1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * v4l2-event.c
4 *
5 * V4L2 events.
6 *
7 * Copyright (C) 2009--2010 Nokia Corporation.
8 *
9 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
10 */
11
12 #include <media/v4l2-dev.h>
13 #include <media/v4l2-fh.h>
14 #include <media/v4l2-event.h>
15
16 #include <linux/mm.h>
17 #include <linux/sched.h>
18 #include <linux/slab.h>
19 #include <linux/export.h>
20
sev_pos(const struct v4l2_subscribed_event * sev,unsigned idx)21 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
22 {
23 idx += sev->first;
24 return idx >= sev->elems ? idx - sev->elems : idx;
25 }
26
__v4l2_event_dequeue(struct v4l2_fh * fh,struct v4l2_event * event)27 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
28 {
29 struct v4l2_kevent *kev;
30 unsigned long flags;
31
32 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
33
34 if (list_empty(&fh->available)) {
35 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
36 return -ENOENT;
37 }
38
39 WARN_ON(fh->navailable == 0);
40
41 kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
42 list_del(&kev->list);
43 fh->navailable--;
44
45 kev->event.pending = fh->navailable;
46 *event = kev->event;
47 event->timestamp = ns_to_timespec(kev->ts);
48 kev->sev->first = sev_pos(kev->sev, 1);
49 kev->sev->in_use--;
50
51 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
52
53 return 0;
54 }
55
v4l2_event_dequeue(struct v4l2_fh * fh,struct v4l2_event * event,int nonblocking)56 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
57 int nonblocking)
58 {
59 int ret;
60
61 if (nonblocking)
62 return __v4l2_event_dequeue(fh, event);
63
64 /* Release the vdev lock while waiting */
65 if (fh->vdev->lock)
66 mutex_unlock(fh->vdev->lock);
67
68 do {
69 ret = wait_event_interruptible(fh->wait,
70 fh->navailable != 0);
71 if (ret < 0)
72 break;
73
74 ret = __v4l2_event_dequeue(fh, event);
75 } while (ret == -ENOENT);
76
77 if (fh->vdev->lock)
78 mutex_lock(fh->vdev->lock);
79
80 return ret;
81 }
82 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
83
84 /* Caller must hold fh->vdev->fh_lock! */
v4l2_event_subscribed(struct v4l2_fh * fh,u32 type,u32 id)85 static struct v4l2_subscribed_event *v4l2_event_subscribed(
86 struct v4l2_fh *fh, u32 type, u32 id)
87 {
88 struct v4l2_subscribed_event *sev;
89
90 assert_spin_locked(&fh->vdev->fh_lock);
91
92 list_for_each_entry(sev, &fh->subscribed, list)
93 if (sev->type == type && sev->id == id)
94 return sev;
95
96 return NULL;
97 }
98
__v4l2_event_queue_fh(struct v4l2_fh * fh,const struct v4l2_event * ev,u64 ts)99 static void __v4l2_event_queue_fh(struct v4l2_fh *fh,
100 const struct v4l2_event *ev, u64 ts)
101 {
102 struct v4l2_subscribed_event *sev;
103 struct v4l2_kevent *kev;
104 bool copy_payload = true;
105
106 /* Are we subscribed? */
107 sev = v4l2_event_subscribed(fh, ev->type, ev->id);
108 if (sev == NULL)
109 return;
110
111 /* Increase event sequence number on fh. */
112 fh->sequence++;
113
114 /* Do we have any free events? */
115 if (sev->in_use == sev->elems) {
116 /* no, remove the oldest one */
117 kev = sev->events + sev_pos(sev, 0);
118 list_del(&kev->list);
119 sev->in_use--;
120 sev->first = sev_pos(sev, 1);
121 fh->navailable--;
122 if (sev->elems == 1) {
123 if (sev->ops && sev->ops->replace) {
124 sev->ops->replace(&kev->event, ev);
125 copy_payload = false;
126 }
127 } else if (sev->ops && sev->ops->merge) {
128 struct v4l2_kevent *second_oldest =
129 sev->events + sev_pos(sev, 0);
130 sev->ops->merge(&kev->event, &second_oldest->event);
131 }
132 }
133
134 /* Take one and fill it. */
135 kev = sev->events + sev_pos(sev, sev->in_use);
136 kev->event.type = ev->type;
137 if (copy_payload)
138 kev->event.u = ev->u;
139 kev->event.id = ev->id;
140 kev->ts = ts;
141 kev->event.sequence = fh->sequence;
142 sev->in_use++;
143 list_add_tail(&kev->list, &fh->available);
144
145 fh->navailable++;
146
147 wake_up_all(&fh->wait);
148 }
149
v4l2_event_queue(struct video_device * vdev,const struct v4l2_event * ev)150 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
151 {
152 struct v4l2_fh *fh;
153 unsigned long flags;
154 u64 ts;
155
156 if (vdev == NULL)
157 return;
158
159 ts = ktime_get_ns();
160
161 spin_lock_irqsave(&vdev->fh_lock, flags);
162
163 list_for_each_entry(fh, &vdev->fh_list, list)
164 __v4l2_event_queue_fh(fh, ev, ts);
165
166 spin_unlock_irqrestore(&vdev->fh_lock, flags);
167 }
168 EXPORT_SYMBOL_GPL(v4l2_event_queue);
169
v4l2_event_queue_fh(struct v4l2_fh * fh,const struct v4l2_event * ev)170 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
171 {
172 unsigned long flags;
173 u64 ts = ktime_get_ns();
174
175 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
176 __v4l2_event_queue_fh(fh, ev, ts);
177 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
178 }
179 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
180
v4l2_event_pending(struct v4l2_fh * fh)181 int v4l2_event_pending(struct v4l2_fh *fh)
182 {
183 return fh->navailable;
184 }
185 EXPORT_SYMBOL_GPL(v4l2_event_pending);
186
__v4l2_event_unsubscribe(struct v4l2_subscribed_event * sev)187 static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
188 {
189 struct v4l2_fh *fh = sev->fh;
190 unsigned int i;
191
192 lockdep_assert_held(&fh->subscribe_lock);
193 assert_spin_locked(&fh->vdev->fh_lock);
194
195 /* Remove any pending events for this subscription */
196 for (i = 0; i < sev->in_use; i++) {
197 list_del(&sev->events[sev_pos(sev, i)].list);
198 fh->navailable--;
199 }
200 list_del(&sev->list);
201 }
202
v4l2_event_subscribe(struct v4l2_fh * fh,const struct v4l2_event_subscription * sub,unsigned elems,const struct v4l2_subscribed_event_ops * ops)203 int v4l2_event_subscribe(struct v4l2_fh *fh,
204 const struct v4l2_event_subscription *sub, unsigned elems,
205 const struct v4l2_subscribed_event_ops *ops)
206 {
207 struct v4l2_subscribed_event *sev, *found_ev;
208 unsigned long flags;
209 unsigned i;
210 int ret = 0;
211
212 if (sub->type == V4L2_EVENT_ALL)
213 return -EINVAL;
214
215 if (elems < 1)
216 elems = 1;
217
218 sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
219 if (!sev)
220 return -ENOMEM;
221 for (i = 0; i < elems; i++)
222 sev->events[i].sev = sev;
223 sev->type = sub->type;
224 sev->id = sub->id;
225 sev->flags = sub->flags;
226 sev->fh = fh;
227 sev->ops = ops;
228 sev->elems = elems;
229
230 mutex_lock(&fh->subscribe_lock);
231
232 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
233 found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
234 if (!found_ev)
235 list_add(&sev->list, &fh->subscribed);
236 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
237
238 if (found_ev) {
239 /* Already listening */
240 kvfree(sev);
241 } else if (sev->ops && sev->ops->add) {
242 ret = sev->ops->add(sev, elems);
243 if (ret) {
244 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
245 __v4l2_event_unsubscribe(sev);
246 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
247 kvfree(sev);
248 }
249 }
250
251 mutex_unlock(&fh->subscribe_lock);
252
253 return ret;
254 }
255 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
256
v4l2_event_unsubscribe_all(struct v4l2_fh * fh)257 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
258 {
259 struct v4l2_event_subscription sub;
260 struct v4l2_subscribed_event *sev;
261 unsigned long flags;
262
263 do {
264 sev = NULL;
265
266 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
267 if (!list_empty(&fh->subscribed)) {
268 sev = list_first_entry(&fh->subscribed,
269 struct v4l2_subscribed_event, list);
270 sub.type = sev->type;
271 sub.id = sev->id;
272 }
273 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
274 if (sev)
275 v4l2_event_unsubscribe(fh, &sub);
276 } while (sev);
277 }
278 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
279
v4l2_event_unsubscribe(struct v4l2_fh * fh,const struct v4l2_event_subscription * sub)280 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
281 const struct v4l2_event_subscription *sub)
282 {
283 struct v4l2_subscribed_event *sev;
284 unsigned long flags;
285
286 if (sub->type == V4L2_EVENT_ALL) {
287 v4l2_event_unsubscribe_all(fh);
288 return 0;
289 }
290
291 mutex_lock(&fh->subscribe_lock);
292
293 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
294
295 sev = v4l2_event_subscribed(fh, sub->type, sub->id);
296 if (sev != NULL)
297 __v4l2_event_unsubscribe(sev);
298
299 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
300
301 if (sev && sev->ops && sev->ops->del)
302 sev->ops->del(sev);
303
304 mutex_unlock(&fh->subscribe_lock);
305
306 kvfree(sev);
307
308 return 0;
309 }
310 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
311
v4l2_event_subdev_unsubscribe(struct v4l2_subdev * sd,struct v4l2_fh * fh,struct v4l2_event_subscription * sub)312 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
313 struct v4l2_event_subscription *sub)
314 {
315 return v4l2_event_unsubscribe(fh, sub);
316 }
317 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
318
v4l2_event_src_replace(struct v4l2_event * old,const struct v4l2_event * new)319 static void v4l2_event_src_replace(struct v4l2_event *old,
320 const struct v4l2_event *new)
321 {
322 u32 old_changes = old->u.src_change.changes;
323
324 old->u.src_change = new->u.src_change;
325 old->u.src_change.changes |= old_changes;
326 }
327
v4l2_event_src_merge(const struct v4l2_event * old,struct v4l2_event * new)328 static void v4l2_event_src_merge(const struct v4l2_event *old,
329 struct v4l2_event *new)
330 {
331 new->u.src_change.changes |= old->u.src_change.changes;
332 }
333
334 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
335 .replace = v4l2_event_src_replace,
336 .merge = v4l2_event_src_merge,
337 };
338
v4l2_src_change_event_subscribe(struct v4l2_fh * fh,const struct v4l2_event_subscription * sub)339 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
340 const struct v4l2_event_subscription *sub)
341 {
342 if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
343 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
344 return -EINVAL;
345 }
346 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
347
v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev * sd,struct v4l2_fh * fh,struct v4l2_event_subscription * sub)348 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
349 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
350 {
351 return v4l2_src_change_event_subscribe(fh, sub);
352 }
353 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);
354
