[media] v4l2-event: Add v4l2_subscribed_event_ops

Just like with ctrl events, drivers may want to get called back on
listener add / remove for other event types too. Rather then special
casing all of this in subscribe / unsubscribe event it is better to
use ops for this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 17 insertions, 7 deletions

diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index 5f14e8895ce2..88fa9a1e0df3 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -78,6 +78,19 @@ struct v4l2_kevent {
         struct v4l2_event       event;
 };
 
+/** struct v4l2_subscribed_event_ops - Subscribed event operations.
+  * @add:       Optional callback, called when a new listener is added
+  * @del:       Optional callback, called when a listener stops listening
+  * @replace:   Optional callback that can replace event 'old' with event 'new'.
+  * @merge:     Optional callback that can merge event 'old' into event 'new'.
+  */
+struct v4l2_subscribed_event_ops {
+        int  (*add)(struct v4l2_subscribed_event *sev);
+        void (*del)(struct v4l2_subscribed_event *sev);
+        void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
+        void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
+};
+
 /** struct v4l2_subscribed_event - Internal struct representing a subscribed event.
   * @list:      List node for the v4l2_fh->subscribed list.
   * @type:      Event type.
@@ -85,8 +98,7 @@ struct v4l2_kevent {
   * @flags:     Copy of v4l2_event_subscription->flags.
   * @fh:        Filehandle that subscribed to this event.
   * @node:      List node that hooks into the object's event list (if there is one).
-  * @replace:   Optional callback that can replace event 'old' with event 'new'.
-  * @merge:     Optional callback that can merge event 'old' into event 'new'.
+  * @ops:       v4l2_subscribed_event_ops
   * @elems:     The number of elements in the events array.
   * @first:     The index of the events containing the oldest available event.
   * @in_use:    The number of queued events.
@@ -99,10 +111,7 @@ struct v4l2_subscribed_event {
         u32                     flags;
         struct v4l2_fh          *fh;
         struct list_head        node;
-        void                    (*replace)(struct v4l2_event *old,
-                                           const struct v4l2_event *new);
-        void                    (*merge)(const struct v4l2_event *old,
-                                         struct v4l2_event *new);
+        const struct v4l2_subscribed_event_ops *ops;
         unsigned                elems;
         unsigned                first;
         unsigned                in_use;
@@ -115,7 +124,8 @@ void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
 int v4l2_event_pending(struct v4l2_fh *fh);
 int v4l2_event_subscribe(struct v4l2_fh *fh,
-                         struct v4l2_event_subscription *sub, unsigned elems);
+                         struct v4l2_event_subscription *sub, unsigned elems,
+                         const struct v4l2_subscribed_event_ops *ops);
 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
                            struct v4l2_event_subscription *sub);
 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);