1 /*
2  * v4l2-event.c
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 
20 #include <media/v4l2-dev.h>
21 #include <media/v4l2-fh.h>
22 #include <media/v4l2-event.h>
23 
24 #include <linux/mm.h>
25 #include <linux/sched.h>
26 #include <linux/slab.h>
27 #include <linux/export.h>
28 
29 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
30 {
31 	idx += sev->first;
32 	return idx >= sev->elems ? idx - sev->elems : idx;
33 }
34 
35 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
36 {
37 	struct v4l2_kevent *kev;
38 	unsigned long flags;
39 
40 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
41 
42 	if (list_empty(&fh->available)) {
43 		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
44 		return -ENOENT;
45 	}
46 
47 	WARN_ON(fh->navailable == 0);
48 
49 	kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
50 	list_del(&kev->list);
51 	fh->navailable--;
52 
53 	kev->event.pending = fh->navailable;
54 	*event = kev->event;
55 	kev->sev->first = sev_pos(kev->sev, 1);
56 	kev->sev->in_use--;
57 
58 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
59 
60 	return 0;
61 }
62 
63 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
64 		       int nonblocking)
65 {
66 	int ret;
67 
68 	if (nonblocking)
69 		return __v4l2_event_dequeue(fh, event);
70 
71 	/* Release the vdev lock while waiting */
72 	if (fh->vdev->lock)
73 		mutex_unlock(fh->vdev->lock);
74 
75 	do {
76 		ret = wait_event_interruptible(fh->wait,
77 					       fh->navailable != 0);
78 		if (ret < 0)
79 			break;
80 
81 		ret = __v4l2_event_dequeue(fh, event);
82 	} while (ret == -ENOENT);
83 
84 	if (fh->vdev->lock)
85 		mutex_lock(fh->vdev->lock);
86 
87 	return ret;
88 }
89 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
90 
91 /* Caller must hold fh->vdev->fh_lock! */
92 static struct v4l2_subscribed_event *v4l2_event_subscribed(
93 		struct v4l2_fh *fh, u32 type, u32 id)
94 {
95 	struct v4l2_subscribed_event *sev;
96 
97 	assert_spin_locked(&fh->vdev->fh_lock);
98 
99 	list_for_each_entry(sev, &fh->subscribed, list)
100 		if (sev->type == type && sev->id == id)
101 			return sev;
102 
103 	return NULL;
104 }
105 
106 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
107 		const struct timespec *ts)
108 {
109 	struct v4l2_subscribed_event *sev;
110 	struct v4l2_kevent *kev;
111 	bool copy_payload = true;
112 
113 	/* Are we subscribed? */
114 	sev = v4l2_event_subscribed(fh, ev->type, ev->id);
115 	if (sev == NULL)
116 		return;
117 
118 	/* Increase event sequence number on fh. */
119 	fh->sequence++;
120 
121 	/* Do we have any free events? */
122 	if (sev->in_use == sev->elems) {
123 		/* no, remove the oldest one */
124 		kev = sev->events + sev_pos(sev, 0);
125 		list_del(&kev->list);
126 		sev->in_use--;
127 		sev->first = sev_pos(sev, 1);
128 		fh->navailable--;
129 		if (sev->elems == 1) {
130 			if (sev->ops && sev->ops->replace) {
131 				sev->ops->replace(&kev->event, ev);
132 				copy_payload = false;
133 			}
134 		} else if (sev->ops && sev->ops->merge) {
135 			struct v4l2_kevent *second_oldest =
136 				sev->events + sev_pos(sev, 0);
137 			sev->ops->merge(&kev->event, &second_oldest->event);
138 		}
139 	}
140 
141 	/* Take one and fill it. */
142 	kev = sev->events + sev_pos(sev, sev->in_use);
143 	kev->event.type = ev->type;
144 	if (copy_payload)
145 		kev->event.u = ev->u;
146 	kev->event.id = ev->id;
147 	kev->event.timestamp = *ts;
148 	kev->event.sequence = fh->sequence;
149 	sev->in_use++;
150 	list_add_tail(&kev->list, &fh->available);
151 
152 	fh->navailable++;
153 
154 	wake_up_all(&fh->wait);
155 }
156 
157 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
158 {
159 	struct v4l2_fh *fh;
160 	unsigned long flags;
161 	struct timespec timestamp;
162 
163 	if (vdev == NULL)
164 		return;
165 
166 	ktime_get_ts(&timestamp);
167 
168 	spin_lock_irqsave(&vdev->fh_lock, flags);
169 
170 	list_for_each_entry(fh, &vdev->fh_list, list)
171 		__v4l2_event_queue_fh(fh, ev, &timestamp);
172 
173 	spin_unlock_irqrestore(&vdev->fh_lock, flags);
174 }
175 EXPORT_SYMBOL_GPL(v4l2_event_queue);
176 
177 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
178 {
179 	unsigned long flags;
180 	struct timespec timestamp;
181 
182 	ktime_get_ts(&timestamp);
183 
184 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
185 	__v4l2_event_queue_fh(fh, ev, &timestamp);
186 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
187 }
188 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
189 
190 int v4l2_event_pending(struct v4l2_fh *fh)
191 {
192 	return fh->navailable;
193 }
194 EXPORT_SYMBOL_GPL(v4l2_event_pending);
195 
196 static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
197 {
198 	struct v4l2_fh *fh = sev->fh;
199 	unsigned int i;
200 
201 	lockdep_assert_held(&fh->subscribe_lock);
202 	assert_spin_locked(&fh->vdev->fh_lock);
203 
204 	/* Remove any pending events for this subscription */
205 	for (i = 0; i < sev->in_use; i++) {
206 		list_del(&sev->events[sev_pos(sev, i)].list);
207 		fh->navailable--;
208 	}
209 	list_del(&sev->list);
210 }
211 
212 int v4l2_event_subscribe(struct v4l2_fh *fh,
213 			 const struct v4l2_event_subscription *sub, unsigned elems,
214 			 const struct v4l2_subscribed_event_ops *ops)
215 {
216 	struct v4l2_subscribed_event *sev, *found_ev;
217 	unsigned long flags;
218 	unsigned i;
219 	int ret = 0;
220 
221 	if (sub->type == V4L2_EVENT_ALL)
222 		return -EINVAL;
223 
224 	if (elems < 1)
225 		elems = 1;
226 
227 	sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
228 	if (!sev)
229 		return -ENOMEM;
230 	for (i = 0; i < elems; i++)
231 		sev->events[i].sev = sev;
232 	sev->type = sub->type;
233 	sev->id = sub->id;
234 	sev->flags = sub->flags;
235 	sev->fh = fh;
236 	sev->ops = ops;
237 	sev->elems = elems;
238 
239 	mutex_lock(&fh->subscribe_lock);
240 
241 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
242 	found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
243 	if (!found_ev)
244 		list_add(&sev->list, &fh->subscribed);
245 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
246 
247 	if (found_ev) {
248 		/* Already listening */
249 		kvfree(sev);
250 	} else if (sev->ops && sev->ops->add) {
251 		ret = sev->ops->add(sev, elems);
252 		if (ret) {
253 			spin_lock_irqsave(&fh->vdev->fh_lock, flags);
254 			__v4l2_event_unsubscribe(sev);
255 			spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
256 			kvfree(sev);
257 		}
258 	}
259 
260 	mutex_unlock(&fh->subscribe_lock);
261 
262 	return ret;
263 }
264 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
265 
266 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
267 {
268 	struct v4l2_event_subscription sub;
269 	struct v4l2_subscribed_event *sev;
270 	unsigned long flags;
271 
272 	do {
273 		sev = NULL;
274 
275 		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
276 		if (!list_empty(&fh->subscribed)) {
277 			sev = list_first_entry(&fh->subscribed,
278 					struct v4l2_subscribed_event, list);
279 			sub.type = sev->type;
280 			sub.id = sev->id;
281 		}
282 		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
283 		if (sev)
284 			v4l2_event_unsubscribe(fh, &sub);
285 	} while (sev);
286 }
287 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
288 
289 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
290 			   const struct v4l2_event_subscription *sub)
291 {
292 	struct v4l2_subscribed_event *sev;
293 	unsigned long flags;
294 
295 	if (sub->type == V4L2_EVENT_ALL) {
296 		v4l2_event_unsubscribe_all(fh);
297 		return 0;
298 	}
299 
300 	mutex_lock(&fh->subscribe_lock);
301 
302 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
303 
304 	sev = v4l2_event_subscribed(fh, sub->type, sub->id);
305 	if (sev != NULL)
306 		__v4l2_event_unsubscribe(sev);
307 
308 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
309 
310 	if (sev && sev->ops && sev->ops->del)
311 		sev->ops->del(sev);
312 
313 	mutex_unlock(&fh->subscribe_lock);
314 
315 	kvfree(sev);
316 
317 	return 0;
318 }
319 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
320 
321 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
322 				  struct v4l2_event_subscription *sub)
323 {
324 	return v4l2_event_unsubscribe(fh, sub);
325 }
326 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
327 
328 static void v4l2_event_src_replace(struct v4l2_event *old,
329 				const struct v4l2_event *new)
330 {
331 	u32 old_changes = old->u.src_change.changes;
332 
333 	old->u.src_change = new->u.src_change;
334 	old->u.src_change.changes |= old_changes;
335 }
336 
337 static void v4l2_event_src_merge(const struct v4l2_event *old,
338 				struct v4l2_event *new)
339 {
340 	new->u.src_change.changes |= old->u.src_change.changes;
341 }
342 
343 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
344 	.replace = v4l2_event_src_replace,
345 	.merge = v4l2_event_src_merge,
346 };
347 
348 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
349 				const struct v4l2_event_subscription *sub)
350 {
351 	if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
352 		return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
353 	return -EINVAL;
354 }
355 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
356 
357 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
358 		struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
359 {
360 	return v4l2_src_change_event_subscribe(fh, sub);
361 }
362 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);
363