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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * v4l2-event.h
4 *
5 * V4L2 events.
6 *
7 * Copyright (C) 2009--2010 Nokia Corporation.
8 *
9 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
10 */
11
12#ifndef V4L2_EVENT_H
13#define V4L2_EVENT_H
14
15#include <linux/types.h>
16#include <linux/videodev2.h>
17#include <linux/wait.h>
18
19struct v4l2_fh;
20struct v4l2_subdev;
21struct v4l2_subscribed_event;
22struct video_device;
23
24/**
25 * struct v4l2_kevent - Internal kernel event struct.
26 * @list: List node for the v4l2_fh->available list.
27 * @sev: Pointer to parent v4l2_subscribed_event.
28 * @event: The event itself.
29 * @ts: The timestamp of the event.
30 */
31struct v4l2_kevent {
32 struct list_head list;
33 struct v4l2_subscribed_event *sev;
34 struct v4l2_event event;
35 u64 ts;
36};
37
38/**
39 * struct v4l2_subscribed_event_ops - Subscribed event operations.
40 *
41 * @add: Optional callback, called when a new listener is added
42 * @del: Optional callback, called when a listener stops listening
43 * @replace: Optional callback that can replace event 'old' with event 'new'.
44 * @merge: Optional callback that can merge event 'old' into event 'new'.
45 */
46struct v4l2_subscribed_event_ops {
47 int (*add)(struct v4l2_subscribed_event *sev, unsigned int elems);
48 void (*del)(struct v4l2_subscribed_event *sev);
49 void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
50 void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
51};
52
53/**
54 * struct v4l2_subscribed_event - Internal struct representing a subscribed
55 * event.
56 *
57 * @list: List node for the v4l2_fh->subscribed list.
58 * @type: Event type.
59 * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
60 * @flags: Copy of v4l2_event_subscription->flags.
61 * @fh: Filehandle that subscribed to this event.
62 * @node: List node that hooks into the object's event list
63 * (if there is one).
64 * @ops: v4l2_subscribed_event_ops
65 * @elems: The number of elements in the events array.
66 * @first: The index of the events containing the oldest available event.
67 * @in_use: The number of queued events.
68 * @events: An array of @elems events.
69 */
70struct v4l2_subscribed_event {
71 struct list_head list;
72 u32 type;
73 u32 id;
74 u32 flags;
75 struct v4l2_fh *fh;
76 struct list_head node;
77 const struct v4l2_subscribed_event_ops *ops;
78 unsigned int elems;
79 unsigned int first;
80 unsigned int in_use;
81 struct v4l2_kevent events[] __counted_by(elems);
82};
83
84/**
85 * v4l2_event_dequeue - Dequeue events from video device.
86 *
87 * @fh: pointer to struct v4l2_fh
88 * @event: pointer to struct v4l2_event
89 * @nonblocking: if not zero, waits for an event to arrive
90 */
91int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
92 int nonblocking);
93
94/**
95 * v4l2_event_queue - Queue events to video device.
96 *
97 * @vdev: pointer to &struct video_device
98 * @ev: pointer to &struct v4l2_event
99 *
100 * The event will be queued for all &struct v4l2_fh file handlers.
101 *
102 * .. note::
103 * The driver's only responsibility is to fill in the type and the data
104 * fields. The other fields will be filled in by V4L2.
105 */
106void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
107
108/**
109 * v4l2_event_queue_fh - Queue events to video device.
110 *
111 * @fh: pointer to &struct v4l2_fh
112 * @ev: pointer to &struct v4l2_event
113 *
114 *
115 * The event will be queued only for the specified &struct v4l2_fh file handler.
116 *
117 * .. note::
118 * The driver's only responsibility is to fill in the type and the data
119 * fields. The other fields will be filled in by V4L2.
120 */
121void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
122
123/**
124 * v4l2_event_wake_all - Wake all filehandles.
125 *
126 * Used when unregistering a video device.
127 *
128 * @vdev: pointer to &struct video_device
129 */
130void v4l2_event_wake_all(struct video_device *vdev);
131
132/**
133 * v4l2_event_pending - Check if an event is available
134 *
135 * @fh: pointer to &struct v4l2_fh
136 *
137 * Returns the number of pending events.
138 */
139int v4l2_event_pending(struct v4l2_fh *fh);
140
141/**
142 * v4l2_event_subscribe - Subscribes to an event
143 *
144 * @fh: pointer to &struct v4l2_fh
145 * @sub: pointer to &struct v4l2_event_subscription
146 * @elems: size of the events queue
147 * @ops: pointer to &v4l2_subscribed_event_ops
148 *
149 * .. note::
150 *
151 * if @elems is zero, the framework will fill in a default value,
152 * with is currently 1 element.
153 */
154int v4l2_event_subscribe(struct v4l2_fh *fh,
155 const struct v4l2_event_subscription *sub,
156 unsigned int elems,
157 const struct v4l2_subscribed_event_ops *ops);
158/**
159 * v4l2_event_unsubscribe - Unsubscribes to an event
160 *
161 * @fh: pointer to &struct v4l2_fh
162 * @sub: pointer to &struct v4l2_event_subscription
163 */
164int v4l2_event_unsubscribe(struct v4l2_fh *fh,
165 const struct v4l2_event_subscription *sub);
166/**
167 * v4l2_event_unsubscribe_all - Unsubscribes to all events
168 *
169 * @fh: pointer to &struct v4l2_fh
170 */
171void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
172
173/**
174 * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
175 *
176 * @sd: pointer to &struct v4l2_subdev
177 * @fh: pointer to &struct v4l2_fh
178 * @sub: pointer to &struct v4l2_event_subscription
179 *
180 * .. note::
181 *
182 * This function should be used for the &struct v4l2_subdev_core_ops
183 * %unsubscribe_event field.
184 */
185int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
186 struct v4l2_fh *fh,
187 struct v4l2_event_subscription *sub);
188/**
189 * v4l2_src_change_event_subscribe - helper function that calls
190 * v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE.
191 *
192 * @fh: pointer to struct v4l2_fh
193 * @sub: pointer to &struct v4l2_event_subscription
194 */
195int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
196 const struct v4l2_event_subscription *sub);
197/**
198 * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
199 * meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
200 *
201 * @sd: pointer to &struct v4l2_subdev
202 * @fh: pointer to &struct v4l2_fh
203 * @sub: pointer to &struct v4l2_event_subscription
204 */
205int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
206 struct v4l2_fh *fh,
207 struct v4l2_event_subscription *sub);
208#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@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/**
84 * struct v4l2_subscribed_event_ops - Subscribed event operations.
85 *
86 * @add: Optional callback, called when a new listener is added
87 * @del: Optional callback, called when a listener stops listening
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 */
91struct v4l2_subscribed_event_ops {
92 int (*add)(struct v4l2_subscribed_event *sev, unsigned int elems);
93 void (*del)(struct v4l2_subscribed_event *sev);
94 void (*replace)(struct v4l2_event *old, const struct v4l2_event *new);
95 void (*merge)(const struct v4l2_event *old, struct v4l2_event *new);
96};
97
98/**
99 * struct v4l2_subscribed_event - Internal struct representing a subscribed
100 * event.
101 *
102 * @list: List node for the v4l2_fh->subscribed list.
103 * @type: Event type.
104 * @id: Associated object ID (e.g. control ID). 0 if there isn't any.
105 * @flags: Copy of v4l2_event_subscription->flags.
106 * @fh: Filehandle that subscribed to this event.
107 * @node: List node that hooks into the object's event list
108 * (if there is one).
109 * @ops: v4l2_subscribed_event_ops
110 * @elems: The number of elements in the events array.
111 * @first: The index of the events containing the oldest available event.
112 * @in_use: The number of queued events.
113 * @events: An array of @elems events.
114 */
115struct v4l2_subscribed_event {
116 struct list_head list;
117 u32 type;
118 u32 id;
119 u32 flags;
120 struct v4l2_fh *fh;
121 struct list_head node;
122 const struct v4l2_subscribed_event_ops *ops;
123 unsigned int elems;
124 unsigned int first;
125 unsigned int in_use;
126 struct v4l2_kevent events[];
127};
128
129/**
130 * v4l2_event_dequeue - Dequeue events from video device.
131 *
132 * @fh: pointer to struct v4l2_fh
133 * @event: pointer to struct v4l2_event
134 * @nonblocking: if not zero, waits for an event to arrive
135 */
136int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
137 int nonblocking);
138
139/**
140 * v4l2_event_queue - Queue events to video device.
141 *
142 * @vdev: pointer to &struct video_device
143 * @ev: pointer to &struct v4l2_event
144 *
145 * The event will be queued for all &struct v4l2_fh file handlers.
146 *
147 * .. note::
148 * The driver's only responsibility is to fill in the type and the data
149 * fields.The other fields will be filled in by V4L2.
150 */
151void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev);
152
153/**
154 * v4l2_event_queue_fh - Queue events to video device.
155 *
156 * @fh: pointer to &struct v4l2_fh
157 * @ev: pointer to &struct v4l2_event
158 *
159 *
160 * The event will be queued only for the specified &struct v4l2_fh file handler.
161 *
162 * .. note::
163 * The driver's only responsibility is to fill in the type and the data
164 * fields.The other fields will be filled in by V4L2.
165 */
166void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
167
168/**
169 * v4l2_event_pending - Check if an event is available
170 *
171 * @fh: pointer to &struct v4l2_fh
172 *
173 * Returns the number of pending events.
174 */
175int v4l2_event_pending(struct v4l2_fh *fh);
176
177/**
178 * v4l2_event_subscribe - Subscribes to an event
179 *
180 * @fh: pointer to &struct v4l2_fh
181 * @sub: pointer to &struct v4l2_event_subscription
182 * @elems: size of the events queue
183 * @ops: pointer to &v4l2_subscribed_event_ops
184 *
185 * .. note::
186 *
187 * if @elems is zero, the framework will fill in a default value,
188 * with is currently 1 element.
189 */
190int v4l2_event_subscribe(struct v4l2_fh *fh,
191 const struct v4l2_event_subscription *sub,
192 unsigned int elems,
193 const struct v4l2_subscribed_event_ops *ops);
194/**
195 * v4l2_event_unsubscribe - Unsubscribes to an event
196 *
197 * @fh: pointer to &struct v4l2_fh
198 * @sub: pointer to &struct v4l2_event_subscription
199 */
200int v4l2_event_unsubscribe(struct v4l2_fh *fh,
201 const struct v4l2_event_subscription *sub);
202/**
203 * v4l2_event_unsubscribe_all - Unsubscribes to all events
204 *
205 * @fh: pointer to &struct v4l2_fh
206 */
207void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
208
209/**
210 * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
211 *
212 * @sd: pointer to &struct v4l2_subdev
213 * @fh: pointer to &struct v4l2_fh
214 * @sub: pointer to &struct v4l2_event_subscription
215 *
216 * .. note::
217 *
218 * This function should be used for the &struct v4l2_subdev_core_ops
219 * %unsubscribe_event field.
220 */
221int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
222 struct v4l2_fh *fh,
223 struct v4l2_event_subscription *sub);
224/**
225 * v4l2_src_change_event_subscribe - helper function that calls
226 * v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE.
227 *
228 * @fh: pointer to struct v4l2_fh
229 * @sub: pointer to &struct v4l2_event_subscription
230 */
231int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
232 const struct v4l2_event_subscription *sub);
233/**
234 * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
235 * meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
236 *
237 * @sd: pointer to &struct v4l2_subdev
238 * @fh: pointer to &struct v4l2_fh
239 * @sub: pointer to &struct v4l2_event_subscription
240 */
241int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
242 struct v4l2_fh *fh,
243 struct v4l2_event_subscription *sub);
244#endif /* V4L2_EVENT_H */