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 int v4l2_event_subscribe(struct v4l2_fh *fh,
197 			 const struct v4l2_event_subscription *sub, unsigned elems,
198 			 const struct v4l2_subscribed_event_ops *ops)
199 {
200 	struct v4l2_subscribed_event *sev, *found_ev;
201 	unsigned long flags;
202 	unsigned i;
203 	int ret = 0;
204 
205 	if (sub->type == V4L2_EVENT_ALL)
206 		return -EINVAL;
207 
208 	if (elems < 1)
209 		elems = 1;
210 
211 	sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
212 	if (!sev)
213 		return -ENOMEM;
214 	for (i = 0; i < elems; i++)
215 		sev->events[i].sev = sev;
216 	sev->type = sub->type;
217 	sev->id = sub->id;
218 	sev->flags = sub->flags;
219 	sev->fh = fh;
220 	sev->ops = ops;
221 	sev->elems = elems;
222 
223 	mutex_lock(&fh->subscribe_lock);
224 
225 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
226 	found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
227 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
228 
229 	if (found_ev) {
230 		/* Already listening */
231 		kvfree(sev);
232 		goto out_unlock;
233 	}
234 
235 	if (sev->ops && sev->ops->add) {
236 		ret = sev->ops->add(sev, elems);
237 		if (ret) {
238 			kvfree(sev);
239 			goto out_unlock;
240 		}
241 	}
242 
243 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
244 	list_add(&sev->list, &fh->subscribed);
245 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
246 
247 out_unlock:
248 	mutex_unlock(&fh->subscribe_lock);
249 
250 	return ret;
251 }
252 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
253 
254 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
255 {
256 	struct v4l2_event_subscription sub;
257 	struct v4l2_subscribed_event *sev;
258 	unsigned long flags;
259 
260 	do {
261 		sev = NULL;
262 
263 		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
264 		if (!list_empty(&fh->subscribed)) {
265 			sev = list_first_entry(&fh->subscribed,
266 					struct v4l2_subscribed_event, list);
267 			sub.type = sev->type;
268 			sub.id = sev->id;
269 		}
270 		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
271 		if (sev)
272 			v4l2_event_unsubscribe(fh, &sub);
273 	} while (sev);
274 }
275 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
276 
277 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
278 			   const struct v4l2_event_subscription *sub)
279 {
280 	struct v4l2_subscribed_event *sev;
281 	unsigned long flags;
282 	int i;
283 
284 	if (sub->type == V4L2_EVENT_ALL) {
285 		v4l2_event_unsubscribe_all(fh);
286 		return 0;
287 	}
288 
289 	mutex_lock(&fh->subscribe_lock);
290 
291 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
292 
293 	sev = v4l2_event_subscribed(fh, sub->type, sub->id);
294 	if (sev != NULL) {
295 		/* Remove any pending events for this subscription */
296 		for (i = 0; i < sev->in_use; i++) {
297 			list_del(&sev->events[sev_pos(sev, i)].list);
298 			fh->navailable--;
299 		}
300 		list_del(&sev->list);
301 	}
302 
303 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
304 
305 	if (sev && sev->ops && sev->ops->del)
306 		sev->ops->del(sev);
307 
308 	mutex_unlock(&fh->subscribe_lock);
309 
310 	kvfree(sev);
311 
312 	return 0;
313 }
314 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
315 
316 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
317 				  struct v4l2_event_subscription *sub)
318 {
319 	return v4l2_event_unsubscribe(fh, sub);
320 }
321 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
322 
323 static void v4l2_event_src_replace(struct v4l2_event *old,
324 				const struct v4l2_event *new)
325 {
326 	u32 old_changes = old->u.src_change.changes;
327 
328 	old->u.src_change = new->u.src_change;
329 	old->u.src_change.changes |= old_changes;
330 }
331 
332 static void v4l2_event_src_merge(const struct v4l2_event *old,
333 				struct v4l2_event *new)
334 {
335 	new->u.src_change.changes |= old->u.src_change.changes;
336 }
337 
338 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
339 	.replace = v4l2_event_src_replace,
340 	.merge = v4l2_event_src_merge,
341 };
342 
343 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
344 				const struct v4l2_event_subscription *sub)
345 {
346 	if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
347 		return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
348 	return -EINVAL;
349 }
350 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
351 
352 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
353 		struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
354 {
355 	return v4l2_src_change_event_subscribe(fh, sub);
356 }
357 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);
358