[media] media: add a linked list to track interfaces by mdev

The media device should list the interface objects, so add a linked list
for those interfaces in struct media_device.
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-device.c

@@ -381,6 +381,7 @@ int __must_check __media_device_register(struct media_device *mdev,
 		return -EINVAL;
 
 	INIT_LIST_HEAD(&mdev->entities);
+	INIT_LIST_HEAD(&mdev->interfaces);
 	spin_lock_init(&mdev->lock);
 	mutex_init(&mdev->graph_mutex);
 

drivers/media/media-entity.c

@@ -849,6 +849,8 @@ static void media_interface_init(struct media_device *mdev,
 	INIT_LIST_HEAD(&intf->links);
 
 	media_gobj_init(mdev, gobj_type, &intf->graph_obj);
+
+	list_add_tail(&intf->list, &mdev->interfaces);
 }
 
 /* Functions related to the media interface via device nodes */
@@ -877,6 +879,7 @@ EXPORT_SYMBOL_GPL(media_devnode_create);
 void media_devnode_remove(struct media_intf_devnode *devnode)
 {
 	media_gobj_remove(&devnode->intf.graph_obj);
+	list_del(&devnode->intf.list);
 	kfree(devnode);
 }
 EXPORT_SYMBOL_GPL(media_devnode_remove);

include/media/media-device.h

@@ -46,6 +46,7 @@ struct device;
  * @link_id:	Unique ID used on the last link registered
  * @intf_devnode_id: Unique ID used on the last interface devnode registered
  * @entities:	List of registered entities
+ * @interfaces:	List of registered interfaces
  * @lock:	Entities list lock
  * @graph_mutex: Entities graph operation lock
  * @link_notify: Link state change notification callback
@@ -77,6 +78,7 @@ struct media_device {
 	u32 intf_devnode_id;
 
 	struct list_head entities;
+	struct list_head interfaces;
 
 	/* Protects the entities list */
 	spinlock_t lock;

include/media/media-entity.h

@@ -156,6 +156,8 @@ struct media_entity {
  * struct media_intf_devnode - Define a Kernel API interface
  *
  * @graph_obj:		embedded graph object
+ * @list:		Linked list used to find other interfaces that belong
+ *			to the same media controller
  * @links:		List of links pointing to graph entities
  * @type:		Type of the interface as defined at the
  *			uapi/media/media.h header, e. g.
@@ -164,6 +166,7 @@ struct media_entity {
  */
 struct media_interface {
 	struct media_gobj		graph_obj;
+	struct list_head		list;
 	struct list_head		links;
 	u32				type;
 	u32				flags;