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Subject[PATCH v3 1/4] tee: add bus driver framework for TEE based devices
Date
Introduce a generic TEE bus driver concept for TEE based kernel drivers
which would like to communicate with TEE based devices/services.

In this TEE bus concept, devices/services are identified via Universally
Unique Identifier (UUID) and drivers register a table of device UUIDs
which they can support.

So this TEE bus framework registers a match() callback function which
iterates over the driver UUID table to find a corresponding match for
device UUID. If a match is found, then this particular device is probed
via corresponding probe api registered by the driver. This process
happens whenever a device or a driver is registered with TEE bus.

Also this framework allows for device enumeration to be specific to
corresponding TEE implementation like OP-TEE etc.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
---
drivers/tee/tee_core.c | 43 ++++++++++++++++++++++++++++++++++++++++---
include/linux/tee_drv.h | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 7b2bb4c..a685940 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -15,7 +15,6 @@
#define pr_fmt(fmt) "%s: " fmt, __func__

#include <linux/cdev.h>
-#include <linux/device.h>
#include <linux/fs.h>
#include <linux/idr.h>
#include <linux/module.h>
@@ -1027,6 +1026,30 @@ int tee_client_invoke_func(struct tee_context *ctx,
}
EXPORT_SYMBOL_GPL(tee_client_invoke_func);

+static int tee_client_device_match(struct device *dev,
+ struct device_driver *drv)
+{
+ struct tee_client_device *tee_device;
+ const struct tee_client_device_id *id_table;
+
+ tee_device = to_tee_client_device(dev);
+ id_table = to_tee_client_driver(drv)->id_table;
+
+ while (!uuid_is_null(&id_table->uuid)) {
+ if (uuid_equal(&tee_device->id.uuid, &id_table->uuid))
+ return 1;
+ id_table++;
+ }
+
+ return 0;
+}
+
+struct bus_type tee_bus_type = {
+ .name = "tee",
+ .match = tee_client_device_match,
+};
+EXPORT_SYMBOL_GPL(tee_bus_type);
+
static int __init tee_init(void)
{
int rc;
@@ -1040,10 +1063,23 @@ static int __init tee_init(void)
rc = alloc_chrdev_region(&tee_devt, 0, TEE_NUM_DEVICES, "tee");
if (rc) {
pr_err("failed to allocate char dev region\n");
- class_destroy(tee_class);
- tee_class = NULL;
+ goto chrdev_err;
}

+ rc = bus_register(&tee_bus_type);
+ if (rc) {
+ pr_err("failed to register tee bus\n");
+ goto bus_err;
+ }
+
+ return 0;
+
+bus_err:
+ unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
+chrdev_err:
+ class_destroy(tee_class);
+ tee_class = NULL;
+
return rc;
}

@@ -1052,6 +1088,7 @@ static void __exit tee_exit(void)
class_destroy(tee_class);
tee_class = NULL;
unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
+ bus_unregister(&tee_bus_type);
}

subsys_initcall(tee_init);
diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
index 6cfe058..ed16bf1 100644
--- a/include/linux/tee_drv.h
+++ b/include/linux/tee_drv.h
@@ -20,6 +20,8 @@
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/tee.h>
+#include <linux/device.h>
+#include <linux/uuid.h>

/*
* The file describes the API provided by the generic TEE driver to the
@@ -538,4 +540,38 @@ static inline bool tee_param_is_memref(struct tee_param *param)
}
}

+extern struct bus_type tee_bus_type;
+
+/**
+ * struct tee_client_device_id - tee based device identifier
+ * @uuid: For TEE based client devices we use the device uuid
+ * as the identifier.
+ */
+struct tee_client_device_id {
+ uuid_t uuid;
+};
+
+/**
+ * struct tee_client_device - tee based device
+ * @id: device identifier
+ * @dev: device structure
+ */
+struct tee_client_device {
+ struct tee_client_device_id id;
+ struct device dev;
+};
+#define to_tee_client_device(d) container_of(d, struct tee_client_device, dev)
+
+/**
+ * struct tee_client_driver - tee client driver
+ * @id_table: device id table supported by this driver
+ * @driver: driver structure
+ */
+struct tee_client_driver {
+ const struct tee_client_device_id *id_table;
+ struct device_driver driver;
+};
+#define to_tee_client_driver(d) \
+ container_of(d, struct tee_client_driver, driver)
+
#endif /*__TEE_DRV_H*/
--
2.7.4
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