rpi3: add RPI3_RUNTIME_UART build option

Some OSes (e.g. Ubuntu 18.04 LTS on Raspberry Pi 3) may disable the
runtime UART in a manner that prevents the system from rebooting if
ATF tries to send runtime messages there.

Also, we don't want the firmware to share the UART with normal
world, as this can be a DoS attack vector into the secure world.

This patch fixes these 2 issues by introducing new build option
RPI3_RUNTIME_UART, that disables the runtime UART by default.

Fixes ARM-software/tf-issues#647

Signed-off-by: Pete Batard <pete@akeo.ie>

diff --git a/docs/plat/rpi3.rst b/docs/plat/rpi3.rst
index db475646b07fc54ec6381feb8783f51a2537752c..ea8171fa02ee5a2371e651f35a6a3c1dcf3effca 100644 (file)
--- a/docs/plat/rpi3.rst
+++ b/docs/plat/rpi3.rst
@@ -231,6 +231,10 @@ The following build options are supported:
   ``RPI3_DIRECT_LINUX_BOOT=1``. This option allows to specify the location of a
   DTB in memory.
 
+- ``RPI3_RUNTIME_UART``: Indicates whether the UART should be used at runtime
+  or disabled. ``-1`` (default) disables the runtime UART. Any other value
+  enables the default UART (currently UART1) for runtime messages.
+
 - ``BL32``: This port can load and run OP-TEE. The OP-TEE image is optional.
   Please use the code from `here <https://github.com/OP-TEE/optee_os>`__.
   Build the Trusted Firmware with option ``BL32=tee-header_v2.bin

diff --git a/plat/rpi3/platform.mk b/plat/rpi3/platform.mk
index 36c1ee2b41991fc0960dced48898e70b72d132c3..07d2bf1e0d233d37e29da53041373f53b6f30b47 100644 (file)
--- a/plat/rpi3/platform.mk
+++ b/plat/rpi3/platform.mk
@@ -109,6 +109,10 @@ RPI3_BL33_IN_AARCH32               := 0
 # Assume that BL33 isn't the Linux kernel by default
 RPI3_DIRECT_LINUX_BOOT         := 0
 
+# UART to use at runtime. -1 means the runtime UART is disabled.
+# Any other value means the default UART will be used.
+RPI3_RUNTIME_UART               := -1
+
 # BL32 location
 RPI3_BL32_RAM_LOCATION := tdram
 ifeq (${RPI3_BL32_RAM_LOCATION}, tsram)
@@ -126,6 +130,7 @@ $(eval $(call add_define,RPI3_BL32_RAM_LOCATION_ID))
 $(eval $(call add_define,RPI3_BL33_IN_AARCH32))
 $(eval $(call add_define,RPI3_DIRECT_LINUX_BOOT))
 $(eval $(call add_define,RPI3_PRELOADED_DTB_BASE))
+$(eval $(call add_define,RPI3_RUNTIME_UART))
 
 # Verify build config
 # -------------------

diff --git a/plat/rpi3/rpi3_common.c b/plat/rpi3/rpi3_common.c
index 18ff1c82ebe7f7d9777d5dc9732c679157afda7f..c7e8b3a755d55a36f0869a94160a3bbf140c26ae 100644 (file)
--- a/plat/rpi3/rpi3_common.c
+++ b/plat/rpi3/rpi3_common.c
@@ -96,6 +96,10 @@ static console_16550_t rpi3_console;
 
 void rpi3_console_init(void)
 {
+       int console_scope = CONSOLE_FLAG_BOOT;
+#if RPI3_RUNTIME_UART != -1
+       console_scope |= CONSOLE_FLAG_RUNTIME;
+#endif
        int rc = console_16550_register(PLAT_RPI3_UART_BASE,
                                        PLAT_RPI3_UART_CLK_IN_HZ,
                                        PLAT_RPI3_UART_BAUDRATE,
@@ -109,8 +113,7 @@ void rpi3_console_init(void)
                panic();
        }
 
-       console_set_scope(&rpi3_console.console,
-                         CONSOLE_FLAG_BOOT | CONSOLE_FLAG_RUNTIME);
+       console_set_scope(&rpi3_console.console, console_scope);
 }
 
 /*******************************************************************************