v4l2-event: v4l2_event_queue: do nothing if vdev == NULL
[linux-3.10.git] / drivers / media / v4l2-core / v4l2-event.c
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
33 static 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
39 static 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
67 int 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 }
93 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
94
95 /* Caller must hold fh->vdev->fh_lock! */
96 static 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
110 static 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
169 void 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         if (vdev == NULL)
176                 return;
177
178         ktime_get_ts(&timestamp);
179
180         spin_lock_irqsave(&vdev->fh_lock, flags);
181
182         list_for_each_entry(fh, &vdev->fh_list, list)
183                 __v4l2_event_queue_fh(fh, ev, &timestamp);
184
185         spin_unlock_irqrestore(&vdev->fh_lock, flags);
186 }
187 EXPORT_SYMBOL_GPL(v4l2_event_queue);
188
189 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
190 {
191         unsigned long flags;
192         struct timespec timestamp;
193
194         ktime_get_ts(&timestamp);
195
196         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
197         __v4l2_event_queue_fh(fh, ev, &timestamp);
198         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
199 }
200 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
201
202 int v4l2_event_pending(struct v4l2_fh *fh)
203 {
204         return fh->navailable;
205 }
206 EXPORT_SYMBOL_GPL(v4l2_event_pending);
207
208 int v4l2_event_subscribe(struct v4l2_fh *fh,
209                          const struct v4l2_event_subscription *sub, unsigned elems,
210                          const struct v4l2_subscribed_event_ops *ops)
211 {
212         struct v4l2_subscribed_event *sev, *found_ev;
213         unsigned long flags;
214         unsigned i;
215
216         if (sub->type == V4L2_EVENT_ALL)
217                 return -EINVAL;
218
219         if (elems < 1)
220                 elems = 1;
221
222         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
223         if (!sev)
224                 return -ENOMEM;
225         for (i = 0; i < elems; i++)
226                 sev->events[i].sev = sev;
227         sev->type = sub->type;
228         sev->id = sub->id;
229         sev->flags = sub->flags;
230         sev->fh = fh;
231         sev->ops = ops;
232
233         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
234         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
235         if (!found_ev)
236                 list_add(&sev->list, &fh->subscribed);
237         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
238
239         if (found_ev) {
240                 kfree(sev);
241                 return 0; /* Already listening */
242         }
243
244         if (sev->ops && sev->ops->add) {
245                 int ret = sev->ops->add(sev, elems);
246                 if (ret) {
247                         sev->ops = NULL;
248                         v4l2_event_unsubscribe(fh, sub);
249                         return ret;
250                 }
251         }
252
253         /* Mark as ready for use */
254         sev->elems = elems;
255
256         return 0;
257 }
258 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
259
260 void 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 }
281 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
282
283 int 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         int i;
289
290         if (sub->type == V4L2_EVENT_ALL) {
291                 v4l2_event_unsubscribe_all(fh);
292                 return 0;
293         }
294
295         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
296
297         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
298         if (sev != NULL) {
299                 /* Remove any pending events for this subscription */
300                 for (i = 0; i < sev->in_use; i++) {
301                         list_del(&sev->events[sev_pos(sev, i)].list);
302                         fh->navailable--;
303                 }
304                 list_del(&sev->list);
305         }
306
307         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
308
309         if (sev && sev->ops && sev->ops->del)
310                 sev->ops->del(sev);
311
312         kfree(sev);
313
314         return 0;
315 }
316 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
317
318 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
319                                   struct v4l2_event_subscription *sub)
320 {
321         return v4l2_event_unsubscribe(fh, sub);
322 }
323 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
324
325 static void v4l2_event_src_replace(struct v4l2_event *old,
326                                 const struct v4l2_event *new)
327 {
328         u32 old_changes = old->u.src_change.changes;
329
330         old->u.src_change = new->u.src_change;
331         old->u.src_change.changes |= old_changes;
332 }
333
334 static void v4l2_event_src_merge(const struct v4l2_event *old,
335                                 struct v4l2_event *new)
336 {
337         new->u.src_change.changes |= old->u.src_change.changes;
338 }
339
340 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
341         .replace = v4l2_event_src_replace,
342         .merge = v4l2_event_src_merge,
343 };
344
345 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
346                                 const struct v4l2_event_subscription *sub)
347 {
348         if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
349                 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
350         return -EINVAL;
351 }
352 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
353
354 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
355                 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
356 {
357         return v4l2_src_change_event_subscribe(fh, sub);
358 }
359 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);