optee: use uuid for sysfs driver entry

With the evolving use-cases for TEE bus, now it's required to support
multi-stage enumeration process. But using a simple index doesn't
suffice this requirement and instead leads to duplicate sysfs entries.
So instead switch to use more informative device UUID for sysfs entry
like:
/sys/bus/tee/devices/optee-ta-<uuid>

Signed-off-by: Maxim Uvarov <[email protected]>
Reviewed-by: Sumit Garg <[email protected]>
Reviewed-by: Jarkko Sakkinen <[email protected]>
Tested-by: Sumit Garg <[email protected]>
Signed-off-by: Jens Wiklander <[email protected]>

Author: muvarov

Documentation/ABI/testing/sysfs-bus-optee-devices

@@ -0,0 +1,8 @@
+What:		/sys/bus/tee/devices/optee-ta-<uuid>/
+Date:           May 2020
+KernelVersion   5.8
+Contact:        [email protected]
+Description:
+		OP-TEE bus provides reference to registered drivers under this directory. The <uuid>
+		matches Trusted Application (TA) driver and corresponding TA in secure OS. Drivers
+		are free to create needed API under optee-ta-<uuid> directory.

MAINTAINERS

@@ -12528,6 +12528,7 @@ OP-TEE DRIVER
 M:	Jens Wiklander <[email protected]>
 L:	[email protected]
 S:	Maintained
+F:	Documentation/ABI/testing/sysfs-bus-optee-devices
 F:	drivers/tee/optee/
 
 OP-TEE RANDOM NUMBER GENERATOR (RNG) DRIVER

drivers/tee/optee/device.c

@@ -65,7 +65,7 @@ static int get_devices(struct tee_context *ctx, u32 session,
 	return 0;
 }
 
-static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
+static int optee_register_device(const uuid_t *device_uuid)
 {
 	struct tee_client_device *optee_device = NULL;
 	int rc;
@@ -75,7 +75,10 @@ static int optee_register_device(const uuid_t *device_uuid, u32 device_id)
 		return -ENOMEM;
 
 	optee_device->dev.bus = &tee_bus_type;
-	dev_set_name(&optee_device->dev, "optee-clnt%u", device_id);
+	if (dev_set_name(&optee_device->dev, "optee-ta-%pUb", device_uuid)) {
+		kfree(optee_device);
+		return -ENOMEM;
+	}
 	uuid_copy(&optee_device->id.uuid, device_uuid);
 
 	rc = device_register(&optee_device->dev);
@@ -144,7 +147,7 @@ int optee_enumerate_devices(void)
 	num_devices = shm_size / sizeof(uuid_t);
 
 	for (idx = 0; idx < num_devices; idx++) {
-		rc = optee_register_device(&device_uuid[idx], idx);
+		rc = optee_register_device(&device_uuid[idx]);
 		if (rc)
 			goto out_shm;
 	}