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 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA
23 */
24
25#include <media/v4l2-dev.h>
26#include <media/v4l2-fh.h>
27#include <media/v4l2-event.h>
28
29#include <linux/sched.h>
30#include <linux/slab.h>
31#include <linux/export.h>
32
33static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
34{
35	idx += sev->first;
36	return idx >= sev->elems ? idx - sev->elems : idx;
37}
38
39static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
40{
41	struct v4l2_kevent *kev;
42	unsigned long flags;
43
44	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
45
46	if (list_empty(&fh->available)) {
47		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
48		return -ENOENT;
49	}
50
51	WARN_ON(fh->navailable == 0);
52
53	kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
54	list_del(&kev->list);
55	fh->navailable--;
56
57	kev->event.pending = fh->navailable;
58	*event = kev->event;
59	kev->sev->first = sev_pos(kev->sev, 1);
60	kev->sev->in_use--;
61
62	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
63
64	return 0;
65}
66
67int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
68		       int nonblocking)
69{
70	int ret;
71
72	if (nonblocking)
73		return __v4l2_event_dequeue(fh, event);
74
75	/* Release the vdev lock while waiting */
76	if (fh->vdev->lock)
77		mutex_unlock(fh->vdev->lock);
78
79	do {
80		ret = wait_event_interruptible(fh->wait,
81					       fh->navailable != 0);
82		if (ret < 0)
83			break;
84
85		ret = __v4l2_event_dequeue(fh, event);
86	} while (ret == -ENOENT);
87
88	if (fh->vdev->lock)
89		mutex_lock(fh->vdev->lock);
90
91	return ret;
92}
93EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
94
95/* Caller must hold fh->vdev->fh_lock! */
96static struct v4l2_subscribed_event *v4l2_event_subscribed(
97		struct v4l2_fh *fh, u32 type, u32 id)
98{
99	struct v4l2_subscribed_event *sev;
100
101	assert_spin_locked(&fh->vdev->fh_lock);
102
103	list_for_each_entry(sev, &fh->subscribed, list)
104		if (sev->type == type && sev->id == id)
105			return sev;
106
107	return NULL;
108}
109
110static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
111		const struct timespec *ts)
112{
113	struct v4l2_subscribed_event *sev;
114	struct v4l2_kevent *kev;
115	bool copy_payload = true;
116
117	/* Are we subscribed? */
118	sev = v4l2_event_subscribed(fh, ev->type, ev->id);
119	if (sev == NULL)
120		return;
121
122	/*
123	 * If the event has been added to the fh->subscribed list, but its
124	 * add op has not completed yet elems will be 0, treat this as
125	 * not being subscribed.
126	 */
127	if (!sev->elems)
128		return;
129
130	/* Increase event sequence number on fh. */
131	fh->sequence++;
132
133	/* Do we have any free events? */
134	if (sev->in_use == sev->elems) {
135		/* no, remove the oldest one */
136		kev = sev->events + sev_pos(sev, 0);
137		list_del(&kev->list);
138		sev->in_use--;
139		sev->first = sev_pos(sev, 1);
140		fh->navailable--;
141		if (sev->elems == 1) {
142			if (sev->ops && sev->ops->replace) {
143				sev->ops->replace(&kev->event, ev);
144				copy_payload = false;
145			}
146		} else if (sev->ops && sev->ops->merge) {
147			struct v4l2_kevent *second_oldest =
148				sev->events + sev_pos(sev, 0);
149			sev->ops->merge(&kev->event, &second_oldest->event);
150		}
151	}
152
153	/* Take one and fill it. */
154	kev = sev->events + sev_pos(sev, sev->in_use);
155	kev->event.type = ev->type;
156	if (copy_payload)
157		kev->event.u = ev->u;
158	kev->event.id = ev->id;
159	kev->event.timestamp = *ts;
160	kev->event.sequence = fh->sequence;
161	sev->in_use++;
162	list_add_tail(&kev->list, &fh->available);
163
164	fh->navailable++;
165
166	wake_up_all(&fh->wait);
167}
168
169void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
170{
171	struct v4l2_fh *fh;
172	unsigned long flags;
173	struct timespec timestamp;
174
175	ktime_get_ts(&timestamp);
176
177	spin_lock_irqsave(&vdev->fh_lock, flags);
178
179	list_for_each_entry(fh, &vdev->fh_list, list)
180		__v4l2_event_queue_fh(fh, ev, &timestamp);
181
182	spin_unlock_irqrestore(&vdev->fh_lock, flags);
183}
184EXPORT_SYMBOL_GPL(v4l2_event_queue);
185
186void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
187{
188	unsigned long flags;
189	struct timespec timestamp;
190
191	ktime_get_ts(&timestamp);
192
193	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
194	__v4l2_event_queue_fh(fh, ev, &timestamp);
195	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
196}
197EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
198
199int v4l2_event_pending(struct v4l2_fh *fh)
200{
201	return fh->navailable;
202}
203EXPORT_SYMBOL_GPL(v4l2_event_pending);
204
205int v4l2_event_subscribe(struct v4l2_fh *fh,
206			 const struct v4l2_event_subscription *sub, unsigned elems,
207			 const struct v4l2_subscribed_event_ops *ops)
208{
209	struct v4l2_subscribed_event *sev, *found_ev;
210	unsigned long flags;
211	unsigned i;
212
213	if (sub->type == V4L2_EVENT_ALL)
214		return -EINVAL;
215
216	if (elems < 1)
217		elems = 1;
218
219	sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
220	if (!sev)
221		return -ENOMEM;
222	for (i = 0; i < elems; i++)
223		sev->events[i].sev = sev;
224	sev->type = sub->type;
225	sev->id = sub->id;
226	sev->flags = sub->flags;
227	sev->fh = fh;
228	sev->ops = ops;
229
230	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
231	found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
232	if (!found_ev)
233		list_add(&sev->list, &fh->subscribed);
234	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
235
236	if (found_ev) {
237		kfree(sev);
238		return 0; /* Already listening */
239	}
240
241	if (sev->ops && sev->ops->add) {
242		int ret = sev->ops->add(sev, elems);
243		if (ret) {
244			sev->ops = NULL;
245			v4l2_event_unsubscribe(fh, sub);
246			return ret;
247		}
248	}
249
250	/* Mark as ready for use */
251	sev->elems = elems;
252
253	return 0;
254}
255EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
256
257void 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}
278EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
279
280int 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	int i;
286
287	if (sub->type == V4L2_EVENT_ALL) {
288		v4l2_event_unsubscribe_all(fh);
289		return 0;
290	}
291
292	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
293
294	sev = v4l2_event_subscribed(fh, sub->type, sub->id);
295	if (sev != NULL) {
296		/* Remove any pending events for this subscription */
297		for (i = 0; i < sev->in_use; i++) {
298			list_del(&sev->events[sev_pos(sev, i)].list);
299			fh->navailable--;
300		}
301		list_del(&sev->list);
302	}
303
304	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
305
306	if (sev && sev->ops && sev->ops->del)
307		sev->ops->del(sev);
308
309	kfree(sev);
310
311	return 0;
312}
313EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
314
315int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
316				  struct v4l2_event_subscription *sub)
317{
318	return v4l2_event_unsubscribe(fh, sub);
319}
320EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
321
322static void v4l2_event_src_replace(struct v4l2_event *old,
323				const struct v4l2_event *new)
324{
325	u32 old_changes = old->u.src_change.changes;
326
327	old->u.src_change = new->u.src_change;
328	old->u.src_change.changes |= old_changes;
329}
330
331static void v4l2_event_src_merge(const struct v4l2_event *old,
332				struct v4l2_event *new)
333{
334	new->u.src_change.changes |= old->u.src_change.changes;
335}
336
337static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
338	.replace = v4l2_event_src_replace,
339	.merge = v4l2_event_src_merge,
340};
341
342int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
343				const struct v4l2_event_subscription *sub)
344{
345	if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
346		return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
347	return -EINVAL;
348}
349EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
350
351int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
352		struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
353{
354	return v4l2_src_change_event_subscribe(fh, sub);
355}
356EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);
357