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Sakari Ailusc3b5b022010-03-01 05:14:18 -03001/*
2 * v4l2-event.h
3 *
4 * V4L2 events.
5 *
6 * Copyright (C) 2009--2010 Nokia Corporation.
7 *
8 * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * version 2 as published by the Free Software Foundation.
13 *
14 * This program is distributed in the hope that it will be useful, but
15 * WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA
23 */
24
25#ifndef V4L2_EVENT_H
26#define V4L2_EVENT_H
27
28#include <linux/types.h>
29#include <linux/videodev2.h>
30#include <linux/wait.h>
31
Hans Verkuil3ad57c32011-06-20 12:00:36 -030032/*
33 * Overview:
34 *
35 * Events are subscribed per-filehandle. An event specification consists of a
36 * type and is optionally associated with an object identified through the
37 * 'id' field. So an event is uniquely identified by the (type, id) tuple.
38 *
39 * The v4l2-fh struct has a list of subscribed events. The v4l2_subscribed_event
40 * struct is added to that list, one for every subscribed event.
41 *
42 * Each v4l2_subscribed_event struct ends with an array of v4l2_kevent structs.
43 * This array (ringbuffer, really) is used to store any events raised by the
44 * driver. The v4l2_kevent struct links into the 'available' list of the
45 * v4l2_fh struct so VIDIOC_DQEVENT will know which event to dequeue first.
46 *
47 * Finally, if the event subscription is associated with a particular object
48 * such as a V4L2 control, then that object needs to know about that as well
49 * so that an event can be raised by that object. So the 'node' field can
50 * be used to link the v4l2_subscribed_event struct into a list of that
51 * object.
52 *
53 * So to summarize:
54 *
55 * struct v4l2_fh has two lists: one of the subscribed events, and one of the
56 * pending events.
57 *
58 * struct v4l2_subscribed_event has a ringbuffer of raised (pending) events of
59 * that particular type.
60 *
61 * If struct v4l2_subscribed_event is associated with a specific object, then
62 * that object will have an internal list of struct v4l2_subscribed_event so
63 * it knows who subscribed an event to that object.
64 */
65
Sakari Ailusc3b5b022010-03-01 05:14:18 -030066struct v4l2_fh;
Hans Verkuilf1e393d2011-06-13 19:24:17 -030067struct v4l2_subscribed_event;
Sakari Ailusc3b5b022010-03-01 05:14:18 -030068struct video_device;
69
Hans Verkuil3f66f0e2011-06-20 11:56:24 -030070/** struct v4l2_kevent - Internal kernel event struct.
71 * @list: List node for the v4l2_fh->available list.
72 * @sev: Pointer to parent v4l2_subscribed_event.
73 * @event: The event itself.
74 */
Sakari Ailusc3b5b022010-03-01 05:14:18 -030075struct v4l2_kevent {
76 struct list_head list;
Hans Verkuilf1e393d2011-06-13 19:24:17 -030077 struct v4l2_subscribed_event *sev;
Sakari Ailusc3b5b022010-03-01 05:14:18 -030078 struct v4l2_event event;
79};
80
Hans de Goedec53c2542012-04-08 12:59:46 -030081/** struct v4l2_subscribed_event_ops - Subscribed event operations.
82 * @add: Optional callback, called when a new listener is added
83 * @del: Optional callback, called when a listener stops listening
84 * @replace: Optional callback that can replace event 'old' with event 'new'.
85 * @merge: Optional callback that can merge event 'old' into event 'new'.
86 */
87struct v4l2_subscribed_event_ops {
Hans Verkuil6e6d76c2012-05-07 16:53:20 -030088 int (*add)(struct v4l2_subscribed_event *sev, unsigned elems);
Hans de Goedec53c2542012-04-08 12:59:46 -030089 void (*del)(struct v4l2_subscribed_event *sev);
90 void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
91 void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
92};
93
Hans Verkuil3f66f0e2011-06-20 11:56:24 -030094/** struct v4l2_subscribed_event - Internal struct representing a subscribed event.
95 * @list: List node for the v4l2_fh->subscribed list.
96 * @type: Event type.
97 * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
98 * @flags: Copy of v4l2_event_subscription->flags.
99 * @fh: Filehandle that subscribed to this event.
100 * @node: List node that hooks into the object's event list (if there is one).
Hans de Goedec53c2542012-04-08 12:59:46 -0300101 * @ops: v4l2_subscribed_event_ops
Hans Verkuil3f66f0e2011-06-20 11:56:24 -0300102 * @elems: The number of elements in the events array.
103 * @first: The index of the events containing the oldest available event.
104 * @in_use: The number of queued events.
105 * @events: An array of @elems events.
106 */
Sakari Ailusc3b5b022010-03-01 05:14:18 -0300107struct v4l2_subscribed_event {
108 struct list_head list;
109 u32 type;
Hans Verkuil6e239392011-06-07 11:13:44 -0300110 u32 id;
Hans Verkuil77068d32011-06-13 18:55:58 -0300111 u32 flags;
Hans Verkuil77068d32011-06-13 18:55:58 -0300112 struct v4l2_fh *fh;
Hans Verkuil77068d32011-06-13 18:55:58 -0300113 struct list_head node;
Hans de Goedec53c2542012-04-08 12:59:46 -0300114 const struct v4l2_subscribed_event_ops *ops;
Hans Verkuilf1e393d2011-06-13 19:24:17 -0300115 unsigned elems;
Hans Verkuilf1e393d2011-06-13 19:24:17 -0300116 unsigned first;
Hans Verkuilf1e393d2011-06-13 19:24:17 -0300117 unsigned in_use;
Hans Verkuilf1e393d2011-06-13 19:24:17 -0300118 struct v4l2_kevent events[];
Sakari Ailusc3b5b022010-03-01 05:14:18 -0300119};
120
Sakari Ailusc3b5b022010-03-01 05:14:18 -0300121int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
122 int nonblocking);
123void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
Hans Verkuil6e239392011-06-07 11:13:44 -0300124void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
Sakari Ailusc3b5b022010-03-01 05:14:18 -0300125int v4l2_event_pending(struct v4l2_fh *fh);
126int v4l2_event_subscribe(struct v4l2_fh *fh,
Hans de Goedec53c2542012-04-08 12:59:46 -0300127 struct v4l2_event_subscription *sub, unsigned elems,
128 const struct v4l2_subscribed_event_ops *ops);
Sakari Ailusc3b5b022010-03-01 05:14:18 -0300129int v4l2_event_unsubscribe(struct v4l2_fh *fh,
130 struct v4l2_event_subscription *sub);
Hans Verkuilf1e393d2011-06-13 19:24:17 -0300131void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
Sakari Ailusc3b5b022010-03-01 05:14:18 -0300132
133#endif /* V4L2_EVENT_H */