media: v4l2-subdev: add v4l2_subdev_get_fwnode_pad_1_to_1

Add a convenience function that can be used as the .get_fwnode_pad
operation for subdevices that map port numbers and pad indexes 1:1.
The function verifies the endpoint is owned by the subdevice, and if
so returns the endpoint port number.
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/v4l2-core/v4l2-subdev.c

@@ -749,6 +749,28 @@ const struct v4l2_file_operations v4l2_subdev_fops = {
 };
 
 #ifdef CONFIG_MEDIA_CONTROLLER
+
+int v4l2_subdev_get_fwnode_pad_1_to_1(struct media_entity *entity,
+				      struct fwnode_endpoint *endpoint)
+{
+	struct fwnode_handle *fwnode;
+	struct v4l2_subdev *sd;
+
+	if (!is_media_entity_v4l2_subdev(entity))
+		return -EINVAL;
+
+	sd = media_entity_to_v4l2_subdev(entity);
+
+	fwnode = fwnode_graph_get_port_parent(endpoint->local_fwnode);
+	fwnode_handle_put(fwnode);
+
+	if (dev_fwnode(sd->dev) == fwnode)
+		return endpoint->port;
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_get_fwnode_pad_1_to_1);
+
 int v4l2_subdev_link_validate_default(struct v4l2_subdev *sd,
 				      struct media_link *link,
 				      struct v4l2_subdev_format *source_fmt,

include/media/v4l2-subdev.h

@@ -1027,6 +1027,23 @@ static inline void *v4l2_get_subdev_hostdata(const struct v4l2_subdev *sd)
 
 #ifdef CONFIG_MEDIA_CONTROLLER
 
+/**
+ * v4l2_subdev_get_fwnode_pad_1_to_1 - Get pad number from a subdev fwnode
+ *                                     endpoint, assuming 1:1 port:pad
+ *
+ * @entity - Pointer to the subdev entity
+ * @endpoint - Pointer to a parsed fwnode endpoint
+ *
+ * This function can be used as the .get_fwnode_pad operation for
+ * subdevices that map port numbers and pad indexes 1:1. If the endpoint
+ * is owned by the subdevice, the function returns the endpoint port
+ * number.
+ *
+ * Returns the endpoint port number on success or a negative error code.
+ */
+int v4l2_subdev_get_fwnode_pad_1_to_1(struct media_entity *entity,
+				      struct fwnode_endpoint *endpoint);
+
 /**
  * v4l2_subdev_link_validate_default - validates a media link
  *