drivers/media/video/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@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 #include <media/v4l2-ctrls.h>
  29
  30 #include <linux/sched.h>
  31 #include <linux/slab.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
 108         return NULL;
 109 }
 110
 111 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 112                 const struct timespec *ts)
 113 {
 114         struct v4l2_subscribed_event *sev;
 115         struct v4l2_kevent *kev;
 116         bool copy_payload = true;
 117
 118         /* Are we subscribed? */
 119         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 120         if (sev == NULL)
 121                 return;
 122
 123         /* Increase event sequence number on fh. */
 124         fh->sequence++;
 125
 126         /* Do we have any free events? */
 127         if (sev->in_use == sev->elems) {
 128                 /* no, remove the oldest one */
 129                 kev = sev->events + sev_pos(sev, 0);
 130                 list_del(&kev->list);
 131                 sev->in_use--;
 132                 sev->first = sev_pos(sev, 1);
 133                 fh->navailable--;
 134                 if (sev->elems == 1) {
 135                         if (sev->replace) {
 136                                 sev->replace(&kev->event, ev);
 137                                 copy_payload = false;
 138                         }
 139                 } else if (sev->merge) {
 140                         struct v4l2_kevent *second_oldest =
 141                                 sev->events + sev_pos(sev, 0);
 142                         sev->merge(&kev->event, &second_oldest->event);
 143                 }
 144         }
 145
 146         /* Take one and fill it. */
 147         kev = sev->events + sev_pos(sev, sev->in_use);
 148         kev->event.type = ev->type;
 149         if (copy_payload)
 150                 kev->event.u = ev->u;
 151         kev->event.id = ev->id;
 152         kev->event.timestamp = *ts;
 153         kev->event.sequence = fh->sequence;
 154         sev->in_use++;
 155         list_add_tail(&kev->list, &fh->available);
 156
 157         fh->navailable++;
 158
 159         wake_up_all(&fh->wait);
 160 }
 161
 162 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 163 {
 164         struct v4l2_fh *fh;
 165         unsigned long flags;
 166         struct timespec timestamp;
 167
 168         ktime_get_ts(&timestamp);
 169
 170         spin_lock_irqsave(&vdev->fh_lock, flags);
 171
 172         list_for_each_entry(fh, &vdev->fh_list, list) {
 173                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 174         }
 175
 176         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 177 }
 178 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 179
 180 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 181 {
 182         unsigned long flags;
 183         struct timespec timestamp;
 184
 185         ktime_get_ts(&timestamp);
 186
 187         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 188         __v4l2_event_queue_fh(fh, ev, &timestamp);
 189         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 190 }
 191 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 192
 193 int v4l2_event_pending(struct v4l2_fh *fh)
 194 {
 195         return fh->navailable;
 196 }
 197 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 198
 199 static void ctrls_replace(struct v4l2_event *old, const struct v4l2_event *new)
 200 {
 201         u32 old_changes = old->u.ctrl.changes;
 202
 203         old->u.ctrl = new->u.ctrl;
 204         old->u.ctrl.changes |= old_changes;
 205 }
 206
 207 static void ctrls_merge(const struct v4l2_event *old, struct v4l2_event *new)
 208 {
 209         new->u.ctrl.changes |= old->u.ctrl.changes;
 210 }
 211
 212 int v4l2_event_subscribe(struct v4l2_fh *fh,
 213                          struct v4l2_event_subscription *sub, unsigned elems)
 214 {
 215         struct v4l2_subscribed_event *sev, *found_ev;
 216         struct v4l2_ctrl *ctrl = NULL;
 217         unsigned long flags;
 218         unsigned i;
 219
 220         if (elems < 1)
 221                 elems = 1;
 222         if (sub->type == V4L2_EVENT_CTRL) {
 223                 ctrl = v4l2_ctrl_find(fh->ctrl_handler, sub->id);
 224                 if (ctrl == NULL)
 225                         return -EINVAL;
 226         }
 227
 228         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 229         if (!sev)
 230                 return -ENOMEM;
 231         for (i = 0; i < elems; i++)
 232                 sev->events[i].sev = sev;
 233         sev->type = sub->type;
 234         sev->id = sub->id;
 235         sev->flags = sub->flags;
 236         sev->fh = fh;
 237         sev->elems = elems;
 238         if (ctrl) {
 239                 sev->replace = ctrls_replace;
 240                 sev->merge = ctrls_merge;
 241         }
 242
 243         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 244         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 245         if (!found_ev)
 246                 list_add(&sev->list, &fh->subscribed);
 247         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 248
 249         /* v4l2_ctrl_add_event uses a mutex, so do this outside the spin lock */
 250         if (found_ev)
 251                 kfree(sev);
 252         else if (ctrl)
 253                 v4l2_ctrl_add_event(ctrl, sev);
 254
 255         return 0;
 256 }
 257 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 258
 259 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 260 {
 261         struct v4l2_event_subscription sub;
 262         struct v4l2_subscribed_event *sev;
 263         unsigned long flags;
 264
 265         do {
 266                 sev = NULL;
 267
 268                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 269                 if (!list_empty(&fh->subscribed)) {
 270                         sev = list_first_entry(&fh->subscribed,
 271                                         struct v4l2_subscribed_event, list);
 272                         sub.type = sev->type;
 273                         sub.id = sev->id;
 274                 }
 275                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 276                 if (sev)
 277                         v4l2_event_unsubscribe(fh, &sub);
 278         } while (sev);
 279 }
 280 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 281
 282 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 283                            struct v4l2_event_subscription *sub)
 284 {
 285         struct v4l2_subscribed_event *sev;
 286         unsigned long flags;
 287
 288         if (sub->type == V4L2_EVENT_ALL) {
 289                 v4l2_event_unsubscribe_all(fh);
 290                 return 0;
 291         }
 292
 293         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 294
 295         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 296         if (sev != NULL) {
 297                 list_del(&sev->list);
 298                 sev->fh = NULL;
 299         }
 300
 301         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 302         if (sev && sev->type == V4L2_EVENT_CTRL) {
 303                 struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);
 304
 305                 if (ctrl)
 306                         v4l2_ctrl_del_event(ctrl, sev);
 307         }
 308
 309         kfree(sev);
 310
 311         return 0;
 312 }
 313 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);