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1/*
2 * v4l2-event.h
3 *
4 * V4L2 events.
5 *
6 * Copyright (C) 2009--2010 Nokia Corporation.
7 *
8 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
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
32/*
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
66struct v4l2_fh;
67struct v4l2_subdev;
68struct v4l2_subscribed_event;
69struct video_device;
70
71/**
72 * struct v4l2_kevent - Internal kernel event struct.
73 * @list: List node for the v4l2_fh->available list.
74 * @sev: Pointer to parent v4l2_subscribed_event.
75 * @event: The event itself.
76 */
77struct v4l2_kevent {
78 struct list_head list;
79 struct v4l2_subscribed_event *sev;
80 struct v4l2_event event;
81};
82
83/** struct v4l2_subscribed_event_ops - Subscribed event operations.
84 *
85 * @add: Optional callback, called when a new listener is added
86 * @del: Optional callback, called when a listener stops listening
87 * @replace: Optional callback that can replace event 'old' with event 'new'.
88 * @merge: Optional callback that can merge event 'old' into event 'new'.
89 */
90struct v4l2_subscribed_event_ops {
91 int (*add)(struct v4l2_subscribed_event *sev, unsigned elems);
92 void (*del)(struct v4l2_subscribed_event *sev);
93 void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
94 void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
95};
96
97/**
98 * struct v4l2_subscribed_event - Internal struct representing a subscribed event.
99 * @list: List node for the v4l2_fh->subscribed list.
100 * @type: Event type.
101 * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
102 * @flags: Copy of v4l2_event_subscription->flags.
103 * @fh: Filehandle that subscribed to this event.
104 * @node: List node that hooks into the object's event list (if there is one).
105 * @ops: v4l2_subscribed_event_ops
106 * @elems: The number of elements in the events array.
107 * @first: The index of the events containing the oldest available event.
108 * @in_use: The number of queued events.
109 * @events: An array of @elems events.
110 */
111struct v4l2_subscribed_event {
112 struct list_head list;
113 u32 type;
114 u32 id;
115 u32 flags;
116 struct v4l2_fh *fh;
117 struct list_head node;
118 const struct v4l2_subscribed_event_ops *ops;
119 unsigned elems;
120 unsigned first;
121 unsigned in_use;
122 struct v4l2_kevent events[];
123};
124
125int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
126 int nonblocking);
127void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
128void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
129int v4l2_event_pending(struct v4l2_fh *fh);
130int v4l2_event_subscribe(struct v4l2_fh *fh,
131 const struct v4l2_event_subscription *sub, unsigned elems,
132 const struct v4l2_subscribed_event_ops *ops);
133int v4l2_event_unsubscribe(struct v4l2_fh *fh,
134 const struct v4l2_event_subscription *sub);
135void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
136int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
137 struct v4l2_event_subscription *sub);
138int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
139 const struct v4l2_event_subscription *sub);
140int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
141 struct v4l2_fh *fh, struct v4l2_event_subscription *sub);
142#endif /* V4L2_EVENT_H */
1/*
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
32/*
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
66struct v4l2_fh;
67struct v4l2_subscribed_event;
68struct video_device;
69
70/** 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 */
75struct v4l2_kevent {
76 struct list_head list;
77 struct v4l2_subscribed_event *sev;
78 struct v4l2_event event;
79};
80
81/** struct v4l2_subscribed_event - Internal struct representing a subscribed event.
82 * @list: List node for the v4l2_fh->subscribed list.
83 * @type: Event type.
84 * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
85 * @flags: Copy of v4l2_event_subscription->flags.
86 * @fh: Filehandle that subscribed to this event.
87 * @node: List node that hooks into the object's event list (if there is one).
88 * @replace: Optional callback that can replace event 'old' with event 'new'.
89 * @merge: Optional callback that can merge event 'old' into event 'new'.
90 * @elems: The number of elements in the events array.
91 * @first: The index of the events containing the oldest available event.
92 * @in_use: The number of queued events.
93 * @events: An array of @elems events.
94 */
95struct v4l2_subscribed_event {
96 struct list_head list;
97 u32 type;
98 u32 id;
99 u32 flags;
100 struct v4l2_fh *fh;
101 struct list_head node;
102 void (*replace)(struct v4l2_event *old,
103 const struct v4l2_event *new);
104 void (*merge)(const struct v4l2_event *old,
105 struct v4l2_event *new);
106 unsigned elems;
107 unsigned first;
108 unsigned in_use;
109 struct v4l2_kevent events[];
110};
111
112int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
113 int nonblocking);
114void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
115void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
116int v4l2_event_pending(struct v4l2_fh *fh);
117int v4l2_event_subscribe(struct v4l2_fh *fh,
118 struct v4l2_event_subscription *sub, unsigned elems);
119int v4l2_event_unsubscribe(struct v4l2_fh *fh,
120 struct v4l2_event_subscription *sub);
121void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
122
123#endif /* V4L2_EVENT_H */