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
19 struct v4l2_fh;
20 struct v4l2_subdev;
21 struct v4l2_subscribed_event;
22 struct 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 */
31 struct 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 */
46 struct 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 */
70 struct 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[];
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 */
91 int 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 */
106 void 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 */
121 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev);
122
123 /**
124 * v4l2_event_pending - Check if an event is available
125 *
126 * @fh: pointer to &struct v4l2_fh
127 *
128 * Returns the number of pending events.
129 */
130 int v4l2_event_pending(struct v4l2_fh *fh);
131
132 /**
133 * v4l2_event_subscribe - Subscribes to an event
134 *
135 * @fh: pointer to &struct v4l2_fh
136 * @sub: pointer to &struct v4l2_event_subscription
137 * @elems: size of the events queue
138 * @ops: pointer to &v4l2_subscribed_event_ops
139 *
140 * .. note::
141 *
142 * if @elems is zero, the framework will fill in a default value,
143 * with is currently 1 element.
144 */
145 int v4l2_event_subscribe(struct v4l2_fh *fh,
146 const struct v4l2_event_subscription *sub,
147 unsigned int elems,
148 const struct v4l2_subscribed_event_ops *ops);
149 /**
150 * v4l2_event_unsubscribe - Unsubscribes to an event
151 *
152 * @fh: pointer to &struct v4l2_fh
153 * @sub: pointer to &struct v4l2_event_subscription
154 */
155 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
156 const struct v4l2_event_subscription *sub);
157 /**
158 * v4l2_event_unsubscribe_all - Unsubscribes to all events
159 *
160 * @fh: pointer to &struct v4l2_fh
161 */
162 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
163
164 /**
165 * v4l2_event_subdev_unsubscribe - Subdev variant of v4l2_event_unsubscribe()
166 *
167 * @sd: pointer to &struct v4l2_subdev
168 * @fh: pointer to &struct v4l2_fh
169 * @sub: pointer to &struct v4l2_event_subscription
170 *
171 * .. note::
172 *
173 * This function should be used for the &struct v4l2_subdev_core_ops
174 * %unsubscribe_event field.
175 */
176 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd,
177 struct v4l2_fh *fh,
178 struct v4l2_event_subscription *sub);
179 /**
180 * v4l2_src_change_event_subscribe - helper function that calls
181 * v4l2_event_subscribe() if the event is %V4L2_EVENT_SOURCE_CHANGE.
182 *
183 * @fh: pointer to struct v4l2_fh
184 * @sub: pointer to &struct v4l2_event_subscription
185 */
186 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
187 const struct v4l2_event_subscription *sub);
188 /**
189 * v4l2_src_change_event_subdev_subscribe - Variant of v4l2_event_subscribe(),
190 * meant to subscribe only events of the type %V4L2_EVENT_SOURCE_CHANGE.
191 *
192 * @sd: pointer to &struct v4l2_subdev
193 * @fh: pointer to &struct v4l2_fh
194 * @sub: pointer to &struct v4l2_event_subscription
195 */
196 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
197 struct v4l2_fh *fh,
198 struct v4l2_event_subscription *sub);
199 #endif /* V4L2_EVENT_H */