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 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 
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 
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! */
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 
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 
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 
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 
181 int v4l2_event_pending(struct v4l2_fh *fh)
182 {
183 	return fh->navailable;
184 }
185 EXPORT_SYMBOL_GPL(v4l2_event_pending);
186 
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 
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 
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 
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 
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 
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 
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 
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 
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