-const (i.e. in the .data section) so they are either uninitialized
+ (zero init) or const.
+
+- Moved the Test Secure-EL1 Payload (BL3-2) to execute in Trusted SRAM by
+ default. The option for it to run in Trusted DRAM remains.
+
+- Implemented a TrustZone Address Space Controller (TZC-400) driver. A
+ default configuration is provided for the Base FVPs. This means the model
+ parameter ``-C bp.secure_memory=1`` is now supported.
+
+- Started saving the PSCI cpu\_suspend 'power\_state' parameter prior to
+ suspending a CPU. This allows platforms that implement multiple power-down
+ states at the same affinity level to identify a specific state.
+
+- Refactored the entire codebase to reduce the amount of nesting in header
+ files and to make the use of system/user includes more consistent. Also
+ split platform.h to separate out the platform porting declarations from the
+ required platform porting definitions and the definitions/declarations
+ specific to the platform port.
+
+- Optimized the data cache clean/invalidate operations.
+
+- Improved the BL3-1 unhandled exception handling and reporting. Unhandled
+ exceptions now result in a dump of registers to the console.
+
+- Major rework to the handover interface between BL stages, in particular the
+ interface to BL3-1. The interface now conforms to a specification and is
+ more future proof.
+
+- Added support for optionally making the BL3-1 entrypoint a reset handler
+ (instead of BL1). This allows platforms with an alternative image loading
+ architecture to re-use BL3-1 with fewer modifications to generic code.
+
+- Reserved some DDR DRAM for secure use on FVP platforms to avoid future
+ compatibility problems with non-secure software.
+
+- Added support for secure interrupts targeting the Secure-EL1 Payload (SP)
+ (using GICv2 routing only). Demonstrated this working by adding an interrupt
+ target and supporting test code to the TSP. Also demonstrated non-secure
+ interrupt handling during TSP processing.
+
+Issues resolved since last release
+----------------------------------
+
+- Now support use of the model parameter ``-C bp.secure_memory=1`` in the Base
+ FVPs (see **New features**).
+
+- Support for secure world interrupt handling now available (see **New
+ features**).
+
+- Made enough SRAM savings (see **New features**) to enable the Test Secure-EL1
+ Payload (BL3-2) to execute in Trusted SRAM by default.
+
+- The tested filesystem used for this release (Linaro AArch64 OpenEmbedded
+ 14.04) now correctly reports progress in the console.
+
+- Improved the Makefile structure to make it easier to separate out parts of
+ the Trusted Firmware for re-use in platform ports. Also, improved target
+ dependency checking.
+
+Known issues
+------------
+
+- GICv3 support is experimental. The Linux kernel patches to support this are
+ not widely available. There are known issues with GICv3 initialization in
+ the ARM Trusted Firmware.
+
+- Dynamic image loading is not available yet. The current image loader
+ implementation (used to load BL2 and all subsequent images) has some
+ limitations. Changing BL2 or BL3-1 load addresses in certain ways can lead
+ to loading errors, even if the images should theoretically fit in memory.
+
+- The ARM Trusted Firmware still uses too much on-chip Trusted SRAM. A number
+ of RAM usage enhancements have been identified to rectify this situation.
+
+- CPU idle does not work on the advertised version of the Foundation FVP.
+ Some FVP fixes are required that are not available externally at the time
+ of writing. This can be worked around by disabling CPU idle in the Linux
+ kernel.
+
+- Various bugs in ARM Trusted Firmware, UEFI and the Linux kernel have been
+ observed when using Linaro toolchain versions later than 13.11. Although
+ most of these have been fixed, some remain at the time of writing. These
+ mainly seem to relate to a subtle change in the way the compiler converts
+ between 64-bit and 32-bit values (e.g. during casting operations), which
+ reveals previously hidden bugs in client code.
+
+- The firmware design documentation for the Test Secure-EL1 Payload (TSP) and
+ its dispatcher (TSPD) is incomplete. Similarly for the PSCI section.
+
+ARM Trusted Firmware - version 0.3
+==================================
+
+New features
+------------
+
+- Support for Foundation FVP Version 2.0 added.
+ The documented UEFI configuration disables some devices that are unavailable
+ in the Foundation FVP, including MMC and CLCD. The resultant UEFI binary can
+ be used on the AEMv8 and Cortex-A57-A53 Base FVPs, as well as the Foundation
+ FVP.
+
+ NOTE: The software will not work on Version 1.0 of the Foundation FVP.
+
+- Enabled third party contributions. Added a new contributing.md containing
+ instructions for how to contribute and updated copyright text in all files
+ to acknowledge contributors.
+
+- The PSCI CPU\_SUSPEND API has been stabilised to the extent where it can be
+ used for entry into power down states with the following restrictions:
+
+ - Entry into standby states is not supported.
+ - The API is only supported on the AEMv8 and Cortex-A57-A53 Base FVPs.
+
+- The PSCI AFFINITY\_INFO api has undergone limited testing on the Base FVPs to
+ allow experimental use.
+
+- Required C library and runtime header files are now included locally in ARM
+ Trusted Firmware instead of depending on the toolchain standard include
+ paths. The local implementation has been cleaned up and reduced in scope.
+
+- Added I/O abstraction framework, primarily to allow generic code to load
+ images in a platform-independent way. The existing image loading code has
+ been reworked to use the new framework. Semi-hosting and NOR flash I/O
+ drivers are provided.
+
+- Introduced Firmware Image Package (FIP) handling code and tools. A FIP
+ combines multiple firmware images with a Table of Contents (ToC) into a
+ single binary image. The new FIP driver is another type of I/O driver. The
+ Makefile builds a FIP by default and the FVP platform code expect to load a
+ FIP from NOR flash, although some support for image loading using semi-
+ hosting is retained.
+
+ NOTE: Building a FIP by default is a non-backwards-compatible change.
+
+ NOTE: Generic BL2 code now loads a BL3-3 (non-trusted firmware) image into
+ DRAM instead of expecting this to be pre-loaded at known location. This is
+ also a non-backwards-compatible change.
+
+ NOTE: Some non-trusted firmware (e.g. UEFI) will need to be rebuilt so that
+ it knows the new location to execute from and no longer needs to copy
+ particular code modules to DRAM itself.
+
+- Reworked BL2 to BL3-1 handover interface. A new composite structure
+ (bl31\_args) holds the superset of information that needs to be passed from
+ BL2 to BL3-1, including information on how handover execution control to
+ BL3-2 (if present) and BL3-3 (non-trusted firmware).
+
+- Added library support for CPU context management, allowing the saving and
+ restoring of
+
+ - Shared system registers between Secure-EL1 and EL1.
+ - VFP registers.
+ - Essential EL3 system registers.
+
+- Added a framework for implementing EL3 runtime services. Reworked the PSCI
+ implementation to be one such runtime service.
+
+- Reworked the exception handling logic, making use of both SP\_EL0 and SP\_EL3
+ stack pointers for determining the type of exception, managing general
+ purpose and system register context on exception entry/exit, and handling
+ SMCs. SMCs are directed to the correct EL3 runtime service.
+
+- Added support for a Test Secure-EL1 Payload (TSP) and a corresponding
+ Dispatcher (TSPD), which is loaded as an EL3 runtime service. The TSPD
+ implements Secure Monitor functionality such as world switching and
+ EL1 context management, and is responsible for communication with the TSP.
+ NOTE: The TSPD does not yet contain support for secure world interrupts.
+ NOTE: The TSP/TSPD is not built by default.
+
+Issues resolved since last release
+----------------------------------
+
+- Support has been added for switching context between secure and normal
+ worlds in EL3.
+
+- PSCI API calls ``AFFINITY_INFO`` & ``PSCI_VERSION`` have now been tested (to
+ a limited extent).
+
+- The ARM Trusted Firmware build artifacts are now placed in the ``./build``
+ directory and sub-directories instead of being placed in the root of the
+ project.
+
+- The ARM Trusted Firmware is now free from build warnings. Build warnings
+ are now treated as errors.
+
+- The ARM Trusted Firmware now provides C library support locally within the
+ project to maintain compatibility between toolchains/systems.
+
+- The PSCI locking code has been reworked so it no longer takes locks in an
+ incorrect sequence.
+
+- The RAM-disk method of loading a Linux file-system has been confirmed to
+ work with the ARM Trusted Firmware and Linux kernel version (based on
+ version 3.13) used in this release, for both Foundation and Base FVPs.
+
+Known issues
+------------
+
+The following is a list of issues which are expected to be fixed in the future
+releases of the ARM Trusted Firmware.
+
+- The TrustZone Address Space Controller (TZC-400) is not being programmed
+ yet. Use of model parameter ``-C bp.secure_memory=1`` is not supported.
+
+- No support yet for secure world interrupt handling.
+
+- GICv3 support is experimental. The Linux kernel patches to support this are
+ not widely available. There are known issues with GICv3 initialization in
+ the ARM Trusted Firmware.
+
+- Dynamic image loading is not available yet. The current image loader
+ implementation (used to load BL2 and all subsequent images) has some
+ limitations. Changing BL2 or BL3-1 load addresses in certain ways can lead
+ to loading errors, even if the images should theoretically fit in memory.
+
+- The ARM Trusted Firmware uses too much on-chip Trusted SRAM. Currently the
+ Test Secure-EL1 Payload (BL3-2) executes in Trusted DRAM since there is not
+ enough SRAM. A number of RAM usage enhancements have been identified to
+ rectify this situation.
+
+- CPU idle does not work on the advertised version of the Foundation FVP.
+ Some FVP fixes are required that are not available externally at the time
+ of writing.
+
+- Various bugs in ARM Trusted Firmware, UEFI and the Linux kernel have been
+ observed when using Linaro toolchain versions later than 13.11. Although
+ most of these have been fixed, some remain at the time of writing. These
+ mainly seem to relate to a subtle change in the way the compiler converts
+ between 64-bit and 32-bit values (e.g. during casting operations), which
+ reveals previously hidden bugs in client code.
+
+- The tested filesystem used for this release (Linaro AArch64 OpenEmbedded
+ 14.01) does not report progress correctly in the console. It only seems to
+ produce error output, not standard output. It otherwise appears to function
+ correctly. Other filesystem versions on the same software stack do not
+ exhibit the problem.
+
+- The Makefile structure doesn't make it easy to separate out parts of the
+ Trusted Firmware for re-use in platform ports, for example if only BL3-1 is
+ required in a platform port. Also, dependency checking in the Makefile is
+ flawed.
+
+- The firmware design documentation for the Test Secure-EL1 Payload (TSP) and
+ its dispatcher (TSPD) is incomplete. Similarly for the PSCI section.
+
+ARM Trusted Firmware - version 0.2
+==================================
+
+New features
+------------
+
+- First source release.
+
+- Code for the PSCI suspend feature is supplied, although this is not enabled
+ by default since there are known issues (see below).
+
+Issues resolved since last release
+----------------------------------
+
+- The "psci" nodes in the FDTs provided in this release now fully comply
+ with the recommendations made in the PSCI specification.
+
+Known issues
+------------
+
+The following is a list of issues which are expected to be fixed in the future
+releases of the ARM Trusted Firmware.
+
+- The TrustZone Address Space Controller (TZC-400) is not being programmed
+ yet. Use of model parameter ``-C bp.secure_memory=1`` is not supported.
+
+- No support yet for secure world interrupt handling or for switching context
+ between secure and normal worlds in EL3.
+
+- GICv3 support is experimental. The Linux kernel patches to support this are
+ not widely available. There are known issues with GICv3 initialization in
+ the ARM Trusted Firmware.
+
+- Dynamic image loading is not available yet. The current image loader
+ implementation (used to load BL2 and all subsequent images) has some
+ limitations. Changing BL2 or BL3-1 load addresses in certain ways can lead
+ to loading errors, even if the images should theoretically fit in memory.
+
+- Although support for PSCI ``CPU_SUSPEND`` is present, it is not yet stable
+ and ready for use.
+
+- PSCI API calls ``AFFINITY_INFO`` & ``PSCI_VERSION`` are implemented but have not
+ been tested.
+
+- The ARM Trusted Firmware make files result in all build artifacts being
+ placed in the root of the project. These should be placed in appropriate
+ sub-directories.
+
+- The compilation of ARM Trusted Firmware is not free from compilation
+ warnings. Some of these warnings have not been investigated yet so they
+ could mask real bugs.
+
+- The ARM Trusted Firmware currently uses toolchain/system include files like
+ stdio.h. It should provide versions of these within the project to maintain
+ compatibility between toolchains/systems.
+
+- The PSCI code takes some locks in an incorrect sequence. This may cause
+ problems with suspend and hotplug in certain conditions.
+
+- The Linux kernel used in this release is based on version 3.12-rc4. Using
+ this kernel with the ARM Trusted Firmware fails to start the file-system as
+ a RAM-disk. It fails to execute user-space ``init`` from the RAM-disk. As an
+ alternative, the VirtioBlock mechanism can be used to provide a file-system
+ to the kernel.
+
+--------------
+
+*Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.*
+
+.. _PSCI Integration Guide: psci-lib-integration-guide.rst
+.. _Developer Certificate of Origin: ../dco.txt
+.. _Contribution Guide: ../contributing.rst
+.. _Authentication framework: auth-framework.rst
+.. _Firmware Update: firmware-update.rst
+.. _TF Reset Design: reset-design.rst
+.. _Power Domain Topology Design: psci-pd-tree.rst
+.. _TF wiki on GitHub: https://github.com/ARM-software/arm-trusted-firmware/wiki/ARM-Trusted-Firmware-Image-Terminology
+.. _Authentication Framework: auth-framework.rst
+.. _OP-TEE Dispatcher: optee-dispatcher.rst
--- /dev/null
+ARM CPU Specific Build Macros
+=============================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+This document describes the various build options present in the CPU specific
+operations framework to enable errata workarounds and to enable optimizations
+for a specific CPU on a platform.
+
+CPU Errata Workarounds
+----------------------
+
+ARM Trusted Firmware exports a series of build flags which control the
+errata workarounds that are applied to each CPU by the reset handler. The
+errata details can be found in the CPU specific errata documents published
+by ARM:
+
+- `Cortex-A53 MPCore Software Developers Errata Notice`_
+- `Cortex-A57 MPCore Software Developers Errata Notice`_
+
+The errata workarounds are implemented for a particular revision or a set of
+processor revisions. This is checked by the reset handler at runtime. Each
+errata workaround is identified by its ``ID`` as specified in the processor's
+errata notice document. The format of the define used to enable/disable the
+errata workaround is ``ERRATA_<Processor name>_<ID>``, where the ``Processor name``
+is for example ``A57`` for the ``Cortex_A57`` CPU.
+
+Refer to the section *CPU errata status reporting* in
+`Firmware Design guide`_ for information on to write errata workaround functions.
+
+All workarounds are disabled by default. The platform is responsible for
+enabling these workarounds according to its requirement by defining the
+errata workaround build flags in the platform specific makefile. In case
+these workarounds are enabled for the wrong CPU revision then the errata
+workaround is not applied. In the DEBUG build, this is indicated by
+printing a warning to the crash console.
+
+In the current implementation, a platform which has more than 1 variant
+with different revisions of a processor has no runtime mechanism available
+for it to specify which errata workarounds should be enabled or not.
+
+The value of the build flags are 0 by default, that is, disabled. Any other
+value will enable it.
+
+For Cortex-A53, following errata build flags are defined :
+
+- ``ERRATA_A53_826319``: This applies errata 826319 workaround to Cortex-A53
+ CPU. This needs to be enabled only for revision <= r0p2 of the CPU.
+
+- ``ERRATA_A53_836870``: This applies errata 836870 workaround to Cortex-A53
+ CPU. This needs to be enabled only for revision <= r0p3 of the CPU. From
+ r0p4 and onwards, this errata is enabled by default in hardware.
+
+- ``ERRATA_A53_855873``: This applies errata 855873 workaround to Cortex-A53
+ CPUs. Though the erratum is present in every revision of the CPU,
+ this workaround is only applied to CPUs from r0p3 onwards, which feature
+ a chicken bit in CPUACTLR\_EL1 to enable a hardware workaround.
+ Earlier revisions of the CPU have other errata which require the same
+ workaround in software, so they should be covered anyway.
+
+For Cortex-A57, following errata build flags are defined :
+
+- ``ERRATA_A57_806969``: This applies errata 806969 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision r0p0 of the CPU.
+
+- ``ERRATA_A57_813419``: This applies errata 813419 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision r0p0 of the CPU.
+
+- ``ERRATA_A57_813420``: This applies errata 813420 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision r0p0 of the CPU.
+
+- ``ERRATA_A57_826974``: This applies errata 826974 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
+
+- ``ERRATA_A57_826977``: This applies errata 826977 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
+
+- ``ERRATA_A57_828024``: This applies errata 828024 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision <= r1p1 of the CPU.
+
+- ``ERRATA_A57_829520``: This applies errata 829520 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision <= r1p2 of the CPU.
+
+- ``ERRATA_A57_833471``: This applies errata 833471 workaround to Cortex-A57
+ CPU. This needs to be enabled only for revision <= r1p2 of the CPU.
+
+CPU Specific optimizations
+--------------------------
+
+This section describes some of the optimizations allowed by the CPU micro
+architecture that can be enabled by the platform as desired.
+
+- ``SKIP_A57_L1_FLUSH_PWR_DWN``: This flag enables an optimization in the
+ Cortex-A57 cluster power down sequence by not flushing the Level 1 data
+ cache. The L1 data cache and the L2 unified cache are inclusive. A flush
+ of the L2 by set/way flushes any dirty lines from the L1 as well. This
+ is a known safe deviation from the Cortex-A57 TRM defined power down
+ sequence. Each Cortex-A57 based platform must make its own decision on
+ whether to use the optimization.
+
+- ``A53_DISABLE_NON_TEMPORAL_HINT``: This flag disables the cache non-temporal
+ hint. The LDNP/STNP instructions as implemented on Cortex-A53 do not behave
+ in a way most programmers expect, and will most probably result in a
+ significant speed degradation to any code that employs them. The ARMv8-A
+ architecture (see ARM DDI 0487A.h, section D3.4.3) allows cores to ignore
+ the non-temporal hint and treat LDNP/STNP as LDP/STP instead. Enabling this
+ flag enforces this behaviour. This needs to be enabled only for revisions
+ <= r0p3 of the CPU and is enabled by default.
+
+- ``A57_DISABLE_NON_TEMPORAL_HINT``: This flag has the same behaviour as
+ ``A53_DISABLE_NON_TEMPORAL_HINT`` but for Cortex-A57. This needs to be
+ enabled only for revisions <= r1p2 of the CPU and is enabled by default,
+ as recommended in section "4.7 Non-Temporal Loads/Stores" of the
+ `Cortex-A57 Software Optimization Guide`_.
+
+--------------
+
+*Copyright (c) 2014-2016, ARM Limited and Contributors. All rights reserved.*
+
+.. _Cortex-A53 MPCore Software Developers Errata Notice: http://infocenter.arm.com/help/topic/com.arm.doc.epm048406/index.html
+.. _Cortex-A57 MPCore Software Developers Errata Notice: http://infocenter.arm.com/help/topic/com.arm.doc.epm049219/cortex_a57_mpcore_software_developers_errata_notice.pdf
+.. _Firmware Design guide: firmware-design.rst
+.. _Cortex-A57 Software Optimization Guide: http://infocenter.arm.com/help/topic/com.arm.doc.uan0015b/Cortex_A57_Software_Optimization_Guide_external.pdf
--- /dev/null
+ARM Trusted Firmware Design
+===========================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+The ARM Trusted Firmware implements a subset of the Trusted Board Boot
+Requirements (TBBR) Platform Design Document (PDD) [1] for ARM reference
+platforms. The TBB sequence starts when the platform is powered on and runs up
+to the stage where it hands-off control to firmware running in the normal
+world in DRAM. This is the cold boot path.
+
+The ARM Trusted Firmware also implements the Power State Coordination Interface
+PDD [2] as a runtime service. PSCI is the interface from normal world software
+to firmware implementing power management use-cases (for example, secondary CPU
+boot, hotplug and idle). Normal world software can access ARM Trusted Firmware
+runtime services via the ARM SMC (Secure Monitor Call) instruction. The SMC
+instruction must be used as mandated by the SMC Calling Convention [3].
+
+The ARM Trusted Firmware implements a framework for configuring and managing
+interrupts generated in either security state. The details of the interrupt
+management framework and its design can be found in ARM Trusted Firmware
+Interrupt Management Design guide [4].
+
+The ARM Trusted Firmware can be built to support either AArch64 or AArch32
+execution state.
+
+Cold boot
+---------
+
+The cold boot path starts when the platform is physically turned on. If
+``COLD_BOOT_SINGLE_CPU=0``, one of the CPUs released from reset is chosen as the
+primary CPU, and the remaining CPUs are considered secondary CPUs. The primary
+CPU is chosen through platform-specific means. The cold boot path is mainly
+executed by the primary CPU, other than essential CPU initialization executed by
+all CPUs. The secondary CPUs are kept in a safe platform-specific state until
+the primary CPU has performed enough initialization to boot them.
+
+Refer to the `Reset Design`_ for more information on the effect of the
+``COLD_BOOT_SINGLE_CPU`` platform build option.
+
+The cold boot path in this implementation of the ARM Trusted Firmware,
+depends on the execution state.
+For AArch64, it is divided into five steps (in order of execution):
+
+- Boot Loader stage 1 (BL1) *AP Trusted ROM*
+- Boot Loader stage 2 (BL2) *Trusted Boot Firmware*
+- Boot Loader stage 3-1 (BL31) *EL3 Runtime Software*
+- Boot Loader stage 3-2 (BL32) *Secure-EL1 Payload* (optional)
+- Boot Loader stage 3-3 (BL33) *Non-trusted Firmware*
+
+For AArch32, it is divided into four steps (in order of execution):
+
+- Boot Loader stage 1 (BL1) *AP Trusted ROM*
+- Boot Loader stage 2 (BL2) *Trusted Boot Firmware*
+- Boot Loader stage 3-2 (BL32) *EL3 Runtime Software*
+- Boot Loader stage 3-3 (BL33) *Non-trusted Firmware*
+
+ARM development platforms (Fixed Virtual Platforms (FVPs) and Juno) implement a
+combination of the following types of memory regions. Each bootloader stage uses
+one or more of these memory regions.
+
+- Regions accessible from both non-secure and secure states. For example,
+ non-trusted SRAM, ROM and DRAM.
+- Regions accessible from only the secure state. For example, trusted SRAM and
+ ROM. The FVPs also implement the trusted DRAM which is statically
+ configured. Additionally, the Base FVPs and Juno development platform
+ configure the TrustZone Controller (TZC) to create a region in the DRAM
+ which is accessible only from the secure state.
+
+The sections below provide the following details:
+
+- initialization and execution of the first three stages during cold boot
+- specification of the EL3 Runtime Software (BL31 for AArch64 and BL32 for
+ AArch32) entrypoint requirements for use by alternative Trusted Boot
+ Firmware in place of the provided BL1 and BL2
+
+BL1
+~~~
+
+This stage begins execution from the platform's reset vector at EL3. The reset
+address is platform dependent but it is usually located in a Trusted ROM area.
+The BL1 data section is copied to trusted SRAM at runtime.
+
+On the ARM development platforms, BL1 code starts execution from the reset
+vector defined by the constant ``BL1_RO_BASE``. The BL1 data section is copied
+to the top of trusted SRAM as defined by the constant ``BL1_RW_BASE``.
+
+The functionality implemented by this stage is as follows.
+
+Determination of boot path
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Whenever a CPU is released from reset, BL1 needs to distinguish between a warm
+boot and a cold boot. This is done using platform-specific mechanisms (see the
+``plat_get_my_entrypoint()`` function in the `Porting Guide`_). In the case of a
+warm boot, a CPU is expected to continue execution from a separate
+entrypoint. In the case of a cold boot, the secondary CPUs are placed in a safe
+platform-specific state (see the ``plat_secondary_cold_boot_setup()`` function in
+the `Porting Guide`_) while the primary CPU executes the remaining cold boot path
+as described in the following sections.
+
+This step only applies when ``PROGRAMMABLE_RESET_ADDRESS=0``. Refer to the
+`Reset Design`_ for more information on the effect of the
+``PROGRAMMABLE_RESET_ADDRESS`` platform build option.
+
+Architectural initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+BL1 performs minimal architectural initialization as follows.
+
+- Exception vectors
+
+ BL1 sets up simple exception vectors for both synchronous and asynchronous
+ exceptions. The default behavior upon receiving an exception is to populate
+ a status code in the general purpose register ``X0/R0`` and call the
+ ``plat_report_exception()`` function (see the `Porting Guide`_). The status
+ code is one of:
+
+ For AArch64:
+
+ ::
+
+ 0x0 : Synchronous exception from Current EL with SP_EL0
+ 0x1 : IRQ exception from Current EL with SP_EL0
+ 0x2 : FIQ exception from Current EL with SP_EL0
+ 0x3 : System Error exception from Current EL with SP_EL0
+ 0x4 : Synchronous exception from Current EL with SP_ELx
+ 0x5 : IRQ exception from Current EL with SP_ELx
+ 0x6 : FIQ exception from Current EL with SP_ELx
+ 0x7 : System Error exception from Current EL with SP_ELx
+ 0x8 : Synchronous exception from Lower EL using aarch64
+ 0x9 : IRQ exception from Lower EL using aarch64
+ 0xa : FIQ exception from Lower EL using aarch64
+ 0xb : System Error exception from Lower EL using aarch64
+ 0xc : Synchronous exception from Lower EL using aarch32
+ 0xd : IRQ exception from Lower EL using aarch32
+ 0xe : FIQ exception from Lower EL using aarch32
+ 0xf : System Error exception from Lower EL using aarch32
+
+ For AArch32:
+
+ ::
+
+ 0x10 : User mode
+ 0x11 : FIQ mode
+ 0x12 : IRQ mode
+ 0x13 : SVC mode
+ 0x16 : Monitor mode
+ 0x17 : Abort mode
+ 0x1a : Hypervisor mode
+ 0x1b : Undefined mode
+ 0x1f : System mode
+
+ The ``plat_report_exception()`` implementation on the ARM FVP port programs
+ the Versatile Express System LED register in the following format to
+ indicate the occurence of an unexpected exception:
+
+ ::
+
+ SYS_LED[0] - Security state (Secure=0/Non-Secure=1)
+ SYS_LED[2:1] - Exception Level (EL3=0x3, EL2=0x2, EL1=0x1, EL0=0x0)
+ For AArch32 it is always 0x0
+ SYS_LED[7:3] - Exception Class (Sync/Async & origin). This is the value
+ of the status code
+
+ A write to the LED register reflects in the System LEDs (S6LED0..7) in the
+ CLCD window of the FVP.
+
+ BL1 does not expect to receive any exceptions other than the SMC exception.
+ For the latter, BL1 installs a simple stub. The stub expects to receive a
+ limited set of SMC types (determined by their function IDs in the general
+ purpose register ``X0/R0``):
+
+ - ``BL1_SMC_RUN_IMAGE``: This SMC is raised by BL2 to make BL1 pass control
+ to EL3 Runtime Software.
+ - All SMCs listed in section "BL1 SMC Interface" in the `Firmware Update`_
+ Design Guide are supported for AArch64 only. These SMCs are currently
+ not supported when BL1 is built for AArch32.
+
+ Any other SMC leads to an assertion failure.
+
+- CPU initialization
+
+ BL1 calls the ``reset_handler()`` function which in turn calls the CPU
+ specific reset handler function (see the section: "CPU specific operations
+ framework").
+
+- Control register setup (for AArch64)
+
+ - ``SCTLR_EL3``. Instruction cache is enabled by setting the ``SCTLR_EL3.I``
+ bit. Alignment and stack alignment checking is enabled by setting the
+ ``SCTLR_EL3.A`` and ``SCTLR_EL3.SA`` bits. Exception endianness is set to
+ little-endian by clearing the ``SCTLR_EL3.EE`` bit.
+
+ - ``SCR_EL3``. The register width of the next lower exception level is set
+ to AArch64 by setting the ``SCR.RW`` bit. The ``SCR.EA`` bit is set to trap
+ both External Aborts and SError Interrupts in EL3. The ``SCR.SIF`` bit is
+ also set to disable instruction fetches from Non-secure memory when in
+ secure state.
+
+ - ``CPTR_EL3``. Accesses to the ``CPACR_EL1`` register from EL1 or EL2, or the
+ ``CPTR_EL2`` register from EL2 are configured to not trap to EL3 by
+ clearing the ``CPTR_EL3.TCPAC`` bit. Access to the trace functionality is
+ configured not to trap to EL3 by clearing the ``CPTR_EL3.TTA`` bit.
+ Instructions that access the registers associated with Floating Point
+ and Advanced SIMD execution are configured to not trap to EL3 by
+ clearing the ``CPTR_EL3.TFP`` bit.
+
+ - ``DAIF``. The SError interrupt is enabled by clearing the SError interrupt
+ mask bit.
+
+ - ``MDCR_EL3``. The trap controls, ``MDCR_EL3.TDOSA``, ``MDCR_EL3.TDA`` and
+ ``MDCR_EL3.TPM``, are set so that accesses to the registers they control
+ do not trap to EL3. AArch64 Secure self-hosted debug is disabled by
+ setting the ``MDCR_EL3.SDD`` bit. Also ``MDCR_EL3.SPD32`` is set to
+ disable AArch32 Secure self-hosted privileged debug from S-EL1.
+
+- Control register setup (for AArch32)
+
+ - ``SCTLR``. Instruction cache is enabled by setting the ``SCTLR.I`` bit.
+ Alignment checking is enabled by setting the ``SCTLR.A`` bit.
+ Exception endianness is set to little-endian by clearing the
+ ``SCTLR.EE`` bit.
+
+ - ``SCR``. The ``SCR.SIF`` bit is set to disable instruction fetches from
+ Non-secure memory when in secure state.
+
+ - ``CPACR``. Allow execution of Advanced SIMD instructions at PL0 and PL1,
+ by clearing the ``CPACR.ASEDIS`` bit. Access to the trace functionality
+ is configured not to trap to undefined mode by clearing the
+ ``CPACR.TRCDIS`` bit.
+
+ - ``NSACR``. Enable non-secure access to Advanced SIMD functionality and
+ system register access to implemented trace registers.
+
+ - ``FPEXC``. Enable access to the Advanced SIMD and floating-point
+ functionality from all Exception levels.
+
+ - ``CPSR.A``. The Asynchronous data abort interrupt is enabled by clearing
+ the Asynchronous data abort interrupt mask bit.
+
+ - ``SDCR``. The ``SDCR.SPD`` field is set to disable AArch32 Secure
+ self-hosted privileged debug.
+
+Platform initialization
+^^^^^^^^^^^^^^^^^^^^^^^
+
+On ARM platforms, BL1 performs the following platform initializations:
+
+- Enable the Trusted Watchdog.
+- Initialize the console.
+- Configure the Interconnect to enable hardware coherency.
+- Enable the MMU and map the memory it needs to access.
+- Configure any required platform storage to load the next bootloader image
+ (BL2).
+
+Firmware Update detection and execution
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+After performing platform setup, BL1 common code calls
+``bl1_plat_get_next_image_id()`` to determine if `Firmware Update`_ is required or
+to proceed with the normal boot process. If the platform code returns
+``BL2_IMAGE_ID`` then the normal boot sequence is executed as described in the
+next section, else BL1 assumes that `Firmware Update`_ is required and execution
+passes to the first image in the `Firmware Update`_ process. In either case, BL1
+retrieves a descriptor of the next image by calling ``bl1_plat_get_image_desc()``.
+The image descriptor contains an ``entry_point_info_t`` structure, which BL1
+uses to initialize the execution state of the next image.
+
+BL2 image load and execution
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In the normal boot flow, BL1 execution continues as follows:
+
+#. BL1 prints the following string from the primary CPU to indicate successful
+ execution of the BL1 stage:
+
+ ::
+
+ "Booting Trusted Firmware"
+
+#. BL1 determines the amount of free trusted SRAM memory available by
+ calculating the extent of its own data section, which also resides in
+ trusted SRAM. BL1 loads a BL2 raw binary image from platform storage, at a
+ platform-specific base address. If the BL2 image file is not present or if
+ there is not enough free trusted SRAM the following error message is
+ printed:
+
+ ::
+
+ "Failed to load BL2 firmware."
+
+ BL1 calculates the amount of Trusted SRAM that can be used by the BL2
+ image. The exact load location of the image is provided as a base address
+ in the platform header. Further description of the memory layout can be
+ found later in this document.
+
+#. BL1 passes control to the BL2 image at Secure EL1 (for AArch64) or at
+ Secure SVC mode (for AArch32), starting from its load address.
+
+#. BL1 also passes information about the amount of trusted SRAM used and
+ available for use. This information is populated at a platform-specific
+ memory address.
+
+BL2
+~~~
+
+BL1 loads and passes control to BL2 at Secure-EL1 (for AArch64) or at Secure
+SVC mode (for AArch32) . BL2 is linked against and loaded at a platform-specific
+base address (more information can be found later in this document).
+The functionality implemented by BL2 is as follows.
+
+Architectural initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+For AArch64, BL2 performs the minimal architectural initialization required
+for subsequent stages of the ARM Trusted Firmware and normal world software.
+EL1 and EL0 are given access to Floating Point and Advanced SIMD registers
+by clearing the ``CPACR.FPEN`` bits.
+
+For AArch32, the minimal architectural initialization required for subsequent
+stages of the ARM Trusted Firmware and normal world software is taken care of
+in BL1 as both BL1 and BL2 execute at PL1.
+
+Platform initialization
+^^^^^^^^^^^^^^^^^^^^^^^
+
+On ARM platforms, BL2 performs the following platform initializations:
+
+- Initialize the console.
+- Configure any required platform storage to allow loading further bootloader
+ images.
+- Enable the MMU and map the memory it needs to access.
+- Perform platform security setup to allow access to controlled components.
+- Reserve some memory for passing information to the next bootloader image
+ EL3 Runtime Software and populate it.
+- Define the extents of memory available for loading each subsequent
+ bootloader image.
+
+Image loading in BL2
+^^^^^^^^^^^^^^^^^^^^
+
+Image loading scheme in BL2 depends on ``LOAD_IMAGE_V2`` build option. If the
+flag is disabled, the BLxx images are loaded, by calling the respective
+load\_blxx() function from BL2 generic code. If the flag is enabled, the BL2
+generic code loads the images based on the list of loadable images provided
+by the platform. BL2 passes the list of executable images provided by the
+platform to the next handover BL image. By default, this flag is disabled for
+AArch64 and the AArch32 build is supported only if this flag is enabled.
+
+SCP\_BL2 (System Control Processor Firmware) image load
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Some systems have a separate System Control Processor (SCP) for power, clock,
+reset and system control. BL2 loads the optional SCP\_BL2 image from platform
+storage into a platform-specific region of secure memory. The subsequent
+handling of SCP\_BL2 is platform specific. For example, on the Juno ARM
+development platform port the image is transferred into SCP's internal memory
+using the Boot Over MHU (BOM) protocol after being loaded in the trusted SRAM
+memory. The SCP executes SCP\_BL2 and signals to the Application Processor (AP)
+for BL2 execution to continue.
+
+EL3 Runtime Software image load
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+BL2 loads the EL3 Runtime Software image from platform storage into a platform-
+specific address in trusted SRAM. If there is not enough memory to load the
+image or image is missing it leads to an assertion failure. If ``LOAD_IMAGE_V2``
+is disabled and if image loads successfully, BL2 updates the amount of trusted
+SRAM used and available for use by EL3 Runtime Software. This information is
+populated at a platform-specific memory address.
+
+AArch64 BL32 (Secure-EL1 Payload) image load
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+BL2 loads the optional BL32 image from platform storage into a platform-
+specific region of secure memory. The image executes in the secure world. BL2
+relies on BL31 to pass control to the BL32 image, if present. Hence, BL2
+populates a platform-specific area of memory with the entrypoint/load-address
+of the BL32 image. The value of the Saved Processor Status Register (``SPSR``)
+for entry into BL32 is not determined by BL2, it is initialized by the
+Secure-EL1 Payload Dispatcher (see later) within BL31, which is responsible for
+managing interaction with BL32. This information is passed to BL31.
+
+BL33 (Non-trusted Firmware) image load
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+BL2 loads the BL33 image (e.g. UEFI or other test or boot software) from
+platform storage into non-secure memory as defined by the platform.
+
+BL2 relies on EL3 Runtime Software to pass control to BL33 once secure state
+initialization is complete. Hence, BL2 populates a platform-specific area of
+memory with the entrypoint and Saved Program Status Register (``SPSR``) of the
+normal world software image. The entrypoint is the load address of the BL33
+image. The ``SPSR`` is determined as specified in Section 5.13 of the
+`PSCI PDD`_. This information is passed to the EL3 Runtime Software.
+
+AArch64 BL31 (EL3 Runtime Software) execution
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+BL2 execution continues as follows:
+
+#. BL2 passes control back to BL1 by raising an SMC, providing BL1 with the
+ BL31 entrypoint. The exception is handled by the SMC exception handler
+ installed by BL1.
+
+#. BL1 turns off the MMU and flushes the caches. It clears the
+ ``SCTLR_EL3.M/I/C`` bits, flushes the data cache to the point of coherency
+ and invalidates the TLBs.
+
+#. BL1 passes control to BL31 at the specified entrypoint at EL3.
+
+AArch64 BL31
+~~~~~~~~~~~~
+
+The image for this stage is loaded by BL2 and BL1 passes control to BL31 at
+EL3. BL31 executes solely in trusted SRAM. BL31 is linked against and
+loaded at a platform-specific base address (more information can be found later
+in this document). The functionality implemented by BL31 is as follows.
+
+Architectural initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Currently, BL31 performs a similar architectural initialization to BL1 as
+far as system register settings are concerned. Since BL1 code resides in ROM,
+architectural initialization in BL31 allows override of any previous
+initialization done by BL1.
+
+BL31 initializes the per-CPU data framework, which provides a cache of
+frequently accessed per-CPU data optimised for fast, concurrent manipulation
+on different CPUs. This buffer includes pointers to per-CPU contexts, crash
+buffer, CPU reset and power down operations, PSCI data, platform data and so on.
+
+It then replaces the exception vectors populated by BL1 with its own. BL31
+exception vectors implement more elaborate support for handling SMCs since this
+is the only mechanism to access the runtime services implemented by BL31 (PSCI
+for example). BL31 checks each SMC for validity as specified by the
+`SMC calling convention PDD`_ before passing control to the required SMC
+handler routine.
+
+BL31 programs the ``CNTFRQ_EL0`` register with the clock frequency of the system
+counter, which is provided by the platform.
+
+Platform initialization
+^^^^^^^^^^^^^^^^^^^^^^^
+
+BL31 performs detailed platform initialization, which enables normal world
+software to function correctly.
+
+On ARM platforms, this consists of the following:
+
+- Initialize the console.
+- Configure the Interconnect to enable hardware coherency.
+- Enable the MMU and map the memory it needs to access.
+- Initialize the generic interrupt controller.
+- Initialize the power controller device.
+- Detect the system topology.
+
+Runtime services initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+BL31 is responsible for initializing the runtime services. One of them is PSCI.
+
+As part of the PSCI initializations, BL31 detects the system topology. It also
+initializes the data structures that implement the state machine used to track
+the state of power domain nodes. The state can be one of ``OFF``, ``RUN`` or
+``RETENTION``. All secondary CPUs are initially in the ``OFF`` state. The cluster
+that the primary CPU belongs to is ``ON``; any other cluster is ``OFF``. It also
+initializes the locks that protect them. BL31 accesses the state of a CPU or
+cluster immediately after reset and before the data cache is enabled in the
+warm boot path. It is not currently possible to use 'exclusive' based spinlocks,
+therefore BL31 uses locks based on Lamport's Bakery algorithm instead.
+
+The runtime service framework and its initialization is described in more
+detail in the "EL3 runtime services framework" section below.
+
+Details about the status of the PSCI implementation are provided in the
+"Power State Coordination Interface" section below.
+
+AArch64 BL32 (Secure-EL1 Payload) image initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If a BL32 image is present then there must be a matching Secure-EL1 Payload
+Dispatcher (SPD) service (see later for details). During initialization
+that service must register a function to carry out initialization of BL32
+once the runtime services are fully initialized. BL31 invokes such a
+registered function to initialize BL32 before running BL33. This initialization
+is not necessary for AArch32 SPs.
+
+Details on BL32 initialization and the SPD's role are described in the
+"Secure-EL1 Payloads and Dispatchers" section below.
+
+BL33 (Non-trusted Firmware) execution
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+EL3 Runtime Software initializes the EL2 or EL1 processor context for normal-
+world cold boot, ensuring that no secure state information finds its way into
+the non-secure execution state. EL3 Runtime Software uses the entrypoint
+information provided by BL2 to jump to the Non-trusted firmware image (BL33)
+at the highest available Exception Level (EL2 if available, otherwise EL1).
+
+Using alternative Trusted Boot Firmware in place of BL1 & BL2 (AArch64 only)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Some platforms have existing implementations of Trusted Boot Firmware that
+would like to use ARM Trusted Firmware BL31 for the EL3 Runtime Software. To
+enable this firmware architecture it is important to provide a fully documented
+and stable interface between the Trusted Boot Firmware and BL31.
+
+Future changes to the BL31 interface will be done in a backwards compatible
+way, and this enables these firmware components to be independently enhanced/
+updated to develop and exploit new functionality.
+
+Required CPU state when calling ``bl31_entrypoint()`` during cold boot
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function must only be called by the primary CPU.
+
+On entry to this function the calling primary CPU must be executing in AArch64
+EL3, little-endian data access, and all interrupt sources masked:
+
+::
+
+ PSTATE.EL = 3
+ PSTATE.RW = 1
+ PSTATE.DAIF = 0xf
+ SCTLR_EL3.EE = 0
+
+X0 and X1 can be used to pass information from the Trusted Boot Firmware to the
+platform code in BL31:
+
+::
+
+ X0 : Reserved for common Trusted Firmware information
+ X1 : Platform specific information
+
+BL31 zero-init sections (e.g. ``.bss``) should not contain valid data on entry,
+these will be zero filled prior to invoking platform setup code.
+
+Use of the X0 and X1 parameters
+'''''''''''''''''''''''''''''''
+
+The parameters are platform specific and passed from ``bl31_entrypoint()`` to
+``bl31_early_platform_setup()``. The value of these parameters is never directly
+used by the common BL31 code.
+
+The convention is that ``X0`` conveys information regarding the BL31, BL32 and
+BL33 images from the Trusted Boot firmware and ``X1`` can be used for other
+platform specific purpose. This convention allows platforms which use ARM
+Trusted Firmware's BL1 and BL2 images to transfer additional platform specific
+information from Secure Boot without conflicting with future evolution of the
+Trusted Firmware using ``X0`` to pass a ``bl31_params`` structure.
+
+BL31 common and SPD initialization code depends on image and entrypoint
+information about BL33 and BL32, which is provided via BL31 platform APIs.
+This information is required until the start of execution of BL33. This
+information can be provided in a platform defined manner, e.g. compiled into
+the platform code in BL31, or provided in a platform defined memory location
+by the Trusted Boot firmware, or passed from the Trusted Boot Firmware via the
+Cold boot Initialization parameters. This data may need to be cleaned out of
+the CPU caches if it is provided by an earlier boot stage and then accessed by
+BL31 platform code before the caches are enabled.
+
+ARM Trusted Firmware's BL2 implementation passes a ``bl31_params`` structure in
+``X0`` and the ARM development platforms interpret this in the BL31 platform
+code.
+
+MMU, Data caches & Coherency
+''''''''''''''''''''''''''''
+
+BL31 does not depend on the enabled state of the MMU, data caches or
+interconnect coherency on entry to ``bl31_entrypoint()``. If these are disabled
+on entry, these should be enabled during ``bl31_plat_arch_setup()``.
+
+Data structures used in the BL31 cold boot interface
+''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+These structures are designed to support compatibility and independent
+evolution of the structures and the firmware images. For example, a version of
+BL31 that can interpret the BL3x image information from different versions of
+BL2, a platform that uses an extended entry\_point\_info structure to convey
+additional register information to BL31, or a ELF image loader that can convey
+more details about the firmware images.
+
+To support these scenarios the structures are versioned and sized, which enables
+BL31 to detect which information is present and respond appropriately. The
+``param_header`` is defined to capture this information:
+
+.. code:: c
+
+ typedef struct param_header {
+ uint8_t type; /* type of the structure */
+ uint8_t version; /* version of this structure */
+ uint16_t size; /* size of this structure in bytes */
+ uint32_t attr; /* attributes: unused bits SBZ */
+ } param_header_t;
+
+The structures using this format are ``entry_point_info``, ``image_info`` and
+``bl31_params``. The code that allocates and populates these structures must set
+the header fields appropriately, and the ``SET_PARAM_HEAD()`` a macro is defined
+to simplify this action.
+
+Required CPU state for BL31 Warm boot initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When requesting a CPU power-on, or suspending a running CPU, ARM Trusted
+Firmware provides the platform power management code with a Warm boot
+initialization entry-point, to be invoked by the CPU immediately after the
+reset handler. On entry to the Warm boot initialization function the calling
+CPU must be in AArch64 EL3, little-endian data access and all interrupt sources
+masked:
+
+::
+
+ PSTATE.EL = 3
+ PSTATE.RW = 1
+ PSTATE.DAIF = 0xf
+ SCTLR_EL3.EE = 0
+
+The PSCI implementation will initialize the processor state and ensure that the
+platform power management code is then invoked as required to initialize all
+necessary system, cluster and CPU resources.
+
+AArch32 EL3 Runtime Software entrypoint interface
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To enable this firmware architecture it is important to provide a fully
+documented and stable interface between the Trusted Boot Firmware and the
+AArch32 EL3 Runtime Software.
+
+Future changes to the entrypoint interface will be done in a backwards
+compatible way, and this enables these firmware components to be independently
+enhanced/updated to develop and exploit new functionality.
+
+Required CPU state when entering during cold boot
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function must only be called by the primary CPU.
+
+On entry to this function the calling primary CPU must be executing in AArch32
+EL3, little-endian data access, and all interrupt sources masked:
+
+::
+
+ PSTATE.AIF = 0x7
+ SCTLR.EE = 0
+
+R0 and R1 are used to pass information from the Trusted Boot Firmware to the
+platform code in AArch32 EL3 Runtime Software:
+
+::
+
+ R0 : Reserved for common Trusted Firmware information
+ R1 : Platform specific information
+
+Use of the R0 and R1 parameters
+'''''''''''''''''''''''''''''''
+
+The parameters are platform specific and the convention is that ``R0`` conveys
+information regarding the BL3x images from the Trusted Boot firmware and ``R1``
+can be used for other platform specific purpose. This convention allows
+platforms which use ARM Trusted Firmware's BL1 and BL2 images to transfer
+additional platform specific information from Secure Boot without conflicting
+with future evolution of the Trusted Firmware using ``R0`` to pass a ``bl_params``
+structure.
+
+The AArch32 EL3 Runtime Software is responsible for entry into BL33. This
+information can be obtained in a platform defined manner, e.g. compiled into
+the AArch32 EL3 Runtime Software, or provided in a platform defined memory
+location by the Trusted Boot firmware, or passed from the Trusted Boot Firmware
+via the Cold boot Initialization parameters. This data may need to be cleaned
+out of the CPU caches if it is provided by an earlier boot stage and then
+accessed by AArch32 EL3 Runtime Software before the caches are enabled.
+
+When using AArch32 EL3 Runtime Software, the ARM development platforms pass a
+``bl_params`` structure in ``R0`` from BL2 to be interpreted by AArch32 EL3 Runtime
+Software platform code.
+
+MMU, Data caches & Coherency
+''''''''''''''''''''''''''''
+
+AArch32 EL3 Runtime Software must not depend on the enabled state of the MMU,
+data caches or interconnect coherency in its entrypoint. They must be explicitly
+enabled if required.
+
+Data structures used in cold boot interface
+'''''''''''''''''''''''''''''''''''''''''''
+
+The AArch32 EL3 Runtime Software cold boot interface uses ``bl_params`` instead
+of ``bl31_params``. The ``bl_params`` structure is based on the convention
+described in AArch64 BL31 cold boot interface section.
+
+Required CPU state for warm boot initialization
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+When requesting a CPU power-on, or suspending a running CPU, AArch32 EL3
+Runtime Software must ensure execution of a warm boot initialization entrypoint.
+If ARM Trusted Firmware BL1 is used and the PROGRAMMABLE\_RESET\_ADDRESS build
+flag is false, then AArch32 EL3 Runtime Software must ensure that BL1 branches
+to the warm boot entrypoint by arranging for the BL1 platform function,
+plat\_get\_my\_entrypoint(), to return a non-zero value.
+
+In this case, the warm boot entrypoint must be in AArch32 EL3, little-endian
+data access and all interrupt sources masked:
+
+::
+
+ PSTATE.AIF = 0x7
+ SCTLR.EE = 0
+
+The warm boot entrypoint may be implemented by using the ARM Trusted Firmware
+``psci_warmboot_entrypoint()`` function. In that case, the platform must fulfil
+the pre-requisites mentioned in the `PSCI Library integration guide`_.
+
+EL3 runtime services framework
+------------------------------
+
+Software executing in the non-secure state and in the secure state at exception
+levels lower than EL3 will request runtime services using the Secure Monitor
+Call (SMC) instruction. These requests will follow the convention described in
+the SMC Calling Convention PDD (`SMCCC`_). The `SMCCC`_ assigns function
+identifiers to each SMC request and describes how arguments are passed and
+returned.
+
+The EL3 runtime services framework enables the development of services by
+different providers that can be easily integrated into final product firmware.
+The following sections describe the framework which facilitates the
+registration, initialization and use of runtime services in EL3 Runtime
+Software (BL31).
+
+The design of the runtime services depends heavily on the concepts and
+definitions described in the `SMCCC`_, in particular SMC Function IDs, Owning
+Entity Numbers (OEN), Fast and Yielding calls, and the SMC32 and SMC64 calling
+conventions. Please refer to that document for more detailed explanation of
+these terms.
+
+The following runtime services are expected to be implemented first. They have
+not all been instantiated in the current implementation.
+
+#. Standard service calls
+
+ This service is for management of the entire system. The Power State
+ Coordination Interface (`PSCI`_) is the first set of standard service calls
+ defined by ARM (see PSCI section later).
+
+#. Secure-EL1 Payload Dispatcher service
+
+ If a system runs a Trusted OS or other Secure-EL1 Payload (SP) then
+ it also requires a *Secure Monitor* at EL3 to switch the EL1 processor
+ context between the normal world (EL1/EL2) and trusted world (Secure-EL1).
+ The Secure Monitor will make these world switches in response to SMCs. The
+ `SMCCC`_ provides for such SMCs with the Trusted OS Call and Trusted
+ Application Call OEN ranges.
+
+ The interface between the EL3 Runtime Software and the Secure-EL1 Payload is
+ not defined by the `SMCCC`_ or any other standard. As a result, each
+ Secure-EL1 Payload requires a specific Secure Monitor that runs as a runtime
+ service - within ARM Trusted Firmware this service is referred to as the
+ Secure-EL1 Payload Dispatcher (SPD).
+
+ ARM Trusted Firmware provides a Test Secure-EL1 Payload (TSP) and its
+ associated Dispatcher (TSPD). Details of SPD design and TSP/TSPD operation
+ are described in the "Secure-EL1 Payloads and Dispatchers" section below.
+
+#. CPU implementation service
+
+ This service will provide an interface to CPU implementation specific
+ services for a given platform e.g. access to processor errata workarounds.
+ This service is currently unimplemented.
+
+Additional services for ARM Architecture, SiP and OEM calls can be implemented.
+Each implemented service handles a range of SMC function identifiers as
+described in the `SMCCC`_.
+
+Registration
+~~~~~~~~~~~~
+
+A runtime service is registered using the ``DECLARE_RT_SVC()`` macro, specifying
+the name of the service, the range of OENs covered, the type of service and
+initialization and call handler functions. This macro instantiates a ``const struct rt_svc_desc`` for the service with these details (see ``runtime_svc.h``).
+This structure is allocated in a special ELF section ``rt_svc_descs``, enabling
+the framework to find all service descriptors included into BL31.
+
+The specific service for a SMC Function is selected based on the OEN and call
+type of the Function ID, and the framework uses that information in the service
+descriptor to identify the handler for the SMC Call.
+
+The service descriptors do not include information to identify the precise set
+of SMC function identifiers supported by this service implementation, the
+security state from which such calls are valid nor the capability to support
+64-bit and/or 32-bit callers (using SMC32 or SMC64). Responding appropriately
+to these aspects of a SMC call is the responsibility of the service
+implementation, the framework is focused on integration of services from
+different providers and minimizing the time taken by the framework before the
+service handler is invoked.
+
+Details of the parameters, requirements and behavior of the initialization and
+call handling functions are provided in the following sections.
+
+Initialization
+~~~~~~~~~~~~~~
+
+``runtime_svc_init()`` in ``runtime_svc.c`` initializes the runtime services
+framework running on the primary CPU during cold boot as part of the BL31
+initialization. This happens prior to initializing a Trusted OS and running
+Normal world boot firmware that might in turn use these services.
+Initialization involves validating each of the declared runtime service
+descriptors, calling the service initialization function and populating the
+index used for runtime lookup of the service.
+
+The BL31 linker script collects all of the declared service descriptors into a
+single array and defines symbols that allow the framework to locate and traverse
+the array, and determine its size.
+
+The framework does basic validation of each descriptor to halt firmware
+initialization if service declaration errors are detected. The framework does
+not check descriptors for the following error conditions, and may behave in an
+unpredictable manner under such scenarios:
+
+#. Overlapping OEN ranges
+#. Multiple descriptors for the same range of OENs and ``call_type``
+#. Incorrect range of owning entity numbers for a given ``call_type``
+
+Once validated, the service ``init()`` callback is invoked. This function carries
+out any essential EL3 initialization before servicing requests. The ``init()``
+function is only invoked on the primary CPU during cold boot. If the service
+uses per-CPU data this must either be initialized for all CPUs during this call,
+or be done lazily when a CPU first issues an SMC call to that service. If
+``init()`` returns anything other than ``0``, this is treated as an initialization
+error and the service is ignored: this does not cause the firmware to halt.
+
+The OEN and call type fields present in the SMC Function ID cover a total of
+128 distinct services, but in practice a single descriptor can cover a range of
+OENs, e.g. SMCs to call a Trusted OS function. To optimize the lookup of a
+service handler, the framework uses an array of 128 indices that map every
+distinct OEN/call-type combination either to one of the declared services or to
+indicate the service is not handled. This ``rt_svc_descs_indices[]`` array is
+populated for all of the OENs covered by a service after the service ``init()``
+function has reported success. So a service that fails to initialize will never
+have it's ``handle()`` function invoked.
+
+The following figure shows how the ``rt_svc_descs_indices[]`` index maps the SMC
+Function ID call type and OEN onto a specific service handler in the
+``rt_svc_descs[]`` array.
+
+|Image 1|
+
+Handling an SMC
+~~~~~~~~~~~~~~~
+
+When the EL3 runtime services framework receives a Secure Monitor Call, the SMC
+Function ID is passed in W0 from the lower exception level (as per the
+`SMCCC`_). If the calling register width is AArch32, it is invalid to invoke an
+SMC Function which indicates the SMC64 calling convention: such calls are
+ignored and return the Unknown SMC Function Identifier result code ``0xFFFFFFFF``
+in R0/X0.
+
+Bit[31] (fast/yielding call) and bits[29:24] (owning entity number) of the SMC
+Function ID are combined to index into the ``rt_svc_descs_indices[]`` array. The
+resulting value might indicate a service that has no handler, in this case the
+framework will also report an Unknown SMC Function ID. Otherwise, the value is
+used as a further index into the ``rt_svc_descs[]`` array to locate the required
+service and handler.
+
+The service's ``handle()`` callback is provided with five of the SMC parameters
+directly, the others are saved into memory for retrieval (if needed) by the
+handler. The handler is also provided with an opaque ``handle`` for use with the
+supporting library for parameter retrieval, setting return values and context
+manipulation; and with ``flags`` indicating the security state of the caller. The
+framework finally sets up the execution stack for the handler, and invokes the
+services ``handle()`` function.
+
+On return from the handler the result registers are populated in X0-X3 before
+restoring the stack and CPU state and returning from the original SMC.
+
+Power State Coordination Interface
+----------------------------------
+
+TODO: Provide design walkthrough of PSCI implementation.
+
+The PSCI v1.0 specification categorizes APIs as optional and mandatory. All the
+mandatory APIs in PSCI v1.0 and all the APIs in PSCI v0.2 draft specification
+`Power State Coordination Interface PDD`_ are implemented. The table lists
+the PSCI v1.0 APIs and their support in generic code.
+
+An API implementation might have a dependency on platform code e.g. CPU\_SUSPEND
+requires the platform to export a part of the implementation. Hence the level
+of support of the mandatory APIs depends upon the support exported by the
+platform port as well. The Juno and FVP (all variants) platforms export all the
+required support.
+
++-----------------------------+-------------+-------------------------------+
+| PSCI v1.0 API | Supported | Comments |
++=============================+=============+===============================+
+| ``PSCI_VERSION`` | Yes | The version returned is 1.0 |
++-----------------------------+-------------+-------------------------------+
+| ``CPU_SUSPEND`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``CPU_OFF`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``CPU_ON`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``AFFINITY_INFO`` | Yes | |
++-----------------------------+-------------+-------------------------------+
+| ``MIGRATE`` | Yes\*\* | |
++-----------------------------+-------------+-------------------------------+
+| ``MIGRATE_INFO_TYPE`` | Yes\*\* | |
++-----------------------------+-------------+-------------------------------+
+| ``MIGRATE_INFO_CPU`` | Yes\*\* | |
++-----------------------------+-------------+-------------------------------+
+| ``SYSTEM_OFF`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``SYSTEM_RESET`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``PSCI_FEATURES`` | Yes | |
++-----------------------------+-------------+-------------------------------+
+| ``CPU_FREEZE`` | No | |
++-----------------------------+-------------+-------------------------------+
+| ``CPU_DEFAULT_SUSPEND`` | No | |
++-----------------------------+-------------+-------------------------------+
+| ``NODE_HW_STATE`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``SYSTEM_SUSPEND`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``PSCI_SET_SUSPEND_MODE`` | No | |
++-----------------------------+-------------+-------------------------------+
+| ``PSCI_STAT_RESIDENCY`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+| ``PSCI_STAT_COUNT`` | Yes\* | |
++-----------------------------+-------------+-------------------------------+
+
+\*Note : These PSCI APIs require platform power management hooks to be
+registered with the generic PSCI code to be supported.
+
+\*\*Note : These PSCI APIs require appropriate Secure Payload Dispatcher
+hooks to be registered with the generic PSCI code to be supported.
+
+The PSCI implementation in ARM Trusted Firmware is a library which can be
+integrated with AArch64 or AArch32 EL3 Runtime Software for ARMv8-A systems.
+A guide to integrating PSCI library with AArch32 EL3 Runtime Software
+can be found `here`_.
+
+Secure-EL1 Payloads and Dispatchers
+-----------------------------------
+
+On a production system that includes a Trusted OS running in Secure-EL1/EL0,
+the Trusted OS is coupled with a companion runtime service in the BL31
+firmware. This service is responsible for the initialisation of the Trusted
+OS and all communications with it. The Trusted OS is the BL32 stage of the
+boot flow in ARM Trusted Firmware. The firmware will attempt to locate, load
+and execute a BL32 image.
+
+ARM Trusted Firmware uses a more general term for the BL32 software that runs
+at Secure-EL1 - the *Secure-EL1 Payload* - as it is not always a Trusted OS.
+
+The ARM Trusted Firmware provides a Test Secure-EL1 Payload (TSP) and a Test
+Secure-EL1 Payload Dispatcher (TSPD) service as an example of how a Trusted OS
+is supported on a production system using the Runtime Services Framework. On
+such a system, the Test BL32 image and service are replaced by the Trusted OS
+and its dispatcher service. The ARM Trusted Firmware build system expects that
+the dispatcher will define the build flag ``NEED_BL32`` to enable it to include
+the BL32 in the build either as a binary or to compile from source depending
+on whether the ``BL32`` build option is specified or not.
+
+The TSP runs in Secure-EL1. It is designed to demonstrate synchronous
+communication with the normal-world software running in EL1/EL2. Communication
+is initiated by the normal-world software
+
+- either directly through a Fast SMC (as defined in the `SMCCC`_)
+
+- or indirectly through a `PSCI`_ SMC. The `PSCI`_ implementation in turn
+ informs the TSPD about the requested power management operation. This allows
+ the TSP to prepare for or respond to the power state change
+
+The TSPD service is responsible for.
+
+- Initializing the TSP
+
+- Routing requests and responses between the secure and the non-secure
+ states during the two types of communications just described
+
+Initializing a BL32 Image
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Secure-EL1 Payload Dispatcher (SPD) service is responsible for initializing
+the BL32 image. It needs access to the information passed by BL2 to BL31 to do
+so. This is provided by:
+
+.. code:: c
+
+ entry_point_info_t *bl31_plat_get_next_image_ep_info(uint32_t);
+
+which returns a reference to the ``entry_point_info`` structure corresponding to
+the image which will be run in the specified security state. The SPD uses this
+API to get entry point information for the SECURE image, BL32.
+
+In the absence of a BL32 image, BL31 passes control to the normal world
+bootloader image (BL33). When the BL32 image is present, it is typical
+that the SPD wants control to be passed to BL32 first and then later to BL33.
+
+To do this the SPD has to register a BL32 initialization function during
+initialization of the SPD service. The BL32 initialization function has this
+prototype:
+
+.. code:: c
+
+ int32_t init(void);
+
+and is registered using the ``bl31_register_bl32_init()`` function.
+
+Trusted Firmware supports two approaches for the SPD to pass control to BL32
+before returning through EL3 and running the non-trusted firmware (BL33):
+
+#. In the BL32 setup function, use ``bl31_set_next_image_type()`` to
+ request that the exit from ``bl31_main()`` is to the BL32 entrypoint in
+ Secure-EL1. BL31 will exit to BL32 using the asynchronous method by
+ calling ``bl31_prepare_next_image_entry()`` and ``el3_exit()``.
+
+ When the BL32 has completed initialization at Secure-EL1, it returns to
+ BL31 by issuing an SMC, using a Function ID allocated to the SPD. On
+ receipt of this SMC, the SPD service handler should switch the CPU context
+ from trusted to normal world and use the ``bl31_set_next_image_type()`` and
+ ``bl31_prepare_next_image_entry()`` functions to set up the initial return to
+ the normal world firmware BL33. On return from the handler the framework
+ will exit to EL2 and run BL33.
+
+#. The BL32 setup function registers an initialization function using
+ ``bl31_register_bl32_init()`` which provides a SPD-defined mechanism to
+ invoke a 'world-switch synchronous call' to Secure-EL1 to run the BL32
+ entrypoint.
+ NOTE: The Test SPD service included with the Trusted Firmware provides one
+ implementation of such a mechanism.
+
+ On completion BL32 returns control to BL31 via a SMC, and on receipt the
+ SPD service handler invokes the synchronous call return mechanism to return
+ to the BL32 initialization function. On return from this function,
+ ``bl31_main()`` will set up the return to the normal world firmware BL33 and
+ continue the boot process in the normal world.
+
+#. .. rubric:: Crash Reporting in BL31
+ :name: crash-reporting-in-bl31
+
+BL31 implements a scheme for reporting the processor state when an unhandled
+exception is encountered. The reporting mechanism attempts to preserve all the
+register contents and report it via a dedicated UART (PL011 console). BL31
+reports the general purpose, EL3, Secure EL1 and some EL2 state registers.
+
+A dedicated per-CPU crash stack is maintained by BL31 and this is retrieved via
+the per-CPU pointer cache. The implementation attempts to minimise the memory
+required for this feature. The file ``crash_reporting.S`` contains the
+implementation for crash reporting.
+
+The sample crash output is shown below.
+
+::
+
+ x0 :0x000000004F00007C
+ x1 :0x0000000007FFFFFF
+ x2 :0x0000000004014D50
+ x3 :0x0000000000000000
+ x4 :0x0000000088007998
+ x5 :0x00000000001343AC
+ x6 :0x0000000000000016
+ x7 :0x00000000000B8A38
+ x8 :0x00000000001343AC
+ x9 :0x00000000000101A8
+ x10 :0x0000000000000002
+ x11 :0x000000000000011C
+ x12 :0x00000000FEFDC644
+ x13 :0x00000000FED93FFC
+ x14 :0x0000000000247950
+ x15 :0x00000000000007A2
+ x16 :0x00000000000007A4
+ x17 :0x0000000000247950
+ x18 :0x0000000000000000
+ x19 :0x00000000FFFFFFFF
+ x20 :0x0000000004014D50
+ x21 :0x000000000400A38C
+ x22 :0x0000000000247950
+ x23 :0x0000000000000010
+ x24 :0x0000000000000024
+ x25 :0x00000000FEFDC868
+ x26 :0x00000000FEFDC86A
+ x27 :0x00000000019EDEDC
+ x28 :0x000000000A7CFDAA
+ x29 :0x0000000004010780
+ x30 :0x000000000400F004
+ scr_el3 :0x0000000000000D3D
+ sctlr_el3 :0x0000000000C8181F
+ cptr_el3 :0x0000000000000000
+ tcr_el3 :0x0000000080803520
+ daif :0x00000000000003C0
+ mair_el3 :0x00000000000004FF
+ spsr_el3 :0x00000000800003CC
+ elr_el3 :0x000000000400C0CC
+ ttbr0_el3 :0x00000000040172A0
+ esr_el3 :0x0000000096000210
+ sp_el3 :0x0000000004014D50
+ far_el3 :0x000000004F00007C
+ spsr_el1 :0x0000000000000000
+ elr_el1 :0x0000000000000000
+ spsr_abt :0x0000000000000000
+ spsr_und :0x0000000000000000
+ spsr_irq :0x0000000000000000
+ spsr_fiq :0x0000000000000000
+ sctlr_el1 :0x0000000030C81807
+ actlr_el1 :0x0000000000000000
+ cpacr_el1 :0x0000000000300000
+ csselr_el1 :0x0000000000000002
+ sp_el1 :0x0000000004028800
+ esr_el1 :0x0000000000000000
+ ttbr0_el1 :0x000000000402C200
+ ttbr1_el1 :0x0000000000000000
+ mair_el1 :0x00000000000004FF
+ amair_el1 :0x0000000000000000
+ tcr_el1 :0x0000000000003520
+ tpidr_el1 :0x0000000000000000
+ tpidr_el0 :0x0000000000000000
+ tpidrro_el0 :0x0000000000000000
+ dacr32_el2 :0x0000000000000000
+ ifsr32_el2 :0x0000000000000000
+ par_el1 :0x0000000000000000
+ far_el1 :0x0000000000000000
+ afsr0_el1 :0x0000000000000000
+ afsr1_el1 :0x0000000000000000
+ contextidr_el1 :0x0000000000000000
+ vbar_el1 :0x0000000004027000
+ cntp_ctl_el0 :0x0000000000000000
+ cntp_cval_el0 :0x0000000000000000
+ cntv_ctl_el0 :0x0000000000000000
+ cntv_cval_el0 :0x0000000000000000
+ cntkctl_el1 :0x0000000000000000
+ fpexc32_el2 :0x0000000004000700
+ sp_el0 :0x0000000004010780
+
+Guidelines for Reset Handlers
+-----------------------------
+
+Trusted Firmware implements a framework that allows CPU and platform ports to
+perform actions very early after a CPU is released from reset in both the cold
+and warm boot paths. This is done by calling the ``reset_handler()`` function in
+both the BL1 and BL31 images. It in turn calls the platform and CPU specific
+reset handling functions.
+
+Details for implementing a CPU specific reset handler can be found in
+Section 8. Details for implementing a platform specific reset handler can be
+found in the `Porting Guide`_ (see the ``plat_reset_handler()`` function).
+
+When adding functionality to a reset handler, keep in mind that if a different
+reset handling behavior is required between the first and the subsequent
+invocations of the reset handling code, this should be detected at runtime.
+In other words, the reset handler should be able to detect whether an action has
+already been performed and act as appropriate. Possible courses of actions are,
+e.g. skip the action the second time, or undo/redo it.
+
+CPU specific operations framework
+---------------------------------
+
+Certain aspects of the ARMv8 architecture are implementation defined,
+that is, certain behaviours are not architecturally defined, but must be defined
+and documented by individual processor implementations. The ARM Trusted
+Firmware implements a framework which categorises the common implementation
+defined behaviours and allows a processor to export its implementation of that
+behaviour. The categories are:
+
+#. Processor specific reset sequence.
+
+#. Processor specific power down sequences.
+
+#. Processor specific register dumping as a part of crash reporting.
+
+#. Errata status reporting.
+
+Each of the above categories fulfils a different requirement.
+
+#. allows any processor specific initialization before the caches and MMU
+ are turned on, like implementation of errata workarounds, entry into
+ the intra-cluster coherency domain etc.
+
+#. allows each processor to implement the power down sequence mandated in
+ its Technical Reference Manual (TRM).
+
+#. allows a processor to provide additional information to the developer
+ in the event of a crash, for example Cortex-A53 has registers which
+ can expose the data cache contents.
+
+#. allows a processor to define a function that inspects and reports the status
+ of all errata workarounds on that processor.
+
+Please note that only 2. is mandated by the TRM.
+
+The CPU specific operations framework scales to accommodate a large number of
+different CPUs during power down and reset handling. The platform can specify
+any CPU optimization it wants to enable for each CPU. It can also specify
+the CPU errata workarounds to be applied for each CPU type during reset
+handling by defining CPU errata compile time macros. Details on these macros
+can be found in the `cpu-specific-build-macros.rst`_ file.
+
+The CPU specific operations framework depends on the ``cpu_ops`` structure which
+needs to be exported for each type of CPU in the platform. It is defined in
+``include/lib/cpus/aarch64/cpu_macros.S`` and has the following fields : ``midr``,
+``reset_func()``, ``cpu_pwr_down_ops`` (array of power down functions) and
+``cpu_reg_dump()``.
+
+The CPU specific files in ``lib/cpus`` export a ``cpu_ops`` data structure with
+suitable handlers for that CPU. For example, ``lib/cpus/aarch64/cortex_a53.S``
+exports the ``cpu_ops`` for Cortex-A53 CPU. According to the platform
+configuration, these CPU specific files must be included in the build by
+the platform makefile. The generic CPU specific operations framework code exists
+in ``lib/cpus/aarch64/cpu_helpers.S``.
+
+CPU specific Reset Handling
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+After a reset, the state of the CPU when it calls generic reset handler is:
+MMU turned off, both instruction and data caches turned off and not part
+of any coherency domain.
+
+The BL entrypoint code first invokes the ``plat_reset_handler()`` to allow
+the platform to perform any system initialization required and any system
+errata workarounds that needs to be applied. The ``get_cpu_ops_ptr()`` reads
+the current CPU midr, finds the matching ``cpu_ops`` entry in the ``cpu_ops``
+array and returns it. Note that only the part number and implementer fields
+in midr are used to find the matching ``cpu_ops`` entry. The ``reset_func()`` in
+the returned ``cpu_ops`` is then invoked which executes the required reset
+handling for that CPU and also any errata workarounds enabled by the platform.
+This function must preserve the values of general purpose registers x20 to x29.
+
+Refer to Section "Guidelines for Reset Handlers" for general guidelines
+regarding placement of code in a reset handler.
+
+CPU specific power down sequence
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+During the BL31 initialization sequence, the pointer to the matching ``cpu_ops``
+entry is stored in per-CPU data by ``init_cpu_ops()`` so that it can be quickly
+retrieved during power down sequences.
+
+Various CPU drivers register handlers to perform power down at certain power
+levels for that specific CPU. The PSCI service, upon receiving a power down
+request, determines the highest power level at which to execute power down
+sequence for a particular CPU. It uses the ``prepare_cpu_pwr_dwn()`` function to
+pick the right power down handler for the requested level. The function
+retrieves ``cpu_ops`` pointer member of per-CPU data, and from that, further
+retrieves ``cpu_pwr_down_ops`` array, and indexes into the required level. If the
+requested power level is higher than what a CPU driver supports, the handler
+registered for highest level is invoked.
+
+At runtime the platform hooks for power down are invoked by the PSCI service to
+perform platform specific operations during a power down sequence, for example
+turning off CCI coherency during a cluster power down.
+
+CPU specific register reporting during crash
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+If the crash reporting is enabled in BL31, when a crash occurs, the crash
+reporting framework calls ``do_cpu_reg_dump`` which retrieves the matching
+``cpu_ops`` using ``get_cpu_ops_ptr()`` function. The ``cpu_reg_dump()`` in
+``cpu_ops`` is invoked, which then returns the CPU specific register values to
+be reported and a pointer to the ASCII list of register names in a format
+expected by the crash reporting framework.
+
+CPU errata status reporting
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Errata workarounds for CPUs supported in ARM Trusted Firmware are applied during
+both cold and warm boots, shortly after reset. Individual Errata workarounds are
+enabled as build options. Some errata workarounds have potential run-time
+implications; therefore some are enabled by default, others not. Platform ports
+shall override build options to enable or disable errata as appropriate. The CPU
+drivers take care of applying errata workarounds that are enabled and applicable
+to a given CPU. Refer to the section titled *CPU Errata Workarounds* in `CPUBM`_
+for more information.
+
+Functions in CPU drivers that apply errata workaround must follow the
+conventions listed below.
+
+The errata workaround must be authored as two separate functions:
+
+- One that checks for errata. This function must determine whether that errata
+ applies to the current CPU. Typically this involves matching the current
+ CPUs revision and variant against a value that's known to be affected by the
+ errata. If the function determines that the errata applies to this CPU, it
+ must return ``ERRATA_APPLIES``; otherwise, it must return
+ ``ERRATA_NOT_APPLIES``. The utility functions ``cpu_get_rev_var`` and
+ ``cpu_rev_var_ls`` functions may come in handy for this purpose.
+
+For an errata identified as ``E``, the check function must be named
+``check_errata_E``.
+
+This function will be invoked at different times, both from assembly and from
+C run time. Therefore it must follow AAPCS, and must not use stack.
+
+- Another one that applies the errata workaround. This function would call the
+ check function described above, and applies errata workaround if required.
+
+CPU drivers that apply errata workaround can optionally implement an assembly
+function that report the status of errata workarounds pertaining to that CPU.
+For a driver that registers the CPU, for example, ``cpux`` via. ``declare_cpu_ops``
+macro, the errata reporting function, if it exists, must be named
+``cpux_errata_report``. This function will always be called with MMU enabled; it
+must follow AAPCS and may use stack.
+
+In a debug build of ARM Trusted Firmware, on a CPU that comes out of reset, both
+BL1 and the run time firmware (BL31 in AArch64, and BL32 in AArch32) will invoke
+errata status reporting function, if one exists, for that type of CPU.
+
+To report the status of each errata workaround, the function shall use the
+assembler macro ``report_errata``, passing it:
+
+- The build option that enables the errata;
+
+- The name of the CPU: this must be the same identifier that CPU driver
+ registered itself with, using ``declare_cpu_ops``;
+
+- And the errata identifier: the identifier must match what's used in the
+ errata's check function described above.
+
+The errata status reporting function will be called once per CPU type/errata
+combination during the software's active life time.
+
+It's expected that whenever an errata workaround is submitted to ARM Trusted
+Firmware, the errata reporting function is appropriately extended to report its
+status as well.
+
+Reporting the status of errata workaround is for informational purpose only; it
+has no functional significance.
+
+Memory layout of BL images
+--------------------------
+
+Each bootloader image can be divided in 2 parts:
+
+- the static contents of the image. These are data actually stored in the
+ binary on the disk. In the ELF terminology, they are called ``PROGBITS``
+ sections;
+
+- the run-time contents of the image. These are data that don't occupy any
+ space in the binary on the disk. The ELF binary just contains some
+ metadata indicating where these data will be stored at run-time and the
+ corresponding sections need to be allocated and initialized at run-time.
+ In the ELF terminology, they are called ``NOBITS`` sections.
+
+All PROGBITS sections are grouped together at the beginning of the image,
+followed by all NOBITS sections. This is true for all Trusted Firmware images
+and it is governed by the linker scripts. This ensures that the raw binary
+images are as small as possible. If a NOBITS section was inserted in between
+PROGBITS sections then the resulting binary file would contain zero bytes in
+place of this NOBITS section, making the image unnecessarily bigger. Smaller
+images allow faster loading from the FIP to the main memory.
+
+Linker scripts and symbols
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Each bootloader stage image layout is described by its own linker script. The
+linker scripts export some symbols into the program symbol table. Their values
+correspond to particular addresses. The trusted firmware code can refer to these
+symbols to figure out the image memory layout.
+
+Linker symbols follow the following naming convention in the trusted firmware.
+
+- ``__<SECTION>_START__``
+
+ Start address of a given section named ``<SECTION>``.
+
+- ``__<SECTION>_END__``
+
+ End address of a given section named ``<SECTION>``. If there is an alignment
+ constraint on the section's end address then ``__<SECTION>_END__`` corresponds
+ to the end address of the section's actual contents, rounded up to the right
+ boundary. Refer to the value of ``__<SECTION>_UNALIGNED_END__`` to know the
+ actual end address of the section's contents.
+
+- ``__<SECTION>_UNALIGNED_END__``
+
+ End address of a given section named ``<SECTION>`` without any padding or
+ rounding up due to some alignment constraint.
+
+- ``__<SECTION>_SIZE__``
+
+ Size (in bytes) of a given section named ``<SECTION>``. If there is an
+ alignment constraint on the section's end address then ``__<SECTION>_SIZE__``
+ corresponds to the size of the section's actual contents, rounded up to the
+ right boundary. In other words, ``__<SECTION>_SIZE__ = __<SECTION>_END__ - _<SECTION>_START__``. Refer to the value of ``__<SECTION>_UNALIGNED_SIZE__``
+ to know the actual size of the section's contents.
+
+- ``__<SECTION>_UNALIGNED_SIZE__``
+
+ Size (in bytes) of a given section named ``<SECTION>`` without any padding or
+ rounding up due to some alignment constraint. In other words,
+ ``__<SECTION>_UNALIGNED_SIZE__ = __<SECTION>_UNALIGNED_END__ - __<SECTION>_START__``.
+
+Some of the linker symbols are mandatory as the trusted firmware code relies on
+them to be defined. They are listed in the following subsections. Some of them
+must be provided for each bootloader stage and some are specific to a given
+bootloader stage.
+
+The linker scripts define some extra, optional symbols. They are not actually
+used by any code but they help in understanding the bootloader images' memory
+layout as they are easy to spot in the link map files.
+
+Common linker symbols
+^^^^^^^^^^^^^^^^^^^^^
+
+All BL images share the following requirements:
+
+- The BSS section must be zero-initialised before executing any C code.
+- The coherent memory section (if enabled) must be zero-initialised as well.
+- The MMU setup code needs to know the extents of the coherent and read-only
+ memory regions to set the right memory attributes. When
+ ``SEPARATE_CODE_AND_RODATA=1``, it needs to know more specifically how the
+ read-only memory region is divided between code and data.
+
+The following linker symbols are defined for this purpose:
+
+- ``__BSS_START__``
+- ``__BSS_SIZE__``
+- ``__COHERENT_RAM_START__`` Must be aligned on a page-size boundary.
+- ``__COHERENT_RAM_END__`` Must be aligned on a page-size boundary.
+- ``__COHERENT_RAM_UNALIGNED_SIZE__``
+- ``__RO_START__``
+- ``__RO_END__``
+- ``__TEXT_START__``
+- ``__TEXT_END__``
+- ``__RODATA_START__``
+- ``__RODATA_END__``
+
+BL1's linker symbols
+^^^^^^^^^^^^^^^^^^^^
+
+BL1 being the ROM image, it has additional requirements. BL1 resides in ROM and
+it is entirely executed in place but it needs some read-write memory for its
+mutable data. Its ``.data`` section (i.e. its allocated read-write data) must be
+relocated from ROM to RAM before executing any C code.
+
+The following additional linker symbols are defined for BL1:
+
+- ``__BL1_ROM_END__`` End address of BL1's ROM contents, covering its code
+ and ``.data`` section in ROM.
+- ``__DATA_ROM_START__`` Start address of the ``.data`` section in ROM. Must be
+ aligned on a 16-byte boundary.
+- ``__DATA_RAM_START__`` Address in RAM where the ``.data`` section should be
+ copied over. Must be aligned on a 16-byte boundary.
+- ``__DATA_SIZE__`` Size of the ``.data`` section (in ROM or RAM).
+- ``__BL1_RAM_START__`` Start address of BL1 read-write data.
+- ``__BL1_RAM_END__`` End address of BL1 read-write data.
+
+How to choose the right base addresses for each bootloader stage image
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There is currently no support for dynamic image loading in the Trusted Firmware.
+This means that all bootloader images need to be linked against their ultimate
+runtime locations and the base addresses of each image must be chosen carefully
+such that images don't overlap each other in an undesired way. As the code
+grows, the base addresses might need adjustments to cope with the new memory
+layout.
+
+The memory layout is completely specific to the platform and so there is no
+general recipe for choosing the right base addresses for each bootloader image.
+However, there are tools to aid in understanding the memory layout. These are
+the link map files: ``build/<platform>/<build-type>/bl<x>/bl<x>.map``, with ``<x>``
+being the stage bootloader. They provide a detailed view of the memory usage of
+each image. Among other useful information, they provide the end address of
+each image.
+
+- ``bl1.map`` link map file provides ``__BL1_RAM_END__`` address.
+- ``bl2.map`` link map file provides ``__BL2_END__`` address.
+- ``bl31.map`` link map file provides ``__BL31_END__`` address.
+- ``bl32.map`` link map file provides ``__BL32_END__`` address.
+
+For each bootloader image, the platform code must provide its start address
+as well as a limit address that it must not overstep. The latter is used in the
+linker scripts to check that the image doesn't grow past that address. If that
+happens, the linker will issue a message similar to the following:
+
+::
+
+ aarch64-none-elf-ld: BLx has exceeded its limit.
+
+Additionally, if the platform memory layout implies some image overlaying like
+on FVP, BL31 and TSP need to know the limit address that their PROGBITS
+sections must not overstep. The platform code must provide those.
+
+When LOAD\_IMAGE\_V2 is disabled, Trusted Firmware provides a mechanism to
+verify at boot time that the memory to load a new image is free to prevent
+overwriting a previously loaded image. For this mechanism to work, the platform
+must specify the memory available in the system as regions, where each region
+consists of base address, total size and the free area within it (as defined
+in the ``meminfo_t`` structure). Trusted Firmware retrieves these memory regions
+by calling the corresponding platform API:
+
+- ``meminfo_t *bl1_plat_sec_mem_layout(void)``
+- ``meminfo_t *bl2_plat_sec_mem_layout(void)``
+- ``void bl2_plat_get_scp_bl2_meminfo(meminfo_t *scp_bl2_meminfo)``
+- ``void bl2_plat_get_bl32_meminfo(meminfo_t *bl32_meminfo)``
+- ``void bl2_plat_get_bl33_meminfo(meminfo_t *bl33_meminfo)``
+
+For example, in the case of BL1 loading BL2, ``bl1_plat_sec_mem_layout()`` will
+return the region defined by the platform where BL1 intends to load BL2. The
+``load_image()`` function will check that the memory where BL2 will be loaded is
+within the specified region and marked as free.
+
+The actual number of regions and their base addresses and sizes is platform
+specific. The platform may return the same region or define a different one for
+each API. However, the overlap verification mechanism applies only to a single
+region. Hence, it is the platform responsibility to guarantee that different
+regions do not overlap, or that if they do, the overlapping images are not
+accessed at the same time. This could be used, for example, to load temporary
+images (e.g. certificates) or firmware images prior to being transfered to its
+corresponding processor (e.g. the SCP BL2 image).
+
+To reduce fragmentation and simplify the tracking of free memory, all the free
+memory within a region is always located in one single buffer defined by its
+base address and size. Trusted Firmware implements a top/bottom load approach:
+after a new image is loaded, it checks how much memory remains free above and
+below the image. The smallest area is marked as unavailable, while the larger
+area becomes the new free memory buffer. Platforms should take this behaviour
+into account when defining the base address for each of the images. For example,
+if an image is loaded near the middle of the region, small changes in image size
+could cause a flip between a top load and a bottom load, which may result in an
+unexpected memory layout.
+
+The following diagram is an example of an image loaded in the bottom part of
+the memory region. The region is initially free (nothing has been loaded yet):
+
+::
+
+ Memory region
+ +----------+
+ | |
+ | | <<<<<<<<<<<<< Free
+ | |
+ |----------| +------------+
+ | image | <<<<<<<<<<<<< | image |
+ |----------| +------------+
+ | xxxxxxxx | <<<<<<<<<<<<< Marked as unavailable
+ +----------+
+
+And the following diagram is an example of an image loaded in the top part:
+
+::
+
+ Memory region
+ +----------+
+ | xxxxxxxx | <<<<<<<<<<<<< Marked as unavailable
+ |----------| +------------+
+ | image | <<<<<<<<<<<<< | image |
+ |----------| +------------+
+ | |
+ | | <<<<<<<<<<<<< Free
+ | |
+ +----------+
+
+When LOAD\_IMAGE\_V2 is enabled, Trusted Firmware does not provide any mechanism
+to verify at boot time that the memory to load a new image is free to prevent
+overwriting a previously loaded image. The platform must specify the memory
+available in the system for all the relevant BL images to be loaded.
+
+For example, in the case of BL1 loading BL2, ``bl1_plat_sec_mem_layout()`` will
+return the region defined by the platform where BL1 intends to load BL2. The
+``load_image()`` function performs bounds check for the image size based on the
+base and maximum image size provided by the platforms. Platforms must take
+this behaviour into account when defining the base/size for each of the images.
+
+Memory layout on ARM development platforms
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The following list describes the memory layout on the ARM development platforms:
+
+- A 4KB page of shared memory is used for communication between Trusted
+ Firmware and the platform's power controller. This is located at the base of
+ Trusted SRAM. The amount of Trusted SRAM available to load the bootloader
+ images is reduced by the size of the shared memory.
+
+ The shared memory is used to store the CPUs' entrypoint mailbox. On Juno,
+ this is also used for the MHU payload when passing messages to and from the
+ SCP.
+
+- On FVP, BL1 is originally sitting in the Trusted ROM at address ``0x0``. On
+ Juno, BL1 resides in flash memory at address ``0x0BEC0000``. BL1 read-write
+ data are relocated to the top of Trusted SRAM at runtime.
+
+- EL3 Runtime Software, BL31 for AArch64 and BL32 for AArch32 (e.g. SP\_MIN),
+ is loaded at the top of the Trusted SRAM, such that its NOBITS sections will
+ overwrite BL1 R/W data. This implies that BL1 global variables remain valid
+ only until execution reaches the EL3 Runtime Software entry point during a
+ cold boot.
+
+- BL2 is loaded below EL3 Runtime Software.
+
+- On Juno, SCP\_BL2 is loaded temporarily into the EL3 Runtime Software memory
+ region and transfered to the SCP before being overwritten by EL3 Runtime
+ Software.
+
+- BL32 (for AArch64) can be loaded in one of the following locations:
+
+ - Trusted SRAM
+ - Trusted DRAM (FVP only)
+ - Secure region of DRAM (top 16MB of DRAM configured by the TrustZone
+ controller)
+
+ When BL32 (for AArch64) is loaded into Trusted SRAM, its NOBITS sections
+ are allowed to overlay BL2. This memory layout is designed to give the
+ BL32 image as much memory as possible when it is loaded into Trusted SRAM.
+
+When LOAD\_IMAGE\_V2 is disabled the memory regions for the overlap detection
+mechanism at boot time are defined as follows (shown per API):
+
+- ``meminfo_t *bl1_plat_sec_mem_layout(void)``
+
+ This region corresponds to the whole Trusted SRAM except for the shared
+ memory at the base. This region is initially free. At boot time, BL1 will
+ mark the BL1(rw) section within this region as occupied. The BL1(rw) section
+ is placed at the top of Trusted SRAM.
+
+- ``meminfo_t *bl2_plat_sec_mem_layout(void)``
+
+ This region corresponds to the whole Trusted SRAM as defined by
+ ``bl1_plat_sec_mem_layout()``, but with the BL1(rw) section marked as
+ occupied. This memory region is used to check that BL2 and BL31 do not
+ overlap with each other. BL2\_BASE and BL1\_RW\_BASE are carefully chosen so
+ that the memory for BL31 is top loaded above BL2.
+
+- ``void bl2_plat_get_scp_bl2_meminfo(meminfo_t *scp_bl2_meminfo)``
+
+ This region is an exact copy of the region defined by
+ ``bl2_plat_sec_mem_layout()``. Being a disconnected copy means that all the
+ changes made to this region by the Trusted Firmware will not be propagated.
+ This approach is valid because the SCP BL2 image is loaded temporarily
+ while it is being transferred to the SCP, so this memory is reused
+ afterwards.
+
+- ``void bl2_plat_get_bl32_meminfo(meminfo_t *bl32_meminfo)``
+
+ This region depends on the location of the BL32 image. Currently, ARM
+ platforms support three different locations (detailed below): Trusted SRAM,
+ Trusted DRAM and the TZC-Secured DRAM.
+
+- ``void bl2_plat_get_bl33_meminfo(meminfo_t *bl33_meminfo)``
+
+ This region corresponds to the Non-Secure DDR-DRAM, excluding the
+ TZC-Secured area.
+
+The location of the BL32 image will result in different memory maps. This is
+illustrated for both FVP and Juno in the following diagrams, using the TSP as
+an example.
+
+Note: Loading the BL32 image in TZC secured DRAM doesn't change the memory
+layout of the other images in Trusted SRAM.
+
+**FVP with TSP in Trusted SRAM (default option):**
+(These diagrams only cover the AArch64 case)
+
+::
+
+ Trusted SRAM
+ 0x04040000 +----------+ loaded by BL2 ------------------
+ | BL1 (rw) | <<<<<<<<<<<<< | BL31 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | | <<<<<<<<<<<<< | BL31 PROGBITS |
+ |----------| ------------------
+ | BL2 | <<<<<<<<<<<<< | BL32 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | | <<<<<<<<<<<<< | BL32 PROGBITS |
+ 0x04001000 +----------+ ------------------
+ | Shared |
+ 0x04000000 +----------+
+
+ Trusted ROM
+ 0x04000000 +----------+
+ | BL1 (ro) |
+ 0x00000000 +----------+
+
+**FVP with TSP in Trusted DRAM:**
+
+::
+
+ Trusted DRAM
+ 0x08000000 +----------+
+ | BL32 |
+ 0x06000000 +----------+
+
+ Trusted SRAM
+ 0x04040000 +----------+ loaded by BL2 ------------------
+ | BL1 (rw) | <<<<<<<<<<<<< | BL31 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | | <<<<<<<<<<<<< | BL31 PROGBITS |
+ |----------| ------------------
+ | BL2 |
+ |----------|
+ | |
+ 0x04001000 +----------+
+ | Shared |
+ 0x04000000 +----------+
+
+ Trusted ROM
+ 0x04000000 +----------+
+ | BL1 (ro) |
+ 0x00000000 +----------+
+
+**FVP with TSP in TZC-Secured DRAM:**
+
+::
+
+ DRAM
+ 0xffffffff +----------+
+ | BL32 | (secure)
+ 0xff000000 +----------+
+ | |
+ : : (non-secure)
+ | |
+ 0x80000000 +----------+
+
+ Trusted SRAM
+ 0x04040000 +----------+ loaded by BL2 ------------------
+ | BL1 (rw) | <<<<<<<<<<<<< | BL31 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | | <<<<<<<<<<<<< | BL31 PROGBITS |
+ |----------| ------------------
+ | BL2 |
+ |----------|
+ | |
+ 0x04001000 +----------+
+ | Shared |
+ 0x04000000 +----------+
+
+ Trusted ROM
+ 0x04000000 +----------+
+ | BL1 (ro) |
+ 0x00000000 +----------+
+
+**Juno with BL32 in Trusted SRAM (default option):**
+
+::
+
+ Flash0
+ 0x0C000000 +----------+
+ : :
+ 0x0BED0000 |----------|
+ | BL1 (ro) |
+ 0x0BEC0000 |----------|
+ : :
+ 0x08000000 +----------+ BL31 is loaded
+ after SCP_BL2 has
+ Trusted SRAM been sent to SCP
+ 0x04040000 +----------+ loaded by BL2 ------------------
+ | BL1 (rw) | <<<<<<<<<<<<< | BL31 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | SCP_BL2 | <<<<<<<<<<<<< | BL31 PROGBITS |
+ |----------| ------------------
+ | BL2 | <<<<<<<<<<<<< | BL32 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | | <<<<<<<<<<<<< | BL32 PROGBITS |
+ 0x04001000 +----------+ ------------------
+ | MHU |
+ 0x04000000 +----------+
+
+**Juno with BL32 in TZC-secured DRAM:**
+
+::
+
+ DRAM
+ 0xFFE00000 +----------+
+ | BL32 | (secure)
+ 0xFF000000 |----------|
+ | |
+ : : (non-secure)
+ | |
+ 0x80000000 +----------+
+
+ Flash0
+ 0x0C000000 +----------+
+ : :
+ 0x0BED0000 |----------|
+ | BL1 (ro) |
+ 0x0BEC0000 |----------|
+ : :
+ 0x08000000 +----------+ BL31 is loaded
+ after SCP_BL2 has
+ Trusted SRAM been sent to SCP
+ 0x04040000 +----------+ loaded by BL2 ------------------
+ | BL1 (rw) | <<<<<<<<<<<<< | BL31 NOBITS |
+ |----------| <<<<<<<<<<<<< |----------------|
+ | SCP_BL2 | <<<<<<<<<<<<< | BL31 PROGBITS |
+ |----------| ------------------
+ | BL2 |
+ |----------|
+ | |
+ 0x04001000 +----------+
+ | MHU |
+ 0x04000000 +----------+
+
+Firmware Image Package (FIP)
+----------------------------
+
+Using a Firmware Image Package (FIP) allows for packing bootloader images (and
+potentially other payloads) into a single archive that can be loaded by the ARM
+Trusted Firmware from non-volatile platform storage. A driver to load images
+from a FIP has been added to the storage layer and allows a package to be read
+from supported platform storage. A tool to create Firmware Image Packages is
+also provided and described below.
+
+Firmware Image Package layout
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The FIP layout consists of a table of contents (ToC) followed by payload data.
+The ToC itself has a header followed by one or more table entries. The ToC is
+terminated by an end marker entry. All ToC entries describe some payload data
+that has been appended to the end of the binary package. With the information
+provided in the ToC entry the corresponding payload data can be retrieved.
+
+::
+
+ ------------------
+ | ToC Header |
+ |----------------|
+ | ToC Entry 0 |
+ |----------------|
+ | ToC Entry 1 |
+ |----------------|
+ | ToC End Marker |
+ |----------------|
+ | |
+ | Data 0 |
+ | |
+ |----------------|
+ | |
+ | Data 1 |
+ | |
+ ------------------
+
+The ToC header and entry formats are described in the header file
+``include/tools_share/firmware_image_package.h``. This file is used by both the
+tool and the ARM Trusted firmware.
+
+The ToC header has the following fields:
+
+::
+
+ `name`: The name of the ToC. This is currently used to validate the header.
+ `serial_number`: A non-zero number provided by the creation tool
+ `flags`: Flags associated with this data.
+ Bits 0-31: Reserved
+ Bits 32-47: Platform defined
+ Bits 48-63: Reserved
+
+A ToC entry has the following fields:
+
+::
+
+ `uuid`: All files are referred to by a pre-defined Universally Unique
+ IDentifier [UUID] . The UUIDs are defined in
+ `include/tools_share/firmware_image_package.h`. The platform translates
+ the requested image name into the corresponding UUID when accessing the
+ package.
+ `offset_address`: The offset address at which the corresponding payload data
+ can be found. The offset is calculated from the ToC base address.
+ `size`: The size of the corresponding payload data in bytes.
+ `flags`: Flags associated with this entry. Non are yet defined.
+
+Firmware Image Package creation tool
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The FIP creation tool can be used to pack specified images into a binary package
+that can be loaded by the ARM Trusted Firmware from platform storage. The tool
+currently only supports packing bootloader images. Additional image definitions
+can be added to the tool as required.
+
+The tool can be found in ``tools/fiptool``.
+
+Loading from a Firmware Image Package (FIP)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The Firmware Image Package (FIP) driver can load images from a binary package on
+non-volatile platform storage. For the ARM development platforms, this is
+currently NOR FLASH.
+
+Bootloader images are loaded according to the platform policy as specified by
+the function ``plat_get_image_source()``. For the ARM development platforms, this
+means the platform will attempt to load images from a Firmware Image Package
+located at the start of NOR FLASH0.
+
+The ARM development platforms' policy is to only allow loading of a known set of
+images. The platform policy can be modified to allow additional images.
+
+Use of coherent memory in Trusted Firmware
+------------------------------------------
+
+There might be loss of coherency when physical memory with mismatched
+shareability, cacheability and memory attributes is accessed by multiple CPUs
+(refer to section B2.9 of `ARM ARM`_ for more details). This possibility occurs
+in Trusted Firmware during power up/down sequences when coherency, MMU and
+caches are turned on/off incrementally.
+
+Trusted Firmware defines coherent memory as a region of memory with Device
+nGnRE attributes in the translation tables. The translation granule size in
+Trusted Firmware is 4KB. This is the smallest possible size of the coherent
+memory region.
+
+By default, all data structures which are susceptible to accesses with
+mismatched attributes from various CPUs are allocated in a coherent memory
+region (refer to section 2.1 of `Porting Guide`_). The coherent memory region
+accesses are Outer Shareable, non-cacheable and they can be accessed
+with the Device nGnRE attributes when the MMU is turned on. Hence, at the
+expense of at least an extra page of memory, Trusted Firmware is able to work
+around coherency issues due to mismatched memory attributes.
+
+The alternative to the above approach is to allocate the susceptible data
+structures in Normal WriteBack WriteAllocate Inner shareable memory. This
+approach requires the data structures to be designed so that it is possible to
+work around the issue of mismatched memory attributes by performing software
+cache maintenance on them.
+
+Disabling the use of coherent memory in Trusted Firmware
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+It might be desirable to avoid the cost of allocating coherent memory on
+platforms which are memory constrained. Trusted Firmware enables inclusion of
+coherent memory in firmware images through the build flag ``USE_COHERENT_MEM``.
+This flag is enabled by default. It can be disabled to choose the second
+approach described above.
+
+The below sections analyze the data structures allocated in the coherent memory
+region and the changes required to allocate them in normal memory.
+
+Coherent memory usage in PSCI implementation
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``psci_non_cpu_pd_nodes`` data structure stores the platform's power domain
+tree information for state management of power domains. By default, this data
+structure is allocated in the coherent memory region in the Trusted Firmware
+because it can be accessed by multple CPUs, either with caches enabled or
+disabled.
+
+.. code:: c
+
+ typedef struct non_cpu_pwr_domain_node {
+ /*
+ * Index of the first CPU power domain node level 0 which has this node
+ * as its parent.
+ */
+ unsigned int cpu_start_idx;
+
+ /*
+ * Number of CPU power domains which are siblings of the domain indexed
+ * by 'cpu_start_idx' i.e. all the domains in the range 'cpu_start_idx
+ * -> cpu_start_idx + ncpus' have this node as their parent.
+ */
+ unsigned int ncpus;
+
+ /*
+ * Index of the parent power domain node.
+ * TODO: Figure out whether to whether using pointer is more efficient.
+ */
+ unsigned int parent_node;
+
+ plat_local_state_t local_state;
+
+ unsigned char level;
+
+ /* For indexing the psci_lock array*/
+ unsigned char lock_index;
+ } non_cpu_pd_node_t;
+
+In order to move this data structure to normal memory, the use of each of its
+fields must be analyzed. Fields like ``cpu_start_idx``, ``ncpus``, ``parent_node``
+``level`` and ``lock_index`` are only written once during cold boot. Hence removing
+them from coherent memory involves only doing a clean and invalidate of the
+cache lines after these fields are written.
+
+The field ``local_state`` can be concurrently accessed by multiple CPUs in
+different cache states. A Lamport's Bakery lock ``psci_locks`` is used to ensure
+mutual exlusion to this field and a clean and invalidate is needed after it
+is written.
+
+Bakery lock data
+~~~~~~~~~~~~~~~~
+
+The bakery lock data structure ``bakery_lock_t`` is allocated in coherent memory
+and is accessed by multiple CPUs with mismatched attributes. ``bakery_lock_t`` is
+defined as follows:
+
+.. code:: c
+
+ typedef struct bakery_lock {
+ /*
+ * The lock_data is a bit-field of 2 members:
+ * Bit[0] : choosing. This field is set when the CPU is
+ * choosing its bakery number.
+ * Bits[1 - 15] : number. This is the bakery number allocated.
+ */
+ volatile uint16_t lock_data[BAKERY_LOCK_MAX_CPUS];
+ } bakery_lock_t;
+
+It is a characteristic of Lamport's Bakery algorithm that the volatile per-CPU
+fields can be read by all CPUs but only written to by the owning CPU.
+
+Depending upon the data cache line size, the per-CPU fields of the
+``bakery_lock_t`` structure for multiple CPUs may exist on a single cache line.
+These per-CPU fields can be read and written during lock contention by multiple
+CPUs with mismatched memory attributes. Since these fields are a part of the
+lock implementation, they do not have access to any other locking primitive to
+safeguard against the resulting coherency issues. As a result, simple software
+cache maintenance is not enough to allocate them in coherent memory. Consider
+the following example.
+
+CPU0 updates its per-CPU field with data cache enabled. This write updates a
+local cache line which contains a copy of the fields for other CPUs as well. Now
+CPU1 updates its per-CPU field of the ``bakery_lock_t`` structure with data cache
+disabled. CPU1 then issues a DCIVAC operation to invalidate any stale copies of
+its field in any other cache line in the system. This operation will invalidate
+the update made by CPU0 as well.
+
+To use bakery locks when ``USE_COHERENT_MEM`` is disabled, the lock data structure
+has been redesigned. The changes utilise the characteristic of Lamport's Bakery
+algorithm mentioned earlier. The bakery\_lock structure only allocates the memory
+for a single CPU. The macro ``DEFINE_BAKERY_LOCK`` allocates all the bakery locks
+needed for a CPU into a section ``bakery_lock``. The linker allocates the memory
+for other cores by using the total size allocated for the bakery\_lock section
+and multiplying it with (PLATFORM\_CORE\_COUNT - 1). This enables software to
+perform software cache maintenance on the lock data structure without running
+into coherency issues associated with mismatched attributes.
+
+The bakery lock data structure ``bakery_info_t`` is defined for use when
+``USE_COHERENT_MEM`` is disabled as follows:
+
+.. code:: c
+
+ typedef struct bakery_info {
+ /*
+ * The lock_data is a bit-field of 2 members:
+ * Bit[0] : choosing. This field is set when the CPU is
+ * choosing its bakery number.
+ * Bits[1 - 15] : number. This is the bakery number allocated.
+ */
+ volatile uint16_t lock_data;
+ } bakery_info_t;
+
+The ``bakery_info_t`` represents a single per-CPU field of one lock and
+the combination of corresponding ``bakery_info_t`` structures for all CPUs in the
+system represents the complete bakery lock. The view in memory for a system
+with n bakery locks are:
+
+::
+
+ bakery_lock section start
+ |----------------|
+ | `bakery_info_t`| <-- Lock_0 per-CPU field
+ | Lock_0 | for CPU0
+ |----------------|
+ | `bakery_info_t`| <-- Lock_1 per-CPU field
+ | Lock_1 | for CPU0
+ |----------------|
+ | .... |
+ |----------------|
+ | `bakery_info_t`| <-- Lock_N per-CPU field
+ | Lock_N | for CPU0
+ ------------------
+ | XXXXX |
+ | Padding to |
+ | next Cache WB | <--- Calculate PERCPU_BAKERY_LOCK_SIZE, allocate
+ | Granule | continuous memory for remaining CPUs.
+ ------------------
+ | `bakery_info_t`| <-- Lock_0 per-CPU field
+ | Lock_0 | for CPU1
+ |----------------|
+ | `bakery_info_t`| <-- Lock_1 per-CPU field
+ | Lock_1 | for CPU1
+ |----------------|
+ | .... |
+ |----------------|
+ | `bakery_info_t`| <-- Lock_N per-CPU field
+ | Lock_N | for CPU1
+ ------------------
+ | XXXXX |
+ | Padding to |
+ | next Cache WB |
+ | Granule |
+ ------------------
+
+Consider a system of 2 CPUs with 'N' bakery locks as shown above. For an
+operation on Lock\_N, the corresponding ``bakery_info_t`` in both CPU0 and CPU1
+``bakery_lock`` section need to be fetched and appropriate cache operations need
+to be performed for each access.
+
+On ARM Platforms, bakery locks are used in psci (``psci_locks``) and power controller
+driver (``arm_lock``).
+
+Non Functional Impact of removing coherent memory
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Removal of the coherent memory region leads to the additional software overhead
+of performing cache maintenance for the affected data structures. However, since
+the memory where the data structures are allocated is cacheable, the overhead is
+mostly mitigated by an increase in performance.
+
+There is however a performance impact for bakery locks, due to:
+
+- Additional cache maintenance operations, and
+- Multiple cache line reads for each lock operation, since the bakery locks
+ for each CPU are distributed across different cache lines.
+
+The implementation has been optimized to minimize this additional overhead.
+Measurements indicate that when bakery locks are allocated in Normal memory, the
+minimum latency of acquiring a lock is on an average 3-4 micro seconds whereas
+in Device memory the same is 2 micro seconds. The measurements were done on the
+Juno ARM development platform.
+
+As mentioned earlier, almost a page of memory can be saved by disabling
+``USE_COHERENT_MEM``. Each platform needs to consider these trade-offs to decide
+whether coherent memory should be used. If a platform disables
+``USE_COHERENT_MEM`` and needs to use bakery locks in the porting layer, it can
+optionally define macro ``PLAT_PERCPU_BAKERY_LOCK_SIZE`` (see the
+`Porting Guide`_). Refer to the reference platform code for examples.
+
+Isolating code and read-only data on separate memory pages
+----------------------------------------------------------
+
+In the ARMv8 VMSA, translation table entries include fields that define the
+properties of the target memory region, such as its access permissions. The
+smallest unit of memory that can be addressed by a translation table entry is
+a memory page. Therefore, if software needs to set different permissions on two
+memory regions then it needs to map them using different memory pages.
+
+The default memory layout for each BL image is as follows:
+
+::
+
+ | ... |
+ +-------------------+
+ | Read-write data |
+ +-------------------+ Page boundary
+ | <Padding> |
+ +-------------------+
+ | Exception vectors |
+ +-------------------+ 2 KB boundary
+ | <Padding> |
+ +-------------------+
+ | Read-only data |
+ +-------------------+
+ | Code |
+ +-------------------+ BLx_BASE
+
+Note: The 2KB alignment for the exception vectors is an architectural
+requirement.
+
+The read-write data start on a new memory page so that they can be mapped with
+read-write permissions, whereas the code and read-only data below are configured
+as read-only.
+
+However, the read-only data are not aligned on a page boundary. They are
+contiguous to the code. Therefore, the end of the code section and the beginning
+of the read-only data one might share a memory page. This forces both to be
+mapped with the same memory attributes. As the code needs to be executable, this
+means that the read-only data stored on the same memory page as the code are
+executable as well. This could potentially be exploited as part of a security
+attack.
+
+TF provides the build flag ``SEPARATE_CODE_AND_RODATA`` to isolate the code and
+read-only data on separate memory pages. This in turn allows independent control
+of the access permissions for the code and read-only data. In this case,
+platform code gets a finer-grained view of the image layout and can
+appropriately map the code region as executable and the read-only data as
+execute-never.
+
+This has an impact on memory footprint, as padding bytes need to be introduced
+between the code and read-only data to ensure the segragation of the two. To
+limit the memory cost, this flag also changes the memory layout such that the
+code and exception vectors are now contiguous, like so:
+
+::
+
+ | ... |
+ +-------------------+
+ | Read-write data |
+ +-------------------+ Page boundary
+ | <Padding> |
+ +-------------------+
+ | Read-only data |
+ +-------------------+ Page boundary
+ | <Padding> |
+ +-------------------+
+ | Exception vectors |
+ +-------------------+ 2 KB boundary
+ | <Padding> |
+ +-------------------+
+ | Code |
+ +-------------------+ BLx_BASE
+
+With this more condensed memory layout, the separation of read-only data will
+add zero or one page to the memory footprint of each BL image. Each platform
+should consider the trade-off between memory footprint and security.
+
+This build flag is disabled by default, minimising memory footprint. On ARM
+platforms, it is enabled.
+
+Performance Measurement Framework
+---------------------------------
+
+The Performance Measurement Framework (PMF) facilitates collection of
+timestamps by registered services and provides interfaces to retrieve
+them from within the ARM Trusted Firmware. A platform can choose to
+expose appropriate SMCs to retrieve these collected timestamps.
+
+By default, the global physical counter is used for the timestamp
+value and is read via ``CNTPCT_EL0``. The framework allows to retrieve
+timestamps captured by other CPUs.
+
+Timestamp identifier format
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A PMF timestamp is uniquely identified across the system via the
+timestamp ID or ``tid``. The ``tid`` is composed as follows:
+
+::
+
+ Bits 0-7: The local timestamp identifier.
+ Bits 8-9: Reserved.
+ Bits 10-15: The service identifier.
+ Bits 16-31: Reserved.
+
+#. The service identifier. Each PMF service is identified by a
+ service name and a service identifier. Both the service name and
+ identifier are unique within the system as a whole.
+
+#. The local timestamp identifier. This identifier is unique within a given
+ service.
+
+Registering a PMF service
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To register a PMF service, the ``PMF_REGISTER_SERVICE()`` macro from ``pmf.h``
+is used. The arguments required are the service name, the service ID,
+the total number of local timestamps to be captured and a set of flags.
+
+The ``flags`` field can be specified as a bitwise-OR of the following values:
+
+::
+
+ PMF_STORE_ENABLE: The timestamp is stored in memory for later retrieval.
+ PMF_DUMP_ENABLE: The timestamp is dumped on the serial console.
+
+The ``PMF_REGISTER_SERVICE()`` reserves memory to store captured
+timestamps in a PMF specific linker section at build time.
+Additionally, it defines necessary functions to capture and
+retrieve a particular timestamp for the given service at runtime.
+
+The macro ``PMF_REGISTER_SERVICE()`` only enables capturing PMF
+timestamps from within ARM Trusted Firmware. In order to retrieve
+timestamps from outside of ARM Trusted Firmware, the
+``PMF_REGISTER_SERVICE_SMC()`` macro must be used instead. This macro
+accepts the same set of arguments as the ``PMF_REGISTER_SERVICE()``
+macro but additionally supports retrieving timestamps using SMCs.
+
+Capturing a timestamp
+~~~~~~~~~~~~~~~~~~~~~
+
+PMF timestamps are stored in a per-service timestamp region. On a
+system with multiple CPUs, each timestamp is captured and stored
+in a per-CPU cache line aligned memory region.
+
+Having registered the service, the ``PMF_CAPTURE_TIMESTAMP()`` macro can be
+used to capture a timestamp at the location where it is used. The macro
+takes the service name, a local timestamp identifier and a flag as arguments.
+
+The ``flags`` field argument can be zero, or ``PMF_CACHE_MAINT`` which
+instructs PMF to do cache maintenance following the capture. Cache
+maintenance is required if any of the service's timestamps are captured
+with data cache disabled.
+
+To capture a timestamp in assembly code, the caller should use
+``pmf_calc_timestamp_addr`` macro (defined in ``pmf_asm_macros.S``) to
+calculate the address of where the timestamp would be stored. The
+caller should then read ``CNTPCT_EL0`` register to obtain the timestamp
+and store it at the determined address for later retrieval.
+
+Retrieving a timestamp
+~~~~~~~~~~~~~~~~~~~~~~
+
+From within ARM Trusted Firmware, timestamps for individual CPUs can
+be retrieved using either ``PMF_GET_TIMESTAMP_BY_MPIDR()`` or
+``PMF_GET_TIMESTAMP_BY_INDEX()`` macros. These macros accept the CPU's MPIDR
+value, or its ordinal position, respectively.
+
+From outside ARM Trusted Firmware, timestamps for individual CPUs can be
+retrieved by calling into ``pmf_smc_handler()``.
+
+.. code:: c
+
+ Interface : pmf_smc_handler()
+ Argument : unsigned int smc_fid, u_register_t x1,
+ u_register_t x2, u_register_t x3,
+ u_register_t x4, void *cookie,
+ void *handle, u_register_t flags
+ Return : uintptr_t
+
+ smc_fid: Holds the SMC identifier which is either `PMF_SMC_GET_TIMESTAMP_32`
+ when the caller of the SMC is running in AArch32 mode
+ or `PMF_SMC_GET_TIMESTAMP_64` when the caller is running in AArch64 mode.
+ x1: Timestamp identifier.
+ x2: The `mpidr` of the CPU for which the timestamp has to be retrieved.
+ This can be the `mpidr` of a different core to the one initiating
+ the SMC. In that case, service specific cache maintenance may be
+ required to ensure the updated copy of the timestamp is returned.
+ x3: A flags value that is either 0 or `PMF_CACHE_MAINT`. If
+ `PMF_CACHE_MAINT` is passed, then the PMF code will perform a
+ cache invalidate before reading the timestamp. This ensures
+ an updated copy is returned.
+
+The remaining arguments, ``x4``, ``cookie``, ``handle`` and ``flags`` are unused
+in this implementation.
+
+PMF code structure
+~~~~~~~~~~~~~~~~~~
+
+#. ``pmf_main.c`` consists of core functions that implement service registration,
+ initialization, storing, dumping and retrieving timestamps.
+
+#. ``pmf_smc.c`` contains the SMC handling for registered PMF services.
+
+#. ``pmf.h`` contains the public interface to Performance Measurement Framework.
+
+#. ``pmf_asm_macros.S`` consists of macros to facilitate capturing timestamps in
+ assembly code.
+
+#. ``pmf_helpers.h`` is an internal header used by ``pmf.h``.
+
+#. .. rubric:: ARMv8 Architecture Extensions
+ :name: armv8-architecture-extensions
+
+ARM Trusted Firmware makes use of ARMv8 Architecture Extensions where
+applicable. This section lists the usage of Architecture Extensions, and build
+flags controlling them.
+
+In general, and unless individually mentioned, the build options
+``ARM_ARCH_MAJOR`` and ``ARM_ARCH_MINOR`` selects the Architecture Extension to
+target when building ARM Trusted Firmware. Subsequent ARM Architecture
+Extensions are backward compatible with previous versions.
+
+The build system only requires that ``ARM_ARCH_MAJOR`` and ``ARM_ARCH_MINOR`` have a
+valid numeric value. These build options only control whether or not
+Architecture Extension-specific code is included in the build. Otherwise, ARM
+Trusted Firmware targets the base ARMv8.0 architecture; i.e. as if
+``ARM_ARCH_MAJOR`` == 8 and ``ARM_ARCH_MINOR`` == 0, which are also their respective
+default values.
+
+See also the *Summary of build options* in `User Guide`_.
+
+For details on the Architecture Extension and available features, please refer
+to the respective Architecture Extension Supplement.
+
+ARMv8.1
+~~~~~~~
+
+This Architecture Extension is targeted when ``ARM_ARCH_MAJOR`` >= 8, or when
+``ARM_ARCH_MAJOR`` == 8 and ``ARM_ARCH_MINOR`` >= 1.
+
+- The Compare and Swap instruction is used to implement spinlocks. Otherwise,
+ the load-/store-exclusive instruction pair is used.
+
+Code Structure
+--------------
+
+Trusted Firmware code is logically divided between the three boot loader
+stages mentioned in the previous sections. The code is also divided into the
+following categories (present as directories in the source code):
+
+- **Platform specific.** Choice of architecture specific code depends upon
+ the platform.
+- **Common code.** This is platform and architecture agnostic code.
+- **Library code.** This code comprises of functionality commonly used by all
+ other code. The PSCI implementation and other EL3 runtime frameworks reside
+ as Library components.
+- **Stage specific.** Code specific to a boot stage.
+- **Drivers.**
+- **Services.** EL3 runtime services (eg: SPD). Specific SPD services
+ reside in the ``services/spd`` directory (e.g. ``services/spd/tspd``).
+
+Each boot loader stage uses code from one or more of the above mentioned
+categories. Based upon the above, the code layout looks like this:
+
+::
+
+ Directory Used by BL1? Used by BL2? Used by BL31?
+ bl1 Yes No No
+ bl2 No Yes No
+ bl31 No No Yes
+ plat Yes Yes Yes
+ drivers Yes No Yes
+ common Yes Yes Yes
+ lib Yes Yes Yes
+ services No No Yes
+
+The build system provides a non configurable build option IMAGE\_BLx for each
+boot loader stage (where x = BL stage). e.g. for BL1 , IMAGE\_BL1 will be
+defined by the build system. This enables the Trusted Firmware to compile
+certain code only for specific boot loader stages
+
+All assembler files have the ``.S`` extension. The linker source files for each
+boot stage have the extension ``.ld.S``. These are processed by GCC to create the
+linker scripts which have the extension ``.ld``.
+
+FDTs provide a description of the hardware platform and are used by the Linux
+kernel at boot time. These can be found in the ``fdts`` directory.
+
+References
+----------
+
+#. Trusted Board Boot Requirements CLIENT PDD (ARM DEN 0006B-5). Available
+ under NDA through your ARM account representative.
+
+#. `Power State Coordination Interface PDD`_
+
+#. `SMC Calling Convention PDD`_
+
+#. `ARM Trusted Firmware Interrupt Management Design guide`_.
+
+--------------
+
+*Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.*
+
+.. _Reset Design: ./reset-design.rst
+.. _Porting Guide: ./porting-guide.rst
+.. _Firmware Update: ./firmware-update.rst
+.. _PSCI PDD: http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf
+.. _SMC calling convention PDD: http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf
+.. _PSCI Library integration guide: ./psci-lib-integration-guide.rst
+.. _SMCCC: http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf
+.. _Power State Coordination Interface PDD: http://infocenter.arm.com/help/topic/com.arm.doc.den0022d/Power_State_Coordination_Interface_PDD_v1_1_DEN0022D.pdf
+.. _here: ./psci-lib-integration-guide.rst
+.. _cpu-specific-build-macros.rst: ./cpu-specific-build-macros.rst
+.. _CPUBM: ./cpu-specific-build-macros.rst
+.. _ARM ARM: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0487a.e/index.html
+.. _User Guide: ./user-guide.rst
+.. _SMC Calling Convention PDD: http://infocenter.arm.com/help/topic/com.arm.doc.den0028b/ARM_DEN0028B_SMC_Calling_Convention.pdf
+.. _ARM Trusted Firmware Interrupt Management Design guide: ./interrupt-framework-design.rst
+
+.. |Image 1| image:: diagrams/rt-svc-descs-layout.png?raw=true
--- /dev/null
+ARM Trusted Firmware - Firmware Update Design Guide
+===================================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+--------------
+
+Introduction
+------------
+
+This document describes the design of the Firmware Update (FWU) feature, which
+enables authenticated firmware to update firmware images from external
+interfaces such as USB, UART, SD-eMMC, NAND, NOR or Ethernet to SoC Non-Volatile
+memories such as NAND Flash, LPPDR2-NVM or any memory determined by the
+platform. This feature functions even when the current firmware in the system
+is corrupt or missing; it therefore may be used as a recovery mode. It may also
+be complemented by other, higher level firmware update software.
+
+FWU implements a specific part of the Trusted Board Boot Requirements (TBBR)
+specification, ARM DEN0006C-1. It should be used in conjunction with the
+`Trusted Board Boot`_ design document, which describes the image authentication
+parts of the Trusted Firmware (TF) TBBR implementation.
+
+Scope
+~~~~~
+
+This document describes the secure world FWU design. It is beyond its scope to
+describe how normal world FWU images should operate. To implement normal world
+FWU images, please refer to the "Non-Trusted Firmware Updater" requirements in
+the TBBR.
+
+FWU Overview
+------------
+
+The FWU boot flow is primarily mediated by BL1. Since BL1 executes in ROM, and
+it is usually desirable to minimize the amount of ROM code, the design allows
+some parts of FWU to be implemented in other secure and normal world images.
+Platform code may choose which parts are implemented in which images but the
+general expectation is:
+
+- BL1 handles:
+
+ - Detection and initiation of the FWU boot flow.
+ - Copying images from non-secure to secure memory
+ - FWU image authentication
+ - Context switching between the normal and secure world during the FWU
+ process.
+
+- Other secure world FWU images handle platform initialization required by
+ the FWU process.
+- Normal world FWU images handle loading of firmware images from external
+ interfaces to non-secure memory.
+
+The primary requirements of the FWU feature are:
+
+#. Export a BL1 SMC interface to interoperate with other FWU images executing
+ at other Exception Levels.
+#. Export a platform interface to provide FWU common code with the information
+ it needs, and to enable platform specific FWU functionality. See the
+ `Porting Guide`_ for details of this interface.
+
+TF uses abbreviated image terminology for FWU images like for other TF images.
+An overview of this terminology can be found `here`_.
+
+The following diagram shows the FWU boot flow for ARM development platforms.
+ARM CSS platforms like Juno have a System Control Processor (SCP), and these
+use all defined FWU images. Other platforms may use a subset of these.
+
+|Flow Diagram|
+
+Image Identification
+--------------------
+
+Each FWU image and certificate is identified by a unique ID, defined by the
+platform, which BL1 uses to fetch an image descriptor (``image_desc_t``) via a
+call to ``bl1_plat_get_image_desc()``. The same ID is also used to prepare the
+Chain of Trust (Refer to the `Authentication Framework Design`_
+for more information).
+
+The image descriptor includes the following information:
+
+- Executable or non-executable image. This indicates whether the normal world
+ is permitted to request execution of a secure world FWU image (after
+ authentication). Secure world certificates and non-AP images are examples
+ of non-executable images.
+- Secure or non-secure image. This indicates whether the image is
+ authenticated/executed in secure or non-secure memory.
+- Image base address and size.
+- Image entry point configuration (an ``entry_point_info_t``).
+- FWU image state.
+
+BL1 uses the FWU image descriptors to:
+
+- Validate the arguments of FWU SMCs
+- Manage the state of the FWU process
+- Initialize the execution state of the next FWU image.
+
+FWU State Machine
+-----------------
+
+BL1 maintains state for each FWU image during FWU execution. FWU images at lower
+Exception Levels raise SMCs to invoke FWU functionality in BL1, which causes
+BL1 to update its FWU image state. The BL1 image states and valid state
+transitions are shown in the diagram below. Note that secure images have a more
+complex state machine than non-secure images.
+
+|FWU state machine|
+
+The following is a brief description of the supported states:
+
+- RESET: This is the initial state of every image at the start of FWU.
+ Authentication failure also leads to this state. A secure
+ image may yield to this state if it has completed execution.
+ It can also be reached by using ``FWU_SMC_IMAGE_RESET``.
+
+- COPYING: This is the state of a secure image while BL1 is copying it
+ in blocks from non-secure to secure memory.
+
+- COPIED: This is the state of a secure image when BL1 has completed
+ copying it to secure memory.
+
+- AUTHENTICATED: This is the state of an image when BL1 has successfully
+ authenticated it.
+
+- EXECUTED: This is the state of a secure, executable image when BL1 has
+ passed execution control to it.
+
+- INTERRUPTED: This is the state of a secure, executable image after it has
+ requested BL1 to resume normal world execution.
+
+BL1 SMC Interface
+-----------------
+
+BL1\_SMC\_CALL\_COUNT
+~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x0
+
+ Return:
+ uint32_t
+
+This SMC returns the number of SMCs supported by BL1.
+
+BL1\_SMC\_UID
+~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x1
+
+ Return:
+ UUID : 32 bits in each of w0-w3 (or r0-r3 for AArch32 callers)
+
+This SMC returns the 128-bit `Universally Unique Identifier`_ for the
+BL1 SMC service.
+
+BL1\_SMC\_VERSION
+~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument:
+ uint32_t function ID : 0x3
+
+ Return:
+ uint32_t : Bits [31:16] Major Version
+ Bits [15:0] Minor Version
+
+This SMC returns the current version of the BL1 SMC service.
+
+BL1\_SMC\_RUN\_IMAGE
+~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x4
+ entry_point_info_t *ep_info
+
+ Return:
+ void
+
+ Pre-conditions:
+ if (normal world caller) synchronous exception
+ if (ep_info not EL3) synchronous exception
+
+This SMC passes execution control to an EL3 image described by the provided
+``entry_point_info_t`` structure. In the normal TF boot flow, BL2 invokes this SMC
+for BL1 to pass execution control to BL31.
+
+FWU\_SMC\_IMAGE\_COPY
+~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x10
+ unsigned int image_id
+ uintptr_t image_addr
+ unsigned int block_size
+ unsigned int image_size
+
+ Return:
+ int : 0 (Success)
+ : -ENOMEM
+ : -EPERM
+
+ Pre-conditions:
+ if (image_id is invalid) return -EPERM
+ if (image_id is non-secure image) return -EPERM
+ if (image_id state is not (RESET or COPYING)) return -EPERM
+ if (secure world caller) return -EPERM
+ if (image_addr + block_size overflows) return -ENOMEM
+ if (image destination address + image_size overflows) return -ENOMEM
+ if (source block is in secure memory) return -ENOMEM
+ if (source block is not mapped into BL1) return -ENOMEM
+ if (image_size > free secure memory) return -ENOMEM
+ if (image overlaps another image) return -EPERM
+
+This SMC copies the secure image indicated by ``image_id`` from non-secure memory
+to secure memory for later authentication. The image may be copied in a single
+block or multiple blocks. In either case, the total size of the image must be
+provided in ``image_size`` when invoking this SMC for the first time for each
+image; it is ignored in subsequent calls (if any) for the same image.
+
+The ``image_addr`` and ``block_size`` specify the source memory block to copy from.
+The destination address is provided by the platform code.
+
+If ``block_size`` is greater than the amount of remaining bytes to copy for this
+image then the former is truncated to the latter. The copy operation is then
+considered as complete and the FWU state machine transitions to the "COPIED"
+state. If there is still more to copy, the FWU state machine stays in or
+transitions to the COPYING state (depending on the previous state).
+
+When using multiple blocks, the source blocks do not necessarily need to be in
+contiguous memory.
+
+Once the SMC is handled, BL1 returns from exception to the normal world caller.
+
+FWU\_SMC\_IMAGE\_AUTH
+~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x11
+ unsigned int image_id
+ uintptr_t image_addr
+ unsigned int image_size
+
+ Return:
+ int : 0 (Success)
+ : -ENOMEM
+ : -EPERM
+ : -EAUTH
+
+ Pre-conditions:
+ if (image_id is invalid) return -EPERM
+ if (secure world caller)
+ if (image_id state is not RESET) return -EPERM
+ if (image_addr/image_size is not mappped into BL1) return -ENOMEM
+ else // normal world caller
+ if (image_id is secure image)
+ if (image_id state is not COPIED) return -EPERM
+ else // image_id is non-secure image
+ if (image_id state is not RESET) return -EPERM
+ if (image_addr/image_size is in secure memory) return -ENOMEM
+ if (image_addr/image_size not mappped into BL1) return -ENOMEM
+
+This SMC authenticates the image specified by ``image_id``. If the image is in the
+RESET state, BL1 authenticates the image in place using the provided
+``image_addr`` and ``image_size``. If the image is a secure image in the COPIED
+state, BL1 authenticates the image from the secure memory that BL1 previously
+copied the image into.
+
+BL1 returns from exception to the caller. If authentication succeeds then BL1
+sets the image state to AUTHENTICATED. If authentication fails then BL1 returns
+the -EAUTH error and sets the image state back to RESET.
+
+FWU\_SMC\_IMAGE\_EXECUTE
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x12
+ unsigned int image_id
+
+ Return:
+ int : 0 (Success)
+ : -EPERM
+
+ Pre-conditions:
+ if (image_id is invalid) return -EPERM
+ if (secure world caller) return -EPERM
+ if (image_id is non-secure image) return -EPERM
+ if (image_id is non-executable image) return -EPERM
+ if (image_id state is not AUTHENTICATED) return -EPERM
+
+This SMC initiates execution of a previously authenticated image specified by
+``image_id``, in the other security world to the caller. The current
+implementation only supports normal world callers initiating execution of a
+secure world image.
+
+BL1 saves the normal world caller's context, sets the secure image state to
+EXECUTED, and returns from exception to the secure image.
+
+FWU\_SMC\_IMAGE\_RESUME
+~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x13
+ register_t image_param
+
+ Return:
+ register_t : image_param (Success)
+ : -EPERM
+
+ Pre-conditions:
+ if (normal world caller and no INTERRUPTED secure image) return -EPERM
+
+This SMC resumes execution in the other security world while there is a secure
+image in the EXECUTED/INTERRUPTED state.
+
+For normal world callers, BL1 sets the previously interrupted secure image state
+to EXECUTED. For secure world callers, BL1 sets the previously executing secure
+image state to INTERRUPTED. In either case, BL1 saves the calling world's
+context, restores the resuming world's context and returns from exception into
+the resuming world. If the call is successful then the caller provided
+``image_param`` is returned to the resumed world, otherwise an error code is
+returned to the caller.
+
+FWU\_SMC\_SEC\_IMAGE\_DONE
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x14
+
+ Return:
+ int : 0 (Success)
+ : -EPERM
+
+ Pre-conditions:
+ if (normal world caller) return -EPERM
+
+This SMC indicates completion of a previously executing secure image.
+
+BL1 sets the previously executing secure image state to the RESET state,
+restores the normal world context and returns from exception into the normal
+world.
+
+FWU\_SMC\_UPDATE\_DONE
+~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x15
+ register_t client_cookie
+
+ Return:
+ N/A
+
+This SMC completes the firmware update process. BL1 calls the platform specific
+function ``bl1_plat_fwu_done``, passing the optional argument ``client_cookie`` as
+a ``void *``. The SMC does not return.
+
+FWU\_SMC\_IMAGE\_RESET
+~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Arguments:
+ uint32_t function ID : 0x16
+ unsigned int image_id
+
+ Return:
+ int : 0 (Success)
+ : -EPERM
+
+ Pre-conditions:
+ if (secure world caller) return -EPERM
+ if (image in EXECUTED) return -EPERM
+
+This SMC sets the state of an image to RESET and zeroes the memory used by it.
+
+This is only allowed if the image is not being executed.
+
+--------------
+
+*Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.*
+
+.. _Trusted Board Boot: ./trusted-board-boot.rst
+.. _Porting Guide: ./porting-guide.rst
+.. _here: https://github.com/ARM-software/arm-trusted-firmware/wiki/ARM-Trusted-Firmware-Image-Terminology
+.. _Authentication Framework Design: ./auth-framework.rst
+.. _Universally Unique Identifier: https://tools.ietf.org/rfc/rfc4122.txt
+
+.. |Flow Diagram| image:: diagrams/fwu_flow.png?raw=true
+.. |FWU state machine| image:: diagrams/fwu_states.png?raw=true
--- /dev/null
+ARM Trusted Firmware Interrupt Management Design guide
+======================================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+This framework is responsible for managing interrupts routed to EL3. It also
+allows EL3 software to configure the interrupt routing behavior. Its main
+objective is to implement the following two requirements.
+
+#. It should be possible to route interrupts meant to be handled by secure
+ software (Secure interrupts) to EL3, when execution is in non-secure state
+ (normal world). The framework should then take care of handing control of
+ the interrupt to either software in EL3 or Secure-EL1 depending upon the
+ software configuration and the GIC implementation. This requirement ensures
+ that secure interrupts are under the control of the secure software with
+ respect to their delivery and handling without the possibility of
+ intervention from non-secure software.
+
+#. It should be possible to route interrupts meant to be handled by
+ non-secure software (Non-secure interrupts) to the last executed exception
+ level in the normal world when the execution is in secure world at
+ exception levels lower than EL3. This could be done with or without the
+ knowledge of software executing in Secure-EL1/Secure-EL0. The choice of
+ approach should be governed by the secure software. This requirement
+ ensures that non-secure software is able to execute in tandem with the
+ secure software without overriding it.
+
+Concepts
+--------
+
+Interrupt types
+~~~~~~~~~~~~~~~
+
+The framework categorises an interrupt to be one of the following depending upon
+the exception level(s) it is handled in.
+
+#. Secure EL1 interrupt. This type of interrupt can be routed to EL3 or
+ Secure-EL1 depending upon the security state of the current execution
+ context. It is always handled in Secure-EL1.
+
+#. Non-secure interrupt. This type of interrupt can be routed to EL3,
+ Secure-EL1, Non-secure EL1 or EL2 depending upon the security state of the
+ current execution context. It is always handled in either Non-secure EL1
+ or EL2.
+
+#. EL3 interrupt. This type of interrupt can be routed to EL3 or Secure-EL1
+ depending upon the security state of the current execution context. It is
+ always handled in EL3.
+
+The following constants define the various interrupt types in the framework
+implementation.
+
+::
+
+ #define INTR_TYPE_S_EL1 0
+ #define INTR_TYPE_EL3 1
+ #define INTR_TYPE_NS 2
+
+Routing model
+~~~~~~~~~~~~~
+
+A type of interrupt can be either generated as an FIQ or an IRQ. The target
+exception level of an interrupt type is configured through the FIQ and IRQ bits
+in the Secure Configuration Register at EL3 (``SCR_EL3.FIQ`` and ``SCR_EL3.IRQ``
+bits). When ``SCR_EL3.FIQ``\ =1, FIQs are routed to EL3. Otherwise they are routed
+to the First Exception Level (FEL) capable of handling interrupts. When
+``SCR_EL3.IRQ``\ =1, IRQs are routed to EL3. Otherwise they are routed to the
+FEL. This register is configured independently by EL3 software for each security
+state prior to entry into a lower exception level in that security state.
+
+A routing model for a type of interrupt (generated as FIQ or IRQ) is defined as
+its target exception level for each security state. It is represented by a
+single bit for each security state. A value of ``0`` means that the interrupt
+should be routed to the FEL. A value of ``1`` means that the interrupt should be
+routed to EL3. A routing model is applicable only when execution is not in EL3.
+
+The default routing model for an interrupt type is to route it to the FEL in
+either security state.
+
+Valid routing models
+~~~~~~~~~~~~~~~~~~~~
+
+The framework considers certain routing models for each type of interrupt to be
+incorrect as they conflict with the requirements mentioned in Section 1. The
+following sub-sections describe all the possible routing models and specify
+which ones are valid or invalid. EL3 interrupts are currently supported only
+for GIC version 3.0 (ARM GICv3) and only the Secure-EL1 and Non-secure interrupt
+types are supported for GIC version 2.0 (ARM GICv2) (See 1.2). The terminology
+used in the following sub-sections is explained below.
+
+#. **CSS**. Current Security State. ``0`` when secure and ``1`` when non-secure
+
+#. **TEL3**. Target Exception Level 3. ``0`` when targeted to the FEL. ``1`` when
+ targeted to EL3.
+
+Secure-EL1 interrupts
+^^^^^^^^^^^^^^^^^^^^^
+
+#. **CSS=0, TEL3=0**. Interrupt is routed to the FEL when execution is in
+ secure state. This is a valid routing model as secure software is in
+ control of handling secure interrupts.
+
+#. **CSS=0, TEL3=1**. Interrupt is routed to EL3 when execution is in secure
+ state. This is a valid routing model as secure software in EL3 can
+ handover the interrupt to Secure-EL1 for handling.
+
+#. **CSS=1, TEL3=0**. Interrupt is routed to the FEL when execution is in
+ non-secure state. This is an invalid routing model as a secure interrupt
+ is not visible to the secure software which violates the motivation behind
+ the ARM Security Extensions.
+
+#. **CSS=1, TEL3=1**. Interrupt is routed to EL3 when execution is in
+ non-secure state. This is a valid routing model as secure software in EL3
+ can handover the interrupt to Secure-EL1 for handling.
+
+Non-secure interrupts
+^^^^^^^^^^^^^^^^^^^^^
+
+#. **CSS=0, TEL3=0**. Interrupt is routed to the FEL when execution is in
+ secure state. This allows the secure software to trap non-secure
+ interrupts, perform its book-keeping and hand the interrupt to the
+ non-secure software through EL3. This is a valid routing model as secure
+ software is in control of how its execution is preempted by non-secure
+ interrupts.
+
+#. **CSS=0, TEL3=1**. Interrupt is routed to EL3 when execution is in secure
+ state. This is a valid routing model as secure software in EL3 can save
+ the state of software in Secure-EL1/Secure-EL0 before handing the
+ interrupt to non-secure software. This model requires additional
+ coordination between Secure-EL1 and EL3 software to ensure that the
+ former's state is correctly saved by the latter.
+
+#. **CSS=1, TEL3=0**. Interrupt is routed to FEL when execution is in
+ non-secure state. This is an valid routing model as a non-secure interrupt
+ is handled by non-secure software.
+
+#. **CSS=1, TEL3=1**. Interrupt is routed to EL3 when execution is in
+ non-secure state. This is an invalid routing model as there is no valid
+ reason to route the interrupt to EL3 software and then hand it back to
+ non-secure software for handling.
+
+EL3 interrupts
+^^^^^^^^^^^^^^
+
+#. **CSS=0, TEL3=0**. Interrupt is routed to the FEL when execution is in
+ Secure-EL1/Secure-EL0. This is a valid routing model as secure software
+ in Secure-EL1/Secure-EL0 is in control of how its execution is preempted
+ by EL3 interrupt and can handover the interrupt to EL3 for handling.
+
+#. **CSS=0, TEL3=1**. Interrupt is routed to EL3 when execution is in
+ Secure-EL1/Secure-EL0. This is a valid routing model as secure software
+ in EL3 can handle the interrupt.
+
+#. **CSS=1, TEL3=0**. Interrupt is routed to the FEL when execution is in
+ non-secure state. This is an invalid routing model as a secure interrupt
+ is not visible to the secure software which violates the motivation behind
+ the ARM Security Extensions.
+
+#. **CSS=1, TEL3=1**. Interrupt is routed to EL3 when execution is in
+ non-secure state. This is a valid routing model as secure software in EL3
+ can handle the interrupt.
+
+Mapping of interrupt type to signal
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The framework is meant to work with any interrupt controller implemented by a
+platform. A interrupt controller could generate a type of interrupt as either an
+FIQ or IRQ signal to the CPU depending upon the current security state. The
+mapping between the type and signal is known only to the platform. The framework
+uses this information to determine whether the IRQ or the FIQ bit should be
+programmed in ``SCR_EL3`` while applying the routing model for a type of
+interrupt. The platform provides this information through the
+``plat_interrupt_type_to_line()`` API (described in the
+`Porting Guide`_). For example, on the FVP port when the platform uses an ARM GICv2
+interrupt controller, Secure-EL1 interrupts are signaled through the FIQ signal
+while Non-secure interrupts are signaled through the IRQ signal. This applies
+when execution is in either security state.
+
+Effect of mapping of several interrupt types to one signal
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It should be noted that if more than one interrupt type maps to a single
+interrupt signal, and if any one of the interrupt type sets **TEL3=1** for a
+particular security state, then interrupt signal will be routed to EL3 when in
+that security state. This means that all the other interrupt types using the
+same interrupt signal will be forced to the same routing model. This should be
+borne in mind when choosing the routing model for an interrupt type.
+
+For example, in ARM GICv3, when the execution context is Secure-EL1/
+Secure-EL0, both the EL3 and the non secure interrupt types map to the FIQ
+signal. So if either one of the interrupt type sets the routing model so
+that **TEL3=1** when **CSS=0**, the FIQ bit in ``SCR_EL3`` will be programmed to
+route the FIQ signal to EL3 when executing in Secure-EL1/Secure-EL0, thereby
+effectively routing the other interrupt type also to EL3.
+
+Assumptions in Interrupt Management Framework
+---------------------------------------------
+
+The framework makes the following assumptions to simplify its implementation.
+
+#. Although the framework has support for 2 types of secure interrupts (EL3
+ and Secure-EL1 interrupt), only interrupt controller architectures
+ like ARM GICv3 has architectural support for EL3 interrupts in the form of
+ Group 0 interrupts. In ARM GICv2, all secure interrupts are assumed to be
+ handled in Secure-EL1. They can be delivered to Secure-EL1 via EL3 but they
+ cannot be handled in EL3.
+
+#. Interrupt exceptions (``PSTATE.I`` and ``F`` bits) are masked during execution
+ in EL3.
+
+#. .. rubric:: Interrupt management
+ :name: interrupt-management
+
+ The following sections describe how interrupts are managed by the interrupt
+ handling framework. This entails:
+
+#. Providing an interface to allow registration of a handler and specification
+ of the routing model for a type of interrupt.
+
+#. Implementing support to hand control of an interrupt type to its registered
+ handler when the interrupt is generated.
+
+Both aspects of interrupt management involve various components in the secure
+software stack spanning from EL3 to Secure-EL1. These components are described
+in the section 2.1. The framework stores information associated with each type
+of interrupt in the following data structure.
+
+.. code:: c
+
+ typedef struct intr_type_desc {
+ interrupt_type_handler_t handler;
+ uint32_t flags;
+ uint32_t scr_el3[2];
+ } intr_type_desc_t;
+
+The ``flags`` field stores the routing model for the interrupt type in
+bits[1:0]. Bit[0] stores the routing model when execution is in the secure
+state. Bit[1] stores the routing model when execution is in the non-secure
+state. As mentioned in Section 1.2.2, a value of ``0`` implies that the interrupt
+should be targeted to the FEL. A value of ``1`` implies that it should be targeted
+to EL3. The remaining bits are reserved and SBZ. The helper macro
+``set_interrupt_rm_flag()`` should be used to set the bits in the ``flags``
+parameter.
+
+The ``scr_el3[2]`` field also stores the routing model but as a mapping of the
+model in the ``flags`` field to the corresponding bit in the ``SCR_EL3`` for each
+security state.
+
+The framework also depends upon the platform port to configure the interrupt
+controller to distinguish between secure and non-secure interrupts. The platform
+is expected to be aware of the secure devices present in the system and their
+associated interrupt numbers. It should configure the interrupt controller to
+enable the secure interrupts, ensure that their priority is always higher than
+the non-secure interrupts and target them to the primary CPU. It should also
+export the interface described in the `Porting Guide`_ to enable
+handling of interrupts.
+
+In the remainder of this document, for the sake of simplicity a ARM GICv2 system
+is considered and it is assumed that the FIQ signal is used to generate Secure-EL1
+interrupts and the IRQ signal is used to generate non-secure interrupts in either
+security state. EL3 interrupts are not considered.
+
+Software components
+-------------------
+
+Roles and responsibilities for interrupt management are sub-divided between the
+following components of software running in EL3 and Secure-EL1. Each component is
+briefly described below.
+
+#. EL3 Runtime Firmware. This component is common to all ports of the ARM
+ Trusted Firmware.
+
+#. Secure Payload Dispatcher (SPD) service. This service interfaces with the
+ Secure Payload (SP) software which runs in Secure-EL1/Secure-EL0 and is
+ responsible for switching execution between secure and non-secure states.
+ A switch is triggered by a Secure Monitor Call and it uses the APIs
+ exported by the Context management library to implement this functionality.
+ Switching execution between the two security states is a requirement for
+ interrupt management as well. This results in a significant dependency on
+ the SPD service. ARM Trusted firmware implements an example Test Secure
+ Payload Dispatcher (TSPD) service.
+
+ An SPD service plugs into the EL3 runtime firmware and could be common to
+ some ports of the ARM Trusted Firmware.
+
+#. Secure Payload (SP). On a production system, the Secure Payload corresponds
+ to a Secure OS which runs in Secure-EL1/Secure-EL0. It interfaces with the
+ SPD service to manage communication with non-secure software. ARM Trusted
+ Firmware implements an example secure payload called Test Secure Payload
+ (TSP) which runs only in Secure-EL1.
+
+ A Secure payload implementation could be common to some ports of the ARM
+ Trusted Firmware just like the SPD service.
+
+Interrupt registration
+----------------------
+
+This section describes in detail the role of each software component (see 2.1)
+during the registration of a handler for an interrupt type.
+
+EL3 runtime firmware
+~~~~~~~~~~~~~~~~~~~~
+
+This component declares the following prototype for a handler of an interrupt type.
+
+.. code:: c
+
+ typedef uint64_t (*interrupt_type_handler_t)(uint32_t id,
+ uint32_t flags,
+ void *handle,
+ void *cookie);
+
+The ``id`` is parameter is reserved and could be used in the future for passing
+the interrupt id of the highest pending interrupt only if there is a foolproof
+way of determining the id. Currently it contains ``INTR_ID_UNAVAILABLE``.
+
+The ``flags`` parameter contains miscellaneous information as follows.
+
+#. Security state, bit[0]. This bit indicates the security state of the lower
+ exception level when the interrupt was generated. A value of ``1`` means
+ that it was in the non-secure state. A value of ``0`` indicates that it was
+ in the secure state. This bit can be used by the handler to ensure that
+ interrupt was generated and routed as per the routing model specified
+ during registration.
+
+#. Reserved, bits[31:1]. The remaining bits are reserved for future use.
+
+The ``handle`` parameter points to the ``cpu_context`` structure of the current CPU
+for the security state specified in the ``flags`` parameter.
+
+Once the handler routine completes, execution will return to either the secure
+or non-secure state. The handler routine must return a pointer to
+``cpu_context`` structure of the current CPU for the target security state. On
+AArch64, this return value is currently ignored by the caller as the
+appropriate ``cpu_context`` to be used is expected to be set by the handler
+via the context management library APIs.
+A portable interrupt handler implementation must set the target context both in
+the structure pointed to by the returned pointer and via the context management
+library APIs. The handler should treat all error conditions as critical errors
+and take appropriate action within its implementation e.g. use assertion
+failures.
+
+The runtime firmware provides the following API for registering a handler for a
+particular type of interrupt. A Secure Payload Dispatcher service should use
+this API to register a handler for Secure-EL1 and optionally for non-secure
+interrupts. This API also requires the caller to specify the routing model for
+the type of interrupt.
+
+.. code:: c
+
+ int32_t register_interrupt_type_handler(uint32_t type,
+ interrupt_type_handler handler,
+ uint64_t flags);
+
+The ``type`` parameter can be one of the three interrupt types listed above i.e.
+``INTR_TYPE_S_EL1``, ``INTR_TYPE_NS`` & ``INTR_TYPE_EL3``. The ``flags`` parameter
+is as described in Section 2.
+
+The function will return ``0`` upon a successful registration. It will return
+``-EALREADY`` in case a handler for the interrupt type has already been
+registered. If the ``type`` is unrecognised or the ``flags`` or the ``handler`` are
+invalid it will return ``-EINVAL``.
+
+Interrupt routing is governed by the configuration of the ``SCR_EL3.FIQ/IRQ`` bits
+prior to entry into a lower exception level in either security state. The
+context management library maintains a copy of the ``SCR_EL3`` system register for
+each security state in the ``cpu_context`` structure of each CPU. It exports the
+following APIs to let EL3 Runtime Firmware program and retrieve the routing
+model for each security state for the current CPU. The value of ``SCR_EL3`` stored
+in the ``cpu_context`` is used by the ``el3_exit()`` function to program the
+``SCR_EL3`` register prior to returning from the EL3 exception level.
+
+.. code:: c
+
+ uint32_t cm_get_scr_el3(uint32_t security_state);
+ void cm_write_scr_el3_bit(uint32_t security_state,
+ uint32_t bit_pos,
+ uint32_t value);
+
+``cm_get_scr_el3()`` returns the value of the ``SCR_EL3`` register for the specified
+security state of the current CPU. ``cm_write_scr_el3()`` writes a ``0`` or ``1`` to
+the bit specified by ``bit_pos``. ``register_interrupt_type_handler()`` invokes
+``set_routing_model()`` API which programs the ``SCR_EL3`` according to the routing
+model using the ``cm_get_scr_el3()`` and ``cm_write_scr_el3_bit()`` APIs.
+
+It is worth noting that in the current implementation of the framework, the EL3
+runtime firmware is responsible for programming the routing model. The SPD is
+responsible for ensuring that the routing model has been adhered to upon
+receiving an interrupt.
+
+Secure payload dispatcher
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A SPD service is responsible for determining and maintaining the interrupt
+routing model supported by itself and the Secure Payload. It is also responsible
+for ferrying interrupts between secure and non-secure software depending upon
+the routing model. It could determine the routing model at build time or at
+runtime. It must use this information to register a handler for each interrupt
+type using the ``register_interrupt_type_handler()`` API in EL3 runtime firmware.
+
+If the routing model is not known to the SPD service at build time, then it must
+be provided by the SP as the result of its initialisation. The SPD should
+program the routing model only after SP initialisation has completed e.g. in the
+SPD initialisation function pointed to by the ``bl32_init`` variable.
+
+The SPD should determine the mechanism to pass control to the Secure Payload
+after receiving an interrupt from the EL3 runtime firmware. This information
+could either be provided to the SPD service at build time or by the SP at
+runtime.
+
+Test secure payload dispatcher behavior
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The TSPD only handles Secure-EL1 interrupts and is provided with the following
+routing model at build time.
+
+- Secure-EL1 interrupts are routed to EL3 when execution is in non-secure
+ state and are routed to the FEL when execution is in the secure state
+ i.e **CSS=0, TEL3=0** & **CSS=1, TEL3=1** for Secure-EL1 interrupts
+
+- When the build flag ``TSP_NS_INTR_ASYNC_PREEMPT`` is zero, the default routing
+ model is used for non-secure interrupts. They are routed to the FEL in
+ either security state i.e **CSS=0, TEL3=0** & **CSS=1, TEL3=0** for
+ Non-secure interrupts.
+
+- When the build flag ``TSP_NS_INTR_ASYNC_PREEMPT`` is defined to 1, then the
+ non secure interrupts are routed to EL3 when execution is in secure state
+ i.e **CSS=0, TEL3=1** for non-secure interrupts. This effectively preempts
+ Secure-EL1. The default routing model is used for non secure interrupts in
+ non-secure state. i.e **CSS=1, TEL3=0**.
+
+It performs the following actions in the ``tspd_init()`` function to fulfill the
+requirements mentioned earlier.
+
+#. It passes control to the Test Secure Payload to perform its
+ initialisation. The TSP provides the address of the vector table
+ ``tsp_vectors`` in the SP which also includes the handler for Secure-EL1
+ interrupts in the ``sel1_intr_entry`` field. The TSPD passes control to the TSP at
+ this address when it receives a Secure-EL1 interrupt.
+
+ The handover agreement between the TSP and the TSPD requires that the TSPD
+ masks all interrupts (``PSTATE.DAIF`` bits) when it calls
+ ``tsp_sel1_intr_entry()``. The TSP has to preserve the callee saved general
+ purpose, SP\_EL1/Secure-EL0, LR, VFP and system registers. It can use
+ ``x0-x18`` to enable its C runtime.
+
+#. The TSPD implements a handler function for Secure-EL1 interrupts. This
+ function is registered with the EL3 runtime firmware using the
+ ``register_interrupt_type_handler()`` API as follows
+
+ .. code:: c
+
+ /* Forward declaration */
+ interrupt_type_handler tspd_secure_el1_interrupt_handler;
+ int32_t rc, flags = 0;
+ set_interrupt_rm_flag(flags, NON_SECURE);
+ rc = register_interrupt_type_handler(INTR_TYPE_S_EL1,
+ tspd_secure_el1_interrupt_handler,
+ flags);
+ if (rc)
+ panic();
+
+#. When the build flag ``TSP_NS_INTR_ASYNC_PREEMPT`` is defined to 1, the TSPD
+ implements a handler function for non-secure interrupts. This function is
+ registered with the EL3 runtime firmware using the
+ ``register_interrupt_type_handler()`` API as follows
+
+ .. code:: c
+
+ /* Forward declaration */
+ interrupt_type_handler tspd_ns_interrupt_handler;
+ int32_t rc, flags = 0;
+ set_interrupt_rm_flag(flags, SECURE);
+ rc = register_interrupt_type_handler(INTR_TYPE_NS,
+ tspd_ns_interrupt_handler,
+ flags);
+ if (rc)
+ panic();
+
+Secure payload
+~~~~~~~~~~~~~~
+
+A Secure Payload must implement an interrupt handling framework at Secure-EL1
+(Secure-EL1 IHF) to support its chosen interrupt routing model. Secure payload
+execution will alternate between the below cases.
+
+#. In the code where IRQ, FIQ or both interrupts are enabled, if an interrupt
+ type is targeted to the FEL, then it will be routed to the Secure-EL1
+ exception vector table. This is defined as the **asynchronous mode** of
+ handling interrupts. This mode applies to both Secure-EL1 and non-secure
+ interrupts.
+
+#. In the code where both interrupts are disabled, if an interrupt type is
+ targeted to the FEL, then execution will eventually migrate to the
+ non-secure state. Any non-secure interrupts will be handled as described
+ in the routing model where **CSS=1 and TEL3=0**. Secure-EL1 interrupts
+ will be routed to EL3 (as per the routing model where **CSS=1 and
+ TEL3=1**) where the SPD service will hand them to the SP. This is defined
+ as the **synchronous mode** of handling interrupts.
+
+The interrupt handling framework implemented by the SP should support one or
+both these interrupt handling models depending upon the chosen routing model.
+
+The following list briefly describes how the choice of a valid routing model
+(See 1.2.3) effects the implementation of the Secure-EL1 IHF. If the choice of
+the interrupt routing model is not known to the SPD service at compile time,
+then the SP should pass this information to the SPD service at runtime during
+its initialisation phase.
+
+As mentioned earlier, a ARM GICv2 system is considered and it is assumed that
+the FIQ signal is used to generate Secure-EL1 interrupts and the IRQ signal
+is used to generate non-secure interrupts in either security state.
+
+Secure payload IHF design w.r.t secure-EL1 interrupts
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. **CSS=0, TEL3=0**. If ``PSTATE.F=0``, Secure-EL1 interrupts will be
+ triggered at one of the Secure-EL1 FIQ exception vectors. The Secure-EL1
+ IHF should implement support for handling FIQ interrupts asynchronously.
+
+ If ``PSTATE.F=1`` then Secure-EL1 interrupts will be handled as per the
+ synchronous interrupt handling model. The SP could implement this scenario
+ by exporting a separate entrypoint for Secure-EL1 interrupts to the SPD
+ service during the registration phase. The SPD service would also need to
+ know the state of the system, general purpose and the ``PSTATE`` registers
+ in which it should arrange to return execution to the SP. The SP should
+ provide this information in an implementation defined way during the
+ registration phase if it is not known to the SPD service at build time.
+
+#. **CSS=1, TEL3=1**. Interrupts are routed to EL3 when execution is in
+ non-secure state. They should be handled through the synchronous interrupt
+ handling model as described in 1. above.
+
+#. **CSS=0, TEL3=1**. Secure-EL1 interrupts are routed to EL3 when execution
+ is in secure state. They will not be visible to the SP. The ``PSTATE.F`` bit
+ in Secure-EL1/Secure-EL0 will not mask FIQs. The EL3 runtime firmware will
+ call the handler registered by the SPD service for Secure-EL1 interrupts.
+ Secure-EL1 IHF should then handle all Secure-EL1 interrupt through the
+ synchronous interrupt handling model described in 1. above.
+
+Secure payload IHF design w.r.t non-secure interrupts
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+#. **CSS=0, TEL3=0**. If ``PSTATE.I=0``, non-secure interrupts will be
+ triggered at one of the Secure-EL1 IRQ exception vectors . The Secure-EL1
+ IHF should co-ordinate with the SPD service to transfer execution to the
+ non-secure state where the interrupt should be handled e.g the SP could
+ allocate a function identifier to issue a SMC64 or SMC32 to the SPD
+ service which indicates that the SP execution has been preempted by a
+ non-secure interrupt. If this function identifier is not known to the SPD
+ service at compile time then the SP could provide it during the
+ registration phase.
+
+ If ``PSTATE.I=1`` then the non-secure interrupt will pend until execution
+ resumes in the non-secure state.
+
+#. **CSS=0, TEL3=1**. Non-secure interrupts are routed to EL3. They will not
+ be visible to the SP. The ``PSTATE.I`` bit in Secure-EL1/Secure-EL0 will
+ have not effect. The SPD service should register a non-secure interrupt
+ handler which should save the SP state correctly and resume execution in
+ the non-secure state where the interrupt will be handled. The Secure-EL1
+ IHF does not need to take any action.
+
+#. **CSS=1, TEL3=0**. Non-secure interrupts are handled in the FEL in
+ non-secure state (EL1/EL2) and are not visible to the SP. This routing
+ model does not affect the SP behavior.
+
+A Secure Payload must also ensure that all Secure-EL1 interrupts are correctly
+configured at the interrupt controller by the platform port of the EL3 runtime
+firmware. It should configure any additional Secure-EL1 interrupts which the EL3
+runtime firmware is not aware of through its platform port.
+
+Test secure payload behavior
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The routing model for Secure-EL1 and non-secure interrupts chosen by the TSP is
+described in Section 2.2.2. It is known to the TSPD service at build time.
+
+The TSP implements an entrypoint (``tsp_sel1_intr_entry()``) for handling Secure-EL1
+interrupts taken in non-secure state and routed through the TSPD service
+(synchronous handling model). It passes the reference to this entrypoint via
+``tsp_vectors`` to the TSPD service.
+
+The TSP also replaces the default exception vector table referenced through the
+``early_exceptions`` variable, with a vector table capable of handling FIQ and IRQ
+exceptions taken at the same (Secure-EL1) exception level. This table is
+referenced through the ``tsp_exceptions`` variable and programmed into the
+VBAR\_EL1. It caters for the asynchronous handling model.
+
+The TSP also programs the Secure Physical Timer in the ARM Generic Timer block
+to raise a periodic interrupt (every half a second) for the purpose of testing
+interrupt management across all the software components listed in 2.1
+
+Interrupt handling
+------------------
+
+This section describes in detail the role of each software component (see
+Section 2.1) in handling an interrupt of a particular type.
+
+EL3 runtime firmware
+~~~~~~~~~~~~~~~~~~~~
+
+The EL3 runtime firmware populates the IRQ and FIQ exception vectors referenced
+by the ``runtime_exceptions`` variable as follows.
+
+#. IRQ and FIQ exceptions taken from the current exception level with
+ ``SP_EL0`` or ``SP_EL3`` are reported as irrecoverable error conditions. As
+ mentioned earlier, EL3 runtime firmware always executes with the
+ ``PSTATE.I`` and ``PSTATE.F`` bits set.
+
+#. The following text describes how the IRQ and FIQ exceptions taken from a
+ lower exception level using AArch64 or AArch32 are handled.
+
+When an interrupt is generated, the vector for each interrupt type is
+responsible for:
+
+#. Saving the entire general purpose register context (x0-x30) immediately
+ upon exception entry. The registers are saved in the per-cpu ``cpu_context``
+ data structure referenced by the ``SP_EL3``\ register.
+
+#. Saving the ``ELR_EL3``, ``SP_EL0`` and ``SPSR_EL3`` system registers in the
+ per-cpu ``cpu_context`` data structure referenced by the ``SP_EL3`` register.
+
+#. Switching to the C runtime stack by restoring the ``CTX_RUNTIME_SP`` value
+ from the per-cpu ``cpu_context`` data structure in ``SP_EL0`` and
+ executing the ``msr spsel, #0`` instruction.
+
+#. Determining the type of interrupt. Secure-EL1 interrupts will be signaled
+ at the FIQ vector. Non-secure interrupts will be signaled at the IRQ
+ vector. The platform should implement the following API to determine the
+ type of the pending interrupt.
+
+ .. code:: c
+
+ uint32_t plat_ic_get_interrupt_type(void);
+
+ It should return either ``INTR_TYPE_S_EL1`` or ``INTR_TYPE_NS``.
+
+#. Determining the handler for the type of interrupt that has been generated.
+ The following API has been added for this purpose.
+
+ .. code:: c
+
+ interrupt_type_handler get_interrupt_type_handler(uint32_t interrupt_type);
+
+ It returns the reference to the registered handler for this interrupt
+ type. The ``handler`` is retrieved from the ``intr_type_desc_t`` structure as
+ described in Section 2. ``NULL`` is returned if no handler has been
+ registered for this type of interrupt. This scenario is reported as an
+ irrecoverable error condition.
+
+#. Calling the registered handler function for the interrupt type generated.
+ The ``id`` parameter is set to ``INTR_ID_UNAVAILABLE`` currently. The id along
+ with the current security state and a reference to the ``cpu_context_t``
+ structure for the current security state are passed to the handler function
+ as its arguments.
+
+ The handler function returns a reference to the per-cpu ``cpu_context_t``
+ structure for the target security state.
+
+#. Calling ``el3_exit()`` to return from EL3 into a lower exception level in
+ the security state determined by the handler routine. The ``el3_exit()``
+ function is responsible for restoring the register context from the
+ ``cpu_context_t`` data structure for the target security state.
+
+Secure payload dispatcher
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Interrupt entry
+^^^^^^^^^^^^^^^
+
+The SPD service begins handling an interrupt when the EL3 runtime firmware calls
+the handler function for that type of interrupt. The SPD service is responsible
+for the following:
+
+#. Validating the interrupt. This involves ensuring that the interrupt was
+ generating according to the interrupt routing model specified by the SPD
+ service during registration. It should use the security state of the
+ exception level (passed in the ``flags`` parameter of the handler) where
+ the interrupt was taken from to determine this. If the interrupt is not
+ recognised then the handler should treat it as an irrecoverable error
+ condition.
+
+ A SPD service can register a handler for Secure-EL1 and/or Non-secure
+ interrupts. A non-secure interrupt should never be routed to EL3 from
+ from non-secure state. Also if a routing model is chosen where Secure-EL1
+ interrupts are routed to S-EL1 when execution is in Secure state, then a
+ S-EL1 interrupt should never be routed to EL3 from secure state. The handler
+ could use the security state flag to check this.
+
+#. Determining whether a context switch is required. This depends upon the
+ routing model and interrupt type. For non secure and S-EL1 interrupt,
+ if the security state of the execution context where the interrupt was
+ generated is not the same as the security state required for handling
+ the interrupt, a context switch is required. The following 2 cases
+ require a context switch from secure to non-secure or vice-versa:
+
+ #. A Secure-EL1 interrupt taken from the non-secure state should be
+ routed to the Secure Payload.
+
+ #. A non-secure interrupt taken from the secure state should be routed
+ to the last known non-secure exception level.
+
+ The SPD service must save the system register context of the current
+ security state. It must then restore the system register context of the
+ target security state. It should use the ``cm_set_next_eret_context()`` API
+ to ensure that the next ``cpu_context`` to be restored is of the target
+ security state.
+
+ If the target state is secure then execution should be handed to the SP as
+ per the synchronous interrupt handling model it implements. A Secure-EL1
+ interrupt can be routed to EL3 while execution is in the SP. This implies
+ that SP execution can be preempted while handling an interrupt by a
+ another higher priority Secure-EL1 interrupt or a EL3 interrupt. The SPD
+ service should be able to handle this preemption or manage secure interrupt
+ priorities before handing control to the SP.
+
+#. Setting the return value of the handler to the per-cpu ``cpu_context`` if
+ the interrupt has been successfully validated and ready to be handled at a
+ lower exception level.
+
+The routing model allows non-secure interrupts to interrupt Secure-EL1 when in
+secure state if it has been configured to do so. The SPD service and the SP
+should implement a mechanism for routing these interrupts to the last known
+exception level in the non-secure state. The former should save the SP context,
+restore the non-secure context and arrange for entry into the non-secure state
+so that the interrupt can be handled.
+
+Interrupt exit
+^^^^^^^^^^^^^^
+
+When the Secure Payload has finished handling a Secure-EL1 interrupt, it could
+return control back to the SPD service through a SMC32 or SMC64. The SPD service
+should handle this secure monitor call so that execution resumes in the
+exception level and the security state from where the Secure-EL1 interrupt was
+originally taken.
+
+Test secure payload dispatcher Secure-EL1 interrupt handling
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The example TSPD service registers a handler for Secure-EL1 interrupts taken
+from the non-secure state. During execution in S-EL1, the TSPD expects that the
+Secure-EL1 interrupts are handled in S-EL1 by TSP. Its handler
+``tspd_secure_el1_interrupt_handler()`` expects only to be invoked for Secure-EL1
+originating from the non-secure state. It takes the following actions upon being
+invoked.
+
+#. It uses the security state provided in the ``flags`` parameter to ensure
+ that the secure interrupt originated from the non-secure state. It asserts
+ if this is not the case.
+
+#. It saves the system register context for the non-secure state by calling
+ ``cm_el1_sysregs_context_save(NON_SECURE);``.
+
+#. It sets the ``ELR_EL3`` system register to ``tsp_sel1_intr_entry`` and sets the
+ ``SPSR_EL3.DAIF`` bits in the secure CPU context. It sets ``x0`` to
+ ``TSP_HANDLE_SEL1_INTR_AND_RETURN``. If the TSP was preempted earlier by a non
+ secure interrupt during ``yielding`` SMC processing, save the registers that
+ will be trashed, which is the ``ELR_EL3`` and ``SPSR_EL3``, in order to be able
+ to re-enter TSP for Secure-EL1 interrupt processing. It does not need to
+ save any other secure context since the TSP is expected to preserve it
+ (see Section 2.2.2.1).
+
+#. It restores the system register context for the secure state by calling
+ ``cm_el1_sysregs_context_restore(SECURE);``.
+
+#. It ensures that the secure CPU context is used to program the next
+ exception return from EL3 by calling ``cm_set_next_eret_context(SECURE);``.
+
+#. It returns the per-cpu ``cpu_context`` to indicate that the interrupt can
+ now be handled by the SP. ``x1`` is written with the value of ``elr_el3``
+ register for the non-secure state. This information is used by the SP for
+ debugging purposes.
+
+The figure below describes how the interrupt handling is implemented by the TSPD
+when a Secure-EL1 interrupt is generated when execution is in the non-secure
+state.
+
+|Image 1|
+
+The TSP issues an SMC with ``TSP_HANDLED_S_EL1_INTR`` as the function identifier to
+signal completion of interrupt handling.
+
+The TSPD service takes the following actions in ``tspd_smc_handler()`` function
+upon receiving an SMC with ``TSP_HANDLED_S_EL1_INTR`` as the function identifier:
+
+#. It ensures that the call originated from the secure state otherwise
+ execution returns to the non-secure state with ``SMC_UNK`` in ``x0``.
+
+#. It restores the saved ``ELR_EL3`` and ``SPSR_EL3`` system registers back to
+ the secure CPU context (see step 3 above) in case the TSP had been preempted
+ by a non secure interrupt earlier.
+
+#. It restores the system register context for the non-secure state by
+ calling ``cm_el1_sysregs_context_restore(NON_SECURE)``.
+
+#. It ensures that the non-secure CPU context is used to program the next
+ exception return from EL3 by calling ``cm_set_next_eret_context(NON_SECURE)``.
+
+#. ``tspd_smc_handler()`` returns a reference to the non-secure ``cpu_context``
+ as the return value.
+
+Test secure payload dispatcher non-secure interrupt handling
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The TSP in Secure-EL1 can be preempted by a non-secure interrupt during
+``yielding`` SMC processing or by a higher priority EL3 interrupt during
+Secure-EL1 interrupt processing. Currently only non-secure interrupts can
+cause preemption of TSP since there are no EL3 interrupts in the
+system.
+
+It should be noted that while TSP is preempted, the TSPD only allows entry into
+the TSP either for Secure-EL1 interrupt handling or for resuming the preempted
+``yielding`` SMC in response to the ``TSP_FID_RESUME`` SMC from the normal world.
+(See Section 3).
+
+The non-secure interrupt triggered in Secure-EL1 during ``yielding`` SMC processing
+can be routed to either EL3 or Secure-EL1 and is controlled by build option
+``TSP_NS_INTR_ASYNC_PREEMPT`` (see Section 2.2.2.1). If the build option is set,
+the TSPD will set the routing model for the non-secure interrupt to be routed to
+EL3 from secure state i.e. **TEL3=1, CSS=0** and registers
+``tspd_ns_interrupt_handler()`` as the non-secure interrupt handler. The
+``tspd_ns_interrupt_handler()`` on being invoked ensures that the interrupt
+originated from the secure state and disables routing of non-secure interrupts
+from secure state to EL3. This is to prevent further preemption (by a non-secure
+interrupt) when TSP is reentered for handling Secure-EL1 interrupts that
+triggered while execution was in the normal world. The
+``tspd_ns_interrupt_handler()`` then invokes ``tspd_handle_sp_preemption()`` for
+further handling.
+
+If the ``TSP_NS_INTR_ASYNC_PREEMPT`` build option is zero (default), the default
+routing model for non-secure interrupt in secure state is in effect
+i.e. **TEL3=0, CSS=0**. During ``yielding`` SMC processing, the IRQ
+exceptions are unmasked i.e. ``PSTATE.I=0``, and a non-secure interrupt will
+trigger at Secure-EL1 IRQ exception vector. The TSP saves the general purpose
+register context and issues an SMC with ``TSP_PREEMPTED`` as the function
+identifier to signal preemption of TSP. The TSPD SMC handler,
+``tspd_smc_handler()``, ensures that the SMC call originated from the
+secure state otherwise execution returns to the non-secure state with
+``SMC_UNK`` in ``x0``. It then invokes ``tspd_handle_sp_preemption()`` for
+further handling.
+
+The ``tspd_handle_sp_preemption()`` takes the following actions upon being
+invoked:
+
+#. It saves the system register context for the secure state by calling
+ ``cm_el1_sysregs_context_save(SECURE)``.
+
+#. It restores the system register context for the non-secure state by
+ calling ``cm_el1_sysregs_context_restore(NON_SECURE)``.
+
+#. It ensures that the non-secure CPU context is used to program the next
+ exception return from EL3 by calling ``cm_set_next_eret_context(NON_SECURE)``.
+
+#. ``SMC_PREEMPTED`` is set in x0 and return to non secure state after
+ restoring non secure context.
+
+The Normal World is expected to resume the TSP after the ``yielding`` SMC preemption
+by issuing an SMC with ``TSP_FID_RESUME`` as the function identifier (see section 3).
+The TSPD service takes the following actions in ``tspd_smc_handler()`` function
+upon receiving this SMC:
+
+#. It ensures that the call originated from the non secure state. An
+ assertion is raised otherwise.
+
+#. Checks whether the TSP needs a resume i.e check if it was preempted. It
+ then saves the system register context for the non-secure state by calling
+ ``cm_el1_sysregs_context_save(NON_SECURE)``.
+
+#. Restores the secure context by calling
+ ``cm_el1_sysregs_context_restore(SECURE)``
+
+#. It ensures that the secure CPU context is used to program the next
+ exception return from EL3 by calling ``cm_set_next_eret_context(SECURE)``.
+
+#. ``tspd_smc_handler()`` returns a reference to the secure ``cpu_context`` as the
+ return value.
+
+The figure below describes how the TSP/TSPD handle a non-secure interrupt when
+it is generated during execution in the TSP with ``PSTATE.I`` = 0 when the
+``TSP_NS_INTR_ASYNC_PREEMPT`` build flag is 0.
+
+|Image 2|
+
+Secure payload
+~~~~~~~~~~~~~~
+
+The SP should implement one or both of the synchronous and asynchronous
+interrupt handling models depending upon the interrupt routing model it has
+chosen (as described in 2.2.3).
+
+In the synchronous model, it should begin handling a Secure-EL1 interrupt after
+receiving control from the SPD service at an entrypoint agreed upon during build
+time or during the registration phase. Before handling the interrupt, the SP
+should save any Secure-EL1 system register context which is needed for resuming
+normal execution in the SP later e.g. ``SPSR_EL1,``\ ELR\_EL1\`. After handling the
+interrupt, the SP could return control back to the exception level and security
+state where the interrupt was originally taken from. The SP should use an SMC32
+or SMC64 to ask the SPD service to do this.
+
+In the asynchronous model, the Secure Payload is responsible for handling
+non-secure and Secure-EL1 interrupts at the IRQ and FIQ vectors in its exception
+vector table when ``PSTATE.I`` and ``PSTATE.F`` bits are 0. As described earlier,
+when a non-secure interrupt is generated, the SP should coordinate with the SPD
+service to pass control back to the non-secure state in the last known exception
+level. This will allow the non-secure interrupt to be handled in the non-secure
+state.
+
+Test secure payload behavior
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The TSPD hands control of a Secure-EL1 interrupt to the TSP at the
+``tsp_sel1_intr_entry()``. The TSP handles the interrupt while ensuring that the
+handover agreement described in Section 2.2.2.1 is maintained. It updates some
+statistics by calling ``tsp_update_sync_sel1_intr_stats()``. It then calls
+``tsp_common_int_handler()`` which.
+
+#. Checks whether the interrupt is the secure physical timer interrupt. It
+ uses the platform API ``plat_ic_get_pending_interrupt_id()`` to get the
+ interrupt number. If it is not the secure physical timer interrupt, then
+ that means that a higher priority interrupt has preempted it. Invoke
+ ``tsp_handle_preemption()`` to handover control back to EL3 by issuing
+ an SMC with ``TSP_PREEMPTED`` as the function identifier.
+
+#. Handles the secure timer interrupt interrupt by acknowledging it using the
+ ``plat_ic_acknowledge_interrupt()`` platform API, calling
+ ``tsp_generic_timer_handler()`` to reprogram the secure physical generic
+ timer and calling the ``plat_ic_end_of_interrupt()`` platform API to signal
+ end of interrupt processing.
+
+The TSP passes control back to the TSPD by issuing an SMC64 with
+``TSP_HANDLED_S_EL1_INTR`` as the function identifier.
+
+The TSP handles interrupts under the asynchronous model as follows.
+
+#. Secure-EL1 interrupts are handled by calling the ``tsp_common_int_handler()``
+ function. The function has been described above.
+
+#. Non-secure interrupts are handled by by calling the ``tsp_common_int_handler()``
+ function which ends up invoking ``tsp_handle_preemption()`` and issuing an
+ SMC64 with ``TSP_PREEMPTED`` as the function identifier. Execution resumes at
+ the instruction that follows this SMC instruction when the TSPD hands
+ control to the TSP in response to an SMC with ``TSP_FID_RESUME`` as the
+ function identifier from the non-secure state (see section 2.3.2.4).
+
+#. .. rubric:: Other considerations
+ :name: other-considerations
+
+Implication of preempted SMC on Non-Secure Software
+---------------------------------------------------
+
+A ``yielding`` SMC call to Secure payload can be preempted by a non-secure
+interrupt and the execution can return to the non-secure world for handling
+the interrupt (For details on ``yielding`` SMC refer `SMC calling convention`_).
+In this case, the SMC call has not completed its execution and the execution
+must return back to the secure payload to resume the preempted SMC call.
+This can be achieved by issuing an SMC call which instructs to resume the
+preempted SMC.
+
+A ``fast`` SMC cannot be preempted and hence this case will not happen for
+a fast SMC call.
+
+In the Test Secure Payload implementation, ``TSP_FID_RESUME`` is designated
+as the resume SMC FID. It is important to note that ``TSP_FID_RESUME`` is a
+``yielding`` SMC which means it too can be be preempted. The typical non
+secure software sequence for issuing a ``yielding`` SMC would look like this,
+assuming ``P.STATE.I=0`` in the non secure state :
+
+.. code:: c
+
+ int rc;
+ rc = smc(TSP_YIELD_SMC_FID, ...); /* Issue a Yielding SMC call */
+ /* The pending non-secure interrupt is handled by the interrupt handler
+ and returns back here. */
+ while (rc == SMC_PREEMPTED) { /* Check if the SMC call is preempted */
+ rc = smc(TSP_FID_RESUME); /* Issue resume SMC call */
+ }
+
+The ``TSP_YIELD_SMC_FID`` is any ``yielding`` SMC function identifier and the smc()
+function invokes a SMC call with the required arguments. The pending non-secure
+interrupt causes an IRQ exception and the IRQ handler registered at the
+exception vector handles the non-secure interrupt and returns. The return value
+from the SMC call is tested for ``SMC_PREEMPTED`` to check whether it is
+preempted. If it is, then the resume SMC call ``TSP_FID_RESUME`` is issued. The
+return value of the SMC call is tested again to check if it is preempted.
+This is done in a loop till the SMC call succeeds or fails. If a ``yielding``
+SMC is preempted, until it is resumed using ``TSP_FID_RESUME`` SMC and
+completed, the current TSPD prevents any other SMC call from re-entering
+TSP by returning ``SMC_UNK`` error.
+
+--------------
+
+*Copyright (c) 2014-2015, ARM Limited and Contributors. All rights reserved.*
+
+.. _Porting Guide: ./porting-guide.rst
+.. _SMC calling convention: http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html
+
+.. |Image 1| image:: diagrams/sec-int-handling.png?raw=true
+.. |Image 2| image:: diagrams/non-sec-int-handling.png?raw=true
--- /dev/null
+Description
+===========
+
+HiKey is one of 96boards. Hisilicon Kirin6220 processor is installed on HiKey.
+
+More information are listed in `link`_.
+
+How to build
+============
+
+Code Locations
+--------------
+
+- ARM Trusted Firmware:
+ `link <https://github.com/ARM-software/arm-trusted-firmware>`__
+
+- edk2:
+ `link <https://github.com/96boards-hikey/edk2/tree/testing/hikey960_v2.5>`__
+
+- OpenPlatformPkg:
+ `link <https://github.com/96boards-hikey/OpenPlatformPkg/tree/testing/hikey960_v1.3.4>`__
+
+- l-loader:
+ `link <https://github.com/96boards-hikey/l-loader/tree/testing/hikey960_v1.2>`__
+
+- uefi-tools:
+ `link <https://github.com/96boards-hikey/uefi-tools/tree/testing/hikey960_v1>`__
+
+- atf-fastboot:
+ `link <https://github.com/96boards-hikey/atf-fastboot/tree/master>`__
+
+Build Procedure
+---------------
+
+- Fetch all the above repositories into local host.
+ Make all the repositories in the same ${BUILD\_PATH}.
+
+- Create the symbol link to OpenPlatformPkg in edk2.
+
+ .. code:: shell
+
+ $cd ${BUILD_PATH}/edk2
+ $ln -sf ../OpenPlatformPkg
+
+- Prepare AARCH64 && AARCH32 toolchain. Prepare python.
+
+- If your hikey hardware is built by CircuitCo, update *uefi-tools/platform.config* first. *(optional)*
+ **Uncomment the below sentence. Otherwise, UEFI can't output messages on serial
+ console on hikey.**
+
+ .. code:: shell
+
+ BUILDFLAGS=-DSERIAL_BASE=0xF8015000
+
+ If your hikey hardware is built by LeMarker, nothing to do.
+
+- Build it as debug mode. Create your own build script file or you could refer to **build\_uefi.sh** in l-loader git repository.
+
+ .. code:: shell
+
+ BUILD_OPTION=DEBUG
+ export AARCH64_TOOLCHAIN=GCC5
+ export UEFI_TOOLS_DIR=${BUILD_PATH}/uefi-tools
+ export EDK2_DIR=${BUILD_PATH}/edk2
+ EDK2_OUTPUT_DIR=${EDK2_DIR}/Build/HiKey/${BUILD_OPTION}_${AARCH64_TOOLCHAIN}
+ # Build fastboot for ARM Trust Firmware. It's used for recovery mode.
+ cd ${BUILD_PATH}/atf-fastboot
+ CROSS_COMPILE=aarch64-linux-gnu- make PLAT=hikey DEBUG=1
+ # Convert DEBUG/RELEASE to debug/release
+ FASTBOOT_BUILD_OPTION=$(echo ${BUILD_OPTION} | tr '[A-Z]' '[a-z]')
+ cd ${EDK2_DIR}
+ # Build UEFI & ARM Trust Firmware
+ ${UEFI_TOOLS_DIR}/uefi-build.sh -b ${BUILD_OPTION} -a ../arm-trusted-firmware hikey
+ # Generate l-loader.bin
+ cd ${BUILD_PATH}/l-loader
+ ln -sf ${EDK2_OUTPUT_DIR}/FV/bl1.bin
+ ln -sf ${EDK2_OUTPUT_DIR}/FV/fip.bin
+ ln -sf ${BUILD_PATH}/atf-fastboot/build/hikey/${FASTBOOT_BUILD_OPTION}/bl1.bin fastboot.bin
+ python gen_loader.py -o l-loader.bin --img_bl1=bl1.bin --img_ns_bl1u=BL33_AP_UEFI.fd
+ arm-linux-gnueabihf-gcc -c -o start.o start.S
+ arm-linux-gnueabihf-ld -Bstatic -Tl-loader.lds -Ttext 0xf9800800 start.o -o loader
+ arm-linux-gnueabihf-objcopy -O binary loader temp
+ python gen_loader_hikey.py -o l-loader.bin --img_loader=temp --img_bl1=bl1.bin --img_ns_bl1u=fastboot.bin
+
+- Generate partition table for aosp. The eMMC capacity is either 4GB or 8GB. Just change "aosp-4g" to "linux-4g" for debian.
+
+ .. code:: shell
+
+ $PTABLE=aosp-4g SECTOR_SIZE=512 bash -x generate_ptable.sh
+
+Setup Console
+-------------
+
+- Install ser2net. Use telnet as the console since UEFI fails to display Boot Manager GUI in minicom. **If you don't need Boot Manager GUI, just ignore this section.**
+
+ .. code:: shell
+
+ $sudo apt-get install ser2net
+
+- Configure ser2net.
+
+ .. code:: shell
+
+ $sudo vi /etc/ser2net.conf
+
+ Append one line for serial-over-USB in below.
+ *#ser2net.conf*
+
+ .. code:: shell
+
+ 2004:telnet:0:/dev/ttyUSB0:115200 8DATABITS NONE 1STOPBIT banner
+
+- Open the console.
+
+ .. code:: shell
+
+ $telnet localhost 2004
+
+ And you could open the console remotely, too.
+
+Flush images in recovery mode
+-----------------------------
+
+- Make sure Pin3-Pin4 on J15 are connected for recovery mode. Then power on HiKey.
+
+- Remove the modemmanager package. This package may cause the idt tool failure.
+
+ .. code:: shell
+
+ $sudo apt-get purge modemmanager
+
+- Run the command to download l-loader.bin into HiKey.
+
+ .. code:: shell
+
+ $sudo python hisi-idt.py -d /dev/ttyUSB1 --img1 l-loader.bin
+
+- Update images. All aosp or debian images could be fetched from `link <https://builds.96boards.org/>`__.
+
+ .. code:: shell
+
+ $sudo fastboot flash ptable prm_ptable.img
+ $sudo fastboot flash fastboot fip.bin
+ $sudo fastboot flash boot boot.img
+ $sudo fastboot flash cache cache.img
+ $sudo fastboot flash system system.img
+ $sudo fastboot flash userdata userdata.img
+
+Boot UEFI in normal mode
+------------------------
+
+- Make sure Pin3-Pin4 on J15 are open for normal boot mode. Then power on HiKey.
+
+- Reference `link <https://github.com/96boards-hikey/tools-images-hikey960/blob/master/build-from-source/README-ATF-UEFI-build-from-source.md>`__
+
+.. _link: https://github.com/96boards/documentation/blob/master/ConsumerEdition/HiKey/Quickstart/README.md
--- /dev/null
+Description
+===========
+
+HiKey960 is one of 96boards. Hisilicon Hi3660 processor is installed on HiKey960.
+
+More information are listed in `link`_.
+
+How to build
+============
+
+Code Locations
+--------------
+
+- ARM Trusted Firmware:
+ `link <https://github.com/ARM-software/arm-trusted-firmware>`__
+
+- edk2:
+ `link <https://github.com/96boards-hikey/edk2/tree/testing/hikey960_v2.5>`__
+
+- OpenPlatformPkg:
+ `link <https://github.com/96boards-hikey/OpenPlatformPkg/tree/testing/hikey960_v1.3.4>`__
+
+- l-loader:
+ `link <https://github.com/96boards-hikey/l-loader/tree/testing/hikey960_v1.2>`__
+
+- uefi-tools:
+ `link <https://github.com/96boards-hikey/uefi-tools/tree/hikey960_v1>`__
+
+Build Procedure
+---------------
+
+- Fetch all the above 5 repositories into local host.
+ Make all the repositories in the same ${BUILD\_PATH}.
+
+- Create the symbol link to OpenPlatformPkg in edk2.
+
+ .. code:: shell
+
+ $cd ${BUILD_PATH}/edk2
+ $ln -sf ../OpenPlatformPkg
+
+- Prepare AARCH64 toolchain.
+
+- If your hikey960 hardware is v1, update *uefi-tools/platform.config* first. *(optional)*
+ **Uncomment the below sentence. Otherwise, UEFI can't output messages on serial
+ console on hikey960 v1.**
+
+ .. code:: shell
+
+ BUILDFLAGS=-DSERIAL_BASE=0xFDF05000
+
+ If your hikey960 hardware is v2 or newer, nothing to do.
+
+- Build it as debug mode. Create script file for build.
+
+ .. code:: shell
+
+ BUILD_OPTION=DEBUG
+ export AARCH64_TOOLCHAIN=GCC48
+ export UEFI_TOOLS_DIR=${BUILD_PATH}/uefi-tools
+ export EDK2_DIR=${BUILD_PATH}/edk2
+ EDK2_OUTPUT_DIR=${EDK2_DIR}/Build/HiKey960/${BUILD_OPTION}_${AARCH64_TOOLCHAIN}
+ cd ${EDK2_DIR}
+ # Build UEFI & ARM Trust Firmware
+ ${UEFI_TOOLS_DIR}/uefi-build.sh -b ${BUILD_OPTION} -a ../arm-trusted-firmware hikey960
+ # Generate l-loader.bin
+ cd ${BUILD_PATH}/l-loader
+ ln -sf ${EDK2_OUTPUT_DIR}/FV/bl1.bin
+ ln -sf ${EDK2_OUTPUT_DIR}/FV/fip.bin
+ ln -sf ${EDK2_OUTPUT_DIR}/FV/BL33_AP_UEFI.fd
+ python gen_loader.py -o l-loader.bin --img_bl1=bl1.bin --img_ns_bl1u=BL33_AP_UEFI.fd
+
+- Generate partition table.
+ *Make sure that you're using the sgdisk in the l-loader directory.*
+
+ .. code:: shell
+
+ $PTABLE=aosp-32g SECTOR_SIZE=4096 SGDISK=./sgdisk bash -x generate_ptable.sh
+
+Setup Console
+-------------
+
+- Install ser2net. Use telnet as the console since UEFI will output window
+ that fails to display in minicom.
+
+ .. code:: shell
+
+ $sudo apt-get install ser2net
+
+- Configure ser2net.
+
+ .. code:: shell
+
+ $sudo vi /etc/ser2net.conf
+
+ Append one line for serial-over-USB in *#ser2net.conf*
+
+ ::
+
+ 2004:telnet:0:/dev/ttyUSB0:115200 8DATABITS NONE 1STOPBIT banner
+
+- Open the console.
+
+ .. code:: shell
+
+ $telnet localhost 2004
+
+ And you could open the console remotely, too.
+
+Boot UEFI in recovery mode
+--------------------------
+
+- Fetch that are used in recovery mode. The code location is in below.
+ `link <https://github.com/96boards-hikey/tools-images-hikey960>`__
+
+- Generate l-loader.bin.
+
+ .. code:: shell
+
+ $cd tools-images-hikey960
+ $ln -sf ${BUILD_PATH}/l-loader/l-loader.bin
+
+- Prepare config file.
+
+ .. code:: shell
+
+ $vi config
+ # The content of config file
+ ./sec_user_xloader.img 0x00020000
+ ./sec_uce_boot.img 0x6A908000
+ ./l-loader.bin 0x1AC00000
+
+- Remove the modemmanager package. This package may causes hikey\_idt tool failure.
+
+ .. code:: shell
+
+ $sudo apt-get purge modemmanager
+
+- Run the command to download l-loader.bin into HiKey960.
+
+ .. code:: shell
+
+ $sudo ./hikey_idt -c config -p /dev/ttyUSB1
+
+- UEFI running in recovery mode.
+ When prompt '.' is displayed on console, press hotkey 'f' in keyboard. Then Android fastboot app is running.
+ The timeout of prompt '.' is 10 seconds.
+
+- Update images.
+
+ .. code:: shell
+
+ $sudo fastboot flash ptable prm_ptable.img
+ $sudo fastboot flash xloader sec_xloader.img
+ $sudo fastboot flash fastboot l-loader.bin
+ $sudo fastboot flash fip fip.bin
+ $sudo fastboot flash boot boot.img
+ $sudo fastboot flash cache cache.img
+ $sudo fastboot flash system system.img
+ $sudo fastboot flash userdata userdata.img
+
+- Notice: UEFI could also boot kernel in recovery mode, but BL31 isn't loaded in
+ recovery mode.
+
+Boot UEFI in normal mode
+------------------------
+
+- Make sure "Boot Mode" switch is OFF for normal boot mode. Then power on HiKey960.
+
+- Reference `link <https://github.com/96boards-hikey/tools-images-hikey960/blob/master/build-from-source/README-ATF-UEFI-build-from-source.md>`__
+
+.. _link: http://www.96boards.org/documentation/ConsumerEdition/HiKey960/README.md
--- /dev/null
+Tegra SoCs - Overview
+=====================
+
+- .. rubric:: T210
+ :name: t210
+
+T210 has Quad ARM® Cortex®-A57 cores in a switched configuration with a
+companion set of quad ARM Cortex-A53 cores. The Cortex-A57 and A53 cores
+support ARMv8, executing both 64-bit Aarch64 code, and 32-bit Aarch32 code
+including legacy ARMv7 applications. The Cortex-A57 processors each have
+48 KB Instruction and 32 KB Data Level 1 caches; and have a 2 MB shared
+Level 2 unified cache. The Cortex-A53 processors each have 32 KB Instruction
+and 32 KB Data Level 1 caches; and have a 512 KB shared Level 2 unified cache.
+
+- .. rubric:: T132
+ :name: t132
+
+Denver is NVIDIA's own custom-designed, 64-bit, dual-core CPU which is
+fully ARMv8 architecture compatible. Each of the two Denver cores
+implements a 7-way superscalar microarchitecture (up to 7 concurrent
+micro-ops can be executed per clock), and includes a 128KB 4-way L1
+instruction cache, a 64KB 4-way L1 data cache, and a 2MB 16-way L2
+cache, which services both cores.
+
+Denver implements an innovative process called Dynamic Code Optimization,
+which optimizes frequently used software routines at runtime into dense,
+highly tuned microcode-equivalent routines. These are stored in a
+dedicated, 128MB main-memory-based optimization cache. After being read
+into the instruction cache, the optimized micro-ops are executed,
+re-fetched and executed from the instruction cache as long as needed and
+capacity allows.
+
+Effectively, this reduces the need to re-optimize the software routines.
+Instead of using hardware to extract the instruction-level parallelism
+(ILP) inherent in the code, Denver extracts the ILP once via software
+techniques, and then executes those routines repeatedly, thus amortizing
+the cost of ILP extraction over the many execution instances.
+
+Denver also features new low latency power-state transitions, in addition
+to extensive power-gating and dynamic voltage and clock scaling based on
+workloads.
+
+Directory structure
+===================
+
+- plat/nvidia/tegra/common - Common code for all Tegra SoCs
+- plat/nvidia/tegra/soc/txxx - Chip specific code
+
+Trusted OS dispatcher
+=====================
+
+Tegra supports multiple Trusted OS', Trusted Little Kernel (TLK) being one of
+them. In order to include the 'tlkd' dispatcher in the image, pass 'SPD=tlkd'
+on the command line while preparing a bl31 image. This allows other Trusted OS
+vendors to use the upstream code and include their dispatchers in the image
+without changing any makefiles.
+
+Preparing the BL31 image to run on Tegra SoCs
+=============================================
+
+.. code:: shell
+
+ CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-none-elf- make PLAT=tegra \
+ TARGET_SOC=<target-soc e.g. t210|t132> SPD=<dispatcher e.g. tlkd> bl31
+
+Platforms wanting to use different TZDRAM\_BASE, can add ``TZDRAM_BASE=<value>``
+to the build command line.
+
+The Tegra platform code expects a pointer to the following platform specific
+structure via 'x1' register from the BL2 layer which is used by the
+bl31\_early\_platform\_setup() handler to extract the TZDRAM carveout base and
+size for loading the Trusted OS and the UART port ID to be used. The Tegra
+memory controller driver programs this base/size in order to restrict NS
+accesses.
+
+typedef struct plat\_params\_from\_bl2 {
+/\* TZ memory size */
+uint64\_t tzdram\_size;
+/* TZ memory base */
+uint64\_t tzdram\_base;
+/* UART port ID \*/
+int uart\_id;
+} plat\_params\_from\_bl2\_t;
+
+Power Management
+================
+
+The PSCI implementation expects each platform to expose the 'power state'
+parameter to be used during the 'SYSTEM SUSPEND' call. The state-id field
+is implementation defined on Tegra SoCs and is preferably defined by
+tegra\_def.h.
+
+Tegra configs
+=============
+
+- 'tegra\_enable\_l2\_ecc\_parity\_prot': This flag enables the L2 ECC and Parity
+ Protection bit, for ARM Cortex-A57 CPUs, during CPU boot. This flag will
+ be enabled by Tegrs SoCs during 'Cluster power up' or 'System Suspend' exit.
--- /dev/null
+ARM Trusted Firmware for QEMU virt ARMv8-A
+==========================================
+
+ARM Trusted Firmware implements the EL3 firmware layer for QEMU virt
+ARMv8-A. BL1 is used as the BootROM, supplied with the -bios argument.
+When QEMU starts all CPUs are released simultaneously, BL1 selects a
+primary CPU to handle the boot and the secondaries are placed in a polling
+loop to be released by normal world via PSCI.
+
+BL2 edits the Flattened Device Tree, FDT, generated by QEMU at run-time to
+add a node describing PSCI and also enable methods for the CPUs.
+
+An ARM64 defonfig v4.5 Linux kernel is known to boot, FTD doesn't need to be
+provided as it's generated by QEMU.
+
+Current limitations:
+
+- Only cold boot is supported
+- No build instructions for QEMU\_EFI.fd and rootfs-arm64.cpio.gz
+- No instructions for how to load a BL32 (Secure Payload)
+
+``QEMU_EFI.fd`` can be dowloaded from
+http://snapshots.linaro.org/components/kernel/leg-virt-tianocore-edk2-upstream/latest/QEMU-KERNEL-AARCH64/RELEASE_GCC49/QEMU_EFI.fd
+
+Boot binaries, except BL1, are primarily loaded via semi-hosting so all
+binaries has to reside in the same directory as QEMU is started from. This
+is conveniently achieved with symlinks the local names as:
+
+- ``bl2.bin`` -> BL2
+- ``bl31.bin`` -> BL31
+- ``bl33.bin`` -> BL33 (``QEMU_EFI.fd``)
+- ``Image`` -> linux/Image
+
+To build:
+
+::
+
+ make CROSS_COMPILE=aarch64-none-elf- PLAT=qemu
+
+To start (QEMU v2.6.0):
+
+::
+
+ qemu-system-aarch64 -nographic -machine virt,secure=on -cpu cortex-a57 \
+ -kernel Image \
+ -append console=ttyAMA0,38400 keep_bootcon root=/dev/vda2 \
+ -initrd rootfs-arm64.cpio.gz -smp 2 -m 1024 -bios bl1.bin \
+ -d unimp -semihosting-config enable,target=native
--- /dev/null
+ARM Trusted Firmware for Socionext UniPhier SoCs
+================================================
+
+Socionext UniPhier ARMv8-A SoCs use ARM Trusted Firmware as the secure world
+firmware, supporting BL1, BL2, and BL31.
+
+UniPhier SoC family implements its internal boot ROM, so BL1 is used as pseudo
+ROM (i.e. runs in RAM). The internal boot ROM loads 64KB `1`_ image from a
+non-volatile storage to the on-chip SRAM. Unfortunately, BL1 does not fit in
+the 64KB limit if `Trusted Board Boot`_ (TBB) is enabled. To solve this problem,
+Socionext provides a first stage loader called `UniPhier BL`_. This loader runs
+in the on-chip SRAM, initializes the DRAM, expands BL1 there, and hands the
+control over to it. Therefore, all images of ARM Trusted Firmware run in DRAM.
+
+The UniPhier platform works with/without TBB. See below for the build process
+of each case. The image authentication for the UniPhier platform fully
+complies with the Trusted Board Boot Requirements (TBBR) specification.
+
+The UniPhier BL does not implement the authentication functionality, that is,
+it can not verify the BL1 image by itself. Instead, the UniPhier BL assures
+the BL1 validity in a different way; BL1 is GZIP-compressed and appended to
+the UniPhier BL. The concatenation of the UniPhier BL and the compressed BL1
+fits in the 64KB limit. The concatenated image is loaded by the boot ROM
+(and verified if the chip fuses are blown).
+
+::
+
+ to the lowest common denominator.
+
+Boot Flow
+---------
+
+#. The Boot ROM
+
+This is hard-wired ROM, so never corrupted. It loads the UniPhier BL (with
+compressed-BL1 appended) into the on-chip SRAM. If the SoC fuses are blown,
+the image is verified by the SoC's own method.
+
+#. UniPhier BL
+
+This runs in the on-chip SRAM. After the minimum SoC initialization and DRAM
+setup, it decompresses the appended BL1 image into the DRAM, then jumps to
+the BL1 entry.
+
+#. BL1
+
+This runs in the DRAM. It extracts BL2 from FIP (Firmware Image Package).
+If TBB is enabled, the BL2 is authenticated by the standard mechanism of ARM
+Trusted Firmware.
+
+#. BL2, BL31, and more
+
+They all run in the DRAM, and are authenticated by the standard mechanism if
+TBB is enabled. See `Firmware Design`_ for details.
+
+Basic Build
+-----------
+
+BL1 must be compressed for the reason above. The UniPhier's platform makefile
+provides a build target ``bl1_gzip`` for this.
+
+For a non-secure boot loader (aka BL33), U-Boot is well supported for UniPhier
+SoCs. The U-Boot image (``u-boot.bin``) must be built in advance. For the build
+procedure of U-Boot, refer to the document in the `U-Boot`_ project.
+
+To build minimum functionality for UniPhier (without TBB):
+
+::
+
+ make CROSS_COMPILE=<gcc-prefix> PLAT=uniphier BL33=<path-to-BL33> bl1_gzip fip
+
+Output images:
+
+- ``bl1.bin.gzip``
+- ``fip.bin``
+
+Optional features
+-----------------
+
+- Trusted Board Boot
+
+`mbed TLS`_ is needed as the cryptographic and image parser modules.
+Refer to the `User Guide`_ for the appropriate version of mbed TLS.
+
+To enable TBB, add the following options to the build command:
+
+::
+
+ TRUSTED_BOARD_BOOT=1 GENERATE_COT=1 MBEDTLS_DIR=<path-to-mbedtls>
+
+- System Control Processor (SCP)
+
+If desired, FIP can include an SCP BL2 image. If BL2 finds an SCP BL2 image
+in FIP, BL2 loads it into DRAM and kicks the SCP. Most of UniPhier boards
+still work without SCP, but SCP provides better power management support.
+
+To include SCP\_BL2, add the following option to the build command:
+
+::
+
+ SCP_BL2=<path-to-SCP>
+
+- BL32 (Secure Payload)
+
+To enable BL32, add the following option to the build command:
+
+::
+
+ SPD=<spd> BL32=<path-to-BL32>
+
+If you use TSP for BL32, ``BL32=<path-to-BL32>`` is not required. Just add the
+following:
+
+::
+
+ SPD=tspd
+
+.. _1: Some%20SoCs%20can%20load%2080KB,%20but%20the%20software%20implementation%20must%20be%20aligned
+.. _Trusted Board Boot: ../trusted-board-boot.rst
+.. _UniPhier BL: https://github.com/uniphier/uniphier-bl
+.. _Firmware Design: ../firmware-design.rst
+.. _U-Boot: https://www.denx.de/wiki/U-Boot
+.. _mbed TLS: https://tls.mbed.org/
+.. _User Guide: ../user-guide.rst
--- /dev/null
+ARM Trusted Firmware for Xilinx Zynq UltraScale+ MPSoC
+======================================================
+
+ARM Trusted Firmware implements the EL3 firmware layer for Xilinx Zynq
+UltraScale + MPSoC.
+The platform only uses the runtime part of ATF as ZynqMP already has a
+BootROM (BL1) and FSBL (BL2).
+
+BL31 is ATF.
+BL32 is an optional Secure Payload.
+BL33 is the non-secure world software (U-Boot, Linux etc).
+
+To build:
+
+.. code:: bash
+
+ make ERROR_DEPRECATED=1 CROSS_COMPILE=aarch64-none-elf- PLAT=zynqmp bl31
+
+To build bl32 TSP you have to rebuild bl31 too:
+
+.. code:: bash
+
+ make ERROR_DEPRECATED=1 CROSS_COMPILE=aarch64-none-elf- PLAT=zynqmp SPD=tspd bl31 bl32
+
+ZynqMP platform specific build options
+======================================
+
+- ``ZYNQMP_ATF_MEM_BASE``: Specifies the base address of the bl31 binary.
+- ``ZYNQMP_ATF_MEM_SIZE``: Specifies the size of the memory region of the bl31 binary.
+- ``ZYNQMP_BL32_MEM_BASE``: Specifies the base address of the bl32 binary.
+- ``ZYNQMP_BL32_MEM_SIZE``: Specifies the size of the memory region of the bl32 binary.
+
+- ``ZYNQMP_CONSOLE``: Select the console driver. Options:
+
+ - ``cadence``, ``cadence0``: Cadence UART 0
+ - ``cadence1`` : Cadence UART 1
+
+FSBL->ATF Parameter Passing
+===========================
+
+The FSBL populates a data structure with image information for the ATF. The ATF
+uses that data to hand off to the loaded images. The address of the handoff data
+structure is passed in the ``PMU_GLOBAL.GLOBAL_GEN_STORAGE6`` register. The
+register is free to be used by other software once the ATF is bringing up
+further firmware images.
+
+Power Domain Tree
+=================
+
+The following power domain tree represents the power domain model used by the
+ATF for ZynqMP:
+
+::
+
+ +-+
+ |0|
+ +-+
+ +-------+---+---+-------+
+ | | | |
+ | | | |
+ v v v v
+ +-+ +-+ +-+ +-+
+ |0| |1| |2| |3|
+ +-+ +-+ +-+ +-+
+
+The 4 leaf power domains represent the individual A53 cores, while resources
+common to the cluster are grouped in the power domain on the top.
--- /dev/null
+Guide to migrate to new Platform porting interface
+==================================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+--------------
+
+Introduction
+------------
+
+The PSCI implementation in Trusted Firmware has undergone a redesign because of
+three requirements that the PSCI 1.0 specification introduced :
+
+- Removing the framework assumption about the structure of the MPIDR, and
+ its relation to the power topology enables support for deeper and more
+ complex hierarchies.
+
+- Reworking the power state coordination implementation in the framework
+ to support the more detailed PSCI 1.0 requirements and reduce platform
+ port complexity
+
+- Enable the use of the extended power\_state parameter and the larger StateID
+ field
+
+The PSCI 1.0 implementation introduces new frameworks to fulfill the above
+requirements. These framework changes mean that the platform porting API must
+also be modified. This document is a guide to assist migration of the existing
+platform ports to the new platform API.
+
+This document describes the new platform API and compares it with the
+deprecated API. It also describes the compatibility layer that enables the
+existing platform ports to work with the PSCI 1.0 implementation. The
+deprecated platform API is documented for reference.
+
+Platform API modification due to PSCI framework changes
+-------------------------------------------------------
+
+This section describes changes to the platform APIs.
+
+Power domain topology framework platform API modifications
+----------------------------------------------------------
+
+This removes the assumption in the PSCI implementation that MPIDR
+based affinity instances map directly to power domains. A power domain, as
+described in section 4.2 of `PSCI`_, could contain a core or a logical group
+of cores (a cluster) which share some state on which power management
+operations can be performed. The existing affinity instance based APIs
+``plat_get_aff_count()`` and ``plat_get_aff_state()`` are deprecated. The new
+platform interfaces that are introduced for this framework are:
+
+- ``plat_core_pos_by_mpidr()``
+- ``plat_my_core_pos()``
+- ``plat_get_power_domain_tree_desc()``
+
+``plat_my_core_pos()`` and ``plat_core_pos_by_mpidr()`` are mandatory
+and are meant to replace the existing ``platform_get_core_pos()`` API.
+The description of these APIs can be found in the `Porting Guide`_.
+These are used by the power domain topology framework such that:
+
+#. The generic PSCI code does not generate MPIDRs or use them to query the
+ platform about the number of power domains at a particular power level. The
+ ``plat_get_power_domain_tree_desc()`` provides a description of the power
+ domain tree on the SoC through a pointer to the byte array containing the
+ power domain topology tree description data structure.
+
+#. The linear indices returned by ``plat_core_pos_by_mpidr()`` and
+ ``plat_my_core_pos()`` are used to retrieve core power domain nodes from
+ the power domain tree. These core indices are unique for a core and it is a
+ number between ``0`` and ``PLATFORM_CORE_COUNT - 1``. The platform can choose
+ to implement a static mapping between ``MPIDR`` and core index or implement
+ a dynamic mapping, choosing to skip the unavailable/unused cores to compact
+ the core indices.
+
+In addition, the platforms must define the macros ``PLAT_NUM_PWR_DOMAINS`` and
+``PLAT_MAX_PWR_LVL`` which replace the macros ``PLAT_NUM_AFFS`` and
+``PLATFORM_MAX_AFFLVL`` respectively. On platforms where the affinity instances
+correspond to power domains, the values of new macros remain the same as the
+old ones.
+
+More details on the power domain topology description and its platform
+interface can be found in `psci pd tree`_.
+
+Composite power state framework platform API modifications
+----------------------------------------------------------
+
+The state-ID field in the power-state parameter of a CPU\_SUSPEND call can be
+used to describe the composite power states specific to a platform. The existing
+PSCI state coordination had the limitation that it operates on a run/off
+granularity of power states and it did not interpret the state-ID field. This
+was acceptable as the specification requirement in PSCI 0.2 and the framework's
+approach to coordination only required maintaining a reference
+count of the number of cores that have requested the cluster to remain powered.
+
+In the PSCI 1.0 specification, this approach is non optimal. If composite
+power states are used, the PSCI implementation cannot make global
+decisions about state coordination required because it does not understand the
+platform specific states.
+
+The PSCI 1.0 implementation now defines a generic representation of the
+power-state parameter :
+
+.. code:: c
+
+ typedef struct psci_power_state {
+ plat_local_state_t pwr_domain_state[PLAT_MAX_PWR_LVL + 1];
+ } psci_power_state_t;
+
+``pwr_domain_state`` is an array where each index corresponds to a power level.
+Each entry in the array contains the local power state the power domain at
+that power level could enter. The meaning of the local power state value is
+platform defined, and can vary between levels in a single platform. The PSCI
+implementation constraints the values only so that it can classify the state
+as RUN, RETENTION or OFF as required by the specification:
+
+#. Zero means RUN
+
+#. All OFF state values at all levels must be higher than all
+ RETENTION state values at all levels
+
+The platform is required to define the macros ``PLAT_MAX_RET_STATE`` and
+``PLAT_MAX_OFF_STATE`` to the framework. The requirement for these macros can
+be found in the `Porting Guide <porting-guide.rst>`__.
+
+The PSCI 1.0 implementation adds support to involve the platform in state
+coordination. This enables the platform to decide the final target state.
+During a request to place a power domain in a low power state, the platform
+is passed an array of requested ``plat_local_state_t`` for that power domain by
+each core within it through the ``plat_get_target_pwr_state()`` API. This API
+coordinates amongst these requested states to determine a target
+``plat_local_state_t`` for that power domain. A default weak implementation of
+this API is provided in the platform layer which returns the minimum of the
+requested local states back to the PSCI state coordination. More details
+of ``plat_get_target_pwr_state()`` API can be found in the
+`Porting Guide <porting-guide.rst#user-content-function--plat_get_target_pwr_state-optional>`__.
+
+The PSCI Generic implementation expects platform ports to populate the handlers
+for the ``plat_psci_ops`` structure which is declared as :
+
+.. code:: c
+
+ typedef struct plat_psci_ops {
+ void (*cpu_standby)(plat_local_state_t cpu_state);
+ int (*pwr_domain_on)(u_register_t mpidr);
+ void (*pwr_domain_off)(const psci_power_state_t *target_state);
+ void (*pwr_domain_suspend)(const psci_power_state_t *target_state);
+ void (*pwr_domain_on_finish)(const psci_power_state_t *target_state);
+ void (*pwr_domain_suspend_finish)(
+ const psci_power_state_t *target_state);
+ void (*system_off)(void) __dead2;
+ void (*system_reset)(void) __dead2;
+ int (*validate_power_state)(unsigned int power_state,
+ psci_power_state_t *req_state);
+ int (*validate_ns_entrypoint)(unsigned long ns_entrypoint);
+ void (*get_sys_suspend_power_state)(
+ psci_power_state_t *req_state);
+ } plat_psci_ops_t;
+
+The description of these handlers can be found in the `Porting Guide <porting-guide.rst#user-content-function--plat_setup_psci_ops-mandatory>`__.
+The previous ``plat_pm_ops`` structure is deprecated. Compared with the previous
+handlers, the major differences are:
+
+- Difference in parameters
+
+The PSCI 1.0 implementation depends on the ``validate_power_state`` handler to
+convert the power-state parameter (possibly encoding a composite power state)
+passed in a PSCI ``CPU_SUSPEND`` to the ``psci_power_state`` format. This handler
+is now mandatory for PSCI ``CPU_SUSPEND`` support.
+
+The ``plat_psci_ops`` handlers, ``pwr_domain_off`` and ``pwr_domain_suspend``, are
+passed the target local state for each affected power domain. The platform
+must execute operations specific to these target states. Similarly,
+``pwr_domain_on_finish`` and ``pwr_domain_suspend_finish`` are passed the local
+states of the affected power domains before wakeup. The platform
+must execute actions to restore these power domains from these specific
+local states.
+
+- Difference in invocation
+
+Whereas the power management handlers in ``plat_pm_ops`` used to be invoked
+for each affinity level till the target affinity level, the new handlers
+are only invoked once. The ``target_state`` encodes the target low power
+state or the low power state woken up from for each affected power domain.
+
+- Difference in semantics
+
+Although the previous ``suspend`` handlers could be used for power down as well
+as retention at different affinity levels, the new handlers make this support
+explicit. The ``pwr_domain_suspend`` can be used to specify powerdown and
+retention at various power domain levels subject to the conditions mentioned
+in section 4.2.1 of `PSCI`_
+
+Unlike the previous ``standby`` handler, the ``cpu_standby()`` handler is only used
+as a fast path for placing a core power domain into a standby or retention
+state.
+
+The below diagram shows the sequence of a PSCI SUSPEND call and the interaction
+with the platform layer depicting the exchange of data between PSCI Generic
+layer and the platform layer.
+
+|Image 1|
+
+Refer `plat/arm/board/fvp/fvp\_pm.c`_ for the implementation details of
+these handlers for the FVP. The commit `38dce70f51fb83b27958ba3e2ad15f5635cb1061`_
+demonstrates the migration of ARM reference platforms to the new platform API.
+
+Miscellaneous modifications
+---------------------------
+
+In addition to the framework changes, unification of warm reset entry points on
+wakeup from low power modes has led to a change in the platform API. In the
+earlier implementation, the warm reset entry used to be programmed into the
+mailboxes by the 'ON' and 'SUSPEND' power management hooks. In the PSCI 1.0
+implementation, this information is not required, because it can figure that
+out by querying affinity info state whether to execute the 'suspend\_finisher\`
+or 'on\_finisher'.
+
+As a result, the warm reset entry point must be programmed only once. The
+``plat_setup_psci_ops()`` API takes the secure entry point as an
+additional parameter to enable the platforms to configure their mailbox. The
+plat\_psci\_ops handlers ``pwr_domain_on`` and ``pwr_domain_suspend`` no longer take
+the warm reset entry point as a parameter.
+
+Also, some platform APIs which took ``MPIDR`` as an argument were only ever
+invoked to perform actions specific to the caller core which makes the argument
+redundant. Therefore the platform APIs ``plat_get_my_entrypoint()``,
+``plat_is_my_cpu_primary()``, ``plat_set_my_stack()`` and
+``plat_get_my_stack()`` are defined which are meant to be invoked only for
+operations on the current caller core instead of ``platform_get_entrypoint()``,
+``platform_is_primary_cpu()``, ``platform_set_stack()`` and ``platform_get_stack()``.
+
+Compatibility layer
+-------------------
+
+To ease the migration of the platform ports to the new porting interface,
+a compatibility layer is introduced that essentially implements a glue layer
+between the old platform API and the new API. The build flag
+``ENABLE_PLAT_COMPAT`` (enabled by default), specifies whether to enable this
+layer or not. A platform port which has migrated to the new API can disable
+this flag within the platform specific makefile.
+
+The compatibility layer works on the assumption that the onus of
+state coordination, in case multiple low power states are supported,
+is with the platform. The generic PSCI implementation only takes into
+account whether the suspend request is power down or not. This corresponds
+with the behavior of the PSCI implementation before the introduction of
+new frameworks. Also, it assumes that the affinity levels of the platform
+correspond directly to the power domain levels.
+
+The compatibility layer dynamically constructs the new topology
+description array by querying the platform using ``plat_get_aff_count()``
+and ``plat_get_aff_state()`` APIs. The linear index returned by
+``platform_get_core_pos()`` is used as the core index for the cores. The
+higher level (non-core) power domain nodes must know the cores contained
+within its domain. It does so by storing the core index of first core
+within it and number of core indexes following it. This means that core
+indices returned by ``platform_get_core_pos()`` for cores within a particular
+power domain must be consecutive. We expect that this is the case for most
+platform ports including ARM reference platforms.
+
+The old PSCI helpers like ``psci_get_suspend_powerstate()``,
+``psci_get_suspend_stateid()``, ``psci_get_suspend_stateid_by_mpidr()``,
+``psci_get_max_phys_off_afflvl()`` and ``psci_get_suspend_afflvl()`` are also
+implemented for the compatibility layer. This allows the existing
+platform ports to work with the new PSCI frameworks without significant
+rework.
+
+Deprecated Platform API
+-----------------------
+
+This section documents the deprecated platform porting API.
+
+Common mandatory modifications
+------------------------------
+
+The mandatory macros to be defined by the platform port in ``platform_def.h``
+
+- **#define : PLATFORM\_NUM\_AFFS**
+
+ Defines the total number of nodes in the affinity hierarchy at all affinity
+ levels used by the platform.
+
+- **#define : PLATFORM\_MAX\_AFFLVL**
+
+ Defines the maximum affinity level that the power management operations
+ should apply to. ARMv8-A has support for four affinity levels. It is likely
+ that hardware will implement fewer affinity levels. This macro allows the
+ PSCI implementation to consider only those affinity levels in the system
+ that the platform implements. For example, the Base AEM FVP implements two
+ clusters with a configurable number of cores. It reports the maximum
+ affinity level as 1, resulting in PSCI power control up to the cluster
+ level.
+
+The following functions must be implemented by the platform port to enable
+the reset vector code to perform the required tasks.
+
+Function : platform\_get\_entrypoint() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned long
+ Return : unsigned long
+
+This function is called with the ``SCTLR.M`` and ``SCTLR.C`` bits disabled. The core
+is identified by its ``MPIDR``, which is passed as the argument. The function is
+responsible for distinguishing between a warm and cold reset using platform-
+specific means. If it is a warm reset, it returns the entrypoint into the
+BL31 image that the core must jump to. If it is a cold reset, this function
+must return zero.
+
+This function is also responsible for implementing a platform-specific mechanism
+to handle the condition where the core has been warm reset but there is no
+entrypoint to jump to.
+
+This function does not follow the Procedure Call Standard used by the
+Application Binary Interface for the ARM 64-bit architecture. The caller should
+not assume that callee saved registers are preserved across a call to this
+function.
+
+Function : platform\_is\_primary\_cpu() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned long
+ Return : unsigned int
+
+This function identifies a core by its ``MPIDR``, which is passed as the argument,
+to determine whether this core is the primary core or a secondary core. A return
+value of zero indicates that the core is not the primary core, while a non-zero
+return value indicates that the core is the primary core.
+
+Common optional modifications
+-----------------------------
+
+Function : platform\_get\_core\_pos()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned long
+ Return : int
+
+A platform may need to convert the ``MPIDR`` of a core to an absolute number, which
+can be used as a core-specific linear index into blocks of memory (for example
+while allocating per-core stacks). This routine contains a simple mechanism
+to perform this conversion, using the assumption that each cluster contains a
+maximum of four cores:
+
+::
+
+ linear index = cpu_id + (cluster_id * 4)
+
+ cpu_id = 8-bit value in MPIDR at affinity level 0
+ cluster_id = 8-bit value in MPIDR at affinity level 1
+
+Function : platform\_set\_stack()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned long
+ Return : void
+
+This function sets the current stack pointer to the normal memory stack that
+has been allocated for the core specified by MPIDR. For BL images that only
+require a stack for the primary core the parameter is ignored. The size of
+the stack allocated to each core is specified by the platform defined constant
+``PLATFORM_STACK_SIZE``.
+
+Common implementations of this function for the UP and MP BL images are
+provided in `plat/common/aarch64/platform\_up\_stack.S`_ and
+`plat/common/aarch64/platform\_mp\_stack.S`_
+
+Function : platform\_get\_stack()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned long
+ Return : unsigned long
+
+This function returns the base address of the normal memory stack that
+has been allocated for the core specificed by MPIDR. For BL images that only
+require a stack for the primary core the parameter is ignored. The size of
+the stack allocated to each core is specified by the platform defined constant
+``PLATFORM_STACK_SIZE``.
+
+Common implementations of this function for the UP and MP BL images are
+provided in `plat/common/aarch64/platform\_up\_stack.S`_ and
+`plat/common/aarch64/platform\_mp\_stack.S`_
+
+Modifications for Power State Coordination Interface (in BL31)
+--------------------------------------------------------------
+
+The following functions must be implemented to initialize PSCI functionality in
+the ARM Trusted Firmware.
+
+Function : plat\_get\_aff\_count() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int, unsigned long
+ Return : unsigned int
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initializations in ``bl31_plat_arch_setup()``. It is only
+called by the primary core.
+
+This function is called by the PSCI initialization code to detect the system
+topology. Its purpose is to return the number of affinity instances implemented
+at a given ``affinity level`` (specified by the first argument) and a given
+``MPIDR`` (specified by the second argument). For example, on a dual-cluster
+system where first cluster implements two cores and the second cluster
+implements four cores, a call to this function with an ``MPIDR`` corresponding
+to the first cluster (``0x0``) and affinity level 0, would return 2. A call
+to this function with an ``MPIDR`` corresponding to the second cluster (``0x100``)
+and affinity level 0, would return 4.
+
+Function : plat\_get\_aff\_state() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int, unsigned long
+ Return : unsigned int
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initializations in ``bl31_plat_arch_setup()``. It is only
+called by the primary core.
+
+This function is called by the PSCI initialization code. Its purpose is to
+return the state of an affinity instance. The affinity instance is determined by
+the affinity ID at a given ``affinity level`` (specified by the first argument)
+and an ``MPIDR`` (specified by the second argument). The state can be one of
+``PSCI_AFF_PRESENT`` or ``PSCI_AFF_ABSENT``. The latter state is used to cater for
+system topologies where certain affinity instances are unimplemented. For
+example, consider a platform that implements a single cluster with four cores and
+another core implemented directly on the interconnect with the cluster. The
+``MPIDR``\ s of the cluster would range from ``0x0-0x3``. The ``MPIDR`` of the single
+core is 0x100 to indicate that it does not belong to cluster 0. Cluster 1
+is missing but needs to be accounted for to reach this single core in the
+topology tree. Therefore it is marked as ``PSCI_AFF_ABSENT``.
+
+Function : platform\_setup\_pm() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : const plat_pm_ops **
+ Return : int
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initializations in ``bl31_plat_arch_setup()``. It is only
+called by the primary core.
+
+This function is called by PSCI initialization code. Its purpose is to export
+handler routines for platform-specific power management actions by populating
+the passed pointer with a pointer to the private ``plat_pm_ops`` structure of
+BL31.
+
+A description of each member of this structure is given below. A platform port
+is expected to implement these handlers if the corresponding PSCI operation
+is to be supported and these handlers are expected to succeed if the return
+type is ``void``.
+
+plat\_pm\_ops.affinst\_standby()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Perform the platform-specific setup to enter the standby state indicated by the
+passed argument. The generic code expects the handler to succeed.
+
+plat\_pm\_ops.affinst\_on()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Perform the platform specific setup to power on an affinity instance, specified
+by the ``MPIDR`` (first argument) and ``affinity level`` (third argument). The
+``state`` (fourth argument) contains the current state of that affinity instance
+(ON or OFF). This is useful to determine whether any action must be taken. For
+example, while powering on a core, the cluster that contains this core might
+already be in the ON state. The platform decides what actions must be taken to
+transition from the current state to the target state (indicated by the power
+management operation). The generic code expects the platform to return
+E\_SUCCESS on success or E\_INTERN\_FAIL for any failure.
+
+plat\_pm\_ops.affinst\_off()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Perform the platform specific setup to power off an affinity instance of the
+calling core. It is called by the PSCI ``CPU_OFF`` API implementation.
+
+The ``affinity level`` (first argument) and ``state`` (second argument) have
+a similar meaning as described in the ``affinst_on()`` operation. They
+identify the affinity instance on which the call is made and its
+current state. This gives the platform port an indication of the
+state transition it must make to perform the requested action. For example, if
+the calling core is the last powered on core in the cluster, after powering down
+affinity level 0 (the core), the platform port should power down affinity
+level 1 (the cluster) as well. The generic code expects the handler to succeed.
+
+plat\_pm\_ops.affinst\_suspend()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Perform the platform specific setup to power off an affinity instance of the
+calling core. It is called by the PSCI ``CPU_SUSPEND`` API and ``SYSTEM_SUSPEND``
+API implementation
+
+The ``affinity level`` (second argument) and ``state`` (third argument) have a
+similar meaning as described in the ``affinst_on()`` operation. They are used to
+identify the affinity instance on which the call is made and its current state.
+This gives the platform port an indication of the state transition it must
+make to perform the requested action. For example, if the calling core is the
+last powered on core in the cluster, after powering down affinity level 0
+(the core), the platform port should power down affinity level 1 (the cluster)
+as well.
+
+The difference between turning an affinity instance off and suspending it
+is that in the former case, the affinity instance is expected to re-initialize
+its state when it is next powered on (see ``affinst_on_finish()``). In the latter
+case, the affinity instance is expected to save enough state so that it can
+resume execution by restoring this state when it is powered on (see
+``affinst_suspend_finish()``).The generic code expects the handler to succeed.
+
+plat\_pm\_ops.affinst\_on\_finish()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function is called by the PSCI implementation after the calling core is
+powered on and released from reset in response to an earlier PSCI ``CPU_ON`` call.
+It performs the platform-specific setup required to initialize enough state for
+this core to enter the Normal world and also provide secure runtime firmware
+services.
+
+The ``affinity level`` (first argument) and ``state`` (second argument) have a
+similar meaning as described in the previous operations. The generic code
+expects the handler to succeed.
+
+plat\_pm\_ops.affinst\_suspend\_finish()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function is called by the PSCI implementation after the calling core is
+powered on and released from reset in response to an asynchronous wakeup
+event, for example a timer interrupt that was programmed by the core during the
+``CPU_SUSPEND`` call or ``SYSTEM_SUSPEND`` call. It performs the platform-specific
+setup required to restore the saved state for this core to resume execution
+in the Normal world and also provide secure runtime firmware services.
+
+The ``affinity level`` (first argument) and ``state`` (second argument) have a
+similar meaning as described in the previous operations. The generic code
+expects the platform to succeed.
+
+plat\_pm\_ops.validate\_power\_state()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function is called by the PSCI implementation during the ``CPU_SUSPEND``
+call to validate the ``power_state`` parameter of the PSCI API. If the
+``power_state`` is known to be invalid, the platform must return
+PSCI\_E\_INVALID\_PARAMS as an error, which is propagated back to the Normal
+world PSCI client.
+
+plat\_pm\_ops.validate\_ns\_entrypoint()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function is called by the PSCI implementation during the ``CPU_SUSPEND``,
+``SYSTEM_SUSPEND`` and ``CPU_ON`` calls to validate the Non-secure ``entry_point``
+parameter passed by the Normal world. If the ``entry_point`` is known to be
+invalid, the platform must return PSCI\_E\_INVALID\_PARAMS as an error, which is
+propagated back to the Normal world PSCI client.
+
+plat\_pm\_ops.get\_sys\_suspend\_power\_state()
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This function is called by the PSCI implementation during the ``SYSTEM_SUSPEND``
+call to return the ``power_state`` parameter. This allows the platform to encode
+the appropriate State-ID field within the ``power_state`` parameter which can be
+utilized in ``affinst_suspend()`` to suspend to system affinity level. The
+``power_state`` parameter should be in the same format as specified by the
+PSCI specification for the CPU\_SUSPEND API.
+
+--------------
+
+*Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.*
+
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _Porting Guide: porting-guide.rst#user-content-function--plat_my_core_pos
+.. _psci pd tree: psci-pd-tree.rst
+.. _plat/arm/board/fvp/fvp\_pm.c: ../plat/arm/board/fvp/fvp_pm.c
+.. _38dce70f51fb83b27958ba3e2ad15f5635cb1061: https://github.com/ARM-software/arm-trusted-firmware/commit/38dce70f51fb83b27958ba3e2ad15f5635cb1061
+.. _plat/common/aarch64/platform\_up\_stack.S: ../plat/common/aarch64/platform_up_stack.S
+.. _plat/common/aarch64/platform\_mp\_stack.S: ../plat/common/aarch64/platform_mp_stack.S
+
+.. |Image 1| image:: diagrams/psci-suspend-sequence.png?raw=true
--- /dev/null
+ARM Trusted Firmware Porting Guide
+==================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+--------------
+
+Introduction
+------------
+
+Please note that this document has been updated for the new platform API
+as required by the PSCI v1.0 implementation. Please refer to the
+`Migration Guide`_ for the previous platform API.
+
+Porting the ARM Trusted Firmware to a new platform involves making some
+mandatory and optional modifications for both the cold and warm boot paths.
+Modifications consist of:
+
+- Implementing a platform-specific function or variable,
+- Setting up the execution context in a certain way, or
+- Defining certain constants (for example #defines).
+
+The platform-specific functions and variables are declared in
+`include/plat/common/platform.h`_. The firmware provides a default implementation
+of variables and functions to fulfill the optional requirements. These
+implementations are all weakly defined; they are provided to ease the porting
+effort. Each platform port can override them with its own implementation if the
+default implementation is inadequate.
+
+Platform ports that want to be aligned with standard ARM platforms (for example
+FVP and Juno) may also use `include/plat/arm/common/plat\_arm.h`_ and the
+corresponding source files in ``plat/arm/common/``. These provide standard
+implementations for some of the required platform porting functions. However,
+using these functions requires the platform port to implement additional
+ARM standard platform porting functions. These additional functions are not
+documented here.
+
+Some modifications are common to all Boot Loader (BL) stages. Section 2
+discusses these in detail. The subsequent sections discuss the remaining
+modifications for each BL stage in detail.
+
+This document should be read in conjunction with the ARM Trusted Firmware
+`User Guide`_.
+
+Common modifications
+--------------------
+
+This section covers the modifications that should be made by the platform for
+each BL stage to correctly port the firmware stack. They are categorized as
+either mandatory or optional.
+
+Common mandatory modifications
+------------------------------
+
+A platform port must enable the Memory Management Unit (MMU) as well as the
+instruction and data caches for each BL stage. Setting up the translation
+tables is the responsibility of the platform port because memory maps differ
+across platforms. A memory translation library (see ``lib/xlat_tables/``) is
+provided to help in this setup. Note that although this library supports
+non-identity mappings, this is intended only for re-mapping peripheral physical
+addresses and allows platforms with high I/O addresses to reduce their virtual
+address space. All other addresses corresponding to code and data must currently
+use an identity mapping.
+
+In ARM standard platforms, each BL stage configures the MMU in the
+platform-specific architecture setup function, ``blX_plat_arch_setup()``, and uses
+an identity mapping for all addresses.
+
+If the build option ``USE_COHERENT_MEM`` is enabled, each platform can allocate a
+block of identity mapped secure memory with Device-nGnRE attributes aligned to
+page boundary (4K) for each BL stage. All sections which allocate coherent
+memory are grouped under ``coherent_ram``. For ex: Bakery locks are placed in a
+section identified by name ``bakery_lock`` inside ``coherent_ram`` so that its
+possible for the firmware to place variables in it using the following C code
+directive:
+
+::
+
+ __section("bakery_lock")
+
+Or alternatively the following assembler code directive:
+
+::
+
+ .section bakery_lock
+
+The ``coherent_ram`` section is a sum of all sections like ``bakery_lock`` which are
+used to allocate any data structures that are accessed both when a CPU is
+executing with its MMU and caches enabled, and when it's running with its MMU
+and caches disabled. Examples are given below.
+
+The following variables, functions and constants must be defined by the platform
+for the firmware to work correctly.
+
+File : platform\_def.h [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Each platform must ensure that a header file of this name is in the system
+include path with the following constants defined. This may require updating the
+list of ``PLAT_INCLUDES`` in the ``platform.mk`` file. In the ARM development
+platforms, this file is found in ``plat/arm/board/<plat_name>/include/``.
+
+Platform ports may optionally use the file `include/plat/common/common\_def.h`_,
+which provides typical values for some of the constants below. These values are
+likely to be suitable for all platform ports.
+
+Platform ports that want to be aligned with standard ARM platforms (for example
+FVP and Juno) may also use `include/plat/arm/common/arm\_def.h`_, which provides
+standard values for some of the constants below. However, this requires the
+platform port to define additional platform porting constants in
+``platform_def.h``. These additional constants are not documented here.
+
+- **#define : PLATFORM\_LINKER\_FORMAT**
+
+ Defines the linker format used by the platform, for example
+ ``elf64-littleaarch64``.
+
+- **#define : PLATFORM\_LINKER\_ARCH**
+
+ Defines the processor architecture for the linker by the platform, for
+ example ``aarch64``.
+
+- **#define : PLATFORM\_STACK\_SIZE**
+
+ Defines the normal stack memory available to each CPU. This constant is used
+ by `plat/common/aarch64/platform\_mp\_stack.S`_ and
+ `plat/common/aarch64/platform\_up\_stack.S`_.
+
+- **define : CACHE\_WRITEBACK\_GRANULE**
+
+ Defines the size in bits of the largest cache line across all the cache
+ levels in the platform.
+
+- **#define : FIRMWARE\_WELCOME\_STR**
+
+ Defines the character string printed by BL1 upon entry into the ``bl1_main()``
+ function.
+
+- **#define : PLATFORM\_CORE\_COUNT**
+
+ Defines the total number of CPUs implemented by the platform across all
+ clusters in the system.
+
+- **#define : PLAT\_NUM\_PWR\_DOMAINS**
+
+ Defines the total number of nodes in the power domain topology
+ tree at all the power domain levels used by the platform.
+ This macro is used by the PSCI implementation to allocate
+ data structures to represent power domain topology.
+
+- **#define : PLAT\_MAX\_PWR\_LVL**
+
+ Defines the maximum power domain level that the power management operations
+ should apply to. More often, but not always, the power domain level
+ corresponds to affinity level. This macro allows the PSCI implementation
+ to know the highest power domain level that it should consider for power
+ management operations in the system that the platform implements. For
+ example, the Base AEM FVP implements two clusters with a configurable
+ number of CPUs and it reports the maximum power domain level as 1.
+
+- **#define : PLAT\_MAX\_OFF\_STATE**
+
+ Defines the local power state corresponding to the deepest power down
+ possible at every power domain level in the platform. The local power
+ states for each level may be sparsely allocated between 0 and this value
+ with 0 being reserved for the RUN state. The PSCI implementation uses this
+ value to initialize the local power states of the power domain nodes and
+ to specify the requested power state for a PSCI\_CPU\_OFF call.
+
+- **#define : PLAT\_MAX\_RET\_STATE**
+
+ Defines the local power state corresponding to the deepest retention state
+ possible at every power domain level in the platform. This macro should be
+ a value less than PLAT\_MAX\_OFF\_STATE and greater than 0. It is used by the
+ PSCI implementation to distinguish between retention and power down local
+ power states within PSCI\_CPU\_SUSPEND call.
+
+- **#define : PLAT\_MAX\_PWR\_LVL\_STATES**
+
+ Defines the maximum number of local power states per power domain level
+ that the platform supports. The default value of this macro is 2 since
+ most platforms just support a maximum of two local power states at each
+ power domain level (power-down and retention). If the platform needs to
+ account for more local power states, then it must redefine this macro.
+
+ Currently, this macro is used by the Generic PSCI implementation to size
+ the array used for PSCI\_STAT\_COUNT/RESIDENCY accounting.
+
+- **#define : BL1\_RO\_BASE**
+
+ Defines the base address in secure ROM where BL1 originally lives. Must be
+ aligned on a page-size boundary.
+
+- **#define : BL1\_RO\_LIMIT**
+
+ Defines the maximum address in secure ROM that BL1's actual content (i.e.
+ excluding any data section allocated at runtime) can occupy.
+
+- **#define : BL1\_RW\_BASE**
+
+ Defines the base address in secure RAM where BL1's read-write data will live
+ at runtime. Must be aligned on a page-size boundary.
+
+- **#define : BL1\_RW\_LIMIT**
+
+ Defines the maximum address in secure RAM that BL1's read-write data can
+ occupy at runtime.
+
+- **#define : BL2\_BASE**
+
+ Defines the base address in secure RAM where BL1 loads the BL2 binary image.
+ Must be aligned on a page-size boundary.
+
+- **#define : BL2\_LIMIT**
+
+ Defines the maximum address in secure RAM that the BL2 image can occupy.
+
+- **#define : BL31\_BASE**
+
+ Defines the base address in secure RAM where BL2 loads the BL31 binary
+ image. Must be aligned on a page-size boundary.
+
+- **#define : BL31\_LIMIT**
+
+ Defines the maximum address in secure RAM that the BL31 image can occupy.
+
+For every image, the platform must define individual identifiers that will be
+used by BL1 or BL2 to load the corresponding image into memory from non-volatile
+storage. For the sake of performance, integer numbers will be used as
+identifiers. The platform will use those identifiers to return the relevant
+information about the image to be loaded (file handler, load address,
+authentication information, etc.). The following image identifiers are
+mandatory:
+
+- **#define : BL2\_IMAGE\_ID**
+
+ BL2 image identifier, used by BL1 to load BL2.
+
+- **#define : BL31\_IMAGE\_ID**
+
+ BL31 image identifier, used by BL2 to load BL31.
+
+- **#define : BL33\_IMAGE\_ID**
+
+ BL33 image identifier, used by BL2 to load BL33.
+
+If Trusted Board Boot is enabled, the following certificate identifiers must
+also be defined:
+
+- **#define : TRUSTED\_BOOT\_FW\_CERT\_ID**
+
+ BL2 content certificate identifier, used by BL1 to load the BL2 content
+ certificate.
+
+- **#define : TRUSTED\_KEY\_CERT\_ID**
+
+ Trusted key certificate identifier, used by BL2 to load the trusted key
+ certificate.
+
+- **#define : SOC\_FW\_KEY\_CERT\_ID**
+
+ BL31 key certificate identifier, used by BL2 to load the BL31 key
+ certificate.
+
+- **#define : SOC\_FW\_CONTENT\_CERT\_ID**
+
+ BL31 content certificate identifier, used by BL2 to load the BL31 content
+ certificate.
+
+- **#define : NON\_TRUSTED\_FW\_KEY\_CERT\_ID**
+
+ BL33 key certificate identifier, used by BL2 to load the BL33 key
+ certificate.
+
+- **#define : NON\_TRUSTED\_FW\_CONTENT\_CERT\_ID**
+
+ BL33 content certificate identifier, used by BL2 to load the BL33 content
+ certificate.
+
+- **#define : FWU\_CERT\_ID**
+
+ Firmware Update (FWU) certificate identifier, used by NS\_BL1U to load the
+ FWU content certificate.
+
+- **#define : PLAT\_CRYPTOCELL\_BASE**
+
+ This defines the base address of ARM® TrustZone® CryptoCell and must be
+ defined if CryptoCell crypto driver is used for Trusted Board Boot. For
+ capable ARM platforms, this driver is used if ``ARM_CRYPTOCELL_INTEG`` is
+ set.
+
+If the AP Firmware Updater Configuration image, BL2U is used, the following
+must also be defined:
+
+- **#define : BL2U\_BASE**
+
+ Defines the base address in secure memory where BL1 copies the BL2U binary
+ image. Must be aligned on a page-size boundary.
+
+- **#define : BL2U\_LIMIT**
+
+ Defines the maximum address in secure memory that the BL2U image can occupy.
+
+- **#define : BL2U\_IMAGE\_ID**
+
+ BL2U image identifier, used by BL1 to fetch an image descriptor
+ corresponding to BL2U.
+
+If the SCP Firmware Update Configuration Image, SCP\_BL2U is used, the following
+must also be defined:
+
+- **#define : SCP\_BL2U\_IMAGE\_ID**
+
+ SCP\_BL2U image identifier, used by BL1 to fetch an image descriptor
+ corresponding to SCP\_BL2U.
+ NOTE: TF does not provide source code for this image.
+
+If the Non-Secure Firmware Updater ROM, NS\_BL1U is used, the following must
+also be defined:
+
+- **#define : NS\_BL1U\_BASE**
+
+ Defines the base address in non-secure ROM where NS\_BL1U executes.
+ Must be aligned on a page-size boundary.
+ NOTE: TF does not provide source code for this image.
+
+- **#define : NS\_BL1U\_IMAGE\_ID**
+
+ NS\_BL1U image identifier, used by BL1 to fetch an image descriptor
+ corresponding to NS\_BL1U.
+
+If the Non-Secure Firmware Updater, NS\_BL2U is used, the following must also
+be defined:
+
+- **#define : NS\_BL2U\_BASE**
+
+ Defines the base address in non-secure memory where NS\_BL2U executes.
+ Must be aligned on a page-size boundary.
+ NOTE: TF does not provide source code for this image.
+
+- **#define : NS\_BL2U\_IMAGE\_ID**
+
+ NS\_BL2U image identifier, used by BL1 to fetch an image descriptor
+ corresponding to NS\_BL2U.
+
+For the the Firmware update capability of TRUSTED BOARD BOOT, the following
+macros may also be defined:
+
+- **#define : PLAT\_FWU\_MAX\_SIMULTANEOUS\_IMAGES**
+
+ Total number of images that can be loaded simultaneously. If the platform
+ doesn't specify any value, it defaults to 10.
+
+If a SCP\_BL2 image is supported by the platform, the following constants must
+also be defined:
+
+- **#define : SCP\_BL2\_IMAGE\_ID**
+
+ SCP\_BL2 image identifier, used by BL2 to load SCP\_BL2 into secure memory
+ from platform storage before being transfered to the SCP.
+
+- **#define : SCP\_FW\_KEY\_CERT\_ID**
+
+ SCP\_BL2 key certificate identifier, used by BL2 to load the SCP\_BL2 key
+ certificate (mandatory when Trusted Board Boot is enabled).
+
+- **#define : SCP\_FW\_CONTENT\_CERT\_ID**
+
+ SCP\_BL2 content certificate identifier, used by BL2 to load the SCP\_BL2
+ content certificate (mandatory when Trusted Board Boot is enabled).
+
+If a BL32 image is supported by the platform, the following constants must
+also be defined:
+
+- **#define : BL32\_IMAGE\_ID**
+
+ BL32 image identifier, used by BL2 to load BL32.
+
+- **#define : TRUSTED\_OS\_FW\_KEY\_CERT\_ID**
+
+ BL32 key certificate identifier, used by BL2 to load the BL32 key
+ certificate (mandatory when Trusted Board Boot is enabled).
+
+- **#define : TRUSTED\_OS\_FW\_CONTENT\_CERT\_ID**
+
+ BL32 content certificate identifier, used by BL2 to load the BL32 content
+ certificate (mandatory when Trusted Board Boot is enabled).
+
+- **#define : BL32\_BASE**
+
+ Defines the base address in secure memory where BL2 loads the BL32 binary
+ image. Must be aligned on a page-size boundary.
+
+- **#define : BL32\_LIMIT**
+
+ Defines the maximum address that the BL32 image can occupy.
+
+If the Test Secure-EL1 Payload (TSP) instantiation of BL32 is supported by the
+platform, the following constants must also be defined:
+
+- **#define : TSP\_SEC\_MEM\_BASE**
+
+ Defines the base address of the secure memory used by the TSP image on the
+ platform. This must be at the same address or below ``BL32_BASE``.
+
+- **#define : TSP\_SEC\_MEM\_SIZE**
+
+ Defines the size of the secure memory used by the BL32 image on the
+ platform. ``TSP_SEC_MEM_BASE`` and ``TSP_SEC_MEM_SIZE`` must fully accomodate
+ the memory required by the BL32 image, defined by ``BL32_BASE`` and
+ ``BL32_LIMIT``.
+
+- **#define : TSP\_IRQ\_SEC\_PHY\_TIMER**
+
+ Defines the ID of the secure physical generic timer interrupt used by the
+ TSP's interrupt handling code.
+
+If the platform port uses the translation table library code, the following
+constants must also be defined:
+
+- **#define : PLAT\_XLAT\_TABLES\_DYNAMIC**
+
+ Optional flag that can be set per-image to enable the dynamic allocation of
+ regions even when the MMU is enabled. If not defined, only static
+ functionality will be available, if defined and set to 1 it will also
+ include the dynamic functionality.
+
+- **#define : MAX\_XLAT\_TABLES**
+
+ Defines the maximum number of translation tables that are allocated by the
+ translation table library code. To minimize the amount of runtime memory
+ used, choose the smallest value needed to map the required virtual addresses
+ for each BL stage. If ``PLAT_XLAT_TABLES_DYNAMIC`` flag is enabled for a BL
+ image, ``MAX_XLAT_TABLES`` must be defined to accommodate the dynamic regions
+ as well.
+
+- **#define : MAX\_MMAP\_REGIONS**
+
+ Defines the maximum number of regions that are allocated by the translation
+ table library code. A region consists of physical base address, virtual base
+ address, size and attributes (Device/Memory, RO/RW, Secure/Non-Secure), as
+ defined in the ``mmap_region_t`` structure. The platform defines the regions
+ that should be mapped. Then, the translation table library will create the
+ corresponding tables and descriptors at runtime. To minimize the amount of
+ runtime memory used, choose the smallest value needed to register the
+ required regions for each BL stage. If ``PLAT_XLAT_TABLES_DYNAMIC`` flag is
+ enabled for a BL image, ``MAX_MMAP_REGIONS`` must be defined to accommodate
+ the dynamic regions as well.
+
+- **#define : ADDR\_SPACE\_SIZE**
+
+ Defines the total size of the address space in bytes. For example, for a 32
+ bit address space, this value should be ``(1ull << 32)``. This definition is
+ now deprecated, platforms should use ``PLAT_PHY_ADDR_SPACE_SIZE`` and
+ ``PLAT_VIRT_ADDR_SPACE_SIZE`` instead.
+
+- **#define : PLAT\_VIRT\_ADDR\_SPACE\_SIZE**
+
+ Defines the total size of the virtual address space in bytes. For example,
+ for a 32 bit virtual address space, this value should be ``(1ull << 32)``.
+
+- **#define : PLAT\_PHY\_ADDR\_SPACE\_SIZE**
+
+ Defines the total size of the physical address space in bytes. For example,
+ for a 32 bit physical address space, this value should be ``(1ull << 32)``.
+
+If the platform port uses the IO storage framework, the following constants
+must also be defined:
+
+- **#define : MAX\_IO\_DEVICES**
+
+ Defines the maximum number of registered IO devices. Attempting to register
+ more devices than this value using ``io_register_device()`` will fail with
+ -ENOMEM.
+
+- **#define : MAX\_IO\_HANDLES**
+
+ Defines the maximum number of open IO handles. Attempting to open more IO
+ entities than this value using ``io_open()`` will fail with -ENOMEM.
+
+- **#define : MAX\_IO\_BLOCK\_DEVICES**
+
+ Defines the maximum number of registered IO block devices. Attempting to
+ register more devices this value using ``io_dev_open()`` will fail
+ with -ENOMEM. MAX\_IO\_BLOCK\_DEVICES should be less than MAX\_IO\_DEVICES.
+ With this macro, multiple block devices could be supported at the same
+ time.
+
+If the platform needs to allocate data within the per-cpu data framework in
+BL31, it should define the following macro. Currently this is only required if
+the platform decides not to use the coherent memory section by undefining the
+``USE_COHERENT_MEM`` build flag. In this case, the framework allocates the
+required memory within the the per-cpu data to minimize wastage.
+
+- **#define : PLAT\_PCPU\_DATA\_SIZE**
+
+ Defines the memory (in bytes) to be reserved within the per-cpu data
+ structure for use by the platform layer.
+
+The following constants are optional. They should be defined when the platform
+memory layout implies some image overlaying like in ARM standard platforms.
+
+- **#define : BL31\_PROGBITS\_LIMIT**
+
+ Defines the maximum address in secure RAM that the BL31's progbits sections
+ can occupy.
+
+- **#define : TSP\_PROGBITS\_LIMIT**
+
+ Defines the maximum address that the TSP's progbits sections can occupy.
+
+If the platform port uses the PL061 GPIO driver, the following constant may
+optionally be defined:
+
+- **PLAT\_PL061\_MAX\_GPIOS**
+ Maximum number of GPIOs required by the platform. This allows control how
+ much memory is allocated for PL061 GPIO controllers. The default value is
+
+ #. $(eval $(call add\_define,PLAT\_PL061\_MAX\_GPIOS))
+
+If the platform port uses the partition driver, the following constant may
+optionally be defined:
+
+- **PLAT\_PARTITION\_MAX\_ENTRIES**
+ Maximum number of partition entries required by the platform. This allows
+ control how much memory is allocated for partition entries. The default
+ value is 128.
+ `For example, define the build flag in platform.mk`_:
+ PLAT\_PARTITION\_MAX\_ENTRIES := 12
+ $(eval $(call add\_define,PLAT\_PARTITION\_MAX\_ENTRIES))
+
+The following constant is optional. It should be defined to override the default
+behaviour of the ``assert()`` function (for example, to save memory).
+
+- **PLAT\_LOG\_LEVEL\_ASSERT**
+ If ``PLAT_LOG_LEVEL_ASSERT`` is higher or equal than ``LOG_LEVEL_VERBOSE``,
+ ``assert()`` prints the name of the file, the line number and the asserted
+ expression. Else if it is higher than ``LOG_LEVEL_INFO``, it prints the file
+ name and the line number. Else if it is lower than ``LOG_LEVEL_INFO``, it
+ doesn't print anything to the console. If ``PLAT_LOG_LEVEL_ASSERT`` isn't
+ defined, it defaults to ``LOG_LEVEL``.
+
+File : plat\_macros.S [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Each platform must ensure a file of this name is in the system include path with
+the following macro defined. In the ARM development platforms, this file is
+found in ``plat/arm/board/<plat_name>/include/plat_macros.S``.
+
+- **Macro : plat\_crash\_print\_regs**
+
+ This macro allows the crash reporting routine to print relevant platform
+ registers in case of an unhandled exception in BL31. This aids in debugging
+ and this macro can be defined to be empty in case register reporting is not
+ desired.
+
+ For instance, GIC or interconnect registers may be helpful for
+ troubleshooting.
+
+Handling Reset
+--------------
+
+BL1 by default implements the reset vector where execution starts from a cold
+or warm boot. BL31 can be optionally set as a reset vector using the
+``RESET_TO_BL31`` make variable.
+
+For each CPU, the reset vector code is responsible for the following tasks:
+
+#. Distinguishing between a cold boot and a warm boot.
+
+#. In the case of a cold boot and the CPU being a secondary CPU, ensuring that
+ the CPU is placed in a platform-specific state until the primary CPU
+ performs the necessary steps to remove it from this state.
+
+#. In the case of a warm boot, ensuring that the CPU jumps to a platform-
+ specific address in the BL31 image in the same processor mode as it was
+ when released from reset.
+
+The following functions need to be implemented by the platform port to enable
+reset vector code to perform the above tasks.
+
+Function : plat\_get\_my\_entrypoint() [mandatory when PROGRAMMABLE\_RESET\_ADDRESS == 0]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : uintptr_t
+
+This function is called with the MMU and caches disabled
+(``SCTLR_EL3.M`` = 0 and ``SCTLR_EL3.C`` = 0). The function is responsible for
+distinguishing between a warm and cold reset for the current CPU using
+platform-specific means. If it's a warm reset, then it returns the warm
+reset entrypoint point provided to ``plat_setup_psci_ops()`` during
+BL31 initialization. If it's a cold reset then this function must return zero.
+
+This function does not follow the Procedure Call Standard used by the
+Application Binary Interface for the ARM 64-bit architecture. The caller should
+not assume that callee saved registers are preserved across a call to this
+function.
+
+This function fulfills requirement 1 and 3 listed above.
+
+Note that for platforms that support programming the reset address, it is
+expected that a CPU will start executing code directly at the right address,
+both on a cold and warm reset. In this case, there is no need to identify the
+type of reset nor to query the warm reset entrypoint. Therefore, implementing
+this function is not required on such platforms.
+
+Function : plat\_secondary\_cold\_boot\_setup() [mandatory when COLD\_BOOT\_SINGLE\_CPU == 0]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+
+This function is called with the MMU and data caches disabled. It is responsible
+for placing the executing secondary CPU in a platform-specific state until the
+primary CPU performs the necessary actions to bring it out of that state and
+allow entry into the OS. This function must not return.
+
+In the ARM FVP port, when using the normal boot flow, each secondary CPU powers
+itself off. The primary CPU is responsible for powering up the secondary CPUs
+when normal world software requires them. When booting an EL3 payload instead,
+they stay powered on and are put in a holding pen until their mailbox gets
+populated.
+
+This function fulfills requirement 2 above.
+
+Note that for platforms that can't release secondary CPUs out of reset, only the
+primary CPU will execute the cold boot code. Therefore, implementing this
+function is not required on such platforms.
+
+Function : plat\_is\_my\_cpu\_primary() [mandatory when COLD\_BOOT\_SINGLE\_CPU == 0]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : unsigned int
+
+This function identifies whether the current CPU is the primary CPU or a
+secondary CPU. A return value of zero indicates that the CPU is not the
+primary CPU, while a non-zero return value indicates that the CPU is the
+primary CPU.
+
+Note that for platforms that can't release secondary CPUs out of reset, only the
+primary CPU will execute the cold boot code. Therefore, there is no need to
+distinguish between primary and secondary CPUs and implementing this function is
+not required.
+
+Function : platform\_mem\_init() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function is called before any access to data is made by the firmware, in
+order to carry out any essential memory initialization.
+
+Function: plat\_get\_rotpk\_info()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void *, void **, unsigned int *, unsigned int *
+ Return : int
+
+This function is mandatory when Trusted Board Boot is enabled. It returns a
+pointer to the ROTPK stored in the platform (or a hash of it) and its length.
+The ROTPK must be encoded in DER format according to the following ASN.1
+structure:
+
+::
+
+ AlgorithmIdentifier ::= SEQUENCE {
+ algorithm OBJECT IDENTIFIER,
+ parameters ANY DEFINED BY algorithm OPTIONAL
+ }
+
+ SubjectPublicKeyInfo ::= SEQUENCE {
+ algorithm AlgorithmIdentifier,
+ subjectPublicKey BIT STRING
+ }
+
+In case the function returns a hash of the key:
+
+::
+
+ DigestInfo ::= SEQUENCE {
+ digestAlgorithm AlgorithmIdentifier,
+ digest OCTET STRING
+ }
+
+The function returns 0 on success. Any other value is treated as error by the
+Trusted Board Boot. The function also reports extra information related
+to the ROTPK in the flags parameter:
+
+::
+
+ ROTPK_IS_HASH : Indicates that the ROTPK returned by the platform is a
+ hash.
+ ROTPK_NOT_DEPLOYED : This allows the platform to skip certificate ROTPK
+ verification while the platform ROTPK is not deployed.
+ When this flag is set, the function does not need to
+ return a platform ROTPK, and the authentication
+ framework uses the ROTPK in the certificate without
+ verifying it against the platform value. This flag
+ must not be used in a deployed production environment.
+
+Function: plat\_get\_nv\_ctr()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void *, unsigned int *
+ Return : int
+
+This function is mandatory when Trusted Board Boot is enabled. It returns the
+non-volatile counter value stored in the platform in the second argument. The
+cookie in the first argument may be used to select the counter in case the
+platform provides more than one (for example, on platforms that use the default
+TBBR CoT, the cookie will correspond to the OID values defined in
+TRUSTED\_FW\_NVCOUNTER\_OID or NON\_TRUSTED\_FW\_NVCOUNTER\_OID).
+
+The function returns 0 on success. Any other value means the counter value could
+not be retrieved from the platform.
+
+Function: plat\_set\_nv\_ctr()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void *, unsigned int
+ Return : int
+
+This function is mandatory when Trusted Board Boot is enabled. It sets a new
+counter value in the platform. The cookie in the first argument may be used to
+select the counter (as explained in plat\_get\_nv\_ctr()). The second argument is
+the updated counter value to be written to the NV counter.
+
+The function returns 0 on success. Any other value means the counter value could
+not be updated.
+
+Function: plat\_set\_nv\_ctr2()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void *, const auth_img_desc_t *, unsigned int
+ Return : int
+
+This function is optional when Trusted Board Boot is enabled. If this
+interface is defined, then ``plat_set_nv_ctr()`` need not be defined. The
+first argument passed is a cookie and is typically used to
+differentiate between a Non Trusted NV Counter and a Trusted NV
+Counter. The second argument is a pointer to an authentication image
+descriptor and may be used to decide if the counter is allowed to be
+updated or not. The third argument is the updated counter value to
+be written to the NV counter.
+
+The function returns 0 on success. Any other value means the counter value
+either could not be updated or the authentication image descriptor indicates
+that it is not allowed to be updated.
+
+Common mandatory function modifications
+---------------------------------------
+
+The following functions are mandatory functions which need to be implemented
+by the platform port.
+
+Function : plat\_my\_core\_pos()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : unsigned int
+
+This funtion returns the index of the calling CPU which is used as a
+CPU-specific linear index into blocks of memory (for example while allocating
+per-CPU stacks). This function will be invoked very early in the
+initialization sequence which mandates that this function should be
+implemented in assembly and should not rely on the avalability of a C
+runtime environment. This function can clobber x0 - x8 and must preserve
+x9 - x29.
+
+This function plays a crucial role in the power domain topology framework in
+PSCI and details of this can be found in `Power Domain Topology Design`_.
+
+Function : plat\_core\_pos\_by\_mpidr()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : u_register_t
+ Return : int
+
+This function validates the ``MPIDR`` of a CPU and converts it to an index,
+which can be used as a CPU-specific linear index into blocks of memory. In
+case the ``MPIDR`` is invalid, this function returns -1. This function will only
+be invoked by BL31 after the power domain topology is initialized and can
+utilize the C runtime environment. For further details about how ARM Trusted
+Firmware represents the power domain topology and how this relates to the
+linear CPU index, please refer `Power Domain Topology Design`_.
+
+Common optional modifications
+-----------------------------
+
+The following are helper functions implemented by the firmware that perform
+common platform-specific tasks. A platform may choose to override these
+definitions.
+
+Function : plat\_set\_my\_stack()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function sets the current stack pointer to the normal memory stack that
+has been allocated for the current CPU. For BL images that only require a
+stack for the primary CPU, the UP version of the function is used. The size
+of the stack allocated to each CPU is specified by the platform defined
+constant ``PLATFORM_STACK_SIZE``.
+
+Common implementations of this function for the UP and MP BL images are
+provided in `plat/common/aarch64/platform\_up\_stack.S`_ and
+`plat/common/aarch64/platform\_mp\_stack.S`_
+
+Function : plat\_get\_my\_stack()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : uintptr_t
+
+This function returns the base address of the normal memory stack that
+has been allocated for the current CPU. For BL images that only require a
+stack for the primary CPU, the UP version of the function is used. The size
+of the stack allocated to each CPU is specified by the platform defined
+constant ``PLATFORM_STACK_SIZE``.
+
+Common implementations of this function for the UP and MP BL images are
+provided in `plat/common/aarch64/platform\_up\_stack.S`_ and
+`plat/common/aarch64/platform\_mp\_stack.S`_
+
+Function : plat\_report\_exception()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int
+ Return : void
+
+A platform may need to report various information about its status when an
+exception is taken, for example the current exception level, the CPU security
+state (secure/non-secure), the exception type, and so on. This function is
+called in the following circumstances:
+
+- In BL1, whenever an exception is taken.
+- In BL2, whenever an exception is taken.
+
+The default implementation doesn't do anything, to avoid making assumptions
+about the way the platform displays its status information.
+
+For AArch64, this function receives the exception type as its argument.
+Possible values for exceptions types are listed in the
+`include/common/bl\_common.h`_ header file. Note that these constants are not
+related to any architectural exception code; they are just an ARM Trusted
+Firmware convention.
+
+For AArch32, this function receives the exception mode as its argument.
+Possible values for exception modes are listed in the
+`include/lib/aarch32/arch.h`_ header file.
+
+Function : plat\_reset\_handler()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+A platform may need to do additional initialization after reset. This function
+allows the platform to do the platform specific intializations. Platform
+specific errata workarounds could also be implemented here. The api should
+preserve the values of callee saved registers x19 to x29.
+
+The default implementation doesn't do anything. If a platform needs to override
+the default implementation, refer to the `Firmware Design`_ for general
+guidelines.
+
+Function : plat\_disable\_acp()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This api allows a platform to disable the Accelerator Coherency Port (if
+present) during a cluster power down sequence. The default weak implementation
+doesn't do anything. Since this api is called during the power down sequence,
+it has restrictions for stack usage and it can use the registers x0 - x17 as
+scratch registers. It should preserve the value in x18 register as it is used
+by the caller to store the return address.
+
+Function : plat\_error\_handler()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : int
+ Return : void
+
+This API is called when the generic code encounters an error situation from
+which it cannot continue. It allows the platform to perform error reporting or
+recovery actions (for example, reset the system). This function must not return.
+
+The parameter indicates the type of error using standard codes from ``errno.h``.
+Possible errors reported by the generic code are:
+
+- ``-EAUTH``: a certificate or image could not be authenticated (when Trusted
+ Board Boot is enabled)
+- ``-ENOENT``: the requested image or certificate could not be found or an IO
+ error was detected
+- ``-ENOMEM``: resources exhausted. Trusted Firmware does not use dynamic
+ memory, so this error is usually an indication of an incorrect array size
+
+The default implementation simply spins.
+
+Function : plat\_panic\_handler()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This API is called when the generic code encounters an unexpected error
+situation from which it cannot recover. This function must not return,
+and must be implemented in assembly because it may be called before the C
+environment is initialized.
+
+Note: The address from where it was called is stored in x30 (Link Register).
+The default implementation simply spins.
+
+Function : plat\_get\_bl\_image\_load\_info()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : bl_load_info_t *
+
+This function returns pointer to the list of images that the platform has
+populated to load. This function is currently invoked in BL2 to load the
+BL3xx images, when LOAD\_IMAGE\_V2 is enabled.
+
+Function : plat\_get\_next\_bl\_params()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : bl_params_t *
+
+This function returns a pointer to the shared memory that the platform has
+kept aside to pass trusted firmware related information that next BL image
+needs. This function is currently invoked in BL2 to pass this information to
+the next BL image, when LOAD\_IMAGE\_V2 is enabled.
+
+Function : plat\_get\_stack\_protector\_canary()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : u_register_t
+
+This function returns a random value that is used to initialize the canary used
+when the stack protector is enabled with ENABLE\_STACK\_PROTECTOR. A predictable
+value will weaken the protection as the attacker could easily write the right
+value as part of the attack most of the time. Therefore, it should return a
+true random number.
+
+Note: For the protection to be effective, the global data need to be placed at
+a lower address than the stack bases. Failure to do so would allow an attacker
+to overwrite the canary as part of the stack buffer overflow attack.
+
+Function : plat\_flush\_next\_bl\_params()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function flushes to main memory all the image params that are passed to
+next image. This function is currently invoked in BL2 to flush this information
+to the next BL image, when LOAD\_IMAGE\_V2 is enabled.
+
+Modifications specific to a Boot Loader stage
+---------------------------------------------
+
+Boot Loader Stage 1 (BL1)
+-------------------------
+
+BL1 implements the reset vector where execution starts from after a cold or
+warm boot. For each CPU, BL1 is responsible for the following tasks:
+
+#. Handling the reset as described in section 2.2
+
+#. In the case of a cold boot and the CPU being the primary CPU, ensuring that
+ only this CPU executes the remaining BL1 code, including loading and passing
+ control to the BL2 stage.
+
+#. Identifying and starting the Firmware Update process (if required).
+
+#. Loading the BL2 image from non-volatile storage into secure memory at the
+ address specified by the platform defined constant ``BL2_BASE``.
+
+#. Populating a ``meminfo`` structure with the following information in memory,
+ accessible by BL2 immediately upon entry.
+
+ ::
+
+ meminfo.total_base = Base address of secure RAM visible to BL2
+ meminfo.total_size = Size of secure RAM visible to BL2
+ meminfo.free_base = Base address of secure RAM available for
+ allocation to BL2
+ meminfo.free_size = Size of secure RAM available for allocation to BL2
+
+ BL1 places this ``meminfo`` structure at the beginning of the free memory
+ available for its use. Since BL1 cannot allocate memory dynamically at the
+ moment, its free memory will be available for BL2's use as-is. However, this
+ means that BL2 must read the ``meminfo`` structure before it starts using its
+ free memory (this is discussed in Section 3.2).
+
+ In future releases of the ARM Trusted Firmware it will be possible for
+ the platform to decide where it wants to place the ``meminfo`` structure for
+ BL2.
+
+ BL1 implements the ``bl1_init_bl2_mem_layout()`` function to populate the
+ BL2 ``meminfo`` structure. The platform may override this implementation, for
+ example if the platform wants to restrict the amount of memory visible to
+ BL2. Details of how to do this are given below.
+
+The following functions need to be implemented by the platform port to enable
+BL1 to perform the above tasks.
+
+Function : bl1\_early\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only called
+by the primary CPU.
+
+On ARM standard platforms, this function:
+
+- Enables a secure instance of SP805 to act as the Trusted Watchdog.
+
+- Initializes a UART (PL011 console), which enables access to the ``printf``
+ family of functions in BL1.
+
+- Enables issuing of snoop and DVM (Distributed Virtual Memory) requests to
+ the CCI slave interface corresponding to the cluster that includes the
+ primary CPU.
+
+Function : bl1\_plat\_arch\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function performs any platform-specific and architectural setup that the
+platform requires. Platform-specific setup might include configuration of
+memory controllers and the interconnect.
+
+In ARM standard platforms, this function enables the MMU.
+
+This function helps fulfill requirement 2 above.
+
+Function : bl1\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function executes with the MMU and data caches enabled. It is responsible
+for performing any remaining platform-specific setup that can occur after the
+MMU and data cache have been enabled.
+
+In ARM standard platforms, this function initializes the storage abstraction
+layer used to load the next bootloader image.
+
+This function helps fulfill requirement 4 above.
+
+Function : bl1\_plat\_sec\_mem\_layout() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : meminfo *
+
+This function should only be called on the cold boot path. It executes with the
+MMU and data caches enabled. The pointer returned by this function must point to
+a ``meminfo`` structure containing the extents and availability of secure RAM for
+the BL1 stage.
+
+::
+
+ meminfo.total_base = Base address of secure RAM visible to BL1
+ meminfo.total_size = Size of secure RAM visible to BL1
+ meminfo.free_base = Base address of secure RAM available for allocation
+ to BL1
+ meminfo.free_size = Size of secure RAM available for allocation to BL1
+
+This information is used by BL1 to load the BL2 image in secure RAM. BL1 also
+populates a similar structure to tell BL2 the extents of memory available for
+its own use.
+
+This function helps fulfill requirements 4 and 5 above.
+
+Function : bl1\_init\_bl2\_mem\_layout() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : meminfo *, meminfo *
+ Return : void
+
+BL1 needs to tell the next stage the amount of secure RAM available
+for it to use. This information is populated in a ``meminfo``
+structure.
+
+Depending upon where BL2 has been loaded in secure RAM (determined by
+``BL2_BASE``), BL1 calculates the amount of free memory available for BL2 to use.
+BL1 also ensures that its data sections resident in secure RAM are not visible
+to BL2. An illustration of how this is done in ARM standard platforms is given
+in the **Memory layout on ARM development platforms** section in the
+`Firmware Design`_.
+
+Function : bl1\_plat\_prepare\_exit() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : entry_point_info_t *
+ Return : void
+
+This function is called prior to exiting BL1 in response to the
+``BL1_SMC_RUN_IMAGE`` SMC request raised by BL2. It should be used to perform
+platform specific clean up or bookkeeping operations before transferring
+control to the next image. It receives the address of the ``entry_point_info_t``
+structure passed from BL2. This function runs with MMU disabled.
+
+Function : bl1\_plat\_set\_ep\_info() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int image_id, entry_point_info_t *ep_info
+ Return : void
+
+This function allows platforms to override ``ep_info`` for the given ``image_id``.
+
+The default implementation just returns.
+
+Function : bl1\_plat\_get\_next\_image\_id() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : unsigned int
+
+This and the following function must be overridden to enable the FWU feature.
+
+BL1 calls this function after platform setup to identify the next image to be
+loaded and executed. If the platform returns ``BL2_IMAGE_ID`` then BL1 proceeds
+with the normal boot sequence, which loads and executes BL2. If the platform
+returns a different image id, BL1 assumes that Firmware Update is required.
+
+The default implementation always returns ``BL2_IMAGE_ID``. The ARM development
+platforms override this function to detect if firmware update is required, and
+if so, return the first image in the firmware update process.
+
+Function : bl1\_plat\_get\_image\_desc() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int image_id
+ Return : image_desc_t *
+
+BL1 calls this function to get the image descriptor information ``image_desc_t``
+for the provided ``image_id`` from the platform.
+
+The default implementation always returns a common BL2 image descriptor. ARM
+standard platforms return an image descriptor corresponding to BL2 or one of
+the firmware update images defined in the Trusted Board Boot Requirements
+specification.
+
+Function : bl1\_plat\_fwu\_done() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int image_id, uintptr_t image_src,
+ unsigned int image_size
+ Return : void
+
+BL1 calls this function when the FWU process is complete. It must not return.
+The platform may override this function to take platform specific action, for
+example to initiate the normal boot flow.
+
+The default implementation spins forever.
+
+Function : bl1\_plat\_mem\_check() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : uintptr_t mem_base, unsigned int mem_size,
+ unsigned int flags
+ Return : int
+
+BL1 calls this function while handling FWU related SMCs, more specifically when
+copying or authenticating an image. Its responsibility is to ensure that the
+region of memory identified by ``mem_base`` and ``mem_size`` is mapped in BL1, and
+that this memory corresponds to either a secure or non-secure memory region as
+indicated by the security state of the ``flags`` argument.
+
+This function can safely assume that the value resulting from the addition of
+``mem_base`` and ``mem_size`` fits into a ``uintptr_t`` type variable and does not
+overflow.
+
+This function must return 0 on success, a non-null error code otherwise.
+
+The default implementation of this function asserts therefore platforms must
+override it when using the FWU feature.
+
+Boot Loader Stage 2 (BL2)
+-------------------------
+
+The BL2 stage is executed only by the primary CPU, which is determined in BL1
+using the ``platform_is_primary_cpu()`` function. BL1 passed control to BL2 at
+``BL2_BASE``. BL2 executes in Secure EL1 and is responsible for:
+
+#. (Optional) Loading the SCP\_BL2 binary image (if present) from platform
+ provided non-volatile storage. To load the SCP\_BL2 image, BL2 makes use of
+ the ``meminfo`` returned by the ``bl2_plat_get_scp_bl2_meminfo()`` function.
+ The platform also defines the address in memory where SCP\_BL2 is loaded
+ through the optional constant ``SCP_BL2_BASE``. BL2 uses this information
+ to determine if there is enough memory to load the SCP\_BL2 image.
+ Subsequent handling of the SCP\_BL2 image is platform-specific and is
+ implemented in the ``bl2_plat_handle_scp_bl2()`` function.
+ If ``SCP_BL2_BASE`` is not defined then this step is not performed.
+
+#. Loading the BL31 binary image into secure RAM from non-volatile storage. To
+ load the BL31 image, BL2 makes use of the ``meminfo`` structure passed to it
+ by BL1. This structure allows BL2 to calculate how much secure RAM is
+ available for its use. The platform also defines the address in secure RAM
+ where BL31 is loaded through the constant ``BL31_BASE``. BL2 uses this
+ information to determine if there is enough memory to load the BL31 image.
+
+#. (Optional) Loading the BL32 binary image (if present) from platform
+ provided non-volatile storage. To load the BL32 image, BL2 makes use of
+ the ``meminfo`` returned by the ``bl2_plat_get_bl32_meminfo()`` function.
+ The platform also defines the address in memory where BL32 is loaded
+ through the optional constant ``BL32_BASE``. BL2 uses this information
+ to determine if there is enough memory to load the BL32 image.
+ If ``BL32_BASE`` is not defined then this and the next step is not performed.
+
+#. (Optional) Arranging to pass control to the BL32 image (if present) that
+ has been pre-loaded at ``BL32_BASE``. BL2 populates an ``entry_point_info``
+ structure in memory provided by the platform with information about how
+ BL31 should pass control to the BL32 image.
+
+#. (Optional) Loading the normal world BL33 binary image (if not loaded by
+ other means) into non-secure DRAM from platform storage and arranging for
+ BL31 to pass control to this image. This address is determined using the
+ ``plat_get_ns_image_entrypoint()`` function described below.
+
+#. BL2 populates an ``entry_point_info`` structure in memory provided by the
+ platform with information about how BL31 should pass control to the
+ other BL images.
+
+The following functions must be implemented by the platform port to enable BL2
+to perform the above tasks.
+
+Function : bl2\_early\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : meminfo *
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only called
+by the primary CPU. The arguments to this function is the address of the
+``meminfo`` structure populated by BL1.
+
+The platform may copy the contents of the ``meminfo`` structure into a private
+variable as the original memory may be subsequently overwritten by BL2. The
+copied structure is made available to all BL2 code through the
+``bl2_plat_sec_mem_layout()`` function.
+
+On ARM standard platforms, this function also:
+
+- Initializes a UART (PL011 console), which enables access to the ``printf``
+ family of functions in BL2.
+
+- Initializes the storage abstraction layer used to load further bootloader
+ images. It is necessary to do this early on platforms with a SCP\_BL2 image,
+ since the later ``bl2_platform_setup`` must be done after SCP\_BL2 is loaded.
+
+Function : bl2\_plat\_arch\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only called
+by the primary CPU.
+
+The purpose of this function is to perform any architectural initialization
+that varies across platforms.
+
+On ARM standard platforms, this function enables the MMU.
+
+Function : bl2\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initialization in ``bl2_plat_arch_setup()``. It is only
+called by the primary CPU.
+
+The purpose of this function is to perform any platform initialization
+specific to BL2.
+
+In ARM standard platforms, this function performs security setup, including
+configuration of the TrustZone controller to allow non-secure masters access
+to most of DRAM. Part of DRAM is reserved for secure world use.
+
+Function : bl2\_plat\_sec\_mem\_layout() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : meminfo *
+
+This function should only be called on the cold boot path. It may execute with
+the MMU and data caches enabled if the platform port does the necessary
+initialization in ``bl2_plat_arch_setup()``. It is only called by the primary CPU.
+
+The purpose of this function is to return a pointer to a ``meminfo`` structure
+populated with the extents of secure RAM available for BL2 to use. See
+``bl2_early_platform_setup()`` above.
+
+Following function is required only when LOAD\_IMAGE\_V2 is enabled.
+
+Function : bl2\_plat\_handle\_post\_image\_load() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int
+ Return : int
+
+This function can be used by the platforms to update/use image information
+for given ``image_id``. This function is currently invoked in BL2 to handle
+BL image specific information based on the ``image_id`` passed, when
+LOAD\_IMAGE\_V2 is enabled.
+
+Following functions are required only when LOAD\_IMAGE\_V2 is disabled.
+
+Function : bl2\_plat\_get\_scp\_bl2\_meminfo() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : meminfo *
+ Return : void
+
+This function is used to get the memory limits where BL2 can load the
+SCP\_BL2 image. The meminfo provided by this is used by load\_image() to
+validate whether the SCP\_BL2 image can be loaded within the given
+memory from the given base.
+
+Function : bl2\_plat\_handle\_scp\_bl2() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : image_info *
+ Return : int
+
+This function is called after loading SCP\_BL2 image and it is used to perform
+any platform-specific actions required to handle the SCP firmware. Typically it
+transfers the image into SCP memory using a platform-specific protocol and waits
+until SCP executes it and signals to the Application Processor (AP) for BL2
+execution to continue.
+
+This function returns 0 on success, a negative error code otherwise.
+
+Function : bl2\_plat\_get\_bl31\_params() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : bl31_params *
+
+BL2 platform code needs to return a pointer to a ``bl31_params`` structure it
+will use for passing information to BL31. The ``bl31_params`` structure carries
+the following information.
+- Header describing the version information for interpreting the bl31\_param
+structure
+- Information about executing the BL33 image in the ``bl33_ep_info`` field
+- Information about executing the BL32 image in the ``bl32_ep_info`` field
+- Information about the type and extents of BL31 image in the
+``bl31_image_info`` field
+- Information about the type and extents of BL32 image in the
+``bl32_image_info`` field
+- Information about the type and extents of BL33 image in the
+``bl33_image_info`` field
+
+The memory pointed by this structure and its sub-structures should be
+accessible from BL31 initialisation code. BL31 might choose to copy the
+necessary content, or maintain the structures until BL33 is initialised.
+
+Funtion : bl2\_plat\_get\_bl31\_ep\_info() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : entry_point_info *
+
+BL2 platform code returns a pointer which is used to populate the entry point
+information for BL31 entry point. The location pointed by it should be
+accessible from BL1 while processing the synchronous exception to run to BL31.
+
+In ARM standard platforms this is allocated inside a bl2\_to\_bl31\_params\_mem
+structure in BL2 memory.
+
+Function : bl2\_plat\_set\_bl31\_ep\_info() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : image_info *, entry_point_info *
+ Return : void
+
+In the normal boot flow, this function is called after loading BL31 image and
+it can be used to overwrite the entry point set by loader and also set the
+security state and SPSR which represents the entry point system state for BL31.
+
+When booting an EL3 payload instead, this function is called after populating
+its entry point address and can be used for the same purpose for the payload
+image. It receives a null pointer as its first argument in this case.
+
+Function : bl2\_plat\_set\_bl32\_ep\_info() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : image_info *, entry_point_info *
+ Return : void
+
+This function is called after loading BL32 image and it can be used to
+overwrite the entry point set by loader and also set the security state
+and SPSR which represents the entry point system state for BL32.
+
+Function : bl2\_plat\_set\_bl33\_ep\_info() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : image_info *, entry_point_info *
+ Return : void
+
+This function is called after loading BL33 image and it can be used to
+overwrite the entry point set by loader and also set the security state
+and SPSR which represents the entry point system state for BL33.
+
+In the preloaded BL33 alternative boot flow, this function is called after
+populating its entry point address. It is passed a null pointer as its first
+argument in this case.
+
+Function : bl2\_plat\_get\_bl32\_meminfo() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : meminfo *
+ Return : void
+
+This function is used to get the memory limits where BL2 can load the
+BL32 image. The meminfo provided by this is used by load\_image() to
+validate whether the BL32 image can be loaded with in the given
+memory from the given base.
+
+Function : bl2\_plat\_get\_bl33\_meminfo() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : meminfo *
+ Return : void
+
+This function is used to get the memory limits where BL2 can load the
+BL33 image. The meminfo provided by this is used by load\_image() to
+validate whether the BL33 image can be loaded with in the given
+memory from the given base.
+
+This function isn't needed if either ``PRELOADED_BL33_BASE`` or ``EL3_PAYLOAD_BASE``
+build options are used.
+
+Function : bl2\_plat\_flush\_bl31\_params() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+Once BL2 has populated all the structures that needs to be read by BL1
+and BL31 including the bl31\_params structures and its sub-structures,
+the bl31\_ep\_info structure and any platform specific data. It flushes
+all these data to the main memory so that it is available when we jump to
+later Bootloader stages with MMU off
+
+Function : plat\_get\_ns\_image\_entrypoint() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : uintptr_t
+
+As previously described, BL2 is responsible for arranging for control to be
+passed to a normal world BL image through BL31. This function returns the
+entrypoint of that image, which BL31 uses to jump to it.
+
+BL2 is responsible for loading the normal world BL33 image (e.g. UEFI).
+
+This function isn't needed if either ``PRELOADED_BL33_BASE`` or ``EL3_PAYLOAD_BASE``
+build options are used.
+
+FWU Boot Loader Stage 2 (BL2U)
+------------------------------
+
+The AP Firmware Updater Configuration, BL2U, is an optional part of the FWU
+process and is executed only by the primary CPU. BL1 passes control to BL2U at
+``BL2U_BASE``. BL2U executes in Secure-EL1 and is responsible for:
+
+#. (Optional) Transfering the optional SCP\_BL2U binary image from AP secure
+ memory to SCP RAM. BL2U uses the SCP\_BL2U ``image_info`` passed by BL1.
+ ``SCP_BL2U_BASE`` defines the address in AP secure memory where SCP\_BL2U
+ should be copied from. Subsequent handling of the SCP\_BL2U image is
+ implemented by the platform specific ``bl2u_plat_handle_scp_bl2u()`` function.
+ If ``SCP_BL2U_BASE`` is not defined then this step is not performed.
+
+#. Any platform specific setup required to perform the FWU process. For
+ example, ARM standard platforms initialize the TZC controller so that the
+ normal world can access DDR memory.
+
+The following functions must be implemented by the platform port to enable
+BL2U to perform the tasks mentioned above.
+
+Function : bl2u\_early\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : meminfo *mem_info, void *plat_info
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only
+called by the primary CPU. The arguments to this function is the address
+of the ``meminfo`` structure and platform specific info provided by BL1.
+
+The platform may copy the contents of the ``mem_info`` and ``plat_info`` into
+private storage as the original memory may be subsequently overwritten by BL2U.
+
+On ARM CSS platforms ``plat_info`` is interpreted as an ``image_info_t`` structure,
+to extract SCP\_BL2U image information, which is then copied into a private
+variable.
+
+Function : bl2u\_plat\_arch\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only
+called by the primary CPU.
+
+The purpose of this function is to perform any architectural initialization
+that varies across platforms, for example enabling the MMU (since the memory
+map differs across platforms).
+
+Function : bl2u\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initialization in ``bl2u_plat_arch_setup()``. It is only
+called by the primary CPU.
+
+The purpose of this function is to perform any platform initialization
+specific to BL2U.
+
+In ARM standard platforms, this function performs security setup, including
+configuration of the TrustZone controller to allow non-secure masters access
+to most of DRAM. Part of DRAM is reserved for secure world use.
+
+Function : bl2u\_plat\_handle\_scp\_bl2u() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : int
+
+This function is used to perform any platform-specific actions required to
+handle the SCP firmware. Typically it transfers the image into SCP memory using
+a platform-specific protocol and waits until SCP executes it and signals to the
+Application Processor (AP) for BL2U execution to continue.
+
+This function returns 0 on success, a negative error code otherwise.
+This function is included if SCP\_BL2U\_BASE is defined.
+
+Boot Loader Stage 3-1 (BL31)
+----------------------------
+
+During cold boot, the BL31 stage is executed only by the primary CPU. This is
+determined in BL1 using the ``platform_is_primary_cpu()`` function. BL1 passes
+control to BL31 at ``BL31_BASE``. During warm boot, BL31 is executed by all
+CPUs. BL31 executes at EL3 and is responsible for:
+
+#. Re-initializing all architectural and platform state. Although BL1 performs
+ some of this initialization, BL31 remains resident in EL3 and must ensure
+ that EL3 architectural and platform state is completely initialized. It
+ should make no assumptions about the system state when it receives control.
+
+#. Passing control to a normal world BL image, pre-loaded at a platform-
+ specific address by BL2. BL31 uses the ``entry_point_info`` structure that BL2
+ populated in memory to do this.
+
+#. Providing runtime firmware services. Currently, BL31 only implements a
+ subset of the Power State Coordination Interface (PSCI) API as a runtime
+ service. See Section 3.3 below for details of porting the PSCI
+ implementation.
+
+#. Optionally passing control to the BL32 image, pre-loaded at a platform-
+ specific address by BL2. BL31 exports a set of apis that allow runtime
+ services to specify the security state in which the next image should be
+ executed and run the corresponding image. BL31 uses the ``entry_point_info``
+ structure populated by BL2 to do this.
+
+If BL31 is a reset vector, It also needs to handle the reset as specified in
+section 2.2 before the tasks described above.
+
+The following functions must be implemented by the platform port to enable BL31
+to perform the above tasks.
+
+Function : bl31\_early\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : bl31_params *, void *
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only called
+by the primary CPU. The arguments to this function are:
+
+- The address of the ``bl31_params`` structure populated by BL2.
+- An opaque pointer that the platform may use as needed.
+
+The platform can copy the contents of the ``bl31_params`` structure and its
+sub-structures into private variables if the original memory may be
+subsequently overwritten by BL31 and similarly the ``void *`` pointing
+to the platform data also needs to be saved.
+
+In ARM standard platforms, BL2 passes a pointer to a ``bl31_params`` structure
+in BL2 memory. BL31 copies the information in this pointer to internal data
+structures. It also performs the following:
+
+- Initialize a UART (PL011 console), which enables access to the ``printf``
+ family of functions in BL31.
+
+- Enable issuing of snoop and DVM (Distributed Virtual Memory) requests to the
+ CCI slave interface corresponding to the cluster that includes the primary
+ CPU.
+
+Function : bl31\_plat\_arch\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function executes with the MMU and data caches disabled. It is only called
+by the primary CPU.
+
+The purpose of this function is to perform any architectural initialization
+that varies across platforms.
+
+On ARM standard platforms, this function enables the MMU.
+
+Function : bl31\_platform\_setup() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initialization in ``bl31_plat_arch_setup()``. It is only
+called by the primary CPU.
+
+The purpose of this function is to complete platform initialization so that both
+BL31 runtime services and normal world software can function correctly.
+
+On ARM standard platforms, this function does the following:
+
+- Initialize the generic interrupt controller.
+
+ Depending on the GIC driver selected by the platform, the appropriate GICv2
+ or GICv3 initialization will be done, which mainly consists of:
+
+ - Enable secure interrupts in the GIC CPU interface.
+ - Disable the legacy interrupt bypass mechanism.
+ - Configure the priority mask register to allow interrupts of all priorities
+ to be signaled to the CPU interface.
+ - Mark SGIs 8-15 and the other secure interrupts on the platform as secure.
+ - Target all secure SPIs to CPU0.
+ - Enable these secure interrupts in the GIC distributor.
+ - Configure all other interrupts as non-secure.
+ - Enable signaling of secure interrupts in the GIC distributor.
+
+- Enable system-level implementation of the generic timer counter through the
+ memory mapped interface.
+
+- Grant access to the system counter timer module
+
+- Initialize the power controller device.
+
+ In particular, initialise the locks that prevent concurrent accesses to the
+ power controller device.
+
+Function : bl31\_plat\_runtime\_setup() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+The purpose of this function is allow the platform to perform any BL31 runtime
+setup just prior to BL31 exit during cold boot. The default weak
+implementation of this function will invoke ``console_uninit()`` which will
+suppress any BL31 runtime logs.
+
+In ARM Standard platforms, this function will initialize the BL31 runtime
+console which will cause all further BL31 logs to be output to the
+runtime console.
+
+Function : bl31\_get\_next\_image\_info() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int
+ Return : entry_point_info *
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initializations in ``bl31_plat_arch_setup()``.
+
+This function is called by ``bl31_main()`` to retrieve information provided by
+BL2 for the next image in the security state specified by the argument. BL31
+uses this information to pass control to that image in the specified security
+state. This function must return a pointer to the ``entry_point_info`` structure
+(that was copied during ``bl31_early_platform_setup()``) if the image exists. It
+should return NULL otherwise.
+
+Function : plat\_get\_syscnt\_freq2() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : unsigned int
+
+This function is used by the architecture setup code to retrieve the counter
+frequency for the CPU's generic timer. This value will be programmed into the
+``CNTFRQ_EL0`` register. In ARM standard platforms, it returns the base frequency
+of the system counter, which is retrieved from the first entry in the frequency
+modes table.
+
+#define : PLAT\_PERCPU\_BAKERY\_LOCK\_SIZE [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When ``USE_COHERENT_MEM = 0``, this constant defines the total memory (in
+bytes) aligned to the cache line boundary that should be allocated per-cpu to
+accommodate all the bakery locks.
+
+If this constant is not defined when ``USE_COHERENT_MEM = 0``, the linker
+calculates the size of the ``bakery_lock`` input section, aligns it to the
+nearest ``CACHE_WRITEBACK_GRANULE``, multiplies it with ``PLATFORM_CORE_COUNT``
+and stores the result in a linker symbol. This constant prevents a platform
+from relying on the linker and provide a more efficient mechanism for
+accessing per-cpu bakery lock information.
+
+If this constant is defined and its value is not equal to the value
+calculated by the linker then a link time assertion is raised. A compile time
+assertion is raised if the value of the constant is not aligned to the cache
+line boundary.
+
+Power State Coordination Interface (in BL31)
+--------------------------------------------
+
+The ARM Trusted Firmware's implementation of the PSCI API is based around the
+concept of a *power domain*. A *power domain* is a CPU or a logical group of
+CPUs which share some state on which power management operations can be
+performed as specified by `PSCI`_. Each CPU in the system is assigned a cpu
+index which is a unique number between ``0`` and ``PLATFORM_CORE_COUNT - 1``.
+The *power domains* are arranged in a hierarchical tree structure and
+each *power domain* can be identified in a system by the cpu index of any CPU
+that is part of that domain and a *power domain level*. A processing element
+(for example, a CPU) is at level 0. If the *power domain* node above a CPU is
+a logical grouping of CPUs that share some state, then level 1 is that group
+of CPUs (for example, a cluster), and level 2 is a group of clusters
+(for example, the system). More details on the power domain topology and its
+organization can be found in `Power Domain Topology Design`_.
+
+BL31's platform initialization code exports a pointer to the platform-specific
+power management operations required for the PSCI implementation to function
+correctly. This information is populated in the ``plat_psci_ops`` structure. The
+PSCI implementation calls members of the ``plat_psci_ops`` structure for performing
+power management operations on the power domains. For example, the target
+CPU is specified by its ``MPIDR`` in a PSCI ``CPU_ON`` call. The ``pwr_domain_on()``
+handler (if present) is called for the CPU power domain.
+
+The ``power-state`` parameter of a PSCI ``CPU_SUSPEND`` call can be used to
+describe composite power states specific to a platform. The PSCI implementation
+defines a generic representation of the power-state parameter viz which is an
+array of local power states where each index corresponds to a power domain
+level. Each entry contains the local power state the power domain at that power
+level could enter. It depends on the ``validate_power_state()`` handler to
+convert the power-state parameter (possibly encoding a composite power state)
+passed in a PSCI ``CPU_SUSPEND`` call to this representation.
+
+The following functions form part of platform port of PSCI functionality.
+
+Function : plat\_psci\_stat\_accounting\_start() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : const psci_power_state_t *
+ Return : void
+
+This is an optional hook that platforms can implement for residency statistics
+accounting before entering a low power state. The ``pwr_domain_state`` field of
+``state_info`` (first argument) can be inspected if stat accounting is done
+differently at CPU level versus higher levels. As an example, if the element at
+index 0 (CPU power level) in the ``pwr_domain_state`` array indicates a power down
+state, special hardware logic may be programmed in order to keep track of the
+residency statistics. For higher levels (array indices > 0), the residency
+statistics could be tracked in software using PMF. If ``ENABLE_PMF`` is set, the
+default implementation will use PMF to capture timestamps.
+
+Function : plat\_psci\_stat\_accounting\_stop() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : const psci_power_state_t *
+ Return : void
+
+This is an optional hook that platforms can implement for residency statistics
+accounting after exiting from a low power state. The ``pwr_domain_state`` field
+of ``state_info`` (first argument) can be inspected if stat accounting is done
+differently at CPU level versus higher levels. As an example, if the element at
+index 0 (CPU power level) in the ``pwr_domain_state`` array indicates a power down
+state, special hardware logic may be programmed in order to keep track of the
+residency statistics. For higher levels (array indices > 0), the residency
+statistics could be tracked in software using PMF. If ``ENABLE_PMF`` is set, the
+default implementation will use PMF to capture timestamps.
+
+Function : plat\_psci\_stat\_get\_residency() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int, const psci_power_state_t *, int
+ Return : u_register_t
+
+This is an optional interface that is is invoked after resuming from a low power
+state and provides the time spent resident in that low power state by the power
+domain at a particular power domain level. When a CPU wakes up from suspend,
+all its parent power domain levels are also woken up. The generic PSCI code
+invokes this function for each parent power domain that is resumed and it
+identified by the ``lvl`` (first argument) parameter. The ``state_info`` (second
+argument) describes the low power state that the power domain has resumed from.
+The current CPU is the first CPU in the power domain to resume from the low
+power state and the ``last_cpu_idx`` (third parameter) is the index of the last
+CPU in the power domain to suspend and may be needed to calculate the residency
+for that power domain.
+
+Function : plat\_get\_target\_pwr\_state() [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : unsigned int, const plat_local_state_t *, unsigned int
+ Return : plat_local_state_t
+
+The PSCI generic code uses this function to let the platform participate in
+state coordination during a power management operation. The function is passed
+a pointer to an array of platform specific local power state ``states`` (second
+argument) which contains the requested power state for each CPU at a particular
+power domain level ``lvl`` (first argument) within the power domain. The function
+is expected to traverse this array of upto ``ncpus`` (third argument) and return
+a coordinated target power state by the comparing all the requested power
+states. The target power state should not be deeper than any of the requested
+power states.
+
+A weak definition of this API is provided by default wherein it assumes
+that the platform assigns a local state value in order of increasing depth
+of the power state i.e. for two power states X & Y, if X < Y
+then X represents a shallower power state than Y. As a result, the
+coordinated target local power state for a power domain will be the minimum
+of the requested local power state values.
+
+Function : plat\_get\_power\_domain\_tree\_desc() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : const unsigned char *
+
+This function returns a pointer to the byte array containing the power domain
+topology tree description. The format and method to construct this array are
+described in `Power Domain Topology Design`_. The BL31 PSCI initilization code
+requires this array to be described by the platform, either statically or
+dynamically, to initialize the power domain topology tree. In case the array
+is populated dynamically, then plat\_core\_pos\_by\_mpidr() and
+plat\_my\_core\_pos() should also be implemented suitably so that the topology
+tree description matches the CPU indices returned by these APIs. These APIs
+together form the platform interface for the PSCI topology framework.
+
+Function : plat\_setup\_psci\_ops() [mandatory]
+-----------------------------------------------
+
+::
+
+ Argument : uintptr_t, const plat_psci_ops **
+ Return : int
+
+This function may execute with the MMU and data caches enabled if the platform
+port does the necessary initializations in ``bl31_plat_arch_setup()``. It is only
+called by the primary CPU.
+
+This function is called by PSCI initialization code. Its purpose is to let
+the platform layer know about the warm boot entrypoint through the
+``sec_entrypoint`` (first argument) and to export handler routines for
+platform-specific psci power management actions by populating the passed
+pointer with a pointer to BL31's private ``plat_psci_ops`` structure.
+
+A description of each member of this structure is given below. Please refer to
+the ARM FVP specific implementation of these handlers in
+`plat/arm/board/fvp/fvp\_pm.c`_ as an example. For each PSCI function that the
+platform wants to support, the associated operation or operations in this
+structure must be provided and implemented (Refer section 4 of
+`Firmware Design`_ for the PSCI API supported in Trusted Firmware). To disable
+a PSCI function in a platform port, the operation should be removed from this
+structure instead of providing an empty implementation.
+
+plat\_psci\_ops.cpu\_standby()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Perform the platform-specific actions to enter the standby state for a cpu
+indicated by the passed argument. This provides a fast path for CPU standby
+wherein overheads of PSCI state management and lock acquistion is avoided.
+For this handler to be invoked by the PSCI ``CPU_SUSPEND`` API implementation,
+the suspend state type specified in the ``power-state`` parameter should be
+STANDBY and the target power domain level specified should be the CPU. The
+handler should put the CPU into a low power retention state (usually by
+issuing a wfi instruction) and ensure that it can be woken up from that
+state by a normal interrupt. The generic code expects the handler to succeed.
+
+plat\_psci\_ops.pwr\_domain\_on()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Perform the platform specific actions to power on a CPU, specified
+by the ``MPIDR`` (first argument). The generic code expects the platform to
+return PSCI\_E\_SUCCESS on success or PSCI\_E\_INTERN\_FAIL for any failure.
+
+plat\_psci\_ops.pwr\_domain\_off()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Perform the platform specific actions to prepare to power off the calling CPU
+and its higher parent power domain levels as indicated by the ``target_state``
+(first argument). It is called by the PSCI ``CPU_OFF`` API implementation.
+
+The ``target_state`` encodes the platform coordinated target local power states
+for the CPU power domain and its parent power domain levels. The handler
+needs to perform power management operation corresponding to the local state
+at each power level.
+
+For this handler, the local power state for the CPU power domain will be a
+power down state where as it could be either power down, retention or run state
+for the higher power domain levels depending on the result of state
+coordination. The generic code expects the handler to succeed.
+
+plat\_psci\_ops.pwr\_domain\_suspend()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Perform the platform specific actions to prepare to suspend the calling
+CPU and its higher parent power domain levels as indicated by the
+``target_state`` (first argument). It is called by the PSCI ``CPU_SUSPEND``
+API implementation.
+
+The ``target_state`` has a similar meaning as described in
+the ``pwr_domain_off()`` operation. It encodes the platform coordinated
+target local power states for the CPU power domain and its parent
+power domain levels. The handler needs to perform power management operation
+corresponding to the local state at each power level. The generic code
+expects the handler to succeed.
+
+The difference between turning a power domain off versus suspending it
+is that in the former case, the power domain is expected to re-initialize
+its state when it is next powered on (see ``pwr_domain_on_finish()``). In the
+latter case, the power domain is expected to save enough state so that it can
+resume execution by restoring this state when its powered on (see
+``pwr_domain_suspend_finish()``).
+
+plat\_psci\_ops.pwr\_domain\_pwr\_down\_wfi()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is an optional function and, if implemented, is expected to perform
+platform specific actions including the ``wfi`` invocation which allows the
+CPU to powerdown. Since this function is invoked outside the PSCI locks,
+the actions performed in this hook must be local to the CPU or the platform
+must ensure that races between multiple CPUs cannot occur.
+
+The ``target_state`` has a similar meaning as described in the ``pwr_domain_off()``
+operation and it encodes the platform coordinated target local power states for
+the CPU power domain and its parent power domain levels. This function must
+not return back to the caller.
+
+If this function is not implemented by the platform, PSCI generic
+implementation invokes ``psci_power_down_wfi()`` for power down.
+
+plat\_psci\_ops.pwr\_domain\_on\_finish()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by the PSCI implementation after the calling CPU is
+powered on and released from reset in response to an earlier PSCI ``CPU_ON`` call.
+It performs the platform-specific setup required to initialize enough state for
+this CPU to enter the normal world and also provide secure runtime firmware
+services.
+
+The ``target_state`` (first argument) is the prior state of the power domains
+immediately before the CPU was turned on. It indicates which power domains
+above the CPU might require initialization due to having previously been in
+low power states. The generic code expects the handler to succeed.
+
+plat\_psci\_ops.pwr\_domain\_suspend\_finish()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by the PSCI implementation after the calling CPU is
+powered on and released from reset in response to an asynchronous wakeup
+event, for example a timer interrupt that was programmed by the CPU during the
+``CPU_SUSPEND`` call or ``SYSTEM_SUSPEND`` call. It performs the platform-specific
+setup required to restore the saved state for this CPU to resume execution
+in the normal world and also provide secure runtime firmware services.
+
+The ``target_state`` (first argument) has a similar meaning as described in
+the ``pwr_domain_on_finish()`` operation. The generic code expects the platform
+to succeed.
+
+plat\_psci\_ops.system\_off()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by PSCI implementation in response to a ``SYSTEM_OFF``
+call. It performs the platform-specific system poweroff sequence after
+notifying the Secure Payload Dispatcher.
+
+plat\_psci\_ops.system\_reset()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by PSCI implementation in response to a ``SYSTEM_RESET``
+call. It performs the platform-specific system reset sequence after
+notifying the Secure Payload Dispatcher.
+
+plat\_psci\_ops.validate\_power\_state()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by the PSCI implementation during the ``CPU_SUSPEND``
+call to validate the ``power_state`` parameter of the PSCI API and if valid,
+populate it in ``req_state`` (second argument) array as power domain level
+specific local states. If the ``power_state`` is invalid, the platform must
+return PSCI\_E\_INVALID\_PARAMS as error, which is propagated back to the
+normal world PSCI client.
+
+plat\_psci\_ops.validate\_ns\_entrypoint()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by the PSCI implementation during the ``CPU_SUSPEND``,
+``SYSTEM_SUSPEND`` and ``CPU_ON`` calls to validate the non-secure ``entry_point``
+parameter passed by the normal world. If the ``entry_point`` is invalid,
+the platform must return PSCI\_E\_INVALID\_ADDRESS as error, which is
+propagated back to the normal world PSCI client.
+
+plat\_psci\_ops.get\_sys\_suspend\_power\_state()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This function is called by the PSCI implementation during the ``SYSTEM_SUSPEND``
+call to get the ``req_state`` parameter from platform which encodes the power
+domain level specific local states to suspend to system affinity level. The
+``req_state`` will be utilized to do the PSCI state coordination and
+``pwr_domain_suspend()`` will be invoked with the coordinated target state to
+enter system suspend.
+
+plat\_psci\_ops.get\_pwr\_lvl\_state\_idx()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is an optional function and, if implemented, is invoked by the PSCI
+implementation to convert the ``local_state`` (first argument) at a specified
+``pwr_lvl`` (second argument) to an index between 0 and
+``PLAT_MAX_PWR_LVL_STATES`` - 1. This function is only needed if the platform
+supports more than two local power states at each power domain level, that is
+``PLAT_MAX_PWR_LVL_STATES`` is greater than 2, and needs to account for these
+local power states.
+
+plat\_psci\_ops.translate\_power\_state\_by\_mpidr()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is an optional function and, if implemented, verifies the ``power_state``
+(second argument) parameter of the PSCI API corresponding to a target power
+domain. The target power domain is identified by using both ``MPIDR`` (first
+argument) and the power domain level encoded in ``power_state``. The power domain
+level specific local states are to be extracted from ``power_state`` and be
+populated in the ``output_state`` (third argument) array. The functionality
+is similar to the ``validate_power_state`` function described above and is
+envisaged to be used in case the validity of ``power_state`` depend on the
+targeted power domain. If the ``power_state`` is invalid for the targeted power
+domain, the platform must return PSCI\_E\_INVALID\_PARAMS as error. If this
+function is not implemented, then the generic implementation relies on
+``validate_power_state`` function to translate the ``power_state``.
+
+This function can also be used in case the platform wants to support local
+power state encoding for ``power_state`` parameter of PSCI\_STAT\_COUNT/RESIDENCY
+APIs as described in Section 5.18 of `PSCI`_.
+
+plat\_psci\_ops.get\_node\_hw\_state()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is an optional function. If implemented this function is intended to return
+the power state of a node (identified by the first parameter, the ``MPIDR``) in
+the power domain topology (identified by the second parameter, ``power_level``),
+as retrieved from a power controller or equivalent component on the platform.
+Upon successful completion, the implementation must map and return the final
+status among ``HW_ON``, ``HW_OFF`` or ``HW_STANDBY``. Upon encountering failures, it
+must return either ``PSCI_E_INVALID_PARAMS`` or ``PSCI_E_NOT_SUPPORTED`` as
+appropriate.
+
+Implementations are not expected to handle ``power_levels`` greater than
+``PLAT_MAX_PWR_LVL``.
+
+Interrupt Management framework (in BL31)
+----------------------------------------
+
+BL31 implements an Interrupt Management Framework (IMF) to manage interrupts
+generated in either security state and targeted to EL1 or EL2 in the non-secure
+state or EL3/S-EL1 in the secure state. The design of this framework is
+described in the `IMF Design Guide`_
+
+A platform should export the following APIs to support the IMF. The following
+text briefly describes each api and its implementation in ARM standard
+platforms. The API implementation depends upon the type of interrupt controller
+present in the platform. ARM standard platform layer supports both
+`ARM Generic Interrupt Controller version 2.0 (GICv2)`_
+and `3.0 (GICv3)`_. Juno builds the ARM
+Standard layer to use GICv2 and the FVP can be configured to use either GICv2 or
+GICv3 depending on the build flag ``FVP_USE_GIC_DRIVER`` (See FVP platform
+specific build options in `User Guide`_ for more details).
+
+Function : plat\_interrupt\_type\_to\_line() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : uint32_t, uint32_t
+ Return : uint32_t
+
+The ARM processor signals an interrupt exception either through the IRQ or FIQ
+interrupt line. The specific line that is signaled depends on how the interrupt
+controller (IC) reports different interrupt types from an execution context in
+either security state. The IMF uses this API to determine which interrupt line
+the platform IC uses to signal each type of interrupt supported by the framework
+from a given security state. This API must be invoked at EL3.
+
+The first parameter will be one of the ``INTR_TYPE_*`` values (see
+`IMF Design Guide`_) indicating the target type of the interrupt, the second parameter is the
+security state of the originating execution context. The return result is the
+bit position in the ``SCR_EL3`` register of the respective interrupt trap: IRQ=1,
+FIQ=2.
+
+In the case of ARM standard platforms using GICv2, S-EL1 interrupts are
+configured as FIQs and Non-secure interrupts as IRQs from either security
+state.
+
+In the case of ARM standard platforms using GICv3, the interrupt line to be
+configured depends on the security state of the execution context when the
+interrupt is signalled and are as follows:
+
+- The S-EL1 interrupts are signaled as IRQ in S-EL0/1 context and as FIQ in
+ NS-EL0/1/2 context.
+- The Non secure interrupts are signaled as FIQ in S-EL0/1 context and as IRQ
+ in the NS-EL0/1/2 context.
+- The EL3 interrupts are signaled as FIQ in both S-EL0/1 and NS-EL0/1/2
+ context.
+
+Function : plat\_ic\_get\_pending\_interrupt\_type() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : uint32_t
+
+This API returns the type of the highest priority pending interrupt at the
+platform IC. The IMF uses the interrupt type to retrieve the corresponding
+handler function. ``INTR_TYPE_INVAL`` is returned when there is no interrupt
+pending. The valid interrupt types that can be returned are ``INTR_TYPE_EL3``,
+``INTR_TYPE_S_EL1`` and ``INTR_TYPE_NS``. This API must be invoked at EL3.
+
+In the case of ARM standard platforms using GICv2, the *Highest Priority
+Pending Interrupt Register* (``GICC_HPPIR``) is read to determine the id of
+the pending interrupt. The type of interrupt depends upon the id value as
+follows.
+
+#. id < 1022 is reported as a S-EL1 interrupt
+#. id = 1022 is reported as a Non-secure interrupt.
+#. id = 1023 is reported as an invalid interrupt type.
+
+In the case of ARM standard platforms using GICv3, the system register
+``ICC_HPPIR0_EL1``, *Highest Priority Pending group 0 Interrupt Register*,
+is read to determine the id of the pending interrupt. The type of interrupt
+depends upon the id value as follows.
+
+#. id = ``PENDING_G1S_INTID`` (1020) is reported as a S-EL1 interrupt
+#. id = ``PENDING_G1NS_INTID`` (1021) is reported as a Non-secure interrupt.
+#. id = ``GIC_SPURIOUS_INTERRUPT`` (1023) is reported as an invalid interrupt type.
+#. All other interrupt id's are reported as EL3 interrupt.
+
+Function : plat\_ic\_get\_pending\_interrupt\_id() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : uint32_t
+
+This API returns the id of the highest priority pending interrupt at the
+platform IC. ``INTR_ID_UNAVAILABLE`` is returned when there is no interrupt
+pending.
+
+In the case of ARM standard platforms using GICv2, the *Highest Priority
+Pending Interrupt Register* (``GICC_HPPIR``) is read to determine the id of the
+pending interrupt. The id that is returned by API depends upon the value of
+the id read from the interrupt controller as follows.
+
+#. id < 1022. id is returned as is.
+#. id = 1022. The *Aliased Highest Priority Pending Interrupt Register*
+ (``GICC_AHPPIR``) is read to determine the id of the non-secure interrupt.
+ This id is returned by the API.
+#. id = 1023. ``INTR_ID_UNAVAILABLE`` is returned.
+
+In the case of ARM standard platforms using GICv3, if the API is invoked from
+EL3, the system register ``ICC_HPPIR0_EL1``, *Highest Priority Pending Interrupt
+group 0 Register*, is read to determine the id of the pending interrupt. The id
+that is returned by API depends upon the value of the id read from the
+interrupt controller as follows.
+
+#. id < ``PENDING_G1S_INTID`` (1020). id is returned as is.
+#. id = ``PENDING_G1S_INTID`` (1020) or ``PENDING_G1NS_INTID`` (1021). The system
+ register ``ICC_HPPIR1_EL1``, *Highest Priority Pending Interrupt group 1
+ Register* is read to determine the id of the group 1 interrupt. This id
+ is returned by the API as long as it is a valid interrupt id
+#. If the id is any of the special interrupt identifiers,
+ ``INTR_ID_UNAVAILABLE`` is returned.
+
+When the API invoked from S-EL1 for GICv3 systems, the id read from system
+register ``ICC_HPPIR1_EL1``, *Highest Priority Pending group 1 Interrupt
+Register*, is returned if is not equal to GIC\_SPURIOUS\_INTERRUPT (1023) else
+``INTR_ID_UNAVAILABLE`` is returned.
+
+Function : plat\_ic\_acknowledge\_interrupt() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : uint32_t
+
+This API is used by the CPU to indicate to the platform IC that processing of
+the highest pending interrupt has begun. It should return the id of the
+interrupt which is being processed.
+
+This function in ARM standard platforms using GICv2, reads the *Interrupt
+Acknowledge Register* (``GICC_IAR``). This changes the state of the highest
+priority pending interrupt from pending to active in the interrupt controller.
+It returns the value read from the ``GICC_IAR``. This value is the id of the
+interrupt whose state has been changed.
+
+In the case of ARM standard platforms using GICv3, if the API is invoked
+from EL3, the function reads the system register ``ICC_IAR0_EL1``, *Interrupt
+Acknowledge Register group 0*. If the API is invoked from S-EL1, the function
+reads the system register ``ICC_IAR1_EL1``, *Interrupt Acknowledge Register
+group 1*. The read changes the state of the highest pending interrupt from
+pending to active in the interrupt controller. The value read is returned
+and is the id of the interrupt whose state has been changed.
+
+The TSP uses this API to start processing of the secure physical timer
+interrupt.
+
+Function : plat\_ic\_end\_of\_interrupt() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : uint32_t
+ Return : void
+
+This API is used by the CPU to indicate to the platform IC that processing of
+the interrupt corresponding to the id (passed as the parameter) has
+finished. The id should be the same as the id returned by the
+``plat_ic_acknowledge_interrupt()`` API.
+
+ARM standard platforms write the id to the *End of Interrupt Register*
+(``GICC_EOIR``) in case of GICv2, and to ``ICC_EOIR0_EL1`` or ``ICC_EOIR1_EL1``
+system register in case of GICv3 depending on where the API is invoked from,
+EL3 or S-EL1. This deactivates the corresponding interrupt in the interrupt
+controller.
+
+The TSP uses this API to finish processing of the secure physical timer
+interrupt.
+
+Function : plat\_ic\_get\_interrupt\_type() [mandatory]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : uint32_t
+ Return : uint32_t
+
+This API returns the type of the interrupt id passed as the parameter.
+``INTR_TYPE_INVAL`` is returned if the id is invalid. If the id is valid, a valid
+interrupt type (one of ``INTR_TYPE_EL3``, ``INTR_TYPE_S_EL1`` and ``INTR_TYPE_NS``) is
+returned depending upon how the interrupt has been configured by the platform
+IC. This API must be invoked at EL3.
+
+ARM standard platforms using GICv2 configures S-EL1 interrupts as Group0 interrupts
+and Non-secure interrupts as Group1 interrupts. It reads the group value
+corresponding to the interrupt id from the relevant *Interrupt Group Register*
+(``GICD_IGROUPRn``). It uses the group value to determine the type of interrupt.
+
+In the case of ARM standard platforms using GICv3, both the *Interrupt Group
+Register* (``GICD_IGROUPRn``) and *Interrupt Group Modifier Register*
+(``GICD_IGRPMODRn``) is read to figure out whether the interrupt is configured
+as Group 0 secure interrupt, Group 1 secure interrupt or Group 1 NS interrupt.
+
+Crash Reporting mechanism (in BL31)
+-----------------------------------
+
+BL31 implements a crash reporting mechanism which prints the various registers
+of the CPU to enable quick crash analysis and debugging. It requires that a
+console is designated as the crash console by the platform which will be used to
+print the register dump.
+
+The following functions must be implemented by the platform if it wants crash
+reporting mechanism in BL31. The functions are implemented in assembly so that
+they can be invoked without a C Runtime stack.
+
+Function : plat\_crash\_console\_init
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : int
+
+This API is used by the crash reporting mechanism to initialize the crash
+console. It must only use the general purpose registers x0 to x4 to do the
+initialization and returns 1 on success.
+
+Function : plat\_crash\_console\_putc
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : int
+ Return : int
+
+This API is used by the crash reporting mechanism to print a character on the
+designated crash console. It must only use general purpose registers x1 and
+x2 to do its work. The parameter and the return value are in general purpose
+register x0.
+
+Function : plat\_crash\_console\_flush
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : int
+
+This API is used by the crash reporting mechanism to force write of all buffered
+data on the designated crash console. It should only use general purpose
+registers x0 and x1 to do its work. The return value is 0 on successful
+completion; otherwise the return value is -1.
+
+Build flags
+-----------
+
+- **ENABLE\_PLAT\_COMPAT**
+ All the platforms ports conforming to this API specification should define
+ the build flag ``ENABLE_PLAT_COMPAT`` to 0 as the compatibility layer should
+ be disabled. For more details on compatibility layer, refer
+ `Migration Guide`_.
+
+There are some build flags which can be defined by the platform to control
+inclusion or exclusion of certain BL stages from the FIP image. These flags
+need to be defined in the platform makefile which will get included by the
+build system.
+
+- **NEED\_BL33**
+ By default, this flag is defined ``yes`` by the build system and ``BL33``
+ build option should be supplied as a build option. The platform has the
+ option of excluding the BL33 image in the ``fip`` image by defining this flag
+ to ``no``. If any of the options ``EL3_PAYLOAD_BASE`` or ``PRELOADED_BL33_BASE``
+ are used, this flag will be set to ``no`` automatically.
+
+C Library
+---------
+
+To avoid subtle toolchain behavioral dependencies, the header files provided
+by the compiler are not used. The software is built with the ``-nostdinc`` flag
+to ensure no headers are included from the toolchain inadvertently. Instead the
+required headers are included in the ARM Trusted Firmware source tree. The
+library only contains those C library definitions required by the local
+implementation. If more functionality is required, the needed library functions
+will need to be added to the local implementation.
+
+Versions of `FreeBSD`_ headers can be found in ``include/lib/stdlib``. Some of
+these headers have been cut down in order to simplify the implementation. In
+order to minimize changes to the header files, the `FreeBSD`_ layout has been
+maintained. The generic C library definitions can be found in
+``include/lib/stdlib`` with more system and machine specific declarations in
+``include/lib/stdlib/sys`` and ``include/lib/stdlib/machine``.
+
+The local C library implementations can be found in ``lib/stdlib``. In order to
+extend the C library these files may need to be modified. It is recommended to
+use a release version of `FreeBSD`_ as a starting point.
+
+The C library header files in the `FreeBSD`_ source tree are located in the
+``include`` and ``sys/sys`` directories. `FreeBSD`_ machine specific definitions
+can be found in the ``sys/<machine-type>`` directories. These files define things
+like 'the size of a pointer' and 'the range of an integer'. Since an AArch64
+port for `FreeBSD`_ does not yet exist, the machine specific definitions are
+based on existing machine types with similar properties (for example SPARC64).
+
+Where possible, C library function implementations were taken from `FreeBSD`_
+as found in the ``lib/libc`` directory.
+
+A copy of the `FreeBSD`_ sources can be downloaded with ``git``.
+
+::
+
+ git clone git://github.com/freebsd/freebsd.git -b origin/release/9.2.0
+
+Storage abstraction layer
+-------------------------
+
+In order to improve platform independence and portability an storage abstraction
+layer is used to load data from non-volatile platform storage.
+
+Each platform should register devices and their drivers via the Storage layer.
+These drivers then need to be initialized by bootloader phases as
+required in their respective ``blx_platform_setup()`` functions. Currently
+storage access is only required by BL1 and BL2 phases. The ``load_image()``
+function uses the storage layer to access non-volatile platform storage.
+
+It is mandatory to implement at least one storage driver. For the ARM
+development platforms the Firmware Image Package (FIP) driver is provided as
+the default means to load data from storage (see the "Firmware Image Package"
+section in the `User Guide`_). The storage layer is described in the header file
+``include/drivers/io/io_storage.h``. The implementation of the common library
+is in ``drivers/io/io_storage.c`` and the driver files are located in
+``drivers/io/``.
+
+Each IO driver must provide ``io_dev_*`` structures, as described in
+``drivers/io/io_driver.h``. These are returned via a mandatory registration
+function that is called on platform initialization. The semi-hosting driver
+implementation in ``io_semihosting.c`` can be used as an example.
+
+The Storage layer provides mechanisms to initialize storage devices before
+IO operations are called. The basic operations supported by the layer
+include ``open()``, ``close()``, ``read()``, ``write()``, ``size()`` and ``seek()``.
+Drivers do not have to implement all operations, but each platform must
+provide at least one driver for a device capable of supporting generic
+operations such as loading a bootloader image.
+
+The current implementation only allows for known images to be loaded by the
+firmware. These images are specified by using their identifiers, as defined in
+[include/plat/common/platform\_def.h] (or a separate header file included from
+there). The platform layer (``plat_get_image_source()``) then returns a reference
+to a device and a driver-specific ``spec`` which will be understood by the driver
+to allow access to the image data.
+
+The layer is designed in such a way that is it possible to chain drivers with
+other drivers. For example, file-system drivers may be implemented on top of
+physical block devices, both represented by IO devices with corresponding
+drivers. In such a case, the file-system "binding" with the block device may
+be deferred until the file-system device is initialised.
+
+The abstraction currently depends on structures being statically allocated
+by the drivers and callers, as the system does not yet provide a means of
+dynamically allocating memory. This may also have the affect of limiting the
+amount of open resources per driver.
+
+--------------
+
+*Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.*
+
+.. _Migration Guide: platform-migration-guide.rst
+.. _include/plat/common/platform.h: ../include/plat/common/platform.h
+.. _include/plat/arm/common/plat\_arm.h: ../include/plat/arm/common/plat_arm.h%5D
+.. _User Guide: user-guide.rst
+.. _include/plat/common/common\_def.h: ../include/plat/common/common_def.h
+.. _include/plat/arm/common/arm\_def.h: ../include/plat/arm/common/arm_def.h
+.. _plat/common/aarch64/platform\_mp\_stack.S: ../plat/common/aarch64/platform_mp_stack.S
+.. _plat/common/aarch64/platform\_up\_stack.S: ../plat/common/aarch64/platform_up_stack.S
+.. _For example, define the build flag in platform.mk: PLAT_PL061_MAX_GPIOS%20:=%20160
+.. _Power Domain Topology Design: psci-pd-tree.rst
+.. _include/common/bl\_common.h: ../include/common/bl_common.h
+.. _include/lib/aarch32/arch.h: ../include/lib/aarch32/arch.h
+.. _Firmware Design: firmware-design.rst
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _plat/arm/board/fvp/fvp\_pm.c: ../plat/arm/board/fvp/fvp_pm.c
+.. _IMF Design Guide: interrupt-framework-design.rst
+.. _ARM Generic Interrupt Controller version 2.0 (GICv2): http://infocenter.arm.com/help/topic/com.arm.doc.ihi0048b/index.html
+.. _3.0 (GICv3): http://infocenter.arm.com/help/topic/com.arm.doc.ihi0069b/index.html
+.. _FreeBSD: http://www.freebsd.org
--- /dev/null
+PSCI Library Integration guide for ARMv8-A AArch32 systems
+==========================================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+This document describes the PSCI library interface with a focus on how to
+integrate with a suitable Trusted OS for an ARMv8-A AArch32 system. The PSCI
+Library implements the PSCI Standard as described in `PSCI spec`_ and is meant
+to be integrated with EL3 Runtime Software which invokes the PSCI Library
+interface appropriately. **EL3 Runtime Software** refers to software executing
+at the highest secure privileged mode, which is EL3 in AArch64 or Secure SVC/
+Monitor mode in AArch32, and provides runtime services to the non-secure world.
+The runtime service request is made via SMC (Secure Monitor Call) and the call
+must adhere to `SMCCC`_. In AArch32, EL3 Runtime Software may additionally
+include Trusted OS functionality. A minimal AArch32 Secure Payload, SP-MIN, is
+provided in ARM Trusted Firmware to illustrate the usage and integration of the
+PSCI library. The description of PSCI library interface and its integration
+with EL3 Runtime Software in this document is targeted towards AArch32 systems.
+
+Generic call sequence for PSCI Library interface (AArch32)
+----------------------------------------------------------
+
+The generic call sequence of PSCI Library interfaces (see
+`section 4`_) during cold boot in AArch32
+system is described below:
+
+#. After cold reset, the EL3 Runtime Software performs its cold boot
+ initialization including the PSCI library pre-requisites mentioned in
+ `section 4`_, and also the necessary platform
+ setup.
+
+#. Call ``psci_setup()`` in Monitor mode.
+
+#. Optionally call ``psci_register_spd_pm_hook()`` to register callbacks to
+ do bookkeeping for the EL3 Runtime Software during power management.
+
+#. Call ``psci_prepare_next_non_secure_ctx()`` to initialize the non-secure CPU
+ context.
+
+#. Get the non-secure ``cpu_context_t`` for the current CPU by calling
+ ``cm_get_context()`` , then programming the registers in the non-secure
+ context and exiting to non-secure world. If the EL3 Runtime Software needs
+ additional configuration to be set for non-secure context, like routing
+ FIQs to the secure world, the values of the registers can be modified prior
+ to programming. See `section 3`_ for more
+ details on CPU context management.
+
+The generic call sequence of PSCI library interfaces during warm boot in
+AArch32 systems is described below:
+
+#. After warm reset, the EL3 Runtime Software performs the necessary warm
+ boot initialization including the PSCI library pre-requisites mentioned in
+ `section 4`_ (Note that the Data cache
+ **must not** be enabled).
+
+#. Call ``psci_warmboot_entrypoint()`` in Monitor mode. This interface
+ initializes/restores the non-secure CPU context as well.
+
+#. Do step 5 of the cold boot call sequence described above.
+
+The generic call sequence of PSCI library interfaces on receipt of a PSCI SMC
+on an AArch32 system is described below:
+
+#. On receipt of an SMC, save the register context as per `SMCCC`_.
+
+#. If the SMC function identifier corresponds to a SMC32 PSCI API, construct
+ the appropriate arguments and call the ``psci_smc_handler()`` interface.
+ The invocation may or may not return back to the caller depending on
+ whether the PSCI API resulted in power down of the CPU.
+
+#. If ``psci_smc_handler()`` returns, populate the return value in R0 (AArch32)/
+ X0 (AArch64) and restore other registers as per `SMCCC`_.
+
+#. .. rubric:: PSCI CPU context management
+ :name: psci-cpu-context-management
+
+PSCI library is in charge of initializing/restoring the non-secure CPU system
+registers according to `PSCI specification`_ during cold/warm boot.
+This is referred to as ``PSCI CPU Context Management``. Registers that need to
+be preserved across CPU power down/power up cycles are maintained in
+``cpu_context_t`` data structure. The initialization of other non-secure CPU
+system registers which do not require coordination with the EL3 Runtime
+Software is done directly by the PSCI library (see ``cm_prepare_el3_exit()``).
+
+The EL3 Runtime Software is responsible for managing register context
+during switch between Normal and Secure worlds. The register context to be
+saved and restored depends on the mechanism used to trigger the world switch.
+For example, if the world switch was triggered by an SMC call, then the
+registers need to be saved and restored according to `SMCCC`_. In AArch64,
+due to the tight integration with BL31, both BL31 and PSCI library
+use the same ``cpu_context_t`` data structure for PSCI CPU context management
+and register context management during world switch. This cannot be assumed
+for AArch32 EL3 Runtime Software since most AArch32 Trusted OSes already implement
+a mechanism for register context management during world switch. Hence, when
+the PSCI library is integrated with a AArch32 EL3 Runtime Software, the
+``cpu_context_t`` is stripped down for just PSCI CPU context management.
+
+During cold/warm boot, after invoking appropriate PSCI library interfaces, it
+is expected that the EL3 Runtime Software will query the ``cpu_context_t`` and
+write appropriate values to the corresponding system registers. This mechanism
+resolves 2 additional problems for AArch32 EL3 Runtime Software:
+
+#. Values for certain system registers like SCR and SCTLR cannot be
+ unilaterally determined by PSCI library and need inputs from the EL3
+ Runtime Software. Using ``cpu_context_t`` as an intermediary data store
+ allows EL3 Runtime Software to modify the register values appropriately
+ before programming them.
+
+#. The PSCI library provides appropriate LR and SPSR values (entrypoint
+ information) for exit into non-secure world. Using ``cpu_context_t`` as an
+ intermediary data store allows the EL3 Runtime Software to store these
+ values safely until it is ready for exit to non-secure world.
+
+Currently the ``cpu_context_t`` data structure for AArch32 stores the following
+registers: R0 - R3, LR (R14), SCR, SPSR, SCTLR.
+
+The EL3 Runtime Software must implement accessors to get/set pointers
+to CPU context ``cpu_context_t`` data and these are described in
+`section 5.2`_.
+
+PSCI Library Interface
+----------------------
+
+The PSCI library implements the `PSCI Specification`_. The interfaces
+to this library are declared in ``psci.h`` and are as listed below:
+
+.. code:: c
+
+ u_register_t psci_smc_handler(uint32_t smc_fid, u_register_t x1,
+ u_register_t x2, u_register_t x3,
+ u_register_t x4, void *cookie,
+ void *handle, u_register_t flags);
+ int psci_setup(const psci_lib_args_t *lib_args);
+ void psci_warmboot_entrypoint(void);
+ void psci_register_spd_pm_hook(const spd_pm_ops_t *pm);
+ void psci_prepare_next_non_secure_ctx(entry_point_info_t *next_image_info);
+
+The CPU context data 'cpu\_context\_t' is programmed to the registers differently
+when PSCI is integrated with an AArch32 EL3 Runtime Software compared to
+when the PSCI is integrated with an AArch64 EL3 Runtime Software (BL31). For
+example, in the case of AArch64, there is no need to retrieve ``cpu_context_t``
+data and program the registers as it will done implicitly as part of
+``el3_exit``. The description below of the PSCI interfaces is targeted at
+integration with an AArch32 EL3 Runtime Software.
+
+The PSCI library is responsible for initializing/restoring the non-secure world
+to an appropriate state after boot and may choose to directly program the
+non-secure system registers. The PSCI generic code takes care not to directly
+modify any of the system registers affecting the secure world and instead
+returns the values to be programmed to these registers via ``cpu_context_t``.
+The EL3 Runtime Software is responsible for programming those registers and
+can use the proposed values provided in the ``cpu_context_t``, modifying the
+values if required.
+
+PSCI library needs the flexibility to access both secure and non-secure
+copies of banked registers. Hence it needs to be invoked in Monitor mode
+for AArch32 and in EL3 for AArch64. The NS bit in SCR (in AArch32) or SCR\_EL3
+(in AArch64) must be set to 0. Additional requirements for the PSCI library
+interfaces are:
+
+- Instruction cache must be enabled
+- Both IRQ and FIQ must be masked for the current CPU
+- The page tables must be setup and the MMU enabled
+- The C runtime environment must be setup and stack initialized
+- The Data cache must be enabled prior to invoking any of the PSCI library
+ interfaces except for ``psci_warmboot_entrypoint()``. For
+ ``psci_warmboot_entrypoint()``, if the build option ``HW_ASSISTED_COHERENCY``
+ is enabled however, data caches are expected to be enabled.
+
+Further requirements for each interface can be found in the interface
+description.
+
+Interface : psci\_setup()
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : const psci_lib_args_t *lib_args
+ Return : void
+
+This function is to be called by the primary CPU during cold boot before
+any other interface to the PSCI library. It takes ``lib_args``, a const pointer
+to ``psci_lib_args_t``, as the argument. The ``psci_lib_args_t`` is a versioned
+structure and is declared in ``psci.h`` header as follows:
+
+.. code:: c
+
+ typedef struct psci_lib_args {
+ /* The version information of PSCI Library Interface */
+ param_header_t h;
+ /* The warm boot entrypoint function */
+ mailbox_entrypoint_t mailbox_ep;
+ } psci_lib_args_t;
+
+The first field ``h``, of ``param_header_t`` type, provides the version
+information. The second field ``mailbox_ep`` is the warm boot entrypoint address
+and is used to configure the platform mailbox. Helper macros are provided in
+psci.h to construct the ``lib_args`` argument statically or during runtime. Prior
+to calling the ``psci_setup()`` interface, the platform setup for cold boot
+must have completed. Major actions performed by this interface are:
+
+- Initializes architecture.
+- Initializes PSCI power domain and state coordination data structures.
+- Calls ``plat_setup_psci_ops()`` with warm boot entrypoint ``mailbox_ep`` as
+ argument.
+- Calls ``cm_set_context_by_index()`` (see
+ `section 5.2`_) for all the CPUs in the
+ platform
+
+Interface : psci\_prepare\_next\_non\_secure\_ctx()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : entry_point_info_t *next_image_info
+ Return : void
+
+After ``psci_setup()`` and prior to exit to the non-secure world, this function
+must be called by the EL3 Runtime Software to initialize the non-secure world
+context. The non-secure world entrypoint information ``next_image_info`` (first
+argument) will be used to determine the non-secure context. After this function
+returns, the EL3 Runtime Software must retrieve the ``cpu_context_t`` (using
+cm\_get\_context()) for the current CPU and program the registers prior to exit
+to the non-secure world.
+
+Interface : psci\_register\_spd\_pm\_hook()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : const spd_pm_ops_t *
+ Return : void
+
+As explained in `section 5.4`_,
+the EL3 Runtime Software may want to perform some bookkeeping during power
+management operations. This function is used to register the ``spd_pm_ops_t``
+(first argument) callbacks with the PSCI library which will be called
+ppropriately during power management. Calling this function is optional and
+need to be called by the primary CPU during the cold boot sequence after
+``psci_setup()`` has completed.
+
+Interface : psci\_smc\_handler()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : uint32_t smc_fid, u_register_t x1,
+ u_register_t x2, u_register_t x3,
+ u_register_t x4, void *cookie,
+ void *handle, u_register_t flags
+ Return : u_register_t
+
+This function is the top level handler for SMCs which fall within the
+PSCI service range specified in `SMCCC`_. The function ID ``smc_fid`` (first
+argument) determines the PSCI API to be called. The ``x1`` to ``x4`` (2nd to 5th
+arguments), are the values of the registers r1 - r4 (in AArch32) or x1 - x4
+(in AArch64) when the SMC is received. These are the arguments to PSCI API as
+described in `PSCI spec`_. The 'flags' (8th argument) is a bit field parameter
+and is detailed in 'smcc.h' header. It includes whether the call is from the
+secure or non-secure world. The ``cookie`` (6th argument) and the ``handle``
+(7th argument) are not used and are reserved for future use.
+
+The return value from this interface is the return value from the underlying
+PSCI API corresponding to ``smc_fid``. This function may not return back to the
+caller if PSCI API causes power down of the CPU. In this case, when the CPU
+wakes up, it will start execution from the warm reset address.
+
+Interface : psci\_warmboot\_entrypoint()
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : void
+ Return : void
+
+This function performs the warm boot initialization/restoration as mandated by
+`PSCI spec`_. For AArch32, on wakeup from power down the CPU resets to secure SVC
+mode and the EL3 Runtime Software must perform the prerequisite initializations
+mentioned at top of this section. This function must be called with Data cache
+disabled (unless build option ``HW_ASSISTED_COHERENCY`` is enabled) but with MMU
+initialized and enabled. The major actions performed by this function are:
+
+- Invalidates the stack and enables the data cache.
+- Initializes architecture and PSCI state coordination.
+- Restores/Initializes the peripheral drivers to the required state via
+ appropriate ``plat_psci_ops_t`` hooks
+- Restores the EL3 Runtime Software context via appropriate ``spd_pm_ops_t``
+ callbacks.
+- Restores/Initializes the non-secure context and populates the
+ ``cpu_context_t`` for the current CPU.
+
+Upon the return of this function, the EL3 Runtime Software must retrieve the
+non-secure ``cpu_context_t`` using ``cm_get_context()`` and program the registers
+prior to exit to the non-secure world.
+
+EL3 Runtime Software dependencies
+---------------------------------
+
+The PSCI Library includes supporting frameworks like context management,
+cpu operations (cpu\_ops) and per-cpu data framework. Other helper library
+functions like bakery locks and spin locks are also included in the library.
+The dependencies which must be fulfilled by the EL3 Runtime Software
+for integration with PSCI library are described below.
+
+General dependencies
+~~~~~~~~~~~~~~~~~~~~
+
+The PSCI library being a Multiprocessor (MP) implementation, EL3 Runtime
+Software must provide an SMC handling framework capable of MP adhering to
+`SMCCC`_ specification.
+
+The EL3 Runtime Software must also export cache maintenance primitives
+and some helper utilities for assert, print and memory operations as listed
+below. The ARM Trusted Firmware source tree provides implementations for all
+these functions but the EL3 Runtime Software may use its own implementation.
+
+**Functions : assert(), memcpy(), memset**
+
+These must be implemented as described in ISO C Standard.
+
+**Function : flush\_dcache\_range()**
+
+::
+
+ Argument : uintptr_t addr, size_t size
+ Return : void
+
+This function cleans and invalidates (flushes) the data cache for memory
+at address ``addr`` (first argument) address and of size ``size`` (second argument).
+
+**Function : inv\_dcache\_range()**
+
+::
+
+ Argument : uintptr_t addr, size_t size
+ Return : void
+
+This function invalidates (flushes) the data cache for memory at address
+``addr`` (first argument) address and of size ``size`` (second argument).
+
+**Function : do\_panic()**
+
+::
+
+ Argument : void
+ Return : void
+
+This function will be called by the PSCI library on encountering a critical
+failure that cannot be recovered from. This function **must not** return.
+
+**Function : tf\_printf()**
+
+This is printf-compatible function, but unlike printf, it does not return any
+value. The ARM Trusted Firmware source tree provides an implementation which
+is optimized for stack usage and supports only a subset of format specifiers.
+The details of the format specifiers supported can be found in the
+``tf_printf.c`` file in ARM Trusted Firmware source tree.
+
+CPU Context management API
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The CPU context management data memory is statically allocated by PSCI library
+in BSS section. The PSCI library requires the EL3 Runtime Software to implement
+APIs to store and retrieve pointers to this CPU context data. SP-MIN
+demonstrates how these APIs can be implemented but the EL3 Runtime Software can
+choose a more optimal implementation (like dedicating the secure TPIDRPRW
+system register (in AArch32) for storing these pointers).
+
+**Function : cm\_set\_context\_by\_index()**
+
+::
+
+ Argument : unsigned int cpu_idx, void *context, unsigned int security_state
+ Return : void
+
+This function is called during cold boot when the ``psci_setup()`` PSCI library
+interface is called.
+
+This function must store the pointer to the CPU context data, ``context`` (2nd
+argument), for the specified ``security_state`` (3rd argument) and CPU identified
+by ``cpu_idx`` (first argument). The ``security_state`` will always be non-secure
+when called by PSCI library and this argument is retained for compatibility
+with BL31. The ``cpu_idx`` will correspond to the index returned by the
+``plat_core_pos_by_mpidr()`` for ``mpidr`` of the CPU.
+
+The actual method of storing the ``context`` pointers is implementation specific.
+For example, SP-MIN stores the pointers in the array ``sp_min_cpu_ctx_ptr``
+declared in ``sp_min_main.c``.
+
+**Function : cm\_get\_context()**
+
+::
+
+ Argument : uint32_t security_state
+ Return : void *
+
+This function must return the pointer to the ``cpu_context_t`` structure for
+the specified ``security_state`` (first argument) for the current CPU. The caller
+must ensure that ``cm_set_context_by_index`` is called first and the appropriate
+context pointers are stored prior to invoking this API. The ``security_state``
+will always be non-secure when called by PSCI library and this argument
+is retained for compatibility with BL31.
+
+**Function : cm\_get\_context\_by\_index()**
+
+::
+
+ Argument : unsigned int cpu_idx, unsigned int security_state
+ Return : void *
+
+This function must return the pointer to the ``cpu_context_t`` structure for
+the specified ``security_state`` (second argument) for the CPU identified by
+``cpu_idx`` (first argument). The caller must ensure that
+``cm_set_context_by_index`` is called first and the appropriate context
+pointers are stored prior to invoking this API. The ``security_state`` will
+always be non-secure when called by PSCI library and this argument is
+retained for compatibility with BL31. The ``cpu_idx`` will correspond to the
+index returned by the ``plat_core_pos_by_mpidr()`` for ``mpidr`` of the CPU.
+
+Platform API
+~~~~~~~~~~~~
+
+The platform layer abstracts the platform-specific details from the generic
+PSCI library. The following platform APIs/macros must be defined by the EL3
+Runtime Software for integration with the PSCI library.
+
+The mandatory platform APIs are:
+
+- plat\_my\_core\_pos
+- plat\_core\_pos\_by\_mpidr
+- plat\_get\_syscnt\_freq2
+- plat\_get\_power\_domain\_tree\_desc
+- plat\_setup\_psci\_ops
+- plat\_reset\_handler
+- plat\_panic\_handler
+- plat\_get\_my\_stack
+
+The mandatory platform macros are:
+
+- PLATFORM\_CORE\_COUNT
+- PLAT\_MAX\_PWR\_LVL
+- PLAT\_NUM\_PWR\_DOMAINS
+- CACHE\_WRITEBACK\_GRANULE
+- PLAT\_MAX\_OFF\_STATE
+- PLAT\_MAX\_RET\_STATE
+- PLAT\_MAX\_PWR\_LVL\_STATES (optional)
+- PLAT\_PCPU\_DATA\_SIZE (optional)
+
+The details of these APIs/macros can be found in `Porting Guide`_.
+
+All platform specific operations for power management are done via
+``plat_psci_ops_t`` callbacks registered by the platform when
+``plat_setup_psci_ops()`` API is called. The description of each of
+the callbacks in ``plat_psci_ops_t`` can be found in PSCI section of the
+`Porting Guide`_. If any these callbacks are not registered, then the
+PSCI API associated with that callback will not be supported by PSCI
+library.
+
+Secure payload power management callback
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+During PSCI power management operations, the EL3 Runtime Software may
+need to perform some bookkeeping, and PSCI library provides
+``spd_pm_ops_t`` callbacks for this purpose. These hooks must be
+populated and registered by using ``psci_register_spd_pm_hook()`` PSCI
+library interface.
+
+Typical bookkeeping during PSCI power management calls include save/restore
+of the EL3 Runtime Software context. Also if the EL3 Runtime Software makes
+use of secure interrupts, then these interrupts must also be managed
+appropriately during CPU power down/power up. Any secure interrupt targeted
+to the current CPU must be disabled or re-targeted to other running CPU prior
+to power down of the current CPU. During power up, these interrupt can be
+enabled/re-targeted back to the current CPU.
+
+.. code:: c
+
+ typedef struct spd_pm_ops {
+ void (*svc_on)(u_register_t target_cpu);
+ int32_t (*svc_off)(u_register_t __unused);
+ void (*svc_suspend)(u_register_t max_off_pwrlvl);
+ void (*svc_on_finish)(u_register_t __unused);
+ void (*svc_suspend_finish)(u_register_t max_off_pwrlvl);
+ int32_t (*svc_migrate)(u_register_t from_cpu, u_register_t to_cpu);
+ int32_t (*svc_migrate_info)(u_register_t *resident_cpu);
+ void (*svc_system_off)(void);
+ void (*svc_system_reset)(void);
+ } spd_pm_ops_t;
+
+A brief description of each callback is given below:
+
+- svc\_on, svc\_off, svc\_on\_finish
+
+ The ``svc_on``, ``svc_off`` callbacks are called during PSCI\_CPU\_ON,
+ PSCI\_CPU\_OFF APIs respectively. The ``svc_on_finish`` is called when the
+ target CPU of PSCI\_CPU\_ON API powers up and executes the
+ ``psci_warmboot_entrypoint()`` PSCI library interface.
+
+- svc\_suspend, svc\_suspend\_finish
+
+ The ``svc_suspend`` callback is called during power down bu either
+ PSCI\_SUSPEND or PSCI\_SYSTEM\_SUSPEND APIs. The ``svc_suspend_finish`` is
+ called when the CPU wakes up from suspend and executes the
+ ``psci_warmboot_entrypoint()`` PSCI library interface. The ``max_off_pwrlvl``
+ (first parameter) denotes the highest power domain level being powered down
+ to or woken up from suspend.
+
+- svc\_system\_off, svc\_system\_reset
+
+ These callbacks are called during PSCI\_SYSTEM\_OFF and PSCI\_SYSTEM\_RESET
+ PSCI APIs respectively.
+
+- svc\_migrate\_info
+
+ This callback is called in response to PSCI\_MIGRATE\_INFO\_TYPE or
+ PSCI\_MIGRATE\_INFO\_UP\_CPU APIs. The return value of this callback must
+ correspond to the return value of PSCI\_MIGRATE\_INFO\_TYPE API as described
+ in `PSCI spec`_. If the secure payload is a Uniprocessor (UP)
+ implementation, then it must update the mpidr of the CPU it is resident in
+ via ``resident_cpu`` (first argument). The updates to ``resident_cpu`` is
+ ignored if the secure payload is a multiprocessor (MP) implementation.
+
+- svc\_migrate
+
+ This callback is only relevant if the secure payload in EL3 Runtime
+ Software is a Uniprocessor (UP) implementation and supports migration from
+ the current CPU ``from_cpu`` (first argument) to another CPU ``to_cpu``
+ (second argument). This callback is called in response to PSCI\_MIGRATE
+ API. This callback is never called if the secure payload is a
+ Multiprocessor (MP) implementation.
+
+CPU operations
+~~~~~~~~~~~~~~
+
+The CPU operations (cpu\_ops) framework implement power down sequence specific
+to the CPU and the details of which can be found in the ``CPU specific operations framework`` section of `Firmware Design`_. The ARM Trusted Firmware
+tree implements the ``cpu_ops`` for various supported CPUs and the EL3 Runtime
+Software needs to include the required ``cpu_ops`` in its build. The start and
+end of the ``cpu_ops`` descriptors must be exported by the EL3 Runtime Software
+via the ``__CPU_OPS_START__`` and ``__CPU_OPS_END__`` linker symbols.
+
+The ``cpu_ops`` descriptors also include reset sequences and may include errata
+workarounds for the CPU. The EL3 Runtime Software can choose to call this
+during cold/warm reset if it does not implement its own reset sequence/errata
+workarounds.
+
+--------------
+
+*Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.*
+
+.. _PSCI spec: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _SMCCC: https://silver.arm.com/download/ARM_and_AMBA_Architecture/AR570-DA-80002-r0p0-00rel0/ARM_DEN0028A_SMC_Calling_Convention.pdf
+.. _section 4: #user-content-psci-library-interface
+.. _section 3: #user-content-psci-cpu-context-management
+.. _PSCI specification: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _section 5.2: #user-content-cpu-context-management-api
+.. _PSCI Specification: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _section 5.4: #user-content-secure-payload-power-management-callback
+.. _Porting Guide: porting-guide.rst
+.. _Firmware Design: ./firmware-design.rst
--- /dev/null
+PSCI Library Integration guide for ARMv8-A AArch32 systems
+==========================================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+--------------
+
+Requirements
+------------
+
+#. A platform must export the ``plat_get_aff_count()`` and
+ ``plat_get_aff_state()`` APIs to enable the generic PSCI code to
+ populate a tree that describes the hierarchy of power domains in the
+ system. This approach is inflexible because a change to the topology
+ requires a change in the code.
+
+ It would be much simpler for the platform to describe its power domain tree
+ in a data structure.
+
+#. The generic PSCI code generates MPIDRs in order to populate the power domain
+ tree. It also uses an MPIDR to find a node in the tree. The assumption that
+ a platform will use exactly the same MPIDRs as generated by the generic PSCI
+ code is not scalable. The use of an MPIDR also restricts the number of
+ levels in the power domain tree to four.
+
+ Therefore, there is a need to decouple allocation of MPIDRs from the
+ mechanism used to populate the power domain topology tree.
+
+#. The current arrangement of the power domain tree requires a binary search
+ over the sibling nodes at a particular level to find a specified power
+ domain node. During a power management operation, the tree is traversed from
+ a 'start' to an 'end' power level. The binary search is required to find the
+ node at each level. The natural way to perform this traversal is to
+ start from a leaf node and follow the parent node pointer to reach the end
+ level.
+
+ Therefore, there is a need to define data structures that implement the tree in
+ a way which facilitates such a traversal.
+
+#. The attributes of a core power domain differ from the attributes of power
+ domains at higher levels. For example, only a core power domain can be identified
+ using an MPIDR. There is no requirement to perform state coordination while
+ performing a power management operation on the core power domain.
+
+ Therefore, there is a need to implement the tree in a way which facilitates this
+ distinction between a leaf and non-leaf node and any associated
+ optimizations.
+
+--------------
+
+Design
+------
+
+Describing a power domain tree
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To fulfill requirement 1., the existing platform APIs
+``plat_get_aff_count()`` and ``plat_get_aff_state()`` have been
+removed. A platform must define an array of unsigned chars such that:
+
+#. The first entry in the array specifies the number of power domains at the
+ highest power level implemented in the platform. This caters for platforms
+ where the power domain tree does not have a single root node, for example,
+ the FVP has two cluster power domains at the highest level (1).
+
+#. Each subsequent entry corresponds to a power domain and contains the number
+ of power domains that are its direct children.
+
+#. The size of the array minus the first entry will be equal to the number of
+ non-leaf power domains.
+
+#. The value in each entry in the array is used to find the number of entries
+ to consider at the next level. The sum of the values (number of children) of
+ all the entries at a level specifies the number of entries in the array for
+ the next level.
+
+The following example power domain topology tree will be used to describe the
+above text further. The leaf and non-leaf nodes in this tree have been numbered
+separately.
+
+::
+
+ +-+
+ |0|
+ +-+
+ / \
+ / \
+ / \
+ / \
+ / \
+ / \
+ / \
+ / \
+ / \
+ / \
+ +-+ +-+
+ |1| |2|
+ +-+ +-+
+ / \ / \
+ / \ / \
+ / \ / \
+ / \ / \
+ +-+ +-+ +-+ +-+
+ |3| |4| |5| |6|
+ +-+ +-+ +-+ +-+
+ +---+-----+ +----+----| +----+----+ +----+-----+-----+
+ | | | | | | | | | | | | |
+ | | | | | | | | | | | | |
+ v v v v v v v v v v v v v
+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +--+ +--+ +--+
+ |0| |1| |2| |3| |4| |5| |6| |7| |8| |9| |10| |11| |12|
+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +--+ +--+ +--+
+
+This tree is defined by the platform as the array described above as follows:
+
+::
+
+ #define PLAT_NUM_POWER_DOMAINS 20
+ #define PLATFORM_CORE_COUNT 13
+ #define PSCI_NUM_NON_CPU_PWR_DOMAINS \
+ (PLAT_NUM_POWER_DOMAINS - PLATFORM_CORE_COUNT)
+
+ unsigned char plat_power_domain_tree_desc[] = { 1, 2, 2, 2, 3, 3, 3, 4};
+
+Removing assumptions about MPIDRs used in a platform
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To fulfill requirement 2., it is assumed that the platform assigns a
+unique number (core index) between ``0`` and ``PLAT_CORE_COUNT - 1`` to each core
+power domain. MPIDRs could be allocated in any manner and will not be used to
+populate the tree.
+
+``plat_core_pos_by_mpidr(mpidr)`` will return the core index for the core
+corresponding to the MPIDR. It will return an error (-1) if an MPIDR is passed
+which is not allocated or corresponds to an absent core. The semantics of this
+platform API have changed since it is required to validate the passed MPIDR. It
+has been made a mandatory API as a result.
+
+Another mandatory API, ``plat_my_core_pos()`` has been added to return the core
+index for the calling core. This API provides a more lightweight mechanism to get
+the index since there is no need to validate the MPIDR of the calling core.
+
+The platform should assign the core indices (as illustrated in the diagram above)
+such that, if the core nodes are numbered from left to right, then the index
+for a core domain will be the same as the index returned by
+``plat_core_pos_by_mpidr()`` or ``plat_my_core_pos()`` for that core. This
+relationship allows the core nodes to be allocated in a separate array
+(requirement 4.) during ``psci_setup()`` in such an order that the index of the
+core in the array is the same as the return value from these APIs.
+
+Dealing with holes in MPIDR allocation
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+For platforms where the number of allocated MPIDRs is equal to the number of
+core power domains, for example, Juno and FVPs, the logic to convert an MPIDR to
+a core index should remain unchanged. Both Juno and FVP use a simple collision
+proof hash function to do this.
+
+It is possible that on some platforms, the allocation of MPIDRs is not
+contiguous or certain cores have been disabled. This essentially means that the
+MPIDRs have been sparsely allocated, that is, the size of the range of MPIDRs
+used by the platform is not equal to the number of core power domains.
+
+The platform could adopt one of the following approaches to deal with this
+scenario:
+
+#. Implement more complex logic to convert a valid MPIDR to a core index while
+ maintaining the relationship described earlier. This means that the power
+ domain tree descriptor will not describe any core power domains which are
+ disabled or absent. Entries will not be allocated in the tree for these
+ domains.
+
+#. Treat unallocated MPIDRs and disabled cores as absent but still describe them
+ in the power domain descriptor, that is, the number of core nodes described
+ is equal to the size of the range of MPIDRs allocated. This approach will
+ lead to memory wastage since entries will be allocated in the tree but will
+ allow use of a simpler logic to convert an MPIDR to a core index.
+
+Traversing through and distinguishing between core and non-core power domains
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To fulfill requirement 3 and 4, separate data structures have been defined
+to represent leaf and non-leaf power domain nodes in the tree.
+
+.. code:: c
+
+ /*******************************************************************************
+ * The following two data structures implement the power domain tree. The tree
+ * is used to track the state of all the nodes i.e. power domain instances
+ * described by the platform. The tree consists of nodes that describe CPU power
+ * domains i.e. leaf nodes and all other power domains which are parents of a
+ * CPU power domain i.e. non-leaf nodes.
+ ******************************************************************************/
+ typedef struct non_cpu_pwr_domain_node {
+ /*
+ * Index of the first CPU power domain node level 0 which has this node
+ * as its parent.
+ */
+ unsigned int cpu_start_idx;
+
+ /*
+ * Number of CPU power domains which are siblings of the domain indexed
+ * by 'cpu_start_idx' i.e. all the domains in the range 'cpu_start_idx
+ * -> cpu_start_idx + ncpus' have this node as their parent.
+ */
+ unsigned int ncpus;
+
+ /* Index of the parent power domain node */
+ unsigned int parent_node;
+
+ -----
+ } non_cpu_pd_node_t;
+
+ typedef struct cpu_pwr_domain_node {
+ u_register_t mpidr;
+
+ /* Index of the parent power domain node */
+ unsigned int parent_node;
+
+ -----
+ } cpu_pd_node_t;
+
+The power domain tree is implemented as a combination of the following data
+structures.
+
+::
+
+ non_cpu_pd_node_t psci_non_cpu_pd_nodes[PSCI_NUM_NON_CPU_PWR_DOMAINS];
+ cpu_pd_node_t psci_cpu_pd_nodes[PLATFORM_CORE_COUNT];
+
+Populating the power domain tree
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``populate_power_domain_tree()`` function in ``psci_setup.c`` implements the
+algorithm to parse the power domain descriptor exported by the platform to
+populate the two arrays. It is essentially a breadth-first-search. The nodes for
+each level starting from the root are laid out one after another in the
+``psci_non_cpu_pd_nodes`` and ``psci_cpu_pd_nodes`` arrays as follows:
+
+::
+
+ psci_non_cpu_pd_nodes -> [[Level 3 nodes][Level 2 nodes][Level 1 nodes]]
+ psci_cpu_pd_nodes -> [Level 0 nodes]
+
+For the example power domain tree illustrated above, the ``psci_cpu_pd_nodes``
+will be populated as follows. The value in each entry is the index of the parent
+node. Other fields have been ignored for simplicity.
+
+::
+
+ +-------------+ ^
+ CPU0 | 3 | |
+ +-------------+ |
+ CPU1 | 3 | |
+ +-------------+ |
+ CPU2 | 3 | |
+ +-------------+ |
+ CPU3 | 4 | |
+ +-------------+ |
+ CPU4 | 4 | |
+ +-------------+ |
+ CPU5 | 4 | | PLATFORM_CORE_COUNT
+ +-------------+ |
+ CPU6 | 5 | |
+ +-------------+ |
+ CPU7 | 5 | |
+ +-------------+ |
+ CPU8 | 5 | |
+ +-------------+ |
+ CPU9 | 6 | |
+ +-------------+ |
+ CPU10 | 6 | |
+ +-------------+ |
+ CPU11 | 6 | |
+ +-------------+ |
+ CPU12 | 6 | v
+ +-------------+
+
+The ``psci_non_cpu_pd_nodes`` array will be populated as follows. The value in
+each entry is the index of the parent node.
+
+::
+
+ +-------------+ ^
+ PD0 | -1 | |
+ +-------------+ |
+ PD1 | 0 | |
+ +-------------+ |
+ PD2 | 0 | |
+ +-------------+ |
+ PD3 | 1 | | PLAT_NUM_POWER_DOMAINS -
+ +-------------+ | PLATFORM_CORE_COUNT
+ PD4 | 1 | |
+ +-------------+ |
+ PD5 | 2 | |
+ +-------------+ |
+ PD6 | 2 | |
+ +-------------+ v
+
+Each core can find its node in the ``psci_cpu_pd_nodes`` array using the
+``plat_my_core_pos()`` function. When a core is turned on, the normal world
+provides an MPIDR. The ``plat_core_pos_by_mpidr()`` function is used to validate
+the MPIDR before using it to find the corresponding core node. The non-core power
+domain nodes do not need to be identified.
+
+--------------
+
+*Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.*
--- /dev/null
+ARM Trusted Firmware Reset Design
+=================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+This document describes the high-level design of the framework to handle CPU
+resets in ARM Trusted Firmware. It also describes how the platform integrator
+can tailor this code to the system configuration to some extent, resulting in a
+simplified and more optimised boot flow.
+
+This document should be used in conjunction with the `Firmware Design`_, which
+provides greater implementation details around the reset code, specifically
+for the cold boot path.
+
+General reset code flow
+-----------------------
+
+The ARM Trusted Firmware (TF) reset code is implemented in BL1 by default. The
+following high-level diagram illustrates this:
+
+|Default reset code flow|
+
+This diagram shows the default, unoptimised reset flow. Depending on the system
+configuration, some of these steps might be unnecessary. The following sections
+guide the platform integrator by indicating which build options exclude which
+steps, depending on the capability of the platform.
+
+Note: If BL31 is used as the Trusted Firmware entry point instead of BL1, the
+diagram above is still relevant, as all these operations will occur in BL31 in
+this case. Please refer to section 6 "Using BL31 entrypoint as the reset
+address" for more information.
+
+Programmable CPU reset address
+------------------------------
+
+By default, the TF assumes that the CPU reset address is not programmable.
+Therefore, all CPUs start at the same address (typically address 0) whenever
+they reset. Further logic is then required to identify whether it is a cold or
+warm boot to direct CPUs to the right execution path.
+
+If the reset vector address (reflected in the reset vector base address register
+``RVBAR_EL3``) is programmable then it is possible to make each CPU start directly
+at the right address, both on a cold and warm reset. Therefore, the boot type
+detection can be skipped, resulting in the following boot flow:
+
+|Reset code flow with programmable reset address|
+
+To enable this boot flow, compile the TF with ``PROGRAMMABLE_RESET_ADDRESS=1``.
+This option only affects the TF reset image, which is BL1 by default or BL31 if
+``RESET_TO_BL31=1``.
+
+On both the FVP and Juno platforms, the reset vector address is not programmable
+so both ports use ``PROGRAMMABLE_RESET_ADDRESS=0``.
+
+Cold boot on a single CPU
+-------------------------
+
+By default, the TF assumes that several CPUs may be released out of reset.
+Therefore, the cold boot code has to arbitrate access to hardware resources
+shared amongst CPUs. This is done by nominating one of the CPUs as the primary,
+which is responsible for initialising shared hardware and coordinating the boot
+flow with the other CPUs.
+
+If the platform guarantees that only a single CPU will ever be brought up then
+no arbitration is required. The notion of primary/secondary CPU itself no longer
+applies. This results in the following boot flow:
+
+|Reset code flow with single CPU released out of reset|
+
+To enable this boot flow, compile the TF with ``COLD_BOOT_SINGLE_CPU=1``. This
+option only affects the TF reset image, which is BL1 by default or BL31 if
+``RESET_TO_BL31=1``.
+
+On both the FVP and Juno platforms, although only one core is powered up by
+default, there are platform-specific ways to release any number of cores out of
+reset. Therefore, both platform ports use ``COLD_BOOT_SINGLE_CPU=0``.
+
+Programmable CPU reset address, Cold boot on a single CPU
+---------------------------------------------------------
+
+It is obviously possible to combine both optimisations on platforms that have
+a programmable CPU reset address and which release a single CPU out of reset.
+This results in the following boot flow:
+
+
+|Reset code flow with programmable reset address and single CPU released out of reset|
+
+To enable this boot flow, compile the TF with both ``COLD_BOOT_SINGLE_CPU=1``
+and ``PROGRAMMABLE_RESET_ADDRESS=1``. These options only affect the TF reset
+image, which is BL1 by default or BL31 if ``RESET_TO_BL31=1``.
+
+Using BL31 entrypoint as the reset address
+------------------------------------------
+
+On some platforms the runtime firmware (BL3x images) for the application
+processors are loaded by some firmware running on a secure system processor
+on the SoC, rather than by BL1 and BL2 running on the primary application
+processor. For this type of SoC it is desirable for the application processor
+to always reset to BL31 which eliminates the need for BL1 and BL2.
+
+TF provides a build-time option ``RESET_TO_BL31`` that includes some additional
+logic in the BL31 entry point to support this use case.
+
+In this configuration, the platform's Trusted Boot Firmware must ensure that
+BL31 is loaded to its runtime address, which must match the CPU's ``RVBAR_EL3``
+reset vector base address, before the application processor is powered on.
+Additionally, platform software is responsible for loading the other BL3x images
+required and providing entry point information for them to BL31. Loading these
+images might be done by the Trusted Boot Firmware or by platform code in BL31.
+
+Although the ARM FVP platform does not support programming the reset base
+address dynamically at run-time, it is possible to set the initial value of the
+``RVBAR_EL3`` register at start-up. This feature is provided on the Base FVP only.
+It allows the ARM FVP port to support the ``RESET_TO_BL31`` configuration, in
+which case the ``bl31.bin`` image must be loaded to its run address in Trusted
+SRAM and all CPU reset vectors be changed from the default ``0x0`` to this run
+address. See the `User Guide`_ for details of running the FVP models in this way.
+
+Although technically it would be possible to program the reset base address with
+the right support in the SCP firmware, this is currently not implemented so the
+Juno port doesn't support the ``RESET_TO_BL31`` configuration.
+
+The ``RESET_TO_BL31`` configuration requires some additions and changes in the
+BL31 functionality:
+
+Determination of boot path
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+In this configuration, BL31 uses the same reset framework and code as the one
+described for BL1 above. Therefore, it is affected by the
+``PROGRAMMABLE_RESET_ADDRESS`` and ``COLD_BOOT_SINGLE_CPU`` build options in the
+same way.
+
+In the default, unoptimised BL31 reset flow, on a warm boot a CPU is directed
+to the PSCI implementation via a platform defined mechanism. On a cold boot,
+the platform must place any secondary CPUs into a safe state while the primary
+CPU executes a modified BL31 initialization, as described below.
+
+Platform initialization
+~~~~~~~~~~~~~~~~~~~~~~~
+
+In this configuration, when the CPU resets to BL31 there are no parameters that
+can be passed in registers by previous boot stages. Instead, the platform code
+in BL31 needs to know, or be able to determine, the location of the BL32 (if
+required) and BL33 images and provide this information in response to the
+``bl31_plat_get_next_image_ep_info()`` function.
+
+Additionally, platform software is responsible for carrying out any security
+initialisation, for example programming a TrustZone address space controller.
+This might be done by the Trusted Boot Firmware or by platform code in BL31.
+
+--------------
+
+*Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.*
+
+.. _Firmware Design: firmware-design.rst
+.. _User Guide: user-guide.rst
+
+.. |Default reset code flow| image:: diagrams/default_reset_code.png?raw=true
+.. |Reset code flow with programmable reset address| image:: diagrams/reset_code_no_boot_type_check.png?raw=true
+.. |Reset code flow with single CPU released out of reset| image:: diagrams/reset_code_no_cpu_check.png?raw=true
+.. |Reset code flow with programmable reset address and single CPU released out of reset| image:: diagrams/reset_code_no_checks.png?raw=true
--- /dev/null
+EL3 Runtime Service Writers Guide for ARM Trusted Firmware
+==========================================================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+--------------
+
+Introduction
+------------
+
+This document describes how to add a runtime service to the EL3 Runtime
+Firmware component of ARM Trusted Firmware (BL31).
+
+Software executing in the normal world and in the trusted world at exception
+levels lower than EL3 will request runtime services using the Secure Monitor
+Call (SMC) instruction. These requests will follow the convention described in
+the SMC Calling Convention PDD (`SMCCC`_). The `SMCCC`_ assigns function
+identifiers to each SMC request and describes how arguments are passed and
+results are returned.
+
+SMC Functions are grouped together based on the implementor of the service, for
+example a subset of the Function IDs are designated as "OEM Calls" (see `SMCCC`_
+for full details). The EL3 runtime services framework in BL31 enables the
+independent implementation of services for each group, which are then compiled
+into the BL31 image. This simplifies the integration of common software from
+ARM to support `PSCI`_, Secure Monitor for a Trusted OS and SoC specific
+software. The common runtime services framework ensures that SMC Functions are
+dispatched to their respective service implementation - the `Firmware Design`_
+provides details of how this is achieved.
+
+The interface and operation of the runtime services depends heavily on the
+concepts and definitions described in the `SMCCC`_, in particular SMC Function
+IDs, Owning Entity Numbers (OEN), Fast and Standard calls, and the SMC32 and
+SMC64 calling conventions. Please refer to that document for a full explanation
+of these terms.
+
+Owning Entities, Call Types and Function IDs
+--------------------------------------------
+
+The SMC Function Identifier includes a OEN field. These values and their
+meaning are described in `SMCCC`_ and summarized in table 1 below. Some entities
+are allocated a range of of OENs. The OEN must be interpreted in conjunction
+with the SMC call type, which is either *Fast* or *Yielding*. Fast calls are
+uninterruptible whereas Yielding calls can be pre-empted. The majority of
+Owning Entities only have allocated ranges for Fast calls: Yielding calls are
+reserved exclusively for Trusted OS providers or for interoperability with
+legacy 32-bit software that predates the `SMCCC`_.
+
+::
+
+ Type OEN Service
+ Fast 0 ARM Architecture calls
+ Fast 1 CPU Service calls
+ Fast 2 SiP Service calls
+ Fast 3 OEM Service calls
+ Fast 4 Standard Service calls
+ Fast 5-47 Reserved for future use
+ Fast 48-49 Trusted Application calls
+ Fast 50-63 Trusted OS calls
+
+ Yielding 0- 1 Reserved for existing ARMv7 calls
+ Yielding 2-63 Trusted OS Standard Calls
+
+*Table 1: Service types and their corresponding Owning Entity Numbers*
+
+Each individual entity can allocate the valid identifiers within the entity
+range as they need - it is not necessary to coordinate with other entities of
+the same type. For example, two SoC providers can use the same Function ID
+within the SiP Service calls OEN range to mean different things - as these
+calls should be specific to the SoC. The Standard Runtime Calls OEN is used for
+services defined by ARM standards, such as `PSCI`_.
+
+The SMC Function ID also indicates whether the call has followed the SMC32
+calling convention, where all parameters are 32-bit, or the SMC64 calling
+convention, where the parameters are 64-bit. The framework identifies and
+rejects invalid calls that use the SMC64 calling convention but that originate
+from an AArch32 caller.
+
+The EL3 runtime services framework uses the call type and OEN to identify a
+specific handler for each SMC call, but it is expected that an individual
+handler will be responsible for all SMC Functions within a given service type.
+
+Getting started
+---------------
+
+ARM Trusted Firmware has a `services`_ directory in the source tree under which
+each owning entity can place the implementation of its runtime service. The
+`PSCI`_ implementation is located here in the `lib/psci`_ directory.
+
+Runtime service sources will need to include the `runtime\_svc.h`_ header file.
+
+Registering a runtime service
+-----------------------------
+
+A runtime service is registered using the ``DECLARE_RT_SVC()`` macro, specifying
+the name of the service, the range of OENs covered, the type of service and
+initialization and call handler functions.
+
+::
+
+ #define DECLARE_RT_SVC(_name, _start, _end, _type, _setup, _smch)
+
+- ``_name`` is used to identify the data structure declared by this macro, and
+ is also used for diagnostic purposes
+
+- ``_start`` and ``_end`` values must be based on the ``OEN_*`` values defined in
+ `smcc.h`_
+
+- ``_type`` must be one of ``SMC_TYPE_FAST`` or ``SMC_TYPE_YIELD``
+
+- ``_setup`` is the initialization function with the ``rt_svc_init`` signature:
+
+ .. code:: c
+
+ typedef int32_t (*rt_svc_init)(void);
+
+- ``_smch`` is the SMC handler function with the ``rt_svc_handle`` signature:
+
+ .. code:: c
+
+ typedef uintptr_t (*rt_svc_handle_t)(uint32_t smc_fid,
+ u_register_t x1, u_register_t x2,
+ u_register_t x3, u_register_t x4,
+ void *cookie,
+ void *handle,
+ u_register_t flags);
+
+Details of the requirements and behavior of the two callbacks is provided in
+the following sections.
+
+During initialization the services framework validates each declared service
+to ensure that the following conditions are met:
+
+#. The ``_start`` OEN is not greater than the ``_end`` OEN
+#. The ``_end`` OEN does not exceed the maximum OEN value (63)
+#. The ``_type`` is one of ``SMC_TYPE_FAST`` or ``SMC_TYPE_YIELD``
+#. ``_setup`` and ``_smch`` routines have been specified
+
+`std\_svc\_setup.c`_ provides an example of registering a runtime service:
+
+.. code:: c
+
+ /* Register Standard Service Calls as runtime service */
+ DECLARE_RT_SVC(
+ std_svc,
+ OEN_STD_START,
+ OEN_STD_END,
+ SMC_TYPE_FAST,
+ std_svc_setup,
+ std_svc_smc_handler
+ );
+
+Initializing a runtime service
+------------------------------
+
+Runtime services are initialized once, during cold boot, by the primary CPU
+after platform and architectural initialization is complete. The framework
+performs basic validation of the declared service before calling
+the service initialization function (``_setup`` in the declaration). This
+function must carry out any essential EL3 initialization prior to receiving a
+SMC Function call via the handler function.
+
+On success, the initialization function must return ``0``. Any other return value
+will cause the framework to issue a diagnostic:
+
+::
+
+ Error initializing runtime service <name of the service>
+
+and then ignore the service - the system will continue to boot but SMC calls
+will not be passed to the service handler and instead return the *Unknown SMC
+Function ID* result ``0xFFFFFFFF``.
+
+If the system must not be allowed to proceed without the service, the
+initialization function must itself cause the firmware boot to be halted.
+
+If the service uses per-CPU data this must either be initialized for all CPUs
+during this call, or be done lazily when a CPU first issues an SMC call to that
+service.
+
+Handling runtime service requests
+---------------------------------
+
+SMC calls for a service are forwarded by the framework to the service's SMC
+handler function (``_smch`` in the service declaration). This function must have
+the following signature:
+
+.. code:: c
+
+ typedef uintptr_t (*rt_svc_handle_t)(uint32_t smc_fid,
+ u_register_t x1, u_register_t x2,
+ u_register_t x3, u_register_t x4,
+ void *cookie,
+ void *handle,
+ u_register_t flags);
+
+The handler is responsible for:
+
+#. Determining that ``smc_fid`` is a valid and supported SMC Function ID,
+ otherwise completing the request with the *Unknown SMC Function ID*:
+
+ .. code:: c
+
+ SMC_RET1(handle, SMC_UNK);
+
+#. Determining if the requested function is valid for the calling security
+ state. SMC Calls can be made from both the normal and trusted worlds and
+ the framework will forward all calls to the service handler.
+
+ The ``flags`` parameter to this function indicates the caller security state
+ in bit[0], where a value of ``1`` indicates a non-secure caller. The
+ ``is_caller_secure(flags)`` and ``is_caller_non_secure(flags)`` can be used to
+ test this condition.
+
+ If invalid, the request should be completed with:
+
+ .. code:: c
+
+ SMC_RET1(handle, SMC_UNK);
+
+#. Truncating parameters for calls made using the SMC32 calling convention.
+ Such calls can be determined by checking the CC field in bit[30] of the
+ ``smc_fid`` parameter, for example by using:
+
+ ::
+
+ if (GET_SMC_CC(smc_fid) == SMC_32) ...
+
+ For such calls, the upper bits of the parameters x1-x4 and the saved
+ parameters X5-X7 are UNDEFINED and must be explicitly ignored by the
+ handler. This can be done by truncating the values to a suitable 32-bit
+ integer type before use, for example by ensuring that functions defined
+ to handle individual SMC Functions use appropriate 32-bit parameters.
+
+#. Providing the service requested by the SMC Function, utilizing the
+ immediate parameters x1-x4 and/or the additional saved parameters X5-X7.
+ The latter can be retrieved using the ``SMC_GET_GP(handle, ref)`` function,
+ supplying the appropriate ``CTX_GPREG_Xn`` reference, e.g.
+
+ .. code:: c
+
+ uint64_t x6 = SMC_GET_GP(handle, CTX_GPREG_X6);
+
+#. Implementing the standard SMC32 Functions that provide information about
+ the implementation of the service. These are the Call Count, Implementor
+ UID and Revision Details for each service documented in section 6 of the
+ `SMCCC`_.
+
+ The ARM Trusted Firmware expects owning entities to follow this
+ recommendation.
+
+#. Returning the result to the caller. The `SMCCC`_ allows for up to 256 bits
+ of return value in SMC64 using X0-X3 and 128 bits in SMC32 using W0-W3. The
+ framework provides a family of macros to set the multi-register return
+ value and complete the handler:
+
+ .. code:: c
+
+ SMC_RET1(handle, x0);
+ SMC_RET2(handle, x0, x1);
+ SMC_RET3(handle, x0, x1, x2);
+ SMC_RET4(handle, x0, x1, x2, x3);
+
+The ``cookie`` parameter to the handler is reserved for future use and can be
+ignored. The ``handle`` is returned by the SMC handler - completion of the
+handler function must always be via one of the ``SMC_RETn()`` macros.
+
+NOTE: The PSCI and Test Secure-EL1 Payload Dispatcher services do not follow
+all of the above requirements yet.
+
+Services that contain multiple sub-services
+-------------------------------------------
+
+It is possible that a single owning entity implements multiple sub-services. For
+example, the Standard calls service handles ``0x84000000``-``0x8400FFFF`` and
+``0xC4000000``-``0xC400FFFF`` functions. Within that range, the `PSCI`_ service
+handles the ``0x84000000``-``0x8400001F`` and ``0xC4000000``-``0xC400001F`` functions.
+In that respect, `PSCI`_ is a 'sub-service' of the Standard calls service. In
+future, there could be additional such sub-services in the Standard calls
+service which perform independent functions.
+
+In this situation it may be valuable to introduce a second level framework to
+enable independent implementation of sub-services. Such a framework might look
+very similar to the current runtime services framework, but using a different
+part of the SMC Function ID to identify the sub-service. Trusted Firmware does
+not provide such a framework at present.
+
+Secure-EL1 Payload Dispatcher service (SPD)
+-------------------------------------------
+
+Services that handle SMC Functions targeting a Trusted OS, Trusted Application,
+or other Secure-EL1 Payload are special. These services need to manage the
+Secure-EL1 context, provide the *Secure Monitor* functionality of switching
+between the normal and secure worlds, deliver SMC Calls through to Secure-EL1
+and generally manage the Secure-EL1 Payload through CPU power-state transitions.
+
+TODO: Provide details of the additional work required to implement a SPD and
+the BL31 support for these services. Or a reference to the document that will
+provide this information....
+
+--------------
+
+*Copyright (c) 2014-2015, ARM Limited and Contributors. All rights reserved.*
+
+.. _SMCCC: http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _Firmware Design: ./firmware-design.rst
+.. _services: ../services
+.. _lib/psci: ../lib/psci
+.. _runtime\_svc.h: ../include/common/runtime_svc.h
+.. _smcc.h: ../include/lib/smcc.h
+.. _std\_svc\_setup.c: ../services/std_svc/std_svc_setup.c
--- /dev/null
+OP-TEE Dispatcher
+=================
+
+`OP-TEE OS`_ is a Trusted OS running as Secure EL1.
+
+To build and execute OP-TEE follow the instructions at
+`OP-TEE build.git`_
+
+--------------
+
+*Copyright (c) 2014-2017, ARM Limited and Contributors. All rights reserved.*
+
+.. _OP-TEE OS: https://github.com/OP-TEE/build
+.. _OP-TEE build.git: https://github.com/OP-TEE/build
--- /dev/null
+Trusted Little Kernel (TLK) Dispatcher
+======================================
+
+TLK dispatcher adds support for NVIDIA's Trusted Little Kernel (TLK) to work
+with the Trusted Firmware. TLK-D can be compiled by including it in the
+platform's makefile. TLK is primarily meant to work with Tegra SoCs, so until
+Trusted Firmware starts supporting Tegra, the dispatcher code can only be
+compiled for other platforms.
+
+In order to compile TLK-D, we need a BL32 image to be present. Since, TLKD
+just needs to compile, any BL32 image would do. To use TLK as the BL32, please
+refer to the "Build TLK" section.
+
+Once a BL32 is ready, TLKD can be included in the image by adding "SPD=tlkd"
+to the build command.
+
+Trusted Little Kernel (TLK)
+===========================
+
+TLK is a Trusted OS running as Secure EL1. It is a Free Open Source Software
+(FOSS) release of the NVIDIA® Trusted Little Kernel (TLK) technology, which
+extends technology made available with the development of the Little Kernel (LK).
+You can download the LK modular embedded preemptive kernel for use on ARM,
+x86, and AVR32 systems from https://github.com/travisg/lk
+
+NVIDIA implemented its Trusted Little Kernel (TLK) technology, designed as a
+free and open-source trusted execution environment (OTE).
+
+TLK features include:
+
+• Small, pre-emptive kernel
+• Supports multi-threading, IPCs, and thread scheduling
+• Added TrustZone features
+• Added Secure Storage
+• Under MIT/FreeBSD license
+
+NVIDIA extensions to Little Kernel (LK) include:
+
+• User mode
+• Address-space separation for TAs
+• TLK Client Application (CA) library
+• TLK TA library
+• Crypto library (encrypt/decrypt, key handling) via OpenSSL
+• Linux kernel driver
+• Cortex A9/A15 support
+• Power Management
+• TrustZone memory carve-out (reconfigurable)
+• Page table management
+• Debugging support over UART (USB planned)
+
+TLK is hosted by NVIDIA on http://nv-tegra.nvidia.com under the
+3rdparty/ote\_partner/tlk.git repository. Detailed information about
+TLK and OTE can be found in the Tegra\_BSP\_for\_Android\_TLK\_FOSS\_Reference.pdf
+manual located under the "documentation" directory\_.
+
+Build TLK
+=========
+
+To build and execute TLK, follow the instructions from "Building a TLK Device"
+section from Tegra\_BSP\_for\_Android\_TLK\_FOSS\_Reference.pdf manual.
+
+Input parameters to TLK
+=======================
+
+TLK expects the TZDRAM size and a structure containing the boot arguments. BL2
+passes this information to the EL3 software as members of the bl32\_ep\_info
+struct, where bl32\_ep\_info is part of bl31\_params\_t (passed by BL2 in X0)
+
+Example:
+--------
+
+::
+
+ bl32_ep_info->args.arg0 = TZDRAM size available for BL32
+ bl32_ep_info->args.arg1 = unused (used only on ARMv7)
+ bl32_ep_info->args.arg2 = pointer to boot args
--- /dev/null
+Trusty Dispatcher
+=================
+
+Trusty is a a set of software components, supporting a Trusted Execution
+Environment (TEE) on mobile devices, published and maintained by Google.
+
+Detailed information and build instructions can be found on the Android
+Open Source Project (AOSP) webpage for Trusty hosted at
+https://source.android.com/security/trusty
+
+Supported platforms
+===================
+
+Out of all the platforms supported by the ARM Trusted Firmware, Trusty is
+verified and supported by NVIDIA's Tegra SoCs.
--- /dev/null
+Trusted Board Boot Design Guide
+===============================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+The Trusted Board Boot (TBB) feature prevents malicious firmware from running on
+the platform by authenticating all firmware images up to and including the
+normal world bootloader. It does this by establishing a Chain of Trust using
+Public-Key-Cryptography Standards (PKCS).
+
+This document describes the design of ARM Trusted Firmware TBB, which is an
+implementation of the Trusted Board Boot Requirements (TBBR) specification,
+ARM DEN0006C-1. It should be used in conjunction with the `Firmware Update`_
+design document, which implements a specific aspect of the TBBR.
+
+Chain of Trust
+--------------
+
+A Chain of Trust (CoT) starts with a set of implicitly trusted components. On
+the ARM development platforms, these components are:
+
+- A SHA-256 hash of the Root of Trust Public Key (ROTPK). It is stored in the
+ trusted root-key storage registers.
+
+- The BL1 image, on the assumption that it resides in ROM so cannot be
+ tampered with.
+
+The remaining components in the CoT are either certificates or boot loader
+images. The certificates follow the `X.509 v3`_ standard. This standard
+enables adding custom extensions to the certificates, which are used to store
+essential information to establish the CoT.
+
+In the TBB CoT all certificates are self-signed. There is no need for a
+Certificate Authority (CA) because the CoT is not established by verifying the
+validity of a certificate's issuer but by the content of the certificate
+extensions. To sign the certificates, the PKCS#1 SHA-256 with RSA Encryption
+signature scheme is used with a RSA key length of 2048 bits. Future version of
+Trusted Firmware will support additional cryptographic algorithms.
+
+The certificates are categorised as "Key" and "Content" certificates. Key
+certificates are used to verify public keys which have been used to sign content
+certificates. Content certificates are used to store the hash of a boot loader
+image. An image can be authenticated by calculating its hash and matching it
+with the hash extracted from the content certificate. The SHA-256 function is
+used to calculate all hashes. The public keys and hashes are included as
+non-standard extension fields in the `X.509 v3`_ certificates.
+
+The keys used to establish the CoT are:
+
+- **Root of trust key**
+
+ The private part of this key is used to sign the BL2 content certificate and
+ the trusted key certificate. The public part is the ROTPK.
+
+- **Trusted world key**
+
+ The private part is used to sign the key certificates corresponding to the
+ secure world images (SCP\_BL2, BL31 and BL32). The public part is stored in
+ one of the extension fields in the trusted world certificate.
+
+- **Non-trusted world key**
+
+ The private part is used to sign the key certificate corresponding to the
+ non secure world image (BL33). The public part is stored in one of the
+ extension fields in the trusted world certificate.
+
+- **BL3-X keys**
+
+ For each of SCP\_BL2, BL31, BL32 and BL33, the private part is used to
+ sign the content certificate for the BL3-X image. The public part is stored
+ in one of the extension fields in the corresponding key certificate.
+
+The following images are included in the CoT:
+
+- BL1
+- BL2
+- SCP\_BL2 (optional)
+- BL31
+- BL33
+- BL32 (optional)
+
+The following certificates are used to authenticate the images.
+
+- **BL2 content certificate**
+
+ It is self-signed with the private part of the ROT key. It contains a hash
+ of the BL2 image.
+
+- **Trusted key certificate**
+
+ It is self-signed with the private part of the ROT key. It contains the
+ public part of the trusted world key and the public part of the non-trusted
+ world key.
+
+- **SCP\_BL2 key certificate**
+
+ It is self-signed with the trusted world key. It contains the public part of
+ the SCP\_BL2 key.
+
+- **SCP\_BL2 content certificate**
+
+ It is self-signed with the SCP\_BL2 key. It contains a hash of the SCP\_BL2
+ image.
+
+- **BL31 key certificate**
+
+ It is self-signed with the trusted world key. It contains the public part of
+ the BL31 key.
+
+- **BL31 content certificate**
+
+ It is self-signed with the BL31 key. It contains a hash of the BL31 image.
+
+- **BL32 key certificate**
+
+ It is self-signed with the trusted world key. It contains the public part of
+ the BL32 key.
+
+- **BL32 content certificate**
+
+ It is self-signed with the BL32 key. It contains a hash of the BL32 image.
+
+- **BL33 key certificate**
+
+ It is self-signed with the non-trusted world key. It contains the public
+ part of the BL33 key.
+
+- **BL33 content certificate**
+
+ It is self-signed with the BL33 key. It contains a hash of the BL33 image.
+
+The SCP\_BL2 and BL32 certificates are optional, but they must be present if the
+corresponding SCP\_BL2 or BL32 images are present.
+
+Trusted Board Boot Sequence
+---------------------------
+
+The CoT is verified through the following sequence of steps. The system panics
+if any of the steps fail.
+
+- BL1 loads and verifies the BL2 content certificate. The issuer public key is
+ read from the verified certificate. A hash of that key is calculated and
+ compared with the hash of the ROTPK read from the trusted root-key storage
+ registers. If they match, the BL2 hash is read from the certificate.
+
+ Note: the matching operation is platform specific and is currently
+ unimplemented on the ARM development platforms.
+
+- BL1 loads the BL2 image. Its hash is calculated and compared with the hash
+ read from the certificate. Control is transferred to the BL2 image if all
+ the comparisons succeed.
+
+- BL2 loads and verifies the trusted key certificate. The issuer public key is
+ read from the verified certificate. A hash of that key is calculated and
+ compared with the hash of the ROTPK read from the trusted root-key storage
+ registers. If the comparison succeeds, BL2 reads and saves the trusted and
+ non-trusted world public keys from the verified certificate.
+
+The next two steps are executed for each of the SCP\_BL2, BL31 & BL32 images.
+The steps for the optional SCP\_BL2 and BL32 images are skipped if these images
+are not present.
+
+- BL2 loads and verifies the BL3x key certificate. The certificate signature
+ is verified using the trusted world public key. If the signature
+ verification succeeds, BL2 reads and saves the BL3x public key from the
+ certificate.
+
+- BL2 loads and verifies the BL3x content certificate. The signature is
+ verified using the BL3x public key. If the signature verification succeeds,
+ BL2 reads and saves the BL3x image hash from the certificate.
+
+The next two steps are executed only for the BL33 image.
+
+- BL2 loads and verifies the BL33 key certificate. If the signature
+ verification succeeds, BL2 reads and saves the BL33 public key from the
+ certificate.
+
+- BL2 loads and verifies the BL33 content certificate. If the signature
+ verification succeeds, BL2 reads and saves the BL33 image hash from the
+ certificate.
+
+The next step is executed for all the boot loader images.
+
+- BL2 calculates the hash of each image. It compares it with the hash obtained
+ from the corresponding content certificate. The image authentication succeeds
+ if the hashes match.
+
+The Trusted Board Boot implementation spans both generic and platform-specific
+BL1 and BL2 code, and in tool code on the host build machine. The feature is
+enabled through use of specific build flags as described in the `User Guide`_.
+
+On the host machine, a tool generates the certificates, which are included in
+the FIP along with the boot loader images. These certificates are loaded in
+Trusted SRAM using the IO storage framework. They are then verified by an
+Authentication module included in the Trusted Firmware.
+
+The mechanism used for generating the FIP and the Authentication module are
+described in the following sections.
+
+Authentication Framework
+------------------------
+
+The authentication framework included in the Trusted Firmware provides support
+to implement the desired trusted boot sequence. ARM platforms use this framework
+to implement the boot requirements specified in the TBBR-client document.
+
+More information about the authentication framework can be found in the
+`Auth Framework`_ document.
+
+Certificate Generation Tool
+---------------------------
+
+The ``cert_create`` tool is built and runs on the host machine as part of the
+Trusted Firmware build process when ``GENERATE_COT=1``. It takes the boot loader
+images and keys as inputs (keys must be in PEM format) and generates the
+certificates (in DER format) required to establish the CoT. New keys can be
+generated by the tool in case they are not provided. The certificates are then
+passed as inputs to the ``fiptool`` utility for creating the FIP.
+
+The certificates are also stored individually in the in the output build
+directory.
+
+The tool resides in the ``tools/cert_create`` directory. It uses OpenSSL SSL
+library version 1.0.1 or later to generate the X.509 certificates. Instructions
+for building and using the tool can be found in the `User Guide`_.
+
+--------------
+
+*Copyright (c) 2015, ARM Limited and Contributors. All rights reserved.*
+
+.. _Firmware Update: firmware-update.rst
+.. _X.509 v3: http://www.ietf.org/rfc/rfc5280.txt
+.. _User Guide: user-guide.rst
+.. _Auth Framework: auth-framework.rst
--- /dev/null
+ARM Trusted Firmware User Guide
+===============================
+
+
+.. section-numbering::
+ :suffix: .
+
+.. contents::
+
+This document describes how to build ARM Trusted Firmware (TF) and run it with a
+tested set of other software components using defined configurations on the Juno
+ARM development platform and ARM Fixed Virtual Platform (FVP) models. It is
+possible to use other software components, configurations and platforms but that
+is outside the scope of this document.
+
+This document assumes that the reader has previous experience running a fully
+bootable Linux software stack on Juno or FVP using the prebuilt binaries and
+filesystems provided by `Linaro`_. Further information may
+be found in the `Instructions for using the Linaro software deliverables`_. It also assumes that the user understands the role of
+the different software components required to boot a Linux system:
+
+- Specific firmware images required by the platform (e.g. SCP firmware on Juno)
+- Normal world bootloader (e.g. UEFI or U-Boot)
+- Device tree
+- Linux kernel image
+- Root filesystem
+
+Note: the ARM TF v1.3 release was tested with Linaro Release 16.06, and the
+latest version of ARM TF is tested with Linaro Release 17.01.
+
+This document also assumes that the user is familiar with the FVP models and
+the different command line options available to launch the model.
+
+This document should be used in conjunction with the `Firmware Design`_.
+
+Host machine requirements
+-------------------------
+
+The minimum recommended machine specification for building the software and
+running the FVP models is a dual-core processor running at 2GHz with 12GB of
+RAM. For best performance, use a machine with a quad-core processor running at
+2.6GHz with 16GB of RAM.
+
+The software has been tested on Ubuntu 14.04 LTS (64-bit). Packages used for
+building the software were installed from that distribution unless otherwise
+specified.
+
+The software has also been built on Windows 7 Enterprise SP1, using CMD.EXE,
+Cygwin, and Msys (MinGW) shells, using version 4.9.1 of the GNU toolchain.
+
+Tools
+-----
+
+Install the required packages to build Trusted Firmware with the following
+command:
+
+::
+
+ sudo apt-get install build-essential gcc make git libssl-dev
+
+Download and install the AArch32 or AArch64 little-endian GCC cross compiler.
+The `Linaro Release Notes`_ documents which version of the
+compiler to use for a given Linaro Release. Also, these
+`Linaro instructions`_ provide further guidance.
+
+Optionally, Trusted Firmware can be built using clang or ARM Compiler 6.
+See instructions below on how to switch the default compiler.
+
+In addition, the following optional packages and tools may be needed:
+
+- ``device-tree-compiler`` package if you need to rebuild the Flattened Device
+ Tree (FDT) source files (``.dts`` files) provided with this software.
+
+- For debugging, ARM `Development Studio 5 (DS-5)`_.
+
+Getting the Trusted Firmware source code
+----------------------------------------
+
+Download the Trusted Firmware source code from Github:
+
+::
+
+ git clone https://github.com/ARM-software/arm-trusted-firmware.git
+
+Building the Trusted Firmware
+-----------------------------
+
+- Before building Trusted Firmware, the environment variable ``CROSS_COMPILE``
+ must point to the Linaro cross compiler.
+
+ For AArch64:
+
+ ::
+
+ export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-
+
+ For AArch32:
+
+ ::
+
+ export CROSS_COMPILE=<path-to-aarch32-gcc>/bin/arm-linux-gnueabihf-
+
+ It is possible to build Trusted Firmware using clang or ARM Compiler 6.
+ To do so ``CC`` needs to point to the clang or armclang binary. Only the
+ compiler is switched; the assembler and linker need to be provided by
+ the GNU toolchain, thus ``CROSS_COMPILE`` should be set as described above.
+
+ ARM Compiler 6 will be selected when the base name of the path assigned
+ to ``CC`` matches the string 'armclang'.
+
+ For AArch64 using ARM Compiler 6:
+
+ ::
+
+ export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-
+ make CC=<path-to-armclang>/bin/armclang PLAT=<platform> all
+
+ Clang will be selected when the base name of the path assigned to ``CC``
+ contains the string 'clang'. This is to allow both clang and clang-X.Y
+ to work.
+
+ For AArch64 using clang:
+
+ ::
+
+ export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-
+ make CC=<path-to-clang>/bin/clang PLAT=<platform> all
+
+- Change to the root directory of the Trusted Firmware source tree and build.
+
+ For AArch64:
+
+ ::
+
+ make PLAT=<platform> all
+
+ For AArch32:
+
+ ::
+
+ make PLAT=<platform> ARCH=aarch32 AARCH32_SP=sp_min all
+
+ Notes:
+
+ - If ``PLAT`` is not specified, ``fvp`` is assumed by default. See the
+ `Summary of build options`_ for more information on available build
+ options.
+
+ - (AArch32 only) Currently only ``PLAT=fvp`` is supported.
+
+ - (AArch32 only) ``AARCH32_SP`` is the AArch32 EL3 Runtime Software and it
+ corresponds to the BL32 image. A minimal ``AARCH32_SP``, sp\_min, is
+ provided by ARM Trusted Firmware to demonstrate how PSCI Library can
+ be integrated with an AArch32 EL3 Runtime Software. Some AArch32 EL3
+ Runtime Software may include other runtime services, for example
+ Trusted OS services. A guide to integrate PSCI library with AArch32
+ EL3 Runtime Software can be found `here`_.
+
+ - (AArch64 only) The TSP (Test Secure Payload), corresponding to the BL32
+ image, is not compiled in by default. Refer to the
+ `Building the Test Secure Payload`_ section below.
+
+ - By default this produces a release version of the build. To produce a
+ debug version instead, refer to the "Debugging options" section below.
+
+ - The build process creates products in a ``build`` directory tree, building
+ the objects and binaries for each boot loader stage in separate
+ sub-directories. The following boot loader binary files are created
+ from the corresponding ELF files:
+
+ - ``build/<platform>/<build-type>/bl1.bin``
+ - ``build/<platform>/<build-type>/bl2.bin``
+ - ``build/<platform>/<build-type>/bl31.bin`` (AArch64 only)
+ - ``build/<platform>/<build-type>/bl32.bin`` (mandatory for AArch32)
+
+ where ``<platform>`` is the name of the chosen platform and ``<build-type>``
+ is either ``debug`` or ``release``. The actual number of images might differ
+ depending on the platform.
+
+- Build products for a specific build variant can be removed using:
+
+ ::
+
+ make DEBUG=<D> PLAT=<platform> clean
+
+ ... where ``<D>`` is ``0`` or ``1``, as specified when building.
+
+ The build tree can be removed completely using:
+
+ ::
+
+ make realclean
+
+Summary of build options
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+ARM Trusted Firmware build system supports the following build options. Unless
+mentioned otherwise, these options are expected to be specified at the build
+command line and are not to be modified in any component makefiles. Note that
+the build system doesn't track dependency for build options. Therefore, if any
+of the build options are changed from a previous build, a clean build must be
+performed.
+
+Common build options
+^^^^^^^^^^^^^^^^^^^^
+
+- ``AARCH32_SP`` : Choose the AArch32 Secure Payload component to be built as
+ as the BL32 image when ``ARCH=aarch32``. The value should be the path to the
+ directory containing the SP source, relative to the ``bl32/``; the directory
+ is expected to contain a makefile called ``<aarch32_sp-value>.mk``.
+
+- ``ARCH`` : Choose the target build architecture for ARM Trusted Firmware.
+ It can take either ``aarch64`` or ``aarch32`` as values. By default, it is
+ defined to ``aarch64``.
+
+- ``ARM_CCI_PRODUCT_ID``: Choice of ARM CCI product used by the platform. This
+ is used to determine the number of valid slave interfaces available in the
+ ARM CCI driver. Default is 400 (that is, CCI-400).
+
+- ``ARM_ARCH_MAJOR``: The major version of ARM Architecture to target when
+ compiling ARM Trusted Firmware. Its value must be numeric, and defaults to
+ 8 . See also, *ARMv8 Architecture Extensions* in `Firmware Design`_.
+
+- ``ARM_ARCH_MINOR``: The minor version of ARM Architecture to target when
+ compiling ARM Trusted Firmware. Its value must be a numeric, and defaults
+ to 0. See also, *ARMv8 Architecture Extensions* in `Firmware Design`_.
+
+- ``ARM_GIC_ARCH``: Choice of ARM GIC architecture version used by the ARM
+ Legacy GIC driver for implementing the platform GIC API. This API is used
+ by the interrupt management framework. Default is 2 (that is, version 2.0).
+ This build option is deprecated.
+
+- ``ARM_PLAT_MT``: This flag determines whether the ARM platform layer has to
+ cater for the multi-threading ``MT`` bit when accessing MPIDR. When this
+ flag is set, the functions which deal with MPIDR assume that the ``MT`` bit
+ in MPIDR is set and access the bit-fields in MPIDR accordingly. Default
+ value of this flag is 0.
+
+- ``BL2``: This is an optional build option which specifies the path to BL2
+ image for the ``fip`` target. In this case, the BL2 in the ARM Trusted
+ Firmware will not be built.
+
+- ``BL2U``: This is an optional build option which specifies the path to
+ BL2U image. In this case, the BL2U in the ARM Trusted Firmware will not
+ be built.
+
+- ``BL31``: This is an optional build option which specifies the path to
+ BL31 image for the ``fip`` target. In this case, the BL31 in the ARM
+ Trusted Firmware will not be built.
+
+- ``BL31_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
+ file that contains the BL31 private key in PEM format. If ``SAVE_KEYS=1``,
+ this file name will be used to save the key.
+
+- ``BL32``: This is an optional build option which specifies the path to
+ BL32 image for the ``fip`` target. In this case, the BL32 in the ARM
+ Trusted Firmware will not be built.
+
+- ``BL32_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
+ file that contains the BL32 private key in PEM format. If ``SAVE_KEYS=1``,
+ this file name will be used to save the key.
+
+- ``BL33``: Path to BL33 image in the host file system. This is mandatory for
+ ``fip`` target in case the BL2 from ARM Trusted Firmware is used.
+
+- ``BL33_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
+ file that contains the BL33 private key in PEM format. If ``SAVE_KEYS=1``,
+ this file name will be used to save the key.
+
+- ``BUILD_MESSAGE_TIMESTAMP``: String used to identify the time and date of the
+ compilation of each build. It must be set to a C string (including quotes
+ where applicable). Defaults to a string that contains the time and date of
+ the compilation.
+
+- ``BUILD_STRING``: Input string for VERSION\_STRING, which allows the TF build
+ to be uniquely identified. Defaults to the current git commit id.
+
+- ``CFLAGS``: Extra user options appended on the compiler's command line in
+ addition to the options set by the build system.
+
+- ``COLD_BOOT_SINGLE_CPU``: This option indicates whether the platform may
+ release several CPUs out of reset. It can take either 0 (several CPUs may be
+ brought up) or 1 (only one CPU will ever be brought up during cold reset).
+ Default is 0. If the platform always brings up a single CPU, there is no
+ need to distinguish between primary and secondary CPUs and the boot path can
+ be optimised. The ``plat_is_my_cpu_primary()`` and
+ ``plat_secondary_cold_boot_setup()`` platform porting interfaces do not need
+ to be implemented in this case.
+
+- ``CRASH_REPORTING``: A non-zero value enables a console dump of processor
+ register state when an unexpected exception occurs during execution of
+ BL31. This option defaults to the value of ``DEBUG`` - i.e. by default
+ this is only enabled for a debug build of the firmware.
+
+- ``CREATE_KEYS``: This option is used when ``GENERATE_COT=1``. It tells the
+ certificate generation tool to create new keys in case no valid keys are
+ present or specified. Allowed options are '0' or '1'. Default is '1'.
+
+- ``CTX_INCLUDE_AARCH32_REGS`` : Boolean option that, when set to 1, will cause
+ the AArch32 system registers to be included when saving and restoring the
+ CPU context. The option must be set to 0 for AArch64-only platforms (that
+ is on hardware that does not implement AArch32, or at least not at EL1 and
+ higher ELs). Default value is 1.
+
+- ``CTX_INCLUDE_FPREGS``: Boolean option that, when set to 1, will cause the FP
+ registers to be included when saving and restoring the CPU context. Default
+ is 0.
+
+- ``DEBUG``: Chooses between a debug and release build. It can take either 0
+ (release) or 1 (debug) as values. 0 is the default.
+
+- ``EL3_PAYLOAD_BASE``: This option enables booting an EL3 payload instead of
+ the normal boot flow. It must specify the entry point address of the EL3
+ payload. Please refer to the "Booting an EL3 payload" section for more
+ details.
+
+- ``ENABLE_ASSERTIONS``: This option controls whether or not calls to ``assert()``
+ are compiled out. For debug builds, this option defaults to 1, and calls to
+ ``assert()`` are left in place. For release builds, this option defaults to 0
+ and calls to ``assert()`` function are compiled out. This option can be set
+ independently of ``DEBUG``. It can also be used to hide any auxiliary code
+ that is only required for the assertion and does not fit in the assertion
+ itself.
+
+- ``ENABLE_PMF``: Boolean option to enable support for optional Performance
+ Measurement Framework(PMF). Default is 0.
+
+- ``ENABLE_PSCI_STAT``: Boolean option to enable support for optional PSCI
+ functions ``PSCI_STAT_RESIDENCY`` and ``PSCI_STAT_COUNT``. Default is 0.
+ In the absence of an alternate stat collection backend, ``ENABLE_PMF`` must
+ be enabled. If ``ENABLE_PMF`` is set, the residency statistics are tracked in
+ software.
+
+- ``ENABLE_RUNTIME_INSTRUMENTATION``: Boolean option to enable runtime
+ instrumentation which injects timestamp collection points into
+ Trusted Firmware to allow runtime performance to be measured.
+ Currently, only PSCI is instrumented. Enabling this option enables
+ the ``ENABLE_PMF`` build option as well. Default is 0.
+
+- ``ENABLE_STACK_PROTECTOR``: String option to enable the stack protection
+ checks in GCC. Allowed values are "all", "strong" and "0" (default).
+ "strong" is the recommended stack protection level if this feature is
+ desired. 0 disables the stack protection. For all values other than 0, the
+ ``plat_get_stack_protector_canary()`` platform hook needs to be implemented.
+ The value is passed as the last component of the option
+ ``-fstack-protector-$ENABLE_STACK_PROTECTOR``.
+
+- ``ERROR_DEPRECATED``: This option decides whether to treat the usage of
+ deprecated platform APIs, helper functions or drivers within Trusted
+ Firmware as error. It can take the value 1 (flag the use of deprecated
+ APIs as error) or 0. The default is 0.
+
+- ``FIP_NAME``: This is an optional build option which specifies the FIP
+ filename for the ``fip`` target. Default is ``fip.bin``.
+
+- ``FWU_FIP_NAME``: This is an optional build option which specifies the FWU
+ FIP filename for the ``fwu_fip`` target. Default is ``fwu_fip.bin``.
+
+- ``GENERATE_COT``: Boolean flag used to build and execute the ``cert_create``
+ tool to create certificates as per the Chain of Trust described in
+ `Trusted Board Boot`_. The build system then calls ``fiptool`` to
+ include the certificates in the FIP and FWU\_FIP. Default value is '0'.
+
+ Specify both ``TRUSTED_BOARD_BOOT=1`` and ``GENERATE_COT=1`` to include support
+ for the Trusted Board Boot feature in the BL1 and BL2 images, to generate
+ the corresponding certificates, and to include those certificates in the
+ FIP and FWU\_FIP.
+
+ Note that if ``TRUSTED_BOARD_BOOT=0`` and ``GENERATE_COT=1``, the BL1 and BL2
+ images will not include support for Trusted Board Boot. The FIP will still
+ include the corresponding certificates. This FIP can be used to verify the
+ Chain of Trust on the host machine through other mechanisms.
+
+ Note that if ``TRUSTED_BOARD_BOOT=1`` and ``GENERATE_COT=0``, the BL1 and BL2
+ images will include support for Trusted Board Boot, but the FIP and FWU\_FIP
+ will not include the corresponding certificates, causing a boot failure.
+
+- ``HANDLE_EA_EL3_FIRST``: When defined External Aborts and SError Interrupts
+ will be always trapped in EL3 i.e. in BL31 at runtime.
+
+- ``HW_ASSISTED_COHERENCY``: On most ARM systems to-date, platform-specific
+ software operations are required for CPUs to enter and exit coherency.
+ However, there exists newer systems where CPUs' entry to and exit from
+ coherency is managed in hardware. Such systems require software to only
+ initiate the operations, and the rest is managed in hardware, minimizing
+ active software management. In such systems, this boolean option enables ARM
+ Trusted Firmware to carry out build and run-time optimizations during boot
+ and power management operations. This option defaults to 0 and if it is
+ enabled, then it implies ``WARMBOOT_ENABLE_DCACHE_EARLY`` is also enabled.
+
+- ``JUNO_AARCH32_EL3_RUNTIME``: This build flag enables you to execute EL3
+ runtime software in AArch32 mode, which is required to run AArch32 on Juno.
+ By default this flag is set to '0'. Enabling this flag builds BL1 and BL2 in
+ AArch64 and facilitates the loading of ``SP_MIN`` and BL33 as AArch32 executable
+ images.
+
+- ``LDFLAGS``: Extra user options appended to the linkers' command line in
+ addition to the one set by the build system.
+
+- ``LOAD_IMAGE_V2``: Boolean option to enable support for new version (v2) of
+ image loading, which provides more flexibility and scalability around what
+ images are loaded and executed during boot. Default is 0.
+ Note: ``TRUSTED_BOARD_BOOT`` is currently only supported for AArch64 when
+ ``LOAD_IMAGE_V2`` is enabled.
+
+- ``LOG_LEVEL``: Chooses the log level, which controls the amount of console log
+ output compiled into the build. This should be one of the following:
+
+ ::
+
+ 0 (LOG_LEVEL_NONE)
+ 10 (LOG_LEVEL_NOTICE)
+ 20 (LOG_LEVEL_ERROR)
+ 30 (LOG_LEVEL_WARNING)
+ 40 (LOG_LEVEL_INFO)
+ 50 (LOG_LEVEL_VERBOSE)
+
+ All log output up to and including the log level is compiled into the build.
+ The default value is 40 in debug builds and 20 in release builds.
+
+- ``NON_TRUSTED_WORLD_KEY``: This option is used when ``GENERATE_COT=1``. It
+ specifies the file that contains the Non-Trusted World private key in PEM
+ format. If ``SAVE_KEYS=1``, this file name will be used to save the key.
+
+- ``NS_BL2U``: Path to NS\_BL2U image in the host file system. This image is
+ optional. It is only needed if the platform makefile specifies that it
+ is required in order to build the ``fwu_fip`` target.
+
+- ``NS_TIMER_SWITCH``: Enable save and restore for non-secure timer register
+ contents upon world switch. It can take either 0 (don't save and restore) or
+ 1 (do save and restore). 0 is the default. An SPD may set this to 1 if it
+ wants the timer registers to be saved and restored.
+
+- ``PL011_GENERIC_UART``: Boolean option to indicate the PL011 driver that
+ the underlying hardware is not a full PL011 UART but a minimally compliant
+ generic UART, which is a subset of the PL011. The driver will not access
+ any register that is not part of the SBSA generic UART specification.
+ Default value is 0 (a full PL011 compliant UART is present).
+
+- ``PLAT``: Choose a platform to build ARM Trusted Firmware for. The chosen
+ platform name must be subdirectory of any depth under ``plat/``, and must
+ contain a platform makefile named ``platform.mk``.
+
+- ``PRELOADED_BL33_BASE``: This option enables booting a preloaded BL33 image
+ instead of the normal boot flow. When defined, it must specify the entry
+ point address for the preloaded BL33 image. This option is incompatible with
+ ``EL3_PAYLOAD_BASE``. If both are defined, ``EL3_PAYLOAD_BASE`` has priority
+ over ``PRELOADED_BL33_BASE``.
+
+- ``PROGRAMMABLE_RESET_ADDRESS``: This option indicates whether the reset
+ vector address can be programmed or is fixed on the platform. It can take
+ either 0 (fixed) or 1 (programmable). Default is 0. If the platform has a
+ programmable reset address, it is expected that a CPU will start executing
+ code directly at the right address, both on a cold and warm reset. In this
+ case, there is no need to identify the entrypoint on boot and the boot path
+ can be optimised. The ``plat_get_my_entrypoint()`` platform porting interface
+ does not need to be implemented in this case.
+
+- ``PSCI_EXTENDED_STATE_ID``: As per PSCI1.0 Specification, there are 2 formats
+ possible for the PSCI power-state parameter viz original and extended
+ State-ID formats. This flag if set to 1, configures the generic PSCI layer
+ to use the extended format. The default value of this flag is 0, which
+ means by default the original power-state format is used by the PSCI
+ implementation. This flag should be specified by the platform makefile
+ and it governs the return value of PSCI\_FEATURES API for CPU\_SUSPEND
+ smc function id. When this option is enabled on ARM platforms, the
+ option ``ARM_RECOM_STATE_ID_ENC`` needs to be set to 1 as well.
+
+- ``RESET_TO_BL31``: Enable BL31 entrypoint as the CPU reset vector instead
+ of the BL1 entrypoint. It can take the value 0 (CPU reset to BL1
+ entrypoint) or 1 (CPU reset to BL31 entrypoint).
+ The default value is 0.
+
+- ``RESET_TO_SP_MIN``: SP\_MIN is the minimal AArch32 Secure Payload provided in
+ ARM Trusted Firmware. This flag configures SP\_MIN entrypoint as the CPU
+ reset vector instead of the BL1 entrypoint. It can take the value 0 (CPU
+ reset to BL1 entrypoint) or 1 (CPU reset to SP\_MIN entrypoint). The default
+ value is 0.
+
+- ``ROT_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
+ file that contains the ROT private key in PEM format. If ``SAVE_KEYS=1``, this
+ file name will be used to save the key.
+
+- ``SAVE_KEYS``: This option is used when ``GENERATE_COT=1``. It tells the
+ certificate generation tool to save the keys used to establish the Chain of
+ Trust. Allowed options are '0' or '1'. Default is '0' (do not save).
+
+- ``SCP_BL2``: Path to SCP\_BL2 image in the host file system. This image is optional.
+ If a SCP\_BL2 image is present then this option must be passed for the ``fip``
+ target.
+
+- ``SCP_BL2_KEY``: This option is used when ``GENERATE_COT=1``. It specifies the
+ file that contains the SCP\_BL2 private key in PEM format. If ``SAVE_KEYS=1``,
+ this file name will be used to save the key.
+
+- ``SCP_BL2U``: Path to SCP\_BL2U image in the host file system. This image is
+ optional. It is only needed if the platform makefile specifies that it
+ is required in order to build the ``fwu_fip`` target.
+
+- ``SEPARATE_CODE_AND_RODATA``: Whether code and read-only data should be
+ isolated on separate memory pages. This is a trade-off between security and
+ memory usage. See "Isolating code and read-only data on separate memory
+ pages" section in `Firmware Design`_. This flag is disabled by default and
+ affects all BL images.
+
+- ``SPD``: Choose a Secure Payload Dispatcher component to be built into the
+ Trusted Firmware. This build option is only valid if ``ARCH=aarch64``. The
+ value should be the path to the directory containing the SPD source,
+ relative to ``services/spd/``; the directory is expected to
+ contain a makefile called ``<spd-value>.mk``.
+
+- ``SPIN_ON_BL1_EXIT``: This option introduces an infinite loop in BL1. It can
+ take either 0 (no loop) or 1 (add a loop). 0 is the default. This loop stops
+ execution in BL1 just before handing over to BL31. At this point, all
+ firmware images have been loaded in memory, and the MMU and caches are
+ turned off. Refer to the "Debugging options" section for more details.
+
+- ``TRUSTED_BOARD_BOOT``: Boolean flag to include support for the Trusted Board
+ Boot feature. When set to '1', BL1 and BL2 images include support to load
+ and verify the certificates and images in a FIP, and BL1 includes support
+ for the Firmware Update. The default value is '0'. Generation and inclusion
+ of certificates in the FIP and FWU\_FIP depends upon the value of the
+ ``GENERATE_COT`` option.
+
+ Note: This option depends on ``CREATE_KEYS`` to be enabled. If the keys
+ already exist in disk, they will be overwritten without further notice.
+
+- ``TRUSTED_WORLD_KEY``: This option is used when ``GENERATE_COT=1``. It
+ specifies the file that contains the Trusted World private key in PEM
+ format. If ``SAVE_KEYS=1``, this file name will be used to save the key.
+
+- ``TSP_INIT_ASYNC``: Choose BL32 initialization method as asynchronous or
+ synchronous, (see "Initializing a BL32 Image" section in
+ `Firmware Design`_). It can take the value 0 (BL32 is initialized using
+ synchronous method) or 1 (BL32 is initialized using asynchronous method).
+ Default is 0.
+
+- ``TSP_NS_INTR_ASYNC_PREEMPT``: A non zero value enables the interrupt
+ routing model which routes non-secure interrupts asynchronously from TSP
+ to EL3 causing immediate preemption of TSP. The EL3 is responsible
+ for saving and restoring the TSP context in this routing model. The
+ default routing model (when the value is 0) is to route non-secure
+ interrupts to TSP allowing it to save its context and hand over
+ synchronously to EL3 via an SMC.
+
+- ``USE_COHERENT_MEM``: This flag determines whether to include the coherent
+ memory region in the BL memory map or not (see "Use of Coherent memory in
+ Trusted Firmware" section in `Firmware Design`_). It can take the value 1
+ (Coherent memory region is included) or 0 (Coherent memory region is
+ excluded). Default is 1.
+
+- ``V``: Verbose build. If assigned anything other than 0, the build commands
+ are printed. Default is 0.
+
+- ``VERSION_STRING``: String used in the log output for each TF image. Defaults
+ to a string formed by concatenating the version number, build type and build
+ string.
+
+- ``WARMBOOT_ENABLE_DCACHE_EARLY`` : Boolean option to enable D-cache early on
+ the CPU after warm boot. This is applicable for platforms which do not
+ require interconnect programming to enable cache coherency (eg: single
+ cluster platforms). If this option is enabled, then warm boot path
+ enables D-caches immediately after enabling MMU. This option defaults to 0.
+
+- ``ENABLE_SPE_FOR_LOWER_ELS`` : Boolean option to enable Statistical Profiling
+ extensions. This is an optional architectural feature available only for
+ AArch64 8.2 onwards. This option defaults to 1 but is automatically
+ disabled when the target architecture is AArch32 or AArch64 8.0/8.1.
+
+ARM development platform specific build options
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+- ``ARM_BL31_IN_DRAM``: Boolean option to select loading of BL31 in TZC secured
+ DRAM. By default, BL31 is in the secure SRAM. Set this flag to 1 to load
+ BL31 in TZC secured DRAM. If TSP is present, then setting this option also
+ sets the TSP location to DRAM and ignores the ``ARM_TSP_RAM_LOCATION`` build
+ flag.
+
+- ``ARM_BOARD_OPTIMISE_MEM``: Boolean option to enable or disable optimisation
+ of the memory reserved for each image. This affects the maximum size of each
+ BL image as well as the number of allocated memory regions and translation
+ tables. By default this flag is 0, which means it uses the default
+ unoptimised values for these macros. ARM development platforms that wish to
+ optimise memory usage need to set this flag to 1 and must override the
+ related macros.
+
+- ``ARM_CONFIG_CNTACR``: boolean option to unlock access to the ``CNTBase<N>``
+ frame registers by setting the ``CNTCTLBase.CNTACR<N>`` register bits. The
+ frame number ``<N>`` is defined by ``PLAT_ARM_NSTIMER_FRAME_ID``, which should
+ match the frame used by the Non-Secure image (normally the Linux kernel).
+ Default is true (access to the frame is allowed).
+
+- ``ARM_DISABLE_TRUSTED_WDOG``: boolean option to disable the Trusted Watchdog.
+ By default, ARM platforms use a watchdog to trigger a system reset in case
+ an error is encountered during the boot process (for example, when an image
+ could not be loaded or authenticated). The watchdog is enabled in the early
+ platform setup hook at BL1 and disabled in the BL1 prepare exit hook. The
+ Trusted Watchdog may be disabled at build time for testing or development
+ purposes.
+
+- ``ARM_RECOM_STATE_ID_ENC``: The PSCI1.0 specification recommends an encoding
+ for the construction of composite state-ID in the power-state parameter.
+ The existing PSCI clients currently do not support this encoding of
+ State-ID yet. Hence this flag is used to configure whether to use the
+ recommended State-ID encoding or not. The default value of this flag is 0,
+ in which case the platform is configured to expect NULL in the State-ID
+ field of power-state parameter.
+
+- ``ARM_ROTPK_LOCATION``: used when ``TRUSTED_BOARD_BOOT=1``. It specifies the
+ location of the ROTPK hash returned by the function ``plat_get_rotpk_info()``
+ for ARM platforms. Depending on the selected option, the proper private key
+ must be specified using the ``ROT_KEY`` option when building the Trusted
+ Firmware. This private key will be used by the certificate generation tool
+ to sign the BL2 and Trusted Key certificates. Available options for
+ ``ARM_ROTPK_LOCATION`` are:
+
+ - ``regs`` : return the ROTPK hash stored in the Trusted root-key storage
+ registers. The private key corresponding to this ROTPK hash is not
+ currently available.
+ - ``devel_rsa`` : return a development public key hash embedded in the BL1
+ and BL2 binaries. This hash has been obtained from the RSA public key
+ ``arm_rotpk_rsa.der``, located in ``plat/arm/board/common/rotpk``. To use
+ this option, ``arm_rotprivk_rsa.pem`` must be specified as ``ROT_KEY`` when
+ creating the certificates.
+
+- ``ARM_TSP_RAM_LOCATION``: location of the TSP binary. Options:
+
+ - ``tsram`` : Trusted SRAM (default option)
+ - ``tdram`` : Trusted DRAM (if available)
+ - ``dram`` : Secure region in DRAM (configured by the TrustZone controller)
+
+- ``ARM_XLAT_TABLES_LIB_V1``: boolean option to compile the Trusted Firmware
+ with version 1 of the translation tables library instead of version 2. It is
+ set to 0 by default, which selects version 2.
+
+- ``ARM_CRYPTOCELL_INTEG`` : bool option to enable Trusted Firmware to invoke
+ ARM® TrustZone® CryptoCell functionality for Trusted Board Boot on capable
+ ARM platforms. If this option is specified, then the path to the CryptoCell
+ SBROM library must be specified via ``CCSBROM_LIB_PATH`` flag.
+
+For a better understanding of these options, the ARM development platform memory
+map is explained in the `Firmware Design`_.
+
+ARM CSS platform specific build options
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+- ``CSS_DETECT_PRE_1_7_0_SCP``: Boolean flag to detect SCP version
+ incompatibility. Version 1.7.0 of the SCP firmware made a non-backwards
+ compatible change to the MTL protocol, used for AP/SCP communication.
+ Trusted Firmware no longer supports earlier SCP versions. If this option is
+ set to 1 then Trusted Firmware will detect if an earlier version is in use.
+ Default is 1.
+
+- ``CSS_LOAD_SCP_IMAGES``: Boolean flag, which when set, adds SCP\_BL2 and
+ SCP\_BL2U to the FIP and FWU\_FIP respectively, and enables them to be loaded
+ during boot. Default is 1.
+
+- ``CSS_USE_SCMI_DRIVER``: Boolean flag which selects SCMI driver instead of
+ SCPI driver for communicating with the SCP during power management operations.
+ If this option is set to 1, then SCMI driver will be used. Default is 0.
+
+ARM FVP platform specific build options
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+- ``FVP_CLUSTER_COUNT`` : Configures the cluster count to be used to
+ build the topology tree within Trusted Firmware. By default the
+ Trusted Firmware is configured for dual cluster topology and this option
+ can be used to override the default value.
+
+- ``FVP_INTERCONNECT_DRIVER``: Selects the interconnect driver to be built. The
+ default interconnect driver depends on the value of ``FVP_CLUSTER_COUNT`` as
+ explained in the options below:
+
+ - ``FVP_CCI`` : The CCI driver is selected. This is the default
+ if 0 < ``FVP_CLUSTER_COUNT`` <= 2.
+ - ``FVP_CCN`` : The CCN driver is selected. This is the default
+ if ``FVP_CLUSTER_COUNT`` > 2.
+
+- ``FVP_USE_GIC_DRIVER`` : Selects the GIC driver to be built. Options:
+
+ - ``FVP_GIC600`` : The GIC600 implementation of GICv3 is selected
+ - ``FVP_GICV2`` : The GICv2 only driver is selected
+ - ``FVP_GICV3`` : The GICv3 only driver is selected (default option)
+ - ``FVP_GICV3_LEGACY``: The Legacy GICv3 driver is selected (deprecated)
+ Note: If Trusted Firmware is compiled with this option on FVPs with
+ GICv3 hardware, then it configures the hardware to run in GICv2
+ emulation mode
+
+- ``FVP_USE_SP804_TIMER`` : Use the SP804 timer instead of the Generic Timer
+ for functions that wait for an arbitrary time length (udelay and mdelay).
+ The default value is 0.
+
+Debugging options
+~~~~~~~~~~~~~~~~~
+
+To compile a debug version and make the build more verbose use
+
+::
+
+ make PLAT=<platform> DEBUG=1 V=1 all
+
+AArch64 GCC uses DWARF version 4 debugging symbols by default. Some tools (for
+example DS-5) might not support this and may need an older version of DWARF
+symbols to be emitted by GCC. This can be achieved by using the
+``-gdwarf-<version>`` flag, with the version being set to 2 or 3. Setting the
+version to 2 is recommended for DS-5 versions older than 5.16.
+
+When debugging logic problems it might also be useful to disable all compiler
+optimizations by using ``-O0``.
+
+NOTE: Using ``-O0`` could cause output images to be larger and base addresses
+might need to be recalculated (see the **Memory layout on ARM development
+platforms** section in the `Firmware Design`_).
+
+Extra debug options can be passed to the build system by setting ``CFLAGS`` or
+``LDFLAGS``:
+
+.. code:: makefile
+
+ CFLAGS='-O0 -gdwarf-2' \
+ make PLAT=<platform> DEBUG=1 V=1 all
+
+Note that using ``-Wl,`` style compilation driver options in ``CFLAGS`` will be
+ignored as the linker is called directly.
+
+It is also possible to introduce an infinite loop to help in debugging the
+post-BL2 phase of the Trusted Firmware. This can be done by rebuilding BL1 with
+the ``SPIN_ON_BL1_EXIT=1`` build flag. Refer to the "Summary of build options"
+section. In this case, the developer may take control of the target using a
+debugger when indicated by the console output. When using DS-5, the following
+commands can be used:
+
+::
+
+ # Stop target execution
+ interrupt
+
+ #
+ # Prepare your debugging environment, e.g. set breakpoints
+ #
+
+ # Jump over the debug loop
+ set var $AARCH64::$Core::$PC = $AARCH64::$Core::$PC + 4
+
+ # Resume execution
+ continue
+
+Building the Test Secure Payload
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The TSP is coupled with a companion runtime service in the BL31 firmware,
+called the TSPD. Therefore, if you intend to use the TSP, the BL31 image
+must be recompiled as well. For more information on SPs and SPDs, see the
+`Secure-EL1 Payloads and Dispatchers`_ section in the `Firmware Design`_.
+
+First clean the Trusted Firmware build directory to get rid of any previous
+BL31 binary. Then to build the TSP image use:
+
+::
+
+ make PLAT=<platform> SPD=tspd all
+
+An additional boot loader binary file is created in the ``build`` directory:
+
+::
+
+ build/<platform>/<build-type>/bl32.bin
+
+Checking source code style
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+When making changes to the source for submission to the project, the source
+must be in compliance with the Linux style guide, and to assist with this check
+the project Makefile contains two targets, which both utilise the
+``checkpatch.pl`` script that ships with the Linux source tree.
+
+To check the entire source tree, you must first download a copy of
+``checkpatch.pl`` (or the full Linux source), set the ``CHECKPATCH`` environment
+variable to point to the script and build the target checkcodebase:
+
+::
+
+ make CHECKPATCH=<path-to-linux>/linux/scripts/checkpatch.pl checkcodebase
+
+To just check the style on the files that differ between your local branch and
+the remote master, use:
+
+::
+
+ make CHECKPATCH=<path-to-linux>/linux/scripts/checkpatch.pl checkpatch
+
+If you wish to check your patch against something other than the remote master,
+set the ``BASE_COMMIT`` variable to your desired branch. By default, ``BASE_COMMIT``
+is set to ``origin/master``.
+
+Building and using the FIP tool
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Firmware Image Package (FIP) is a packaging format used by the Trusted Firmware
+project to package firmware images in a single binary. The number and type of
+images that should be packed in a FIP is platform specific and may include TF
+images and other firmware images required by the platform. For example, most
+platforms require a BL33 image which corresponds to the normal world bootloader
+(e.g. UEFI or U-Boot).
+
+The TF build system provides the make target ``fip`` to create a FIP file for the
+specified platform using the FIP creation tool included in the TF project.
+Examples below show how to build a FIP file for FVP, packaging TF images and a
+BL33 image.
+
+For AArch64:
+
+::
+
+ make PLAT=fvp BL33=<path/to/bl33.bin> fip
+
+For AArch32:
+
+::
+
+ make PLAT=fvp ARCH=aarch32 AARCH32_SP=sp_min BL33=<path/to/bl33.bin> fip
+
+Note that AArch32 support for Normal world boot loader (BL33), like U-boot or
+UEFI, on FVP is not available upstream. Hence custom solutions are required to
+allow Linux boot on FVP. These instructions assume such a custom boot loader
+(BL33) is available.
+
+The resulting FIP may be found in:
+
+::
+
+ build/fvp/<build-type>/fip.bin
+
+For advanced operations on FIP files, it is also possible to independently build
+the tool and create or modify FIPs using this tool. To do this, follow these
+steps:
+
+It is recommended to remove old artifacts before building the tool:
+
+::
+
+ make -C tools/fiptool clean
+
+Build the tool:
+
+::
+
+ make [DEBUG=1] [V=1] fiptool
+
+The tool binary can be located in:
+
+::
+
+ ./tools/fiptool/fiptool
+
+Invoking the tool with ``--help`` will print a help message with all available
+options.
+
+Example 1: create a new Firmware package ``fip.bin`` that contains BL2 and BL31:
+
+::
+
+ ./tools/fiptool/fiptool create \
+ --tb-fw build/<platform>/<build-type>/bl2.bin \
+ --soc-fw build/<platform>/<build-type>/bl31.bin \
+ fip.bin
+
+Example 2: view the contents of an existing Firmware package:
+
+::
+
+ ./tools/fiptool/fiptool info <path-to>/fip.bin
+
+Example 3: update the entries of an existing Firmware package:
+
+::
+
+ # Change the BL2 from Debug to Release version
+ ./tools/fiptool/fiptool update \
+ --tb-fw build/<platform>/release/bl2.bin \
+ build/<platform>/debug/fip.bin
+
+Example 4: unpack all entries from an existing Firmware package:
+
+::
+
+ # Images will be unpacked to the working directory
+ ./tools/fiptool/fiptool unpack <path-to>/fip.bin
+
+Example 5: remove an entry from an existing Firmware package:
+
+::
+
+ ./tools/fiptool/fiptool remove \
+ --tb-fw build/<platform>/debug/fip.bin
+
+Note that if the destination FIP file exists, the create, update and
+remove operations will automatically overwrite it.
+
+The unpack operation will fail if the images already exist at the
+destination. In that case, use -f or --force to continue.
+
+More information about FIP can be found in the `Firmware Design`_ document.
+
+Migrating from fip\_create to fiptool
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The previous version of fiptool was called fip\_create. A compatibility script
+that emulates the basic functionality of the previous fip\_create is provided.
+However, users are strongly encouraged to migrate to fiptool.
+
+- To create a new FIP file, replace "fip\_create" with "fiptool create".
+- To update a FIP file, replace "fip\_create" with "fiptool update".
+- To dump the contents of a FIP file, replace "fip\_create --dump"
+ with "fiptool info".
+
+Building FIP images with support for Trusted Board Boot
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Trusted Board Boot primarily consists of the following two features:
+
+- Image Authentication, described in `Trusted Board Boot`_, and
+- Firmware Update, described in `Firmware Update`_
+
+The following steps should be followed to build FIP and (optionally) FWU\_FIP
+images with support for these features:
+
+#. Fulfill the dependencies of the ``mbedtls`` cryptographic and image parser
+ modules by checking out a recent version of the `mbed TLS Repository`_. It
+ is important to use a version that is compatible with TF and fixes any
+ known security vulnerabilities. See `mbed TLS Security Center`_ for more
+ information. The latest version of TF is tested with tag ``mbedtls-2.4.2``.
+
+ The ``drivers/auth/mbedtls/mbedtls_*.mk`` files contain the list of mbed TLS
+ source files the modules depend upon.
+ ``include/drivers/auth/mbedtls/mbedtls_config.h`` contains the configuration
+ options required to build the mbed TLS sources.
+
+ Note that the mbed TLS library is licensed under the Apache version 2.0
+ license. Using mbed TLS source code will affect the licensing of
+ Trusted Firmware binaries that are built using this library.
+
+#. To build the FIP image, ensure the following command line variables are set
+ while invoking ``make`` to build Trusted Firmware:
+
+ - ``MBEDTLS_DIR=<path of the directory containing mbed TLS sources>``
+ - ``TRUSTED_BOARD_BOOT=1``
+ - ``GENERATE_COT=1``
+
+ In the case of ARM platforms, the location of the ROTPK hash must also be
+ specified at build time. Two locations are currently supported (see
+ ``ARM_ROTPK_LOCATION`` build option):
+
+ - ``ARM_ROTPK_LOCATION=regs``: the ROTPK hash is obtained from the Trusted
+ root-key storage registers present in the platform. On Juno, this
+ registers are read-only. On FVP Base and Cortex models, the registers
+ are read-only, but the value can be specified using the command line
+ option ``bp.trusted_key_storage.public_key`` when launching the model.
+ On both Juno and FVP models, the default value corresponds to an
+ ECDSA-SECP256R1 public key hash, whose private part is not currently
+ available.
+
+ - ``ARM_ROTPK_LOCATION=devel_rsa``: use the ROTPK hash that is hardcoded
+ in the ARM platform port. The private/public RSA key pair may be
+ found in ``plat/arm/board/common/rotpk``.
+
+ Example of command line using RSA development keys:
+
+ ::
+
+ MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \
+ make PLAT=<platform> TRUSTED_BOARD_BOOT=1 GENERATE_COT=1 \
+ ARM_ROTPK_LOCATION=devel_rsa \
+ ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem \
+ BL33=<path-to>/<bl33_image> \
+ all fip
+
+ The result of this build will be the bl1.bin and the fip.bin binaries. This
+ FIP will include the certificates corresponding to the Chain of Trust
+ described in the TBBR-client document. These certificates can also be found
+ in the output build directory.
+
+#. The optional FWU\_FIP contains any additional images to be loaded from
+ Non-Volatile storage during the `Firmware Update`_ process. To build the
+ FWU\_FIP, any FWU images required by the platform must be specified on the
+ command line. On ARM development platforms like Juno, these are:
+
+ - NS\_BL2U. The AP non-secure Firmware Updater image.
+ - SCP\_BL2U. The SCP Firmware Update Configuration image.
+
+ Example of Juno command line for generating both ``fwu`` and ``fwu_fip``
+ targets using RSA development:
+
+ ::
+
+ MBEDTLS_DIR=<path of the directory containing mbed TLS sources> \
+ make PLAT=juno TRUSTED_BOARD_BOOT=1 GENERATE_COT=1 \
+ ARM_ROTPK_LOCATION=devel_rsa \
+ ROT_KEY=plat/arm/board/common/rotpk/arm_rotprivk_rsa.pem \
+ BL33=<path-to>/<bl33_image> \
+ SCP_BL2=<path-to>/<scp_bl2_image> \
+ SCP_BL2U=<path-to>/<scp_bl2u_image> \
+ NS_BL2U=<path-to>/<ns_bl2u_image> \
+ all fip fwu_fip
+
+ Note: The BL2U image will be built by default and added to the FWU\_FIP.
+ The user may override this by adding ``BL2U=<path-to>/<bl2u_image>``
+ to the command line above.
+
+ Note: Building and installing the non-secure and SCP FWU images (NS\_BL1U,
+ NS\_BL2U and SCP\_BL2U) is outside the scope of this document.
+
+ The result of this build will be bl1.bin, fip.bin and fwu\_fip.bin binaries.
+ Both the FIP and FWU\_FIP will include the certificates corresponding to the
+ Chain of Trust described in the TBBR-client document. These certificates
+ can also be found in the output build directory.
+
+Building the Certificate Generation Tool
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``cert_create`` tool is built as part of the TF build process when the ``fip``
+make target is specified and TBB is enabled (as described in the previous
+section), but it can also be built separately with the following command:
+
+::
+
+ make PLAT=<platform> [DEBUG=1] [V=1] certtool
+
+For platforms that do not require their own IDs in certificate files,
+the generic 'cert\_create' tool can be built with the following command:
+
+::
+
+ make USE_TBBR_DEFS=1 [DEBUG=1] [V=1] certtool
+
+``DEBUG=1`` builds the tool in debug mode. ``V=1`` makes the build process more
+verbose. The following command should be used to obtain help about the tool:
+
+::
+
+ ./tools/cert_create/cert_create -h
+
+Building a FIP for Juno and FVP
+-------------------------------
+
+This section provides Juno and FVP specific instructions to build Trusted
+Firmware, obtain the additional required firmware, and pack it all together in
+a single FIP binary. It assumes that a `Linaro Release`_
+has been installed.
+
+Note: Linaro Release 16.06 only includes pre-built binaries for AArch64. For
+AArch32, pre-built binaries are only available from Linaro Release 16.12.
+
+Note: follow the full instructions for one platform before switching to a
+different one. Mixing instructions for different platforms may result in
+corrupted binaries.
+
+#. Clean the working directory
+
+ ::
+
+ make realclean
+
+#. Obtain SCP\_BL2 (Juno) and BL33 (all platforms)
+
+ Use the fiptool to extract the SCP\_BL2 and BL33 images from the FIP
+ package included in the Linaro release:
+
+ ::
+
+ # Build the fiptool
+ make [DEBUG=1] [V=1] fiptool
+
+ # Unpack firmware images from Linaro FIP
+ ./tools/fiptool/fiptool unpack \
+ <path/to/linaro/release>/fip.bin
+
+ The unpack operation will result in a set of binary images extracted to the
+ working directory. The SCP\_BL2 image corresponds to ``scp-fw.bin`` and BL33
+ corresponds to ``nt-fw.bin``.
+
+ Note: the fiptool will complain if the images to be unpacked already
+ exist in the current directory. If that is the case, either delete those
+ files or use the ``--force`` option to overwrite.
+
+ Note for AArch32, the instructions below assume that nt-fw.bin is a custom
+ Normal world boot loader that supports AArch32.
+
+#. Build TF images and create a new FIP for FVP
+
+ ::
+
+ # AArch64
+ make PLAT=fvp BL33=nt-fw.bin all fip
+
+ # AArch32
+ make PLAT=fvp ARCH=aarch32 AARCH32_SP=sp_min BL33=nt-fw.bin all fip
+
+#. Build TF images and create a new FIP for Juno
+
+ For AArch64:
+
+ Building for AArch64 on Juno simply requires the addition of ``SCP_BL2``
+ as a build parameter.
+
+ ::
+
+ make PLAT=juno all fip \
+ BL33=<path-to-juno-oe-uboot>/SOFTWARE/bl33-uboot.bin \
+ SCP_BL2=<path-to-juno-busybox-uboot>/SOFTWARE/scp_bl2.bin
+
+ For AArch32:
+
+ Hardware restrictions on Juno prevent cold reset into AArch32 execution mode,
+ therefore BL1 and BL2 must be compiled for AArch64, and BL32 is compiled
+ separately for AArch32.
+
+ - Before building BL32, the environment variable ``CROSS_COMPILE`` must point
+ to the AArch32 Linaro cross compiler.
+
+ ::
+
+ export CROSS_COMPILE=<path-to-aarch32-gcc>/bin/arm-linux-gnueabihf-
+
+ - Build BL32 in AArch32.
+
+ ::
+
+ make ARCH=aarch32 PLAT=juno AARCH32_SP=sp_min \
+ RESET_TO_SP_MIN=1 JUNO_AARCH32_EL3_RUNTIME=1 bl32
+
+ - Before building BL1 and BL2, the environment variable ``CROSS_COMPILE``
+ must point to the AArch64 Linaro cross compiler.
+
+ ::
+
+ export CROSS_COMPILE=<path-to-aarch64-gcc>/bin/aarch64-linux-gnu-
+
+ - The following parameters should be used to build BL1 and BL2 in AArch64
+ and point to the BL32 file.
+
+ ::
+
+ make ARCH=aarch64 PLAT=juno LOAD_IMAGE_V2=1 JUNO_AARCH32_EL3_RUNTIME=1 \
+ BL33=<path-to-juno32-oe-uboot>/SOFTWARE/bl33-uboot.bin \
+ SCP_BL2=<path-to-juno32-oe-uboot>/SOFTWARE/scp_bl2.bin SPD=tspd \
+ BL32=<path-to-bl32>/bl32.bin all fip
+
+The resulting BL1 and FIP images may be found in:
+
+::
+
+ # Juno
+ ./build/juno/release/bl1.bin
+ ./build/juno/release/fip.bin
+
+ # FVP
+ ./build/fvp/release/bl1.bin
+ ./build/fvp/release/fip.bin
+
+EL3 payloads alternative boot flow
+----------------------------------
+
+On a pre-production system, the ability to execute arbitrary, bare-metal code at
+the highest exception level is required. It allows full, direct access to the
+hardware, for example to run silicon soak tests.
+
+Although it is possible to implement some baremetal secure firmware from
+scratch, this is a complex task on some platforms, depending on the level of
+configuration required to put the system in the expected state.
+
+Rather than booting a baremetal application, a possible compromise is to boot
+``EL3 payloads`` through the Trusted Firmware instead. This is implemented as an
+alternative boot flow, where a modified BL2 boots an EL3 payload, instead of
+loading the other BL images and passing control to BL31. It reduces the
+complexity of developing EL3 baremetal code by:
+
+- putting the system into a known architectural state;
+- taking care of platform secure world initialization;
+- loading the SCP\_BL2 image if required by the platform.
+
+When booting an EL3 payload on ARM standard platforms, the configuration of the
+TrustZone controller is simplified such that only region 0 is enabled and is
+configured to permit secure access only. This gives full access to the whole
+DRAM to the EL3 payload.
+
+The system is left in the same state as when entering BL31 in the default boot
+flow. In particular:
+
+- Running in EL3;
+- Current state is AArch64;
+- Little-endian data access;
+- All exceptions disabled;
+- MMU disabled;
+- Caches disabled.
+
+Booting an EL3 payload
+~~~~~~~~~~~~~~~~~~~~~~
+
+The EL3 payload image is a standalone image and is not part of the FIP. It is
+not loaded by the Trusted Firmware. Therefore, there are 2 possible scenarios:
+
+- The EL3 payload may reside in non-volatile memory (NVM) and execute in
+ place. In this case, booting it is just a matter of specifying the right
+ address in NVM through ``EL3_PAYLOAD_BASE`` when building the TF.
+
+- The EL3 payload needs to be loaded in volatile memory (e.g. DRAM) at
+ run-time.
+
+To help in the latter scenario, the ``SPIN_ON_BL1_EXIT=1`` build option can be
+used. The infinite loop that it introduces in BL1 stops execution at the right
+moment for a debugger to take control of the target and load the payload (for
+example, over JTAG).
+
+It is expected that this loading method will work in most cases, as a debugger
+connection is usually available in a pre-production system. The user is free to
+use any other platform-specific mechanism to load the EL3 payload, though.
+
+Booting an EL3 payload on FVP
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The EL3 payloads boot flow requires the CPU's mailbox to be cleared at reset for
+the secondary CPUs holding pen to work properly. Unfortunately, its reset value
+is undefined on the FVP platform and the FVP platform code doesn't clear it.
+Therefore, one must modify the way the model is normally invoked in order to
+clear the mailbox at start-up.
+
+One way to do that is to create an 8-byte file containing all zero bytes using
+the following command:
+
+::
+
+ dd if=/dev/zero of=mailbox.dat bs=1 count=8
+
+and pre-load it into the FVP memory at the mailbox address (i.e. ``0x04000000``)
+using the following model parameters:
+
+::
+
+ --data cluster0.cpu0=mailbox.dat@0x04000000 [Base FVPs]
+ --data=mailbox.dat@0x04000000 [Foundation FVP]
+
+To provide the model with the EL3 payload image, the following methods may be
+used:
+
+#. If the EL3 payload is able to execute in place, it may be programmed into
+ flash memory. On Base Cortex and AEM FVPs, the following model parameter
+ loads it at the base address of the NOR FLASH1 (the NOR FLASH0 is already
+ used for the FIP):
+
+ ::
+
+ -C bp.flashloader1.fname="/path/to/el3-payload"
+
+ On Foundation FVP, there is no flash loader component and the EL3 payload
+ may be programmed anywhere in flash using method 3 below.
+
+#. When using the ``SPIN_ON_BL1_EXIT=1`` loading method, the following DS-5
+ command may be used to load the EL3 payload ELF image over JTAG:
+
+ ::
+
+ load /path/to/el3-payload.elf
+
+#. The EL3 payload may be pre-loaded in volatile memory using the following
+ model parameters:
+
+ ::
+
+ --data cluster0.cpu0="/path/to/el3-payload"@address [Base FVPs]
+ --data="/path/to/el3-payload"@address [Foundation FVP]
+
+ The address provided to the FVP must match the ``EL3_PAYLOAD_BASE`` address
+ used when building the Trusted Firmware.
+
+Booting an EL3 payload on Juno
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+If the EL3 payload is able to execute in place, it may be programmed in flash
+memory by adding an entry in the ``SITE1/HBI0262x/images.txt`` configuration file
+on the Juno SD card (where ``x`` depends on the revision of the Juno board).
+Refer to the `Juno Getting Started Guide`_, section 2.3 "Flash memory
+programming" for more information.
+
+Alternatively, the same DS-5 command mentioned in the FVP section above can
+be used to load the EL3 payload's ELF file over JTAG on Juno.
+
+Preloaded BL33 alternative boot flow
+------------------------------------
+
+Some platforms have the ability to preload BL33 into memory instead of relying
+on Trusted Firmware to load it. This may simplify packaging of the normal world
+code and improve performance in a development environment. When secure world
+cold boot is complete, Trusted Firmware simply jumps to a BL33 base address
+provided at build time.
+
+For this option to be used, the ``PRELOADED_BL33_BASE`` build option has to be
+used when compiling the Trusted Firmware. For example, the following command
+will create a FIP without a BL33 and prepare to jump to a BL33 image loaded at
+address 0x80000000:
+
+::
+
+ make PRELOADED_BL33_BASE=0x80000000 PLAT=fvp all fip
+
+Boot of a preloaded bootwrapped kernel image on Base FVP
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following example uses the AArch64 boot wrapper. This simplifies normal
+world booting while also making use of TF features. It can be obtained from its
+repository with:
+
+::
+
+ git clone git://git.kernel.org/pub/scm/linux/kernel/git/mark/boot-wrapper-aarch64.git
+
+After compiling it, an ELF file is generated. It can be loaded with the
+following command:
+
+::
+
+ <path-to>/FVP_Base_AEMv8A-AEMv8A \
+ -C bp.secureflashloader.fname=bl1.bin \
+ -C bp.flashloader0.fname=fip.bin \
+ -a cluster0.cpu0=<bootwrapped-kernel.elf> \
+ --start cluster0.cpu0=0x0
+
+The ``-a cluster0.cpu0=<bootwrapped-kernel.elf>`` option loads the ELF file. It
+also sets the PC register to the ELF entry point address, which is not the
+desired behaviour, so the ``--start cluster0.cpu0=0x0`` option forces the PC back
+to 0x0 (the BL1 entry point address) on CPU #0. The ``PRELOADED_BL33_BASE`` define
+used when compiling the FIP must match the ELF entry point.
+
+Boot of a preloaded bootwrapped kernel image on Juno
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The procedure to obtain and compile the boot wrapper is very similar to the case
+of the FVP. The execution must be stopped at the end of bl2\_main(), and the
+loading method explained above in the EL3 payload boot flow section may be used
+to load the ELF file over JTAG on Juno.
+
+Running the software on FVP
+---------------------------
+
+The latest version of the AArch64 build of ARM Trusted Firmware has been tested
+on the following ARM FVPs (64-bit host machine only).
+
+- ``Foundation_Platform`` (Version 10.2, Build 10.2.20)
+- ``FVP_Base_AEMv8A-AEMv8A`` (Version 8.4, Build 0.8.8402)
+- ``FVP_Base_Cortex-A57x4-A53x4`` (Version 8.4, Build 0.8.8402)
+
+The latest version of the AArch32 build of ARM Trusted Firmware has been tested
+on the following ARM FVPs (64-bit host machine only).
+
+- ``FVP_Base_AEMv8A-AEMv8A`` (Version 8.4, Build 0.8.8402)
+- ``FVP_Base_Cortex-A32x4`` (Version 10.1, Build 10.1.32)
+
+NOTE: The build numbers quoted above are those reported by launching the FVP
+with the ``--version`` parameter.
+
+NOTE: The software will not work on Version 1.0 of the Foundation FVP.
+The commands below would report an ``unhandled argument`` error in this case.
+
+NOTE: FVPs can be launched with ``--cadi-server`` option such that a
+CADI-compliant debugger (for example, ARM DS-5) can connect to and control its
+execution.
+
+The Foundation FVP is a cut down version of the AArch64 Base FVP. It can be
+downloaded for free from `ARM's website`_.
+
+Please refer to the FVP documentation for a detailed description of the model
+parameter options. A brief description of the important ones that affect the ARM
+Trusted Firmware and normal world software behavior is provided below.
+
+Note the instructions in the following sections assume that Linaro Release 16.06
+is being used.
+
+Obtaining the Flattened Device Trees
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Depending on the FVP configuration and Linux configuration used, different
+FDT files are required. FDTs for the Foundation and Base FVPs can be found in
+the Trusted Firmware source directory under ``fdts/``. The Foundation FVP has a
+subset of the Base FVP components. For example, the Foundation FVP lacks CLCD
+and MMC support, and has only one CPU cluster.
+
+Note: It is not recommended to use the FDTs built along the kernel because not
+all FDTs are available from there.
+
+- ``fvp-base-gicv2-psci.dtb``
+
+ For use with both AEMv8 and Cortex-A57-A53 Base FVPs with
+ Base memory map configuration.
+
+- ``fvp-base-gicv2-psci-aarch32.dtb``
+
+ For use with AEMv8 and Cortex-A32 Base FVPs running Linux in AArch32 state
+ with Base memory map configuration.
+
+- ``fvp-base-gicv3-psci.dtb``
+
+ (Default) For use with both AEMv8 and Cortex-A57-A53 Base FVPs with Base
+ memory map configuration and Linux GICv3 support.
+
+- ``fvp-base-gicv3-psci-aarch32.dtb``
+
+ For use with AEMv8 and Cortex-A32 Base FVPs running Linux in AArch32 state
+ with Base memory map configuration and Linux GICv3 support.
+
+- ``fvp-foundation-gicv2-psci.dtb``
+
+ For use with Foundation FVP with Base memory map configuration.
+
+- ``fvp-foundation-gicv3-psci.dtb``
+
+ (Default) For use with Foundation FVP with Base memory map configuration
+ and Linux GICv3 support.
+
+Running on the Foundation FVP with reset to BL1 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``Foundation_Platform`` parameters should be used to boot Linux with
+4 CPUs using the AArch64 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/Foundation_Platform \
+ --cores=4 \
+ --secure-memory \
+ --visualization \
+ --gicv3 \
+ --data="<path-to>/<bl1-binary>"@0x0 \
+ --data="<path-to>/<FIP-binary>"@0x08000000 \
+ --data="<path-to>/<fdt>"@0x83000000 \
+ --data="<path-to>/<kernel-binary>"@0x80080000 \
+ --block-device="<path-to>/<file-system-image>"
+
+Notes:
+
+- BL1 is loaded at the start of the Trusted ROM.
+- The Firmware Image Package is loaded at the start of NOR FLASH0.
+- The Linux kernel image and device tree are loaded in DRAM.
+- The default use-case for the Foundation FVP is to use the ``--gicv3`` option
+ and enable the GICv3 device in the model. Note that without this option,
+ the Foundation FVP defaults to legacy (Versatile Express) memory map which
+ is not supported by ARM Trusted Firmware.
+
+Running on the AEMv8 Base FVP with reset to BL1 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_AEMv8A-AEMv8A`` parameters should be used to boot Linux
+with 8 CPUs using the AArch64 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_AEMv8A-AEMv8A \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cluster0.NUM_CORES=4 \
+ -C cluster1.NUM_CORES=4 \
+ -C cache_state_modelled=1 \
+ -C bp.secureflashloader.fname="<path-to>/<bl1-binary>" \
+ -C bp.flashloader0.fname="<path-to>/<FIP-binary>" \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Running on the AEMv8 Base FVP (AArch32) with reset to BL1 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_AEMv8A-AEMv8A`` parameters should be used to boot Linux
+with 8 CPUs using the AArch32 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_AEMv8A-AEMv8A \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cluster0.NUM_CORES=4 \
+ -C cluster1.NUM_CORES=4 \
+ -C cache_state_modelled=1 \
+ -C cluster0.cpu0.CONFIG64=0 \
+ -C cluster0.cpu1.CONFIG64=0 \
+ -C cluster0.cpu2.CONFIG64=0 \
+ -C cluster0.cpu3.CONFIG64=0 \
+ -C cluster1.cpu0.CONFIG64=0 \
+ -C cluster1.cpu1.CONFIG64=0 \
+ -C cluster1.cpu2.CONFIG64=0 \
+ -C cluster1.cpu3.CONFIG64=0 \
+ -C bp.secureflashloader.fname="<path-to>/<bl1-binary>" \
+ -C bp.flashloader0.fname="<path-to>/<FIP-binary>" \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Running on the Cortex-A57-A53 Base FVP with reset to BL1 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_Cortex-A57x4-A53x4`` model parameters should be used to
+boot Linux with 8 CPUs using the AArch64 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_Cortex-A57x4-A53x4 \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cache_state_modelled=1 \
+ -C bp.secureflashloader.fname="<path-to>/<bl1-binary>" \
+ -C bp.flashloader0.fname="<path-to>/<FIP-binary>" \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Running on the Cortex-A32 Base FVP (AArch32) with reset to BL1 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_Cortex-A32x4`` model parameters should be used to
+boot Linux with 4 CPUs using the AArch32 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_Cortex-A32x4 \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cache_state_modelled=1 \
+ -C bp.secureflashloader.fname="<path-to>/<bl1-binary>" \
+ -C bp.flashloader0.fname="<path-to>/<FIP-binary>" \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Running on the AEMv8 Base FVP with reset to BL31 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_AEMv8A-AEMv8A`` parameters should be used to boot Linux
+with 8 CPUs using the AArch64 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_AEMv8A-AEMv8A \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cluster0.NUM_CORES=4 \
+ -C cluster1.NUM_CORES=4 \
+ -C cache_state_modelled=1 \
+ -C cluster0.cpu0.RVBAR=0x04023000 \
+ -C cluster0.cpu1.RVBAR=0x04023000 \
+ -C cluster0.cpu2.RVBAR=0x04023000 \
+ -C cluster0.cpu3.RVBAR=0x04023000 \
+ -C cluster1.cpu0.RVBAR=0x04023000 \
+ -C cluster1.cpu1.RVBAR=0x04023000 \
+ -C cluster1.cpu2.RVBAR=0x04023000 \
+ -C cluster1.cpu3.RVBAR=0x04023000 \
+ --data cluster0.cpu0="<path-to>/<bl31-binary>"@0x04023000 \
+ --data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000 \
+ --data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000 \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Notes:
+
+- Since a FIP is not loaded when using BL31 as reset entrypoint, the
+ ``--data="<path-to><bl31|bl32|bl33-binary>"@<base-address-of-binary>``
+ parameter is needed to load the individual bootloader images in memory.
+ BL32 image is only needed if BL31 has been built to expect a Secure-EL1
+ Payload.
+
+- The ``-C cluster<X>.cpu<Y>.RVBAR=@<base-address-of-bl31>`` parameter, where
+ X and Y are the cluster and CPU numbers respectively, is used to set the
+ reset vector for each core.
+
+- Changing the default value of ``ARM_TSP_RAM_LOCATION`` will also require
+ changing the value of
+ ``--data="<path-to><bl32-binary>"@<base-address-of-bl32>`` to the new value of
+ ``BL32_BASE``.
+
+Running on the AEMv8 Base FVP (AArch32) with reset to SP\_MIN entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_AEMv8A-AEMv8A`` parameters should be used to boot Linux
+with 8 CPUs using the AArch32 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_AEMv8A-AEMv8A \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cluster0.NUM_CORES=4 \
+ -C cluster1.NUM_CORES=4 \
+ -C cache_state_modelled=1 \
+ -C cluster0.cpu0.CONFIG64=0 \
+ -C cluster0.cpu1.CONFIG64=0 \
+ -C cluster0.cpu2.CONFIG64=0 \
+ -C cluster0.cpu3.CONFIG64=0 \
+ -C cluster1.cpu0.CONFIG64=0 \
+ -C cluster1.cpu1.CONFIG64=0 \
+ -C cluster1.cpu2.CONFIG64=0 \
+ -C cluster1.cpu3.CONFIG64=0 \
+ -C cluster0.cpu0.RVBAR=0x04001000 \
+ -C cluster0.cpu1.RVBAR=0x04001000 \
+ -C cluster0.cpu2.RVBAR=0x04001000 \
+ -C cluster0.cpu3.RVBAR=0x04001000 \
+ -C cluster1.cpu0.RVBAR=0x04001000 \
+ -C cluster1.cpu1.RVBAR=0x04001000 \
+ -C cluster1.cpu2.RVBAR=0x04001000 \
+ -C cluster1.cpu3.RVBAR=0x04001000 \
+ --data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000 \
+ --data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000 \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Note: The load address of ``<bl32-binary>`` depends on the value ``BL32_BASE``.
+It should match the address programmed into the RVBAR register as well.
+
+Running on the Cortex-A57-A53 Base FVP with reset to BL31 entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_Cortex-A57x4-A53x4`` model parameters should be used to
+boot Linux with 8 CPUs using the AArch64 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_Cortex-A57x4-A53x4 \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cache_state_modelled=1 \
+ -C cluster0.cpu0.RVBARADDR=0x04023000 \
+ -C cluster0.cpu1.RVBARADDR=0x04023000 \
+ -C cluster0.cpu2.RVBARADDR=0x04023000 \
+ -C cluster0.cpu3.RVBARADDR=0x04023000 \
+ -C cluster1.cpu0.RVBARADDR=0x04023000 \
+ -C cluster1.cpu1.RVBARADDR=0x04023000 \
+ -C cluster1.cpu2.RVBARADDR=0x04023000 \
+ -C cluster1.cpu3.RVBARADDR=0x04023000 \
+ --data cluster0.cpu0="<path-to>/<bl31-binary>"@0x04023000 \
+ --data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000 \
+ --data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000 \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Running on the Cortex-A32 Base FVP (AArch32) with reset to SP\_MIN entrypoint
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following ``FVP_Base_Cortex-A32x4`` model parameters should be used to
+boot Linux with 4 CPUs using the AArch32 build of ARM Trusted Firmware.
+
+::
+
+ <path-to>/FVP_Base_Cortex-A32x4 \
+ -C pctl.startup=0.0.0.0 \
+ -C bp.secure_memory=1 \
+ -C bp.tzc_400.diagnostics=1 \
+ -C cache_state_modelled=1 \
+ -C cluster0.cpu0.RVBARADDR=0x04001000 \
+ -C cluster0.cpu1.RVBARADDR=0x04001000 \
+ -C cluster0.cpu2.RVBARADDR=0x04001000 \
+ -C cluster0.cpu3.RVBARADDR=0x04001000 \
+ --data cluster0.cpu0="<path-to>/<bl32-binary>"@0x04001000 \
+ --data cluster0.cpu0="<path-to>/<bl33-binary>"@0x88000000 \
+ --data cluster0.cpu0="<path-to>/<fdt>"@0x83000000 \
+ --data cluster0.cpu0="<path-to>/<kernel-binary>"@0x80080000 \
+ -C bp.virtioblockdevice.image_path="<path-to>/<file-system-image>"
+
+Running the software on Juno
+----------------------------
+
+This version of the ARM Trusted Firmware has been tested on Juno r0 and Juno r1.
+
+To execute the software stack on Juno, the version of the Juno board recovery
+image indicated in the `Linaro Release Notes`_ must be installed. If you have an
+earlier version installed or are unsure which version is installed, please
+re-install the recovery image by following the
+`Instructions for using Linaro's deliverables on Juno`_.
+
+Preparing Trusted Firmware images
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+After building Trusted Firmware, the files ``bl1.bin`` and ``fip.bin`` need copying
+to the ``SOFTWARE/`` directory of the Juno SD card.
+
+Other Juno software information
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Please visit the `ARM Platforms Portal`_ to get support and obtain any other Juno
+software information. Please also refer to the `Juno Getting Started Guide`_ to
+get more detailed information about the Juno ARM development platform and how to
+configure it.
+
+Testing SYSTEM SUSPEND on Juno
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The SYSTEM SUSPEND is a PSCI API which can be used to implement system suspend
+to RAM. For more details refer to section 5.16 of `PSCI`_. To test system suspend
+on Juno, at the linux shell prompt, issue the following command:
+
+::
+
+ echo +10 > /sys/class/rtc/rtc0/wakealarm
+ echo -n mem > /sys/power/state
+
+The Juno board should suspend to RAM and then wakeup after 10 seconds due to
+wakeup interrupt from RTC.
+
+--------------
+
+*Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.*
+
+.. _Linaro: https://community.arm.com/tools/dev-platforms/b/documents/posts/linaro-release-notes-deprecated
+.. _Instructions for using the Linaro software deliverables: https://community.arm.com/dev-platforms/b/documents/posts/instructions-for-using-the-linaro-software-deliverables
+.. _Firmware Design: firmware-design.rst
+.. _Linaro Release Notes: https://community.arm.com/tools/dev-platforms/b/documents/posts/linaro-release-notes-deprecated
+.. _Linaro instructions: https://community.arm.com/dev-platforms/b/documents/posts/instructions-for-using-the-linaro-software-deliverables
+.. _Development Studio 5 (DS-5): http://www.arm.com/products/tools/software-tools/ds-5/index.php
+.. _Summary of build options: #user-content-summary-of-build-options
+.. _here: ./psci-lib-integration-guide.rst
+.. _Building the Test Secure Payload: #user-content-building-the-test-secure-payload
+.. _Trusted Board Boot: trusted-board-boot.rst
+.. _Secure-EL1 Payloads and Dispatchers: firmware-design.rst#user-content-secure-el1-payloads-and-dispatchers
+.. _Firmware Update: ./firmware-update.rst
+.. _mbed TLS Repository: https://github.com/ARMmbed/mbedtls.git
+.. _mbed TLS Security Center: https://tls.mbed.org/security
+.. _Linaro Release: https://community.arm.com/tools/dev-platforms/b/documents/posts/linaro-release-notes-deprecated
+.. _Juno Getting Started Guide: http://infocenter.arm.com/help/topic/com.arm.doc.dui0928e/DUI0928E_juno_arm_development_platform_gsg.pdf
+.. _ARM's website: https://developer.arm.com/products/system-design/fixed-virtual-platforms
+.. _Instructions for using Linaro's deliverables on Juno: https://community.arm.com/dev-platforms/b/documents/posts/using-linaros-deliverables-on-juno
+.. _ARM Platforms Portal: https://community.arm.com/groups/arm-development-platforms
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
--- /dev/null
+Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+- Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+- Redistributions in binary form must reproduce the above copyright notice, this
+ list of conditions and the following disclaimer in the documentation and/or
+ other materials provided with the distribution.
+
+- Neither the name of ARM nor the names of its contributors may be used to
+ endorse or promote products derived from this software without specific prior
+ written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+--------------
+
+Note:
+Individual files contain the following tag instead of the full license text.
+
+::
+
+ SPDX-License-Identifier: BSD-3-Clause
+
+This enables machine processing of license information based on the SPDX
+License Identifiers that are here available: http://spdx.org/licenses/
--- /dev/null
+ARM Trusted Firmware Maintainers
+================================
+
+ARM Trusted Firmware is an ARM maintained project. All contributions are
+ultimately merged by the maintainers listed below. Technical ownership of some
+parts of the codebase is delegated to the sub-maintainers listed below. An
+acknowledgement from these sub-maintainers may be required before the
+maintainers merge a contribution.
+
+Maintainers
+-----------
+
+Dan Handley (dan.handley@arm.com, `danh-arm`_)
+
+David Cunado (david.cunado@arm.com, `davidcunado-arm`_)
+
+OPTEE and QEMU platform sub-maintainer
+--------------------------------------
+
+Jens Wiklander (jens.wiklander@linaro.org, `jenswi-linaro`_)
+
+Files:
+
+- docs/spd/optee-dispatcher.md
+- docs/plat/qemu.md
+- services/spd/opteed/\*
+- plat/qemu/\*
+
+TLK/Trusty SPDs and NVidia platforms sub-maintainer
+---------------------------------------------------
+
+Varun Wadekar (vwadekar@nvidia.com, `vwadekar`_)
+
+Files:
+
+- docs/spd/tlk-dispatcher.md
+- docs/spd/trusty-dispatcher.md
+- include/bl32/payloads/tlk.h
+- include/lib/cpus/aarch64/denver.h
+- lib/cpus/aarch64/denver.S
+- services/spd/tlkd/\*
+- services/spd/trusty/\*
+- plat/nvidia/\*
+
+eMMC/UFS drivers and HiSilicon platform sub-maintainer
+------------------------------------------------------
+
+Haojian Zhuang (haojian.zhuang@linaro.org, `hzhuang1`_)
+
+Files:
+
+- docs/plat/hikey.md
+- docs/plat/hikey960.md
+- drivers/emmc/\*
+- drivers/partition/\*
+- drivers/synopsys/emmc/\*
+- drivers/synopsys/ufs/\*
+- drivers/ufs/\*
+- include/drivers/dw\_ufs.h
+- include/drivers/emmc.h
+- include/drivers/ufs.h
+- include/drivers/synopsys/dw\_mmc.h
+- plat/hisilicon/\*
+
+MediaTek platform sub-maintainer
+--------------------------------
+
+Yidi Lin (林以廸 yidi.lin@mediatek.com, `mtk09422`_)
+
+Files:
+
+- plat/mediatek/\*
+
+RockChip platform sub-maintainer
+--------------------------------
+
+Tony Xie (tony.xie@rock-chips.com, `TonyXie06`_
+or `rkchrome`_)
+
+Files:
+
+- plat/rockchip/\*
+
+Xilinx platform sub-maintainer
+------------------------------
+
+Sören Brinkmann (soren.brinkmann@xilinx.com, `sorenb-xlnx`_)
+
+Files:
+
+- docs/plat/xilinx-zynqmp.md
+- plat/xilinx/\*
+
+.. _danh-arm: https://github.com/danh-arm
+.. _davidcunado-arm: https://github.com/davidcunado-arm
+.. _jenswi-linaro: https://github.com/jenswi-linaro
+.. _vwadekar: https://github.com/vwadekar
+.. _hzhuang1: https://github.com/hzhuang1
+.. _mtk09422: https://github.com/mtk09422
+.. _TonyXie06: https://github.com/TonyXie06
+.. _rkchrome: https://github.com/rkchrome
+.. _sorenb-xlnx: https://github.com/sorenb-xlnx
--- /dev/null
+ARM Trusted Firmware - version 1.3
+==================================
+
+ARM Trusted Firmware provides a reference implementation of secure world
+software for `ARMv8-A`_, including a `Secure Monitor`_ executing at
+Exception Level 3 (EL3). It implements various ARM interface standards, such as
+the Power State Coordination Interface (`PSCI`_), Trusted Board Boot Requirements
+(TBBR, ARM DEN0006C-1) and `SMC Calling Convention`_. As far as possible
+the code is designed for reuse or porting to other ARMv8-A model and hardware
+platforms.
+
+ARM will continue development in collaboration with interested parties to
+provide a full reference implementation of PSCI, TBBR and Secure Monitor code
+to the benefit of all developers working with ARMv8-A TrustZone technology.
+
+License
+-------
+
+The software is provided under a BSD-3-Clause `license`_. Contributions to this
+project are accepted under the same license with developer sign-off as
+described in the `Contributing Guidelines`_.
+
+This project contains code from other projects as listed below. The original
+license text is included in those source files.
+
+- The stdlib source code is derived from FreeBSD code.
+
+- The libfdt source code is dual licensed. It is used by this project under
+ the terms of the BSD-2-Clause license.
+
+This Release
+------------
+
+This release provides a suitable starting point for productization of secure
+world boot and runtime firmware, executing in either the AArch32 or AArch64
+execution state.
+
+Users are encouraged to do their own security validation, including penetration
+testing, on any secure world code derived from ARM Trusted Firmware.
+
+Functionality
+~~~~~~~~~~~~~
+
+- Initialization of the secure world (for example, exception vectors, control
+ registers, interrupt controller and interrupts for the platform), before
+ transitioning into the normal world at the Exception Level and Register
+ Width specified by the platform.
+
+- Library support for CPU specific reset and power down sequences. This
+ includes support for errata workarounds.
+
+- Drivers for both versions 2.0 and 3.0 of the ARM Generic Interrupt
+ Controller specifications (GICv2 and GICv3). The latter also enables GICv3
+ hardware systems that do not contain legacy GICv2 support.
+
+- Drivers to enable standard initialization of ARM System IP, for example
+ Cache Coherent Interconnect (CCI), Cache Coherent Network (CCN), Network
+ Interconnect (NIC) and TrustZone Controller (TZC).
+
+- SMC (Secure Monitor Call) handling, conforming to the
+ `SMC Calling Convention`_ using an EL3 runtime services framework.
+
+- `PSCI`_ library support for the Secondary CPU Boot, CPU Hotplug, CPU Idle
+ and System Shutdown/Reset/Suspend use-cases.
+ This library is pre-integrated with the provided AArch64 EL3 Runtime
+ Software, and is also suitable for integration into other EL3 Runtime
+ Software.
+
+- A minimal AArch32 Secure Payload to demonstrate `PSCI`_ library integration
+ on platforms with AArch32 EL3 Runtime Software.
+
+- Secure Monitor library code such as world switching, EL1 context management
+ and interrupt routing.
+ When using the provided AArch64 EL3 Runtime Software, this must be
+ integrated with a Secure-EL1 Payload Dispatcher (SPD) component to
+ customize the interaction with a Secure-EL1 Payload (SP), for example a
+ Secure OS.
+
+- A Test Secure-EL1 Payload and Dispatcher to demonstrate AArch64 Secure
+ Monitor functionality and Secure-EL1 interaction with PSCI.
+
+- AArch64 SPDs for the `OP-TEE Secure OS`_ and `NVidia Trusted Little Kernel`_.
+
+- A Trusted Board Boot implementation, conforming to all mandatory TBBR
+ requirements. This includes image authentication using certificates, a
+ Firmware Update (or recovery mode) boot flow, and packaging of the various
+ firmware images into a Firmware Image Package (FIP) to be loaded from
+ non-volatile storage.
+ The TBBR implementation is currently only supported in the AArch64 build.
+
+- Support for alternative boot flows. Some platforms have their own boot
+ firmware and only require the AArch64 EL3 Runtime Software provided by this
+ project. Other platforms require minimal initialization before booting
+ into an arbitrary EL3 payload.
+
+For a full description of functionality and implementation details, please
+see the `Firmware Design`_ and supporting documentation. The `Change Log`_
+provides details of changes made since the last release.
+
+Platforms
+~~~~~~~~~
+
+The AArch64 build of this release has been tested on variants r0, r1 and r2
+of the `Juno ARM Development Platform`_ with `Linaro Release 16.06`_.
+
+The AArch64 build of this release has been tested on the following ARM
+`FVP`_\ s (64-bit host machine only, with `Linaro Release 16.06`_):
+
+- ``Foundation_Platform`` (Version 10.1, Build 10.1.32)
+- ``FVP_Base_AEMv8A-AEMv8A`` (Version 7.7, Build 0.8.7701)
+- ``FVP_Base_Cortex-A57x4-A53x4`` (Version 7.7, Build 0.8.7701)
+- ``FVP_Base_Cortex-A57x1-A53x1`` (Version 7.7, Build 0.8.7701)
+- ``FVP_Base_Cortex-A57x2-A53x4`` (Version 7.7, Build 0.8.7701)
+
+The AArch32 build of this release has been tested on the following ARM
+`FVP`_\ s (64-bit host machine only, with `Linaro Release 16.06`_):
+
+- ``FVP_Base_AEMv8A-AEMv8A`` (Version 7.7, Build 0.8.7701)
+- ``FVP_Base_Cortex-A32x4`` (Version 10.1, Build 10.1.32)
+
+The Foundation FVP can be downloaded free of charge. The Base FVPs can be
+licensed from ARM: see `www.arm.com/fvp`_.
+
+This release also contains the following platform support:
+
+- MediaTek MT6795 and MT8173 SoCs
+- NVidia T210 and T132 SoCs
+- QEMU emulator
+- RockChip RK3368 and RK3399 SoCs
+- Xilinx Zynq UltraScale + MPSoC
+
+Still to Come
+~~~~~~~~~~~~~
+
+- AArch32 TBBR support and ongoing TBBR alignment.
+
+- More platform support.
+
+- Ongoing support for new architectural features, CPUs and System IP.
+
+- Ongoing `PSCI`_ alignment and feature support.
+
+- Ongoing security hardening, optimization and quality improvements.
+
+For a full list of detailed issues in the current code, please see the
+`Change Log`_ and the `GitHub issue tracker`_.
+
+Getting Started
+---------------
+
+Get the Trusted Firmware source code from
+`GitHub`_.
+
+See the `User Guide`_ for instructions on how to install, build and use
+the Trusted Firmware with the ARM `FVP`_\ s.
+
+See the `Firmware Design`_ for information on how the ARM Trusted Firmware works.
+
+See the `Porting Guide`_ as well for information about how to use this
+software on another ARMv8-A platform.
+
+See the `Contributing Guidelines`_ for information on how to contribute to this
+project and the `Acknowledgments`_ file for a list of contributors to the
+project.
+
+Feedback and support
+~~~~~~~~~~~~~~~~~~~~
+
+ARM welcomes any feedback on the Trusted Firmware. Please send feedback using
+the `GitHub issue tracker`_.
+
+ARM licensees may contact ARM directly via their partner managers.
+
+--------------
+
+*Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.*
+
+.. _ARMv8-A: http://www.arm.com/products/processors/armv8-architecture.php
+.. _Secure Monitor: http://www.arm.com/products/processors/technologies/trustzone/tee-smc.php
+.. _PSCI: http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
+.. _SMC Calling Convention: http://infocenter.arm.com/help/topic/com.arm.doc.den0028a/index.html
+.. _license: ./license.rst
+.. _Contributing Guidelines: ./contributing.rst
+.. _OP-TEE Secure OS: https://github.com/OP-TEE/optee_os
+.. _NVidia Trusted Little Kernel: http://nv-tegra.nvidia.com/gitweb/?p=3rdparty/ote_partner/tlk.git;a=summary
+.. _Firmware Design: ./docs/firmware-design.rst
+.. _Change Log: ./docs/change-log.rst
+.. _Juno ARM Development Platform: http://www.arm.com/products/tools/development-boards/versatile-express/juno-arm-development-platform.php
+.. _Linaro Release 16.06: https://community.arm.com/docs/DOC-10952#jive_content_id_Linaro_Release_1606
+.. _FVP: http://www.arm.com/fvp
+.. _www.arm.com/fvp: http://www.arm.com/fvp
+.. _GitHub issue tracker: https://github.com/ARM-software/tf-issues/issues
+.. _GitHub: https://www.github.com/ARM-software/arm-trusted-firmware
+.. _User Guide: ./docs/user-guide.rst
+.. _Porting Guide: ./docs/porting-guide.rst
+.. _Acknowledgments: ./acknowledgements.rst
projects / project / bcm63xx / atf.git / commitdiff