tee: add revision sysfs attribute

Add a generic TEE revision sysfs attribute backed by a new
optional get_tee_revision() callback. The revision string is
diagnostic-only and must not be used to infer feature support.

Signed-off-by: Aristo Chen <aristo.chen@canonical.com>
Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

Author: AristoChen

Documentation/ABI/testing/sysfs-class-tee

@@ -13,3 +13,13 @@ Description:
 		space if the variable is absent. The primary purpose
 		of this variable is to let systemd know whether
 		tee-supplicant is needed in the early boot with initramfs.
+
+What:		/sys/class/tee/tee{,priv}X/revision
+Date:		Jan 2026
+KernelVersion:	6.19
+Contact:	op-tee@lists.trustedfirmware.org
+Description:
+		Read-only revision string reported by the TEE driver. This is
+		for diagnostics only and must not be used to infer feature
+		support. Use TEE_IOC_VERSION for capability and compatibility
+		checks.

drivers/tee/tee_core.c

@@ -1146,7 +1146,56 @@ static struct attribute *tee_dev_attrs[] = {
 	NULL
 };
 
-ATTRIBUTE_GROUPS(tee_dev);
+static const struct attribute_group tee_dev_group = {
+	.attrs = tee_dev_attrs,
+};
+
+static ssize_t revision_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct tee_device *teedev = container_of(dev, struct tee_device, dev);
+	char version[TEE_REVISION_STR_SIZE];
+	int ret;
+
+	if (!teedev->desc->ops->get_tee_revision)
+		return -ENODEV;
+
+	ret = teedev->desc->ops->get_tee_revision(teedev, version,
+						  sizeof(version));
+	if (ret)
+		return ret;
+
+	return sysfs_emit(buf, "%s\n", version);
+}
+static DEVICE_ATTR_RO(revision);
+
+static struct attribute *tee_revision_attrs[] = {
+	&dev_attr_revision.attr,
+	NULL
+};
+
+static umode_t tee_revision_attr_is_visible(struct kobject *kobj,
+					    struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct tee_device *teedev = container_of(dev, struct tee_device, dev);
+
+	if (teedev->desc->ops->get_tee_revision)
+		return attr->mode;
+
+	return 0;
+}
+
+static const struct attribute_group tee_revision_group = {
+	.attrs = tee_revision_attrs,
+	.is_visible = tee_revision_attr_is_visible,
+};
+
+static const struct attribute_group *tee_dev_groups[] = {
+	&tee_dev_group,
+	&tee_revision_group,
+	NULL
+};
 
 static const struct class tee_class = {
 	.name = "tee",

include/linux/tee_core.h

@@ -76,6 +76,9 @@ struct tee_device {
 /**
  * struct tee_driver_ops - driver operations vtable
  * @get_version:	returns version of driver
+ * @get_tee_revision:	returns revision string (diagnostic only);
+ *			do not infer feature support from this, use
+ *			TEE_IOC_VERSION instead
  * @open:		called for a context when the device file is opened
  * @close_context:	called when the device file is closed
  * @release:		called to release the context
@@ -95,9 +98,12 @@ struct tee_device {
  * client closes the device file, even if there are existing references to the
  * context. The TEE driver can use @close_context to start cleaning up.
  */
+
 struct tee_driver_ops {
 	void (*get_version)(struct tee_device *teedev,
 			    struct tee_ioctl_version_data *vers);
+	int (*get_tee_revision)(struct tee_device *teedev,
+				char *buf, size_t len);
 	int (*open)(struct tee_context *ctx);
 	void (*close_context)(struct tee_context *ctx);
 	void (*release)(struct tee_context *ctx);
@@ -123,6 +129,9 @@ struct tee_driver_ops {
 	int (*shm_unregister)(struct tee_context *ctx, struct tee_shm *shm);
 };
 
+/* Size for TEE revision string buffer used by get_tee_revision(). */
+#define TEE_REVISION_STR_SIZE	128
+
 /**
  * struct tee_desc - Describes the TEE driver to the subsystem
  * @name:	name of driver