v4l2-event.c revision c3b5b0241f620a356c97d8f43343e721c718806d 
1/*
2 * v4l2-event.c
3 *
4 * V4L2 events.
5 *
6 * Copyright (C) 2009--2010 Nokia Corporation.
7 *
8 * Contact: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
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
32int v4l2_event_init(struct v4l2_fh *fh)
33{
34	fh->events = kzalloc(sizeof(*fh->events), GFP_KERNEL);
35	if (fh->events == NULL)
36		return -ENOMEM;
37
38	init_waitqueue_head(&fh->events->wait);
39
40	INIT_LIST_HEAD(&fh->events->free);
41	INIT_LIST_HEAD(&fh->events->available);
42	INIT_LIST_HEAD(&fh->events->subscribed);
43
44	fh->events->sequence = -1;
45
46	return 0;
47}
48
49int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n)
50{
51	struct v4l2_events *events = fh->events;
52	unsigned long flags;
53
54	if (!events) {
55		WARN_ON(1);
56		return -ENOMEM;
57	}
58
59	while (events->nallocated < n) {
60		struct v4l2_kevent *kev;
61
62		kev = kzalloc(sizeof(*kev), GFP_KERNEL);
63		if (kev == NULL)
64			return -ENOMEM;
65
66		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
67		list_add_tail(&kev->list, &events->free);
68		events->nallocated++;
69		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
70	}
71
72	return 0;
73}
74EXPORT_SYMBOL_GPL(v4l2_event_alloc);
75
76#define list_kfree(list, type, member)				\
77	while (!list_empty(list)) {				\
78		type *hi;					\
79		hi = list_first_entry(list, type, member);	\
80		list_del(&hi->member);				\
81		kfree(hi);					\
82	}
83
84void v4l2_event_free(struct v4l2_fh *fh)
85{
86	struct v4l2_events *events = fh->events;
87
88	if (!events)
89		return;
90
91	list_kfree(&events->free, struct v4l2_kevent, list);
92	list_kfree(&events->available, struct v4l2_kevent, list);
93	list_kfree(&events->subscribed, struct v4l2_subscribed_event, list);
94
95	kfree(events);
96	fh->events = NULL;
97}
98EXPORT_SYMBOL_GPL(v4l2_event_free);
99
100static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
101{
102	struct v4l2_events *events = fh->events;
103	struct v4l2_kevent *kev;
104	unsigned long flags;
105
106	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
107
108	if (list_empty(&events->available)) {
109		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
110		return -ENOENT;
111	}
112
113	WARN_ON(events->navailable == 0);
114
115	kev = list_first_entry(&events->available, struct v4l2_kevent, list);
116	list_move(&kev->list, &events->free);
117	events->navailable--;
118
119	kev->event.pending = events->navailable;
120	*event = kev->event;
121
122	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
123
124	return 0;
125}
126
127int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
128		       int nonblocking)
129{
130	struct v4l2_events *events = fh->events;
131	int ret;
132
133	if (nonblocking)
134		return __v4l2_event_dequeue(fh, event);
135
136	do {
137		ret = wait_event_interruptible(events->wait,
138					       events->navailable != 0);
139		if (ret < 0)
140			return ret;
141
142		ret = __v4l2_event_dequeue(fh, event);
143	} while (ret == -ENOENT);
144
145	return ret;
146}
147
148/* Caller must hold fh->event->lock! */
149static struct v4l2_subscribed_event *v4l2_event_subscribed(
150	struct v4l2_fh *fh, u32 type)
151{
152	struct v4l2_events *events = fh->events;
153	struct v4l2_subscribed_event *sev;
154
155	WARN_ON(!spin_is_locked(&fh->vdev->fh_lock));
156
157	list_for_each_entry(sev, &events->subscribed, list) {
158		if (sev->type == type)
159			return sev;
160	}
161
162	return NULL;
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	ktime_get_ts(&timestamp);
172
173	spin_lock_irqsave(&vdev->fh_lock, flags);
174
175	list_for_each_entry(fh, &vdev->fh_list, list) {
176		struct v4l2_events *events = fh->events;
177		struct v4l2_kevent *kev;
178
179		/* Are we subscribed? */
180		if (!v4l2_event_subscribed(fh, ev->type))
181			continue;
182
183		/* Increase event sequence number on fh. */
184		events->sequence++;
185
186		/* Do we have any free events? */
187		if (list_empty(&events->free))
188			continue;
189
190		/* Take one and fill it. */
191		kev = list_first_entry(&events->free, struct v4l2_kevent, list);
192		kev->event.type = ev->type;
193		kev->event.u = ev->u;
194		kev->event.timestamp = timestamp;
195		kev->event.sequence = events->sequence;
196		list_move_tail(&kev->list, &events->available);
197
198		events->navailable++;
199
200		wake_up_all(&events->wait);
201	}
202
203	spin_unlock_irqrestore(&vdev->fh_lock, flags);
204}
205EXPORT_SYMBOL_GPL(v4l2_event_queue);
206
207int v4l2_event_pending(struct v4l2_fh *fh)
208{
209	return fh->events->navailable;
210}
211EXPORT_SYMBOL_GPL(v4l2_event_pending);
212
213int v4l2_event_subscribe(struct v4l2_fh *fh,
214			 struct v4l2_event_subscription *sub)
215{
216	struct v4l2_events *events = fh->events;
217	struct v4l2_subscribed_event *sev;
218	unsigned long flags;
219
220	if (fh->events == NULL) {
221		WARN_ON(1);
222		return -ENOMEM;
223	}
224
225	sev = kmalloc(sizeof(*sev), GFP_KERNEL);
226	if (!sev)
227		return -ENOMEM;
228
229	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
230
231	if (v4l2_event_subscribed(fh, sub->type) == NULL) {
232		INIT_LIST_HEAD(&sev->list);
233		sev->type = sub->type;
234
235		list_add(&sev->list, &events->subscribed);
236		sev = NULL;
237	}
238
239	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
240
241	kfree(sev);
242
243	return 0;
244}
245EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
246
247static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
248{
249	struct v4l2_events *events = fh->events;
250	struct v4l2_subscribed_event *sev;
251	unsigned long flags;
252
253	do {
254		sev = NULL;
255
256		spin_lock_irqsave(&fh->vdev->fh_lock, flags);
257		if (!list_empty(&events->subscribed)) {
258			sev = list_first_entry(&events->subscribed,
259				       struct v4l2_subscribed_event, list);
260			list_del(&sev->list);
261		}
262		spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
263		kfree(sev);
264	} while (sev);
265}
266
267int v4l2_event_unsubscribe(struct v4l2_fh *fh,
268			   struct v4l2_event_subscription *sub)
269{
270	struct v4l2_subscribed_event *sev;
271	unsigned long flags;
272
273	if (sub->type == V4L2_EVENT_ALL) {
274		v4l2_event_unsubscribe_all(fh);
275		return 0;
276	}
277
278	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
279
280	sev = v4l2_event_subscribed(fh, sub->type);
281	if (sev != NULL)
282		list_del(&sev->list);
283
284	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
285
286	kfree(sev);
287
288	return 0;
289}
290EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
291