--- /dev/null
+What: /sys/bus/mei/devices/.../modalias
+Date: March 2013
+KernelVersion: 3.10
+Contact: Samuel Ortiz <sameo@linux.intel.com>
+ linux-mei@linux.intel.com
+Description: Stores the same MODALIAS value emitted by uevent
+ Format: mei:<mei device name>
--- /dev/null
+Intel(R) Management Engine (ME) Client bus API
+===============================================
+
+
+Rationale
+=========
+MEI misc character device is useful for dedicated applications to send and receive
+data to the many FW appliance found in Intel's ME from the user space.
+However for some of the ME functionalities it make sense to leverage existing software
+stack and expose them through existing kernel subsystems.
+
+In order to plug seamlessly into the kernel device driver model we add kernel virtual
+bus abstraction on top of the MEI driver. This allows implementing linux kernel drivers
+for the various MEI features as a stand alone entities found in their respective subsystem.
+Existing device drivers can even potentially be re-used by adding an MEI CL bus layer to
+the existing code.
+
+
+MEI CL bus API
+===========
+A driver implementation for an MEI Client is very similar to existing bus
+based device drivers. The driver registers itself as an MEI CL bus driver through
+the mei_cl_driver structure:
+
+struct mei_cl_driver {
+ struct device_driver driver;
+ const char *name;
+
+ const struct mei_cl_device_id *id_table;
+
+ int (*probe)(struct mei_cl_device *dev, const struct mei_cl_id *id);
+ int (*remove)(struct mei_cl_device *dev);
+};
+
+struct mei_cl_id {
+ char name[MEI_NAME_SIZE];
+ kernel_ulong_t driver_info;
+};
+
+The mei_cl_id structure allows the driver to bind itself against a device name.
+
+To actually register a driver on the ME Client bus one must call the mei_cl_add_driver()
+API. This is typically called at module init time.
+
+Once registered on the ME Client bus, a driver will typically try to do some I/O on
+this bus and this should be done through the mei_cl_send() and mei_cl_recv()
+routines. The latter is synchronous (blocks and sleeps until data shows up).
+In order for drivers to be notified of pending events waiting for them (e.g.
+an Rx event) they can register an event handler through the
+mei_cl_register_event_cb() routine. Currently only the MEI_EVENT_RX event
+will trigger an event handler call and the driver implementation is supposed
+to call mei_recv() from the event handler in order to fetch the pending
+received buffers.
+
+
+Example
+=======
+As a theoretical example let's pretend the ME comes with a "contact" NFC IP.
+The driver init and exit routines for this device would look like:
+
+#define CONTACT_DRIVER_NAME "contact"
+
+static struct mei_cl_device_id contact_mei_cl_tbl[] = {
+ { CONTACT_DRIVER_NAME, },
+
+ /* required last entry */
+ { }
+};
+MODULE_DEVICE_TABLE(mei_cl, contact_mei_cl_tbl);
+
+static struct mei_cl_driver contact_driver = {
+ .id_table = contact_mei_tbl,
+ .name = CONTACT_DRIVER_NAME,
+
+ .probe = contact_probe,
+ .remove = contact_remove,
+};
+
+static int contact_init(void)
+{
+ int r;
+
+ r = mei_cl_driver_register(&contact_driver);
+ if (r) {
+ pr_err(CONTACT_DRIVER_NAME ": driver registration failed\n");
+ return r;
+ }
+
+ return 0;
+}
+
+static void __exit contact_exit(void)
+{
+ mei_cl_driver_unregister(&contact_driver);
+}
+
+module_init(contact_init);
+module_exit(contact_exit);
+
+And the driver's simplified probe routine would look like that:
+
+int contact_probe(struct mei_cl_device *dev, struct mei_cl_device_id *id)
+{
+ struct contact_driver *contact;
+
+ [...]
+ mei_cl_register_event_cb(dev, contact_event_cb, contact);
+
+ return 0;
+ }
+
+In the probe routine the driver basically registers an ME bus event handler
+which is as close as it can get to registering a threaded IRQ handler.
+The handler implementation will typically call some I/O routine depending on
+the pending events:
+
+#define MAX_NFC_PAYLOAD 128
+
+static void contact_event_cb(struct mei_cl_device *dev, u32 events,
+ void *context)
+{
+ struct contact_driver *contact = context;
+
+ if (events & BIT(MEI_EVENT_RX)) {
+ u8 payload[MAX_NFC_PAYLOAD];
+ int payload_size;
+
+ payload_size = mei_recv(dev, payload, MAX_NFC_PAYLOAD);
+ if (payload_size <= 0)
+ return;
+
+ /* Hook to the NFC subsystem */
+ nfc_hci_recv_frame(contact->hdev, payload, payload_size);
+ }
+}
mei-objs += main.o
mei-objs += amthif.o
mei-objs += wd.o
+mei-objs += bus.o
obj-$(CONFIG_INTEL_MEI_ME) += mei-me.o
mei-me-objs := pci-me.o
--- /dev/null
+/*
+ * Intel Management Engine Interface (Intel MEI) Linux driver
+ * Copyright (c) 2012-2013, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/interrupt.h>
+#include <linux/pci.h>
+#include <linux/mei_cl_bus.h>
+
+#include "mei_dev.h"
+
+#define to_mei_cl_driver(d) container_of(d, struct mei_cl_driver, driver)
+#define to_mei_cl_device(d) container_of(d, struct mei_cl_device, dev)
+
+static int mei_cl_device_match(struct device *dev, struct device_driver *drv)
+{
+ struct mei_cl_device *device = to_mei_cl_device(dev);
+ struct mei_cl_driver *driver = to_mei_cl_driver(drv);
+ const struct mei_cl_device_id *id;
+
+ if (!device)
+ return 0;
+
+ if (!driver || !driver->id_table)
+ return 0;
+
+ id = driver->id_table;
+
+ while (id->name[0]) {
+ if (!strcmp(dev_name(dev), id->name))
+ return 1;
+
+ id++;
+ }
+
+ return 0;
+}
+
+static int mei_cl_device_probe(struct device *dev)
+{
+ struct mei_cl_device *device = to_mei_cl_device(dev);
+ struct mei_cl_driver *driver;
+ struct mei_cl_device_id id;
+
+ if (!device)
+ return 0;
+
+ driver = to_mei_cl_driver(dev->driver);
+ if (!driver || !driver->probe)
+ return -ENODEV;
+
+ dev_dbg(dev, "Device probe\n");
+
+ strncpy(id.name, dev_name(dev), MEI_CL_NAME_SIZE);
+
+ return driver->probe(device, &id);
+}
+
+static int mei_cl_device_remove(struct device *dev)
+{
+ struct mei_cl_device *device = to_mei_cl_device(dev);
+ struct mei_cl_driver *driver;
+
+ if (!device || !dev->driver)
+ return 0;
+
+ driver = to_mei_cl_driver(dev->driver);
+ if (!driver->remove) {
+ dev->driver = NULL;
+
+ return 0;
+ }
+
+ return driver->remove(device);
+}
+
+static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
+ char *buf)
+{
+ int len;
+
+ len = snprintf(buf, PAGE_SIZE, "mei:%s\n", dev_name(dev));
+
+ return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
+}
+
+static struct device_attribute mei_cl_dev_attrs[] = {
+ __ATTR_RO(modalias),
+ __ATTR_NULL,
+};
+
+static int mei_cl_uevent(struct device *dev, struct kobj_uevent_env *env)
+{
+ if (add_uevent_var(env, "MODALIAS=mei:%s", dev_name(dev)))
+ return -ENOMEM;
+
+ return 0;
+}
+
+static struct bus_type mei_cl_bus_type = {
+ .name = "mei",
+ .dev_attrs = mei_cl_dev_attrs,
+ .match = mei_cl_device_match,
+ .probe = mei_cl_device_probe,
+ .remove = mei_cl_device_remove,
+ .uevent = mei_cl_uevent,
+};
+
+static void mei_cl_dev_release(struct device *dev)
+{
+ kfree(to_mei_cl_device(dev));
+}
+
+static struct device_type mei_cl_device_type = {
+ .release = mei_cl_dev_release,
+};
+
+struct mei_cl_device *mei_cl_add_device(struct mei_device *mei_device,
+ uuid_le uuid, char *name)
+{
+ struct mei_cl_device *device;
+ int status;
+
+ device = kzalloc(sizeof(struct mei_cl_device), GFP_KERNEL);
+ if (!device)
+ return NULL;
+
+ device->dev.parent = &mei_device->pdev->dev;
+ device->dev.bus = &mei_cl_bus_type;
+ device->dev.type = &mei_cl_device_type;
+
+ dev_set_name(&device->dev, "%s", name);
+
+ status = device_register(&device->dev);
+ if (status)
+ goto out_err;
+
+ dev_dbg(&device->dev, "client %s registered\n", name);
+
+ return device;
+
+out_err:
+ dev_err(device->dev.parent, "Failed to register MEI client\n");
+
+ kfree(device);
+
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(mei_cl_add_device);
+
+void mei_cl_remove_device(struct mei_cl_device *device)
+{
+ device_unregister(&device->dev);
+}
+EXPORT_SYMBOL_GPL(mei_cl_remove_device);
#include <linux/watchdog.h>
#include <linux/poll.h>
#include <linux/mei.h>
+#include <linux/mei_cl_bus.h>
#include "hw.h"
#include "hw-me-regs.h"
unsigned char *buf, unsigned long len);
};
+/* MEI bus API*/
+struct mei_cl_device *mei_cl_add_device(struct mei_device *dev,
+ uuid_le uuid, char *name);
+void mei_cl_remove_device(struct mei_cl_device *device);
+
+/**
+ * struct mei_cl_device - MEI device handle
+ * An mei_cl_device pointer is returned from mei_add_device()
+ * and links MEI bus clients to their actual ME host client pointer.
+ * Drivers for MEI devices will get an mei_cl_device pointer
+ * when being probed and shall use it for doing ME bus I/O.
+ *
+ * @dev: linux driver model device pointer
+ * @uuid: me client uuid
+ * @cl: mei client
+ * @priv_data: client private data
+ */
+struct mei_cl_device {
+ struct device dev;
+
+ struct mei_cl *cl;
+
+ void *priv_data;
+};
+
/**
* struct mei_device - MEI private device struct
--- /dev/null
+#ifndef _LINUX_MEI_CL_BUS_H
+#define _LINUX_MEI_CL_BUS_H
+
+#include <linux/device.h>
+#include <linux/uuid.h>
+
+struct mei_cl_device;
+
+struct mei_cl_driver {
+ struct device_driver driver;
+ const char *name;
+
+ const struct mei_cl_device_id *id_table;
+
+ int (*probe)(struct mei_cl_device *dev,
+ const struct mei_cl_device_id *id);
+ int (*remove)(struct mei_cl_device *dev);
+};
+
+#endif /* _LINUX_MEI_CL_BUS_H */
#ifdef __KERNEL__
#include <linux/types.h>
+#include <linux/uuid.h>
typedef unsigned long kernel_ulong_t;
#endif
__u32 device; /* Device ID or IPACK_ANY_ID */
};
+#define MEI_CL_MODULE_PREFIX "mei:"
+#define MEI_CL_NAME_SIZE 32
+
+struct mei_cl_device_id {
+ char name[MEI_CL_NAME_SIZE];
+ kernel_ulong_t driver_info;
+};
+
#endif /* LINUX_MOD_DEVICETABLE_H */
DEVID_FIELD(x86_cpu_id, model);
DEVID_FIELD(x86_cpu_id, vendor);
+ DEVID(mei_cl_device_id);
+ DEVID_FIELD(mei_cl_device_id, name);
+
return 0;
}
}
ADD_TO_DEVTABLE("x86cpu", x86_cpu_id, do_x86cpu_entry);
+/* Looks like: mei:S */
+static int do_mei_entry(const char *filename, void *symval,
+ char *alias)
+{
+ DEF_FIELD_ADDR(symval, mei_cl_device_id, name);
+
+ sprintf(alias, MEI_CL_MODULE_PREFIX "%s", *name);
+
+ return 1;
+}
+ADD_TO_DEVTABLE("mei", mei_cl_device_id, do_mei_entry);
+
/* Does namelen bytes of name exactly match the symbol? */
static bool sym_is(const char *name, unsigned namelen, const char *symbol)
{
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