[media] media: add support to link interfaces and entities

Now that we have a new graph object called "interfaces", we
need to be able to link them to the entities.

Add a linked list to the interfaces to allow them to be
linked to the entities.
Acked-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/media-entity.c

@@ -857,6 +857,7 @@ struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
 
 	intf->type = type;
 	intf->flags = flags;
+	INIT_LIST_HEAD(&intf->links);
 
 	devnode->major = major;
 	devnode->minor = minor;
@@ -874,3 +875,40 @@ void media_devnode_remove(struct media_intf_devnode *devnode)
 	kfree(devnode);
 }
 EXPORT_SYMBOL_GPL(media_devnode_remove);
+
+struct media_link *media_create_intf_link(struct media_entity *entity,
+					    struct media_interface *intf,
+					    u32 flags)
+{
+	struct media_link *link;
+
+	link = media_add_link(&intf->links);
+	if (link == NULL)
+		return NULL;
+
+	link->intf = intf;
+	link->entity = entity;
+	link->flags = flags;
+
+	/* Initialize graph object embedded at the new link */
+	media_gobj_init(intf->graph_obj.mdev, MEDIA_GRAPH_LINK,
+			&link->graph_obj);
+
+	return link;
+}
+EXPORT_SYMBOL_GPL(media_create_intf_link);
+
+
+static void __media_remove_intf_link(struct media_link *link)
+{
+	media_gobj_remove(&link->graph_obj);
+	kfree(link);
+}
+
+void media_remove_intf_link(struct media_link *link)
+{
+	mutex_lock(&link->graph_obj.mdev->graph_mutex);
+	__media_remove_intf_link(link);
+	mutex_unlock(&link->graph_obj.mdev->graph_mutex);
+}
+EXPORT_SYMBOL_GPL(media_remove_intf_link);

include/media/media-entity.h

@@ -78,10 +78,12 @@ struct media_link {
 	union {
 		struct media_gobj *gobj0;
 		struct media_pad *source;
+		struct media_interface *intf;
 	};
 	union {
 		struct media_gobj *gobj1;
 		struct media_pad *sink;
+		struct media_entity *entity;
 	};
 	struct media_link *reverse;	/* Link in the reverse direction */
 	unsigned long flags;		/* Link flags (MEDIA_LNK_FL_*) */
@@ -154,6 +156,7 @@ struct media_entity {
  * struct media_intf_devnode - Define a Kernel API interface
  *
  * @graph_obj:		embedded graph object
+ * @links:		List of links pointing to graph entities
  * @type:		Type of the interface as defined at the
  *			uapi/media/media.h header, e. g.
  *			MEDIA_INTF_T_*
@@ -161,6 +164,7 @@ struct media_entity {
  */
 struct media_interface {
 	struct media_gobj		graph_obj;
+	struct list_head		links;
 	u32				type;
 	u32				flags;
 };
@@ -290,6 +294,11 @@ struct media_intf_devnode *media_devnode_create(struct media_device *mdev,
 						u32 major, u32 minor,
 						gfp_t gfp_flags);
 void media_devnode_remove(struct media_intf_devnode *devnode);
+struct media_link *media_create_intf_link(struct media_entity *entity,
+					    struct media_interface *intf,
+					    u32 flags);
+void media_remove_intf_link(struct media_link *link);
+
 #define media_entity_call(entity, operation, args...)			\
 	(((entity)->ops && (entity)->ops->operation) ?			\
 	 (entity)->ops->operation((entity) , ##args) : -ENOIOCTLCMD)