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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 | ||
20 | #ifndef V4L2_EVENT_H | |
21 | #define V4L2_EVENT_H | |
22 | ||
23 | #include <linux/types.h> | |
24 | #include <linux/videodev2.h> | |
25 | #include <linux/wait.h> | |
26 | ||
27 | /* | |
28 | * Overview: | |
29 | * | |
30 | * Events are subscribed per-filehandle. An event specification consists of a | |
31 | * type and is optionally associated with an object identified through the | |
32 | * 'id' field. So an event is uniquely identified by the (type, id) tuple. | |
33 | * | |
34 | * The v4l2-fh struct has a list of subscribed events. The v4l2_subscribed_event | |
35 | * struct is added to that list, one for every subscribed event. | |
36 | * | |
37 | * Each v4l2_subscribed_event struct ends with an array of v4l2_kevent structs. | |
38 | * This array (ringbuffer, really) is used to store any events raised by the | |
39 | * driver. The v4l2_kevent struct links into the 'available' list of the | |
40 | * v4l2_fh struct so VIDIOC_DQEVENT will know which event to dequeue first. | |
41 | * | |
42 | * Finally, if the event subscription is associated with a particular object | |
43 | * such as a V4L2 control, then that object needs to know about that as well | |
44 | * so that an event can be raised by that object. So the 'node' field can | |
45 | * be used to link the v4l2_subscribed_event struct into a list of that | |
46 | * object. | |
47 | * | |
48 | * So to summarize: | |
49 | * | |
50 | * struct v4l2_fh has two lists: one of the subscribed events, and one of the | |
51 | * pending events. | |
52 | * | |
53 | * struct v4l2_subscribed_event has a ringbuffer of raised (pending) events of | |
54 | * that particular type. | |
55 | * | |
56 | * If struct v4l2_subscribed_event is associated with a specific object, then | |
57 | * that object will have an internal list of struct v4l2_subscribed_event so | |
58 | * it knows who subscribed an event to that object. | |
59 | */ | |
60 | ||
61 | struct v4l2_fh; | |
62 | struct v4l2_subdev; | |
63 | struct v4l2_subscribed_event; | |
64 | struct video_device; | |
65 | ||
66 | /** | |
67 | * struct v4l2_kevent - Internal kernel event struct. | |
68 | * @list: List node for the v4l2_fh->available list. | |
69 | * @sev: Pointer to parent v4l2_subscribed_event. | |
70 | * @event: The event itself. | |
71 | */ | |
72 | struct v4l2_kevent { | |
73 | struct list_head list; | |
74 | struct v4l2_subscribed_event *sev; | |
75 | struct v4l2_event event; | |
76 | }; | |
77 | ||
78 | /** | |
79 | * struct v4l2_subscribed_event_ops - Subscribed event operations. | |
80 | * | |
81 | * @add: Optional callback, called when a new listener is added | |
82 | * @del: Optional callback, called when a listener stops listening | |
83 | * @replace: Optional callback that can replace event 'old' with event 'new'. | |
84 | * @merge: Optional callback that can merge event 'old' into event 'new'. | |
85 | */ | |
86 | struct v4l2_subscribed_event_ops { | |
87 | int (*add)(struct v4l2_subscribed_event *sev, unsigned int elems); | |
88 | void (*del)(struct v4l2_subscribed_event *sev); | |
89 | void (*replace)(struct v4l2_event *old, const struct v4l2_event *new); | |
90 | void (*merge)(const struct v4l2_event *old, struct v4l2_event *new); | |
91 | }; | |
92 | ||
93 | /** | |
94 | * struct v4l2_subscribed_event - Internal struct representing a subscribed | |
95 | * event. | |
96 | * | |
97 | * @list: List node for the v4l2_fh->subscribed list. | |
98 | * @type: Event type. | |
99 | * @id: Associated object ID (e.g. control ID). 0 if there isn't any. | |
100 | * @flags: Copy of v4l2_event_subscription->flags. | |
101 | * @fh: Filehandle that subscribed to this event. | |
102 | * @node: List node that hooks into the object's event list | |
103 | * (if there is one). | |
104 | * @ops: v4l2_subscribed_event_ops | |
105 | * @elems: The number of elements in the events array. | |
106 | * @first: The index of the events containing the oldest available event. | |
107 | * @in_use: The number of queued events. | |
108 | * @events: An array of @elems events. | |
109 | */ | |
110 | struct v4l2_subscribed_event { | |
111 | struct list_head list; | |
112 | u32 type; | |
113 | u32 id; | |
114 | u32 flags; | |
115 | struct v4l2_fh *fh; | |
116 | struct list_head node; | |
117 | const struct v4l2_subscribed_event_ops *ops; | |
118 | unsigned int elems; | |
119 | unsigned int first; | |
120 | unsigned int in_use; | |
121 | struct v4l2_kevent events[]; | |
122 | }; | |
123 | ||
124 | /** | |
125 | * v4l2_event_dequeue - Dequeue events from video device. | |
126 | * | |
127 | * @fh: pointer to struct v4l2_fh | |
128 | * @event: pointer to struct v4l2_event | |
129 | * @nonblocking: if not zero, waits for an event to arrive | |
130 | */ | |
131 | int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event, | |
132 | int nonblocking); | |
133 | ||
134 | /** | |
135 | * v4l2_event_queue - Queue events to video device. | |
136 | * | |
137 | * @vdev: pointer to &struct video_device | |
138 | * @ev: pointer to &struct v4l2_event | |
139 | * | |
140 | * The event will be queued for all &struct v4l2_fh file handlers. | |
141 | * | |
142 | * .. note:: | |
143 | * The driver's only responsibility is to fill in the type and the data | |
144 | * fields.The other fields will be filled in by V4L2. | |
145 | */ | |
146 | void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev); | |
147 | ||
148 | /** | |
149 | * v4l2_event_queue_fh - Queue events to video device. | |
150 | * | |
151 | * @fh: pointer to &struct v4l2_fh | |
152 | * @ev: pointer to &struct v4l2_event | |
153 | * | |
154 | * | |
155 | * The event will be queued only for the specified &struct v4l2_fh file handler. | |
156 | * | |
157 | * .. note:: | |
158 | * The driver's only responsibility is to fill in the type and the data | |
159 | * fields.The other fields will be filled in by V4L2. | |
160 | */ | |
161 | void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev); | |
162 | ||
163 | /** | |
164 | * v4l2_event_pending - Check if an event is available | |
165 | * | |
166 | * @fh: pointer to &struct v4l2_fh | |
167 | * | |
168 | * Returns the number of pending events. | |
169 | */ | |
170 | int v4l2_event_pending(struct v4l2_fh *fh); | |
171 | ||
172 | /** | |
173 | * v4l2_event_subscribe - Subscribes to an event | |
174 | * | |
175 | * @fh: pointer to &struct v4l2_fh | |
176 | * @sub: pointer to &struct v4l2_event_subscription | |
177 | * @elems: size of the events queue | |
178 | * @ops: pointer to &v4l2_subscribed_event_ops | |
179 | * | |
180 | * .. note:: | |
181 | * | |
182 | * if @elems is zero, the framework will fill in a default value, | |
183 | * with is currently 1 element. | |
184 | */ | |
185 | int v4l2_event_subscribe(struct v4l2_fh *fh, | |
186 | const struct v4l2_event_subscription *sub, | |
187 | unsigned int elems, | |
188 | const struct v4l2_subscribed_event_ops *ops); | |
189 | /** | |
190 | * v4l2_event_unsubscribe - Unsubscribes to an event | |
191 | * | |
192 | * @fh: pointer to &struct v4l2_fh | |
193 | * @sub: pointer to &struct v4l2_event_subscription | |
194 | */ | |
195 | int v4l2_event_unsubscribe(struct v4l2_fh *fh, | |
196 | const struct v4l2_event_subscription *sub); | |
197 | /** | |
198 | * v4l2_event_unsubscribe_all - Unsubscribes to all events | |
199 | * | |
200 | * @fh: pointer to &struct v4l2_fh | |
201 | */ | |
202 | void v4l2_event_unsubscribe_all(struct v4l2_fh *fh); | |
203 | ||
204 | /** | |
205 | * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe() | |
206 | * | |
207 | * @sd: pointer to &struct v4l2_subdev | |
208 | * @fh: pointer to &struct v4l2_fh | |
209 | * @sub: pointer to &struct v4l2_event_subscription | |
210 | * | |
211 | * .. note:: | |
212 | * | |
213 | * This function should be used for the &struct v4l2_subdev_core_ops | |
214 | * %unsubscribe_event field. | |
215 | */ | |
216 | int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, | |
217 | struct v4l2_fh *fh, | |
218 | struct v4l2_event_subscription *sub); | |
219 | /** | |
220 | * v4l2_src_change_event_subscribe - helper function that calls | |
221 | * v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE. | |
222 | * | |
223 | * @fh: pointer to struct v4l2_fh | |
224 | * @sub: pointer to &struct v4l2_event_subscription | |
225 | */ | |
226 | int v4l2_src_change_event_subscribe(struct v4l2_fh *fh, | |
227 | const struct v4l2_event_subscription *sub); | |
228 | /** | |
229 | * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(), | |
230 | * meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE. | |
231 | * | |
232 | * @sd: pointer to &struct v4l2_subdev | |
233 | * @fh: pointer to &struct v4l2_fh | |
234 | * @sub: pointer to &struct v4l2_event_subscription | |
235 | */ | |
236 | int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd, | |
237 | struct v4l2_fh *fh, | |
238 | struct v4l2_event_subscription *sub); | |
239 | #endif /* V4L2_EVENT_H */ |