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 
21 static unsigned int sev_pos(const struct v4l2_subscribed_event *sev, unsigned int idx)
22 {
23 	idx += sev->first;
24 	return idx >= sev->elems ? idx - sev->elems : idx;
25 }
26 
27 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
28 {
29 	struct v4l2_kevent *kev;
30 	struct timespec64 ts;
31 	unsigned long flags;
32 
33 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
34 
35 	if (list_empty(&fh->available)) {
36 		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
37 		return -ENOENT;
38 	}
39 
40 	WARN_ON(fh->navailable == 0);
41 
42 	kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
43 	list_del(&kev->list);
44 	fh->navailable--;
45 
46 	kev->event.pending = fh->navailable;
47 	*event = kev->event;
48 	ts = ns_to_timespec64(kev->ts);
49 	event->timestamp.tv_sec = ts.tv_sec;
50 	event->timestamp.tv_nsec = ts.tv_nsec;
51 	kev->sev->first = sev_pos(kev->sev, 1);
52 	kev->sev->in_use--;
53 
54 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
55 
56 	return 0;
57 }
58 
59 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
60 		       int nonblocking)
61 {
62 	int ret;
63 
64 	if (nonblocking)
65 		return __v4l2_event_dequeue(fh, event);
66 
67 	/* Release the vdev lock while waiting */
68 	if (fh->vdev->lock)
69 		mutex_unlock(fh->vdev->lock);
70 
71 	do {
72 		ret = wait_event_interruptible(fh->wait,
73 					       fh->navailable != 0);
74 		if (ret < 0)
75 			break;
76 
77 		ret = __v4l2_event_dequeue(fh, event);
78 	} while (ret == -ENOENT);
79 
80 	if (fh->vdev->lock)
81 		mutex_lock(fh->vdev->lock);
82 
83 	return ret;
84 }
85 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
86 
87 /* Caller must hold fh->vdev->fh_lock! */
88 static struct v4l2_subscribed_event *v4l2_event_subscribed(
89 		struct v4l2_fh *fh, u32 type, u32 id)
90 {
91 	struct v4l2_subscribed_event *sev;
92 
93 	assert_spin_locked(&fh->vdev->fh_lock);
94 
95 	list_for_each_entry(sev, &fh->subscribed, list)
96 		if (sev->type == type && sev->id == id)
97 			return sev;
98 
99 	return NULL;
100 }
101 
102 static void __v4l2_event_queue_fh(struct v4l2_fh *fh,
103 				  const struct v4l2_event *ev, u64 ts)
104 {
105 	struct v4l2_subscribed_event *sev;
106 	struct v4l2_kevent *kev;
107 	bool copy_payload = true;
108 
109 	/* Are we subscribed? */
110 	sev = v4l2_event_subscribed(fh, ev->type, ev->id);
111 	if (sev == NULL)
112 		return;
113 
114 	/* Increase event sequence number on fh. */
115 	fh->sequence++;
116 
117 	/* Do we have any free events? */
118 	if (sev->in_use == sev->elems) {
119 		/* no, remove the oldest one */
120 		kev = sev->events + sev_pos(sev, 0);
121 		list_del(&kev->list);
122 		sev->in_use--;
123 		sev->first = sev_pos(sev, 1);
124 		fh->navailable--;
125 		if (sev->elems == 1) {
126 			if (sev->ops && sev->ops->replace) {
127 				sev->ops->replace(&kev->event, ev);
128 				copy_payload = false;
129 			}
130 		} else if (sev->ops && sev->ops->merge) {
131 			struct v4l2_kevent *second_oldest =
132 				sev->events + sev_pos(sev, 0);
133 			sev->ops->merge(&kev->event, &second_oldest->event);
134 		}
135 	}
136 
137 	/* Take one and fill it. */
138 	kev = sev->events + sev_pos(sev, sev->in_use);
139 	kev->event.type = ev->type;
140 	if (copy_payload)
141 		kev->event.u = ev->u;
142 	kev->event.id = ev->id;
143 	kev->ts = ts;
144 	kev->event.sequence = fh->sequence;
145 	sev->in_use++;
146 	list_add_tail(&kev->list, &fh->available);
147 
148 	fh->navailable++;
149 
150 	wake_up_all(&fh->wait);
151 }
152 
153 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
154 {
155 	struct v4l2_fh *fh;
156 	unsigned long flags;
157 	u64 ts;
158 
159 	if (vdev == NULL)
160 		return;
161 
162 	ts = ktime_get_ns();
163 
164 	spin_lock_irqsave(&vdev->fh_lock, flags);
165 
166 	list_for_each_entry(fh, &vdev->fh_list, list)
167 		__v4l2_event_queue_fh(fh, ev, ts);
168 
169 	spin_unlock_irqrestore(&vdev->fh_lock, flags);
170 }
171 EXPORT_SYMBOL_GPL(v4l2_event_queue);
172 
173 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
174 {
175 	unsigned long flags;
176 	u64 ts = ktime_get_ns();
177 
178 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
179 	__v4l2_event_queue_fh(fh, ev, ts);
180 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
181 }
182 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
183 
184 int v4l2_event_pending(struct v4l2_fh *fh)
185 {
186 	return fh->navailable;
187 }
188 EXPORT_SYMBOL_GPL(v4l2_event_pending);
189 
190 void v4l2_event_wake_all(struct video_device *vdev)
191 {
192 	struct v4l2_fh *fh;
193 	unsigned long flags;
194 
195 	if (!vdev)
196 		return;
197 
198 	spin_lock_irqsave(&vdev->fh_lock, flags);
199 
200 	list_for_each_entry(fh, &vdev->fh_list, list)
201 		wake_up_all(&fh->wait);
202 
203 	spin_unlock_irqrestore(&vdev->fh_lock, flags);
204 }
205 EXPORT_SYMBOL_GPL(v4l2_event_wake_all);
206 
207 static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
208 {
209 	struct v4l2_fh *fh = sev->fh;
210 	unsigned int i;
211 
212 	lockdep_assert_held(&fh->subscribe_lock);
213 	assert_spin_locked(&fh->vdev->fh_lock);
214 
215 	/* Remove any pending events for this subscription */
216 	for (i = 0; i < sev->in_use; i++) {
217 		list_del(&sev->events[sev_pos(sev, i)].list);
218 		fh->navailable--;
219 	}
220 	list_del(&sev->list);
221 }
222 
223 int v4l2_event_subscribe(struct v4l2_fh *fh,
224 			 const struct v4l2_event_subscription *sub, unsigned int elems,
225 			 const struct v4l2_subscribed_event_ops *ops)
226 {
227 	struct v4l2_subscribed_event *sev, *found_ev;
228 	unsigned long flags;
229 	unsigned int i;
230 	int ret = 0;
231 
232 	if (sub->type == V4L2_EVENT_ALL)
233 		return -EINVAL;
234 
235 	if (elems < 1)
236 		elems = 1;
237 
238 	sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
239 	if (!sev)
240 		return -ENOMEM;
241 	for (i = 0; i < elems; i++)
242 		sev->events[i].sev = sev;
243 	sev->type = sub->type;
244 	sev->id = sub->id;
245 	sev->flags = sub->flags;
246 	sev->fh = fh;
247 	sev->ops = ops;
248 	sev->elems = elems;
249 
250 	mutex_lock(&fh->subscribe_lock);
251 
252 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
253 	found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
254 	if (!found_ev)
255 		list_add(&sev->list, &fh->subscribed);
256 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
257 
258 	if (found_ev) {
259 		/* Already listening */
260 		kvfree(sev);
261 	} else if (sev->ops && sev->ops->add) {
262 		ret = sev->ops->add(sev, elems);
263 		if (ret) {
264 			spin_lock_irqsave(&fh->vdev->fh_lock, flags);
265 			__v4l2_event_unsubscribe(sev);
266 			spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
267 			kvfree(sev);
268 		}
269 	}
270 
271 	mutex_unlock(&fh->subscribe_lock);
272 
273 	return ret;
274 }
275 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
276 
277 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
278 {
279 	struct v4l2_event_subscription sub;
280 	struct v4l2_subscribed_event *sev;
281 	unsigned long flags;
282 
283 	do {
284 		sev = NULL;
285 
286 		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
287 		if (!list_empty(&fh->subscribed)) {
288 			sev = list_first_entry(&fh->subscribed,
289 					struct v4l2_subscribed_event, list);
290 			sub.type = sev->type;
291 			sub.id = sev->id;
292 		}
293 		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
294 		if (sev)
295 			v4l2_event_unsubscribe(fh, &sub);
296 	} while (sev);
297 }
298 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
299 
300 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
301 			   const struct v4l2_event_subscription *sub)
302 {
303 	struct v4l2_subscribed_event *sev;
304 	unsigned long flags;
305 
306 	if (sub->type == V4L2_EVENT_ALL) {
307 		v4l2_event_unsubscribe_all(fh);
308 		return 0;
309 	}
310 
311 	mutex_lock(&fh->subscribe_lock);
312 
313 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
314 
315 	sev = v4l2_event_subscribed(fh, sub->type, sub->id);
316 	if (sev != NULL)
317 		__v4l2_event_unsubscribe(sev);
318 
319 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
320 
321 	if (sev && sev->ops && sev->ops->del)
322 		sev->ops->del(sev);
323 
324 	mutex_unlock(&fh->subscribe_lock);
325 
326 	kvfree(sev);
327 
328 	return 0;
329 }
330 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
331 
332 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
333 				  struct v4l2_event_subscription *sub)
334 {
335 	return v4l2_event_unsubscribe(fh, sub);
336 }
337 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
338 
339 static void v4l2_event_src_replace(struct v4l2_event *old,
340 				const struct v4l2_event *new)
341 {
342 	u32 old_changes = old->u.src_change.changes;
343 
344 	old->u.src_change = new->u.src_change;
345 	old->u.src_change.changes |= old_changes;
346 }
347 
348 static void v4l2_event_src_merge(const struct v4l2_event *old,
349 				struct v4l2_event *new)
350 {
351 	new->u.src_change.changes |= old->u.src_change.changes;
352 }
353 
354 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
355 	.replace = v4l2_event_src_replace,
356 	.merge = v4l2_event_src_merge,
357 };
358 
359 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
360 				const struct v4l2_event_subscription *sub)
361 {
362 	if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
363 		return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
364 	return -EINVAL;
365 }
366 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
367 
368 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
369 		struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
370 {
371 	return v4l2_src_change_event_subscribe(fh, sub);
372 }
373 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);
374