tee: optee: Fix supplicant based device enumeration

Currently supplicant dependent optee device enumeration only registers
devices whenever tee-supplicant is invoked for the first time. But it
forgets to remove devices when tee-supplicant daemon stops running and
closes its context gracefully. This leads to following error for fTPM
driver during reboot/shutdown:

[   73.466791] tpm tpm0: ftpm_tee_tpm_op_send: SUBMIT_COMMAND invoke error: 0xffff3024

Fix this by adding an attribute for supplicant dependent devices so that
the user-space service can detect and detach supplicant devices before
closing the supplicant:

$ for dev in /sys/bus/tee/devices/*; do if [[ -f "$dev/need_supplicant" && -f "$dev/driver/unbind" ]]; \
      then echo $(basename "$dev") > $dev/driver/unbind; fi done

Reported-by: Jan Kiszka <[email protected]>
Closes: OP-TEE/optee_os#6094
Fixes: 5f178bb ("optee: enable support for multi-stage bus enumeration")
Signed-off-by: Sumit Garg <[email protected]>
Reviewed-by: Ilias Apalodimas <[email protected]>
Acked-by: Jerome Forissier <[email protected]>
[jw: fixed up Date documentation]
Signed-off-by: Jens Wiklander <[email protected]>

Author: b49020

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:	[email protected]
+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;
 	}