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
 21static 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
 27static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
 28{
 29	struct v4l2_kevent *kev;
 30	struct timespec64 ts;
 31	unsigned long flags;
 32
 33	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 34
 35	if (list_empty(&fh->available)) {
 36		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 37		return -ENOENT;
 38	}
 39
 40	WARN_ON(fh->navailable == 0);
 41
 42	kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
 43	list_del(&kev->list);
 44	fh->navailable--;
 45
 46	kev->event.pending = fh->navailable;
 47	*event = kev->event;
 48	ts = ns_to_timespec64(kev->ts);
 49	event->timestamp.tv_sec = ts.tv_sec;
 50	event->timestamp.tv_nsec = ts.tv_nsec;
 51	kev->sev->first = sev_pos(kev->sev, 1);
 52	kev->sev->in_use--;
 53
 54	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 55
 56	return 0;
 57}
 58
 59int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
 60		       int nonblocking)
 61{
 62	int ret;
 63
 64	if (nonblocking)
 65		return __v4l2_event_dequeue(fh, event);
 66
 67	/* Release the vdev lock while waiting */
 68	if (fh->vdev->lock)
 69		mutex_unlock(fh->vdev->lock);
 70
 71	do {
 72		ret = wait_event_interruptible(fh->wait,
 73					       fh->navailable != 0);
 74		if (ret < 0)
 75			break;
 76
 77		ret = __v4l2_event_dequeue(fh, event);
 78	} while (ret == -ENOENT);
 79
 80	if (fh->vdev->lock)
 81		mutex_lock(fh->vdev->lock);
 82
 83	return ret;
 84}
 85EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
 86
 87/* Caller must hold fh->vdev->fh_lock! */
 88static struct v4l2_subscribed_event *v4l2_event_subscribed(
 89		struct v4l2_fh *fh, u32 type, u32 id)
 90{
 91	struct v4l2_subscribed_event *sev;
 92
 93	assert_spin_locked(&fh->vdev->fh_lock);
 94
 95	list_for_each_entry(sev, &fh->subscribed, list)
 96		if (sev->type == type && sev->id == id)
 97			return sev;
 98
 99	return NULL;
100}
101
102static void __v4l2_event_queue_fh(struct v4l2_fh *fh,
103				  const struct v4l2_event *ev, u64 ts)
104{
105	struct v4l2_subscribed_event *sev;
106	struct v4l2_kevent *kev;
107	bool copy_payload = true;
108
109	/* Are we subscribed? */
110	sev = v4l2_event_subscribed(fh, ev->type, ev->id);
111	if (sev == NULL)
112		return;
113
114	/* Increase event sequence number on fh. */
115	fh->sequence++;
116
117	/* Do we have any free events? */
118	if (sev->in_use == sev->elems) {
119		/* no, remove the oldest one */
120		kev = sev->events + sev_pos(sev, 0);
121		list_del(&kev->list);
122		sev->in_use--;
123		sev->first = sev_pos(sev, 1);
124		fh->navailable--;
125		if (sev->elems == 1) {
126			if (sev->ops && sev->ops->replace) {
127				sev->ops->replace(&kev->event, ev);
128				copy_payload = false;
129			}
130		} else if (sev->ops && sev->ops->merge) {
131			struct v4l2_kevent *second_oldest =
132				sev->events + sev_pos(sev, 0);
133			sev->ops->merge(&kev->event, &second_oldest->event);
134		}
135	}
136
137	/* Take one and fill it. */
138	kev = sev->events + sev_pos(sev, sev->in_use);
139	kev->event.type = ev->type;
140	if (copy_payload)
141		kev->event.u = ev->u;
142	kev->event.id = ev->id;
143	kev->ts = ts;
144	kev->event.sequence = fh->sequence;
145	sev->in_use++;
146	list_add_tail(&kev->list, &fh->available);
147
148	fh->navailable++;
149
150	wake_up_all(&fh->wait);
151}
152
153void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
154{
155	struct v4l2_fh *fh;
156	unsigned long flags;
157	u64 ts;
158
159	if (vdev == NULL)
160		return;
161
162	ts = ktime_get_ns();
163
164	spin_lock_irqsave(&vdev->fh_lock, flags);
165
166	list_for_each_entry(fh, &vdev->fh_list, list)
167		__v4l2_event_queue_fh(fh, ev, ts);
168
169	spin_unlock_irqrestore(&vdev->fh_lock, flags);
170}
171EXPORT_SYMBOL_GPL(v4l2_event_queue);
172
173void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
174{
175	unsigned long flags;
176	u64 ts = ktime_get_ns();
177
178	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
179	__v4l2_event_queue_fh(fh, ev, ts);
180	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
181}
182EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
183
184int v4l2_event_pending(struct v4l2_fh *fh)
185{
186	return fh->navailable;
187}
188EXPORT_SYMBOL_GPL(v4l2_event_pending);
189
190static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
191{
192	struct v4l2_fh *fh = sev->fh;
193	unsigned int i;
194
195	lockdep_assert_held(&fh->subscribe_lock);
196	assert_spin_locked(&fh->vdev->fh_lock);
197
198	/* Remove any pending events for this subscription */
199	for (i = 0; i < sev->in_use; i++) {
200		list_del(&sev->events[sev_pos(sev, i)].list);
201		fh->navailable--;
202	}
203	list_del(&sev->list);
204}
205
206int v4l2_event_subscribe(struct v4l2_fh *fh,
207			 const struct v4l2_event_subscription *sub, unsigned elems,
208			 const struct v4l2_subscribed_event_ops *ops)
209{
210	struct v4l2_subscribed_event *sev, *found_ev;
211	unsigned long flags;
212	unsigned i;
213	int ret = 0;
214
215	if (sub->type == V4L2_EVENT_ALL)
216		return -EINVAL;
217
218	if (elems < 1)
219		elems = 1;
220
221	sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
222	if (!sev)
223		return -ENOMEM;
224	for (i = 0; i < elems; i++)
225		sev->events[i].sev = sev;
226	sev->type = sub->type;
227	sev->id = sub->id;
228	sev->flags = sub->flags;
229	sev->fh = fh;
230	sev->ops = ops;
231	sev->elems = elems;
232
233	mutex_lock(&fh->subscribe_lock);
234
235	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
236	found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
237	if (!found_ev)
238		list_add(&sev->list, &fh->subscribed);
239	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
240
241	if (found_ev) {
242		/* Already listening */
243		kvfree(sev);
244	} else if (sev->ops && sev->ops->add) {
245		ret = sev->ops->add(sev, elems);
246		if (ret) {
247			spin_lock_irqsave(&fh->vdev->fh_lock, flags);
248			__v4l2_event_unsubscribe(sev);
249			spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
250			kvfree(sev);
251		}
252	}
253
254	mutex_unlock(&fh->subscribe_lock);
255
256	return ret;
257}
258EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
259
260void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
261{
262	struct v4l2_event_subscription sub;
263	struct v4l2_subscribed_event *sev;
264	unsigned long flags;
265
266	do {
267		sev = NULL;
268
269		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
270		if (!list_empty(&fh->subscribed)) {
271			sev = list_first_entry(&fh->subscribed,
272					struct v4l2_subscribed_event, list);
273			sub.type = sev->type;
274			sub.id = sev->id;
275		}
276		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
277		if (sev)
278			v4l2_event_unsubscribe(fh, &sub);
279	} while (sev);
280}
281EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
282
283int v4l2_event_unsubscribe(struct v4l2_fh *fh,
284			   const struct v4l2_event_subscription *sub)
285{
286	struct v4l2_subscribed_event *sev;
287	unsigned long flags;
288
289	if (sub->type == V4L2_EVENT_ALL) {
290		v4l2_event_unsubscribe_all(fh);
291		return 0;
292	}
293
294	mutex_lock(&fh->subscribe_lock);
295
296	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
297
298	sev = v4l2_event_subscribed(fh, sub->type, sub->id);
299	if (sev != NULL)
300		__v4l2_event_unsubscribe(sev);
301
302	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
303
304	if (sev && sev->ops && sev->ops->del)
305		sev->ops->del(sev);
306
307	mutex_unlock(&fh->subscribe_lock);
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);