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 #include <linux/export.h>
  33
  34 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
  35 {
  36         idx += sev->first;
  37         return idx >= sev->elems ? idx - sev->elems : idx;
  38 }
  39
  40 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  41 {
  42         struct v4l2_kevent *kev;
  43         unsigned long flags;
  44
  45         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  46
  47         if (list_empty(&fh->available)) {
  48                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  49                 return -ENOENT;
  50         }
  51
  52         WARN_ON(fh->navailable == 0);
  53
  54         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  55         list_del(&kev->list);
  56         fh->navailable--;
  57
  58         kev->event.pending = fh->navailable;
  59         *event = kev->event;
  60         kev->sev->first = sev_pos(kev->sev, 1);
  61         kev->sev->in_use--;
  62
  63         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  64
  65         return 0;
  66 }
  67
  68 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  69                        int nonblocking)
  70 {
  71         int ret;
  72
  73         if (nonblocking)
  74                 return __v4l2_event_dequeue(fh, event);
  75
  76         /* Release the vdev lock while waiting */
  77         if (fh->vdev->lock)
  78                 mutex_unlock(fh->vdev->lock);
  79
  80         do {
  81                 ret = wait_event_interruptible(fh->wait,
  82                                                fh->navailable != 0);
  83                 if (ret < 0)
  84                         break;
  85
  86                 ret = __v4l2_event_dequeue(fh, event);
  87         } while (ret == -ENOENT);
  88
  89         if (fh->vdev->lock)
  90                 mutex_lock(fh->vdev->lock);
  91
  92         return ret;
  93 }
  94 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
  95
  96 /* Caller must hold fh->vdev->fh_lock! */
  97 static struct v4l2_subscribed_event *v4l2_event_subscribed(
  98                 struct v4l2_fh *fh, u32 type, u32 id)
  99 {
 100         struct v4l2_subscribed_event *sev;
 101
 102         assert_spin_locked(&fh->vdev->fh_lock);
 103
 104         list_for_each_entry(sev, &fh->subscribed, list)
 105                 if (sev->type == type && sev->id == id)
 106                         return sev;
 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         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 176 }
 177 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 178
 179 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 180 {
 181         unsigned long flags;
 182         struct timespec timestamp;
 183
 184         ktime_get_ts(&timestamp);
 185
 186         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 187         __v4l2_event_queue_fh(fh, ev, &timestamp);
 188         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 189 }
 190 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 191
 192 int v4l2_event_pending(struct v4l2_fh *fh)
 193 {
 194         return fh->navailable;
 195 }
 196 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 197
 198 static void ctrls_replace(struct v4l2_event *old, const struct v4l2_event *new)
 199 {
 200         u32 old_changes = old->u.ctrl.changes;
 201
 202         old->u.ctrl = new->u.ctrl;
 203         old->u.ctrl.changes |= old_changes;
 204 }
 205
 206 static void ctrls_merge(const struct v4l2_event *old, struct v4l2_event *new)
 207 {
 208         new->u.ctrl.changes |= old->u.ctrl.changes;
 209 }
 210
 211 int v4l2_event_subscribe(struct v4l2_fh *fh,
 212                          struct v4l2_event_subscription *sub, unsigned elems)
 213 {
 214         struct v4l2_subscribed_event *sev, *found_ev;
 215         struct v4l2_ctrl *ctrl = NULL;
 216         unsigned long flags;
 217         unsigned i;
 218
 219         if (elems < 1)
 220                 elems = 1;
 221         if (sub->type == V4L2_EVENT_CTRL) {
 222                 ctrl = v4l2_ctrl_find(fh->ctrl_handler, sub->id);
 223                 if (ctrl == NULL)
 224                         return -EINVAL;
 225         }
 226
 227         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 228         if (!sev)
 229                 return -ENOMEM;
 230         for (i = 0; i < elems; i++)
 231                 sev->events[i].sev = sev;
 232         sev->type = sub->type;
 233         sev->id = sub->id;
 234         sev->flags = sub->flags;
 235         sev->fh = fh;
 236         sev->elems = elems;
 237         if (ctrl) {
 238                 sev->replace = ctrls_replace;
 239                 sev->merge = ctrls_merge;
 240         }
 241
 242         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 243         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 244         if (!found_ev)
 245                 list_add(&sev->list, &fh->subscribed);
 246         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 247
 248         /* v4l2_ctrl_add_event uses a mutex, so do this outside the spin lock */
 249         if (found_ev)
 250                 kfree(sev);
 251         else if (ctrl)
 252                 v4l2_ctrl_add_event(ctrl, sev);
 253
 254         return 0;
 255 }
 256 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 257
 258 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 259 {
 260         struct v4l2_event_subscription sub;
 261         struct v4l2_subscribed_event *sev;
 262         unsigned long flags;
 263
 264         do {
 265                 sev = NULL;
 266
 267                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 268                 if (!list_empty(&fh->subscribed)) {
 269                         sev = list_first_entry(&fh->subscribed,
 270                                         struct v4l2_subscribed_event, list);
 271                         sub.type = sev->type;
 272                         sub.id = sev->id;
 273                 }
 274                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 275                 if (sev)
 276                         v4l2_event_unsubscribe(fh, &sub);
 277         } while (sev);
 278 }
 279 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 280
 281 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 282                            struct v4l2_event_subscription *sub)
 283 {
 284         struct v4l2_subscribed_event *sev;
 285         unsigned long flags;
 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                 list_del(&sev->list);
 297                 sev->fh = NULL;
 298         }
 299
 300         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 301         if (sev && sev->type == V4L2_EVENT_CTRL) {
 302                 struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);
 303
 304                 if (ctrl)
 305                         v4l2_ctrl_del_event(ctrl, sev);
 306         }
 307
 308         kfree(sev);
 309
 310         return 0;
 311 }
 312 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);