tee: optee: Fix missing devices unregister during optee_remove

When OP-TEE driver is built as a module, OP-TEE client devices
registered on TEE bus during probe should be unregistered during
optee_remove. So implement optee_unregister_devices() accordingly.

Fixes: c3fa24af ("tee: optee: add TEE bus device enumeration support")
Reported-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/optee/core.c

@@ -585,6 +585,9 @@ static int optee_remove(struct platform_device *pdev)
 {
 	struct optee *optee = platform_get_drvdata(pdev);
 
+	/* Unregister OP-TEE specific client devices on TEE bus */
+	optee_unregister_devices();
+
 	/*
 	 * Ask OP-TEE to free all cached shared memory objects to decrease
 	 * reference counters and also avoid wild pointers in secure world

drivers/tee/optee/device.c

@@ -53,6 +53,13 @@ static int get_devices(struct tee_context *ctx, u32 session,
 	return 0;
 }
 
+static void optee_release_device(struct device *dev)
+{
+	struct tee_client_device *optee_device = to_tee_client_device(dev);
+
+	kfree(optee_device);
+}
+
 static int optee_register_device(const uuid_t *device_uuid)
 {
 	struct tee_client_device *optee_device = NULL;
@@ -63,6 +70,7 @@ static int optee_register_device(const uuid_t *device_uuid)
 		return -ENOMEM;
 
 	optee_device->dev.bus = &tee_bus_type;
+	optee_device->dev.release = optee_release_device;
 	if (dev_set_name(&optee_device->dev, "optee-ta-%pUb", device_uuid)) {
 		kfree(optee_device);
 		return -ENOMEM;
@@ -154,3 +162,17 @@ int optee_enumerate_devices(u32 func)
 {
 	return  __optee_enumerate_devices(func);
 }
+
+static int __optee_unregister_device(struct device *dev, void *data)
+{
+	if (!strncmp(dev_name(dev), "optee-ta", strlen("optee-ta")))
+		device_unregister(dev);
+
+	return 0;
+}
+
+void optee_unregister_devices(void)
+{
+	bus_for_each_dev(&tee_bus_type, NULL, NULL,
+			 __optee_unregister_device);
+}

drivers/tee/optee/optee_private.h

@@ -184,6 +184,7 @@ void optee_fill_pages_list(u64 *dst, struct page **pages, int num_pages,
 #define PTA_CMD_GET_DEVICES		0x0
 #define PTA_CMD_GET_DEVICES_SUPP	0x1
 int optee_enumerate_devices(u32 func);
+void optee_unregister_devices(void);
 
 /*
  * Small helpers