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
 29static 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
 35static 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
 63int 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}
 89EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
 90
 91/* Caller must hold fh->vdev->fh_lock! */
 92static 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
106static 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	/*
119	 * If the event has been added to the fh->subscribed list, but its
120	 * add op has not completed yet elems will be 0, treat this as
121	 * not being subscribed.
122	 */
123	if (!sev->elems)
124		return;
125
126	/* Increase event sequence number on fh. */
127	fh->sequence++;
128
129	/* Do we have any free events? */
130	if (sev->in_use == sev->elems) {
131		/* no, remove the oldest one */
132		kev = sev->events + sev_pos(sev, 0);
133		list_del(&kev->list);
134		sev->in_use--;
135		sev->first = sev_pos(sev, 1);
136		fh->navailable--;
137		if (sev->elems == 1) {
138			if (sev->ops && sev->ops->replace) {
139				sev->ops->replace(&kev->event, ev);
140				copy_payload = false;
141			}
142		} else if (sev->ops && sev->ops->merge) {
143			struct v4l2_kevent *second_oldest =
144				sev->events + sev_pos(sev, 0);
145			sev->ops->merge(&kev->event, &second_oldest->event);
146		}
147	}
148
149	/* Take one and fill it. */
150	kev = sev->events + sev_pos(sev, sev->in_use);
151	kev->event.type = ev->type;
152	if (copy_payload)
153		kev->event.u = ev->u;
154	kev->event.id = ev->id;
155	kev->event.timestamp = *ts;
156	kev->event.sequence = fh->sequence;
157	sev->in_use++;
158	list_add_tail(&kev->list, &fh->available);
159
160	fh->navailable++;
161
162	wake_up_all(&fh->wait);
163}
164
165void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
166{
167	struct v4l2_fh *fh;
168	unsigned long flags;
169	struct timespec timestamp;
170
171	if (vdev == NULL)
172		return;
173
174	ktime_get_ts(&timestamp);
175
176	spin_lock_irqsave(&vdev->fh_lock, flags);
177
178	list_for_each_entry(fh, &vdev->fh_list, list)
179		__v4l2_event_queue_fh(fh, ev, &timestamp);
180
181	spin_unlock_irqrestore(&vdev->fh_lock, flags);
182}
183EXPORT_SYMBOL_GPL(v4l2_event_queue);
184
185void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
186{
187	unsigned long flags;
188	struct timespec timestamp;
189
190	ktime_get_ts(&timestamp);
191
192	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
193	__v4l2_event_queue_fh(fh, ev, &timestamp);
194	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
195}
196EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
197
198int v4l2_event_pending(struct v4l2_fh *fh)
199{
200	return fh->navailable;
201}
202EXPORT_SYMBOL_GPL(v4l2_event_pending);
203
204int v4l2_event_subscribe(struct v4l2_fh *fh,
205			 const struct v4l2_event_subscription *sub, unsigned elems,
206			 const struct v4l2_subscribed_event_ops *ops)
207{
208	struct v4l2_subscribed_event *sev, *found_ev;
209	unsigned long flags;
210	unsigned i;
211
212	if (sub->type == V4L2_EVENT_ALL)
213		return -EINVAL;
214
215	if (elems < 1)
216		elems = 1;
217
218	sev = kvzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems,
219		       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		kvfree(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	kvfree(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);