aboutsummaryrefslogtreecommitdiff
path: root/include/media/v4l2-event.h
diff options
context:
space:
mode:
Diffstat (limited to 'include/media/v4l2-event.h')
-rw-r--r--include/media/v4l2-event.h84
1 files changed, 70 insertions, 14 deletions
diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
index 3b86177c8cd..5f14e8895ce 100644
--- a/include/media/v4l2-event.h
+++ b/include/media/v4l2-event.h
@@ -29,39 +29,95 @@
#include <linux/videodev2.h>
#include <linux/wait.h>
+/*
+ * Overview:
+ *
+ * Events are subscribed per-filehandle. An event specification consists of a
+ * type and is optionally associated with an object identified through the
+ * 'id' field. So an event is uniquely identified by the (type, id) tuple.
+ *
+ * The v4l2-fh struct has a list of subscribed events. The v4l2_subscribed_event
+ * struct is added to that list, one for every subscribed event.
+ *
+ * Each v4l2_subscribed_event struct ends with an array of v4l2_kevent structs.
+ * This array (ringbuffer, really) is used to store any events raised by the
+ * driver. The v4l2_kevent struct links into the 'available' list of the
+ * v4l2_fh struct so VIDIOC_DQEVENT will know which event to dequeue first.
+ *
+ * Finally, if the event subscription is associated with a particular object
+ * such as a V4L2 control, then that object needs to know about that as well
+ * so that an event can be raised by that object. So the 'node' field can
+ * be used to link the v4l2_subscribed_event struct into a list of that
+ * object.
+ *
+ * So to summarize:
+ *
+ * struct v4l2_fh has two lists: one of the subscribed events, and one of the
+ * pending events.
+ *
+ * struct v4l2_subscribed_event has a ringbuffer of raised (pending) events of
+ * that particular type.
+ *
+ * If struct v4l2_subscribed_event is associated with a specific object, then
+ * that object will have an internal list of struct v4l2_subscribed_event so
+ * it knows who subscribed an event to that object.
+ */
+
struct v4l2_fh;
+struct v4l2_subscribed_event;
struct video_device;
+/** struct v4l2_kevent - Internal kernel event struct.
+ * @list: List node for the v4l2_fh->available list.
+ * @sev: Pointer to parent v4l2_subscribed_event.
+ * @event: The event itself.
+ */
struct v4l2_kevent {
struct list_head list;
+ struct v4l2_subscribed_event *sev;
struct v4l2_event event;
};
+/** struct v4l2_subscribed_event - Internal struct representing a subscribed event.
+ * @list: List node for the v4l2_fh->subscribed list.
+ * @type: Event type.
+ * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
+ * @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'.
+ * @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.
+ * @events: An array of @elems events.
+ */
struct v4l2_subscribed_event {
struct list_head list;
u32 type;
+ u32 id;
+ 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);
+ unsigned elems;
+ unsigned first;
+ unsigned in_use;
+ struct v4l2_kevent events[];
};
-struct v4l2_events {
- wait_queue_head_t wait;
- struct list_head subscribed; /* Subscribed events */
- struct list_head free; /* Events ready for use */
- struct list_head available; /* Dequeueable event */
- unsigned int navailable;
- unsigned int nallocated; /* Number of allocated events */
- u32 sequence;
-};
-
-int v4l2_event_init(struct v4l2_fh *fh);
-int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n);
-void v4l2_event_free(struct v4l2_fh *fh);
int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
int nonblocking);
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);
+ struct v4l2_event_subscription *sub, unsigned elems);
int v4l2_event_unsubscribe(struct v4l2_fh *fh,
struct v4l2_event_subscription *sub);
+void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
#endif /* V4L2_EVENT_H */