Merge tag 'optee-supplicant-fix-for-v6.7' of git://git.linaro.org:/people/jens.wiklander/linux-tee into arm/fixes

OP-TEE fix for supplicant based device enumeration

Adds a sysfs attribute for devices depending on supplicant services so
that the user-space service can detect and detach those devices before
closing the supplicant

* tag 'optee-supplicant-fix-for-v6.7' of git://git.linaro.org:/people/jens.wiklander/linux-tee:
  tee: optee: Fix supplicant based device enumeration

Link: https://lore.kernel.org/r/20231114153113.GA1310615@rayden
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: arndb

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

@@ -6,3 +6,12 @@ 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.
+
+What:		/sys/bus/tee/devices/optee-ta-<uuid>/need_supplicant
+Date:		November 2023
+KernelVersion:	6.7
+Contact:	op-tee@lists.trustedfirmware.org
+Description:
+		Allows to distinguish whether an OP-TEE based TA/device requires user-space
+		tee-supplicant to function properly or not. This attribute will be present for
+		devices which depend on tee-supplicant to be running.

drivers/tee/optee/device.c

@@ -60,7 +60,16 @@ static void optee_release_device(struct device *dev)
 	kfree(optee_device);
 }
 
-static int optee_register_device(const uuid_t *device_uuid)
+static ssize_t need_supplicant_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	return 0;
+}
+
+static DEVICE_ATTR_RO(need_supplicant);
+
+static int optee_register_device(const uuid_t *device_uuid, u32 func)
 {
 	struct tee_client_device *optee_device = NULL;
 	int rc;
@@ -83,6 +92,10 @@ static int optee_register_device(const uuid_t *device_uuid)
 		put_device(&optee_device->dev);
 	}
 
+	if (func == PTA_CMD_GET_DEVICES_SUPP)
+		device_create_file(&optee_device->dev,
+				   &dev_attr_need_supplicant);
+
 	return rc;
 }
 
@@ -142,7 +155,7 @@ static int __optee_enumerate_devices(u32 func)
 	num_devices = shm_size / sizeof(uuid_t);
 
 	for (idx = 0; idx < num_devices; idx++) {
-		rc = optee_register_device(&device_uuid[idx]);
+		rc = optee_register_device(&device_uuid[idx], func);
 		if (rc)
 			goto out_shm;
 	}