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         /* Increase event sequence number on fh. */
 123         fh->sequence++;
 124
 125         /* Do we have any free events? */
 126         if (sev->in_use == sev->elems) {
 127                 /* no, remove the oldest one */
 128                 kev = sev->events + sev_pos(sev, 0);
 129                 list_del(&kev->list);
 130                 sev->in_use--;
 131                 sev->first = sev_pos(sev, 1);
 132                 fh->navailable--;
 133                 if (sev->elems == 1) {
 134                         if (sev->ops && sev->ops->replace) {
 135                                 sev->ops->replace(&kev->event, ev);
 136                                 copy_payload = false;
 137                         }
 138                 } else if (sev->ops && sev->ops->merge) {
 139                         struct v4l2_kevent *second_oldest =
 140                                 sev->events + sev_pos(sev, 0);
 141                         sev->ops->merge(&kev->event, &second_oldest->event);
 142                 }
 143         }
 144
 145         /* Take one and fill it. */
 146         kev = sev->events + sev_pos(sev, sev->in_use);
 147         kev->event.type = ev->type;
 148         if (copy_payload)
 149                 kev->event.u = ev->u;
 150         kev->event.id = ev->id;
 151         kev->event.timestamp = *ts;
 152         kev->event.sequence = fh->sequence;
 153         sev->in_use++;
 154         list_add_tail(&kev->list, &fh->available);
 155
 156         fh->navailable++;
 157
 158         wake_up_all(&fh->wait);
 159 }
 160
 161 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 162 {
 163         struct v4l2_fh *fh;
 164         unsigned long flags;
 165         struct timespec timestamp;
 166
 167         if (vdev == NULL)
 168                 return;
 169
 170         ktime_get_ts(&timestamp);
 171
 172         spin_lock_irqsave(&vdev->fh_lock, flags);
 173
 174         list_for_each_entry(fh, &vdev->fh_list, list)
 175                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 176
 177         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 178 }
 179 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 180
 181 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 182 {
 183         unsigned long flags;
 184         struct timespec timestamp;
 185
 186         ktime_get_ts(&timestamp);
 187
 188         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 189         __v4l2_event_queue_fh(fh, ev, &timestamp);
 190         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 191 }
 192 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 193
 194 int v4l2_event_pending(struct v4l2_fh *fh)
 195 {
 196         return fh->navailable;
 197 }
 198 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 199
 200 static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
 201 {
 202         struct v4l2_fh *fh = sev->fh;
 203         unsigned int i;
 204
 205         lockdep_assert_held(&fh->subscribe_lock);
 206         assert_spin_locked(&fh->vdev->fh_lock);
 207
 208         /* Remove any pending events for this subscription */
 209         for (i = 0; i < sev->in_use; i++) {
 210                 list_del(&sev->events[sev_pos(sev, i)].list);
 211                 fh->navailable--;
 212         }
 213         list_del(&sev->list);
 214 }
 215
 216 int v4l2_event_subscribe(struct v4l2_fh *fh,
 217                          const struct v4l2_event_subscription *sub, unsigned elems,
 218                          const struct v4l2_subscribed_event_ops *ops)
 219 {
 220         struct v4l2_subscribed_event *sev, *found_ev;
 221         unsigned long flags;
 222         unsigned i;
 223         int ret = 0;
 224
 225         if (sub->type == V4L2_EVENT_ALL)
 226                 return -EINVAL;
 227
 228         if (elems < 1)
 229                 elems = 1;
 230
 231         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 232         if (!sev)
 233                 return -ENOMEM;
 234         for (i = 0; i < elems; i++)
 235                 sev->events[i].sev = sev;
 236         sev->type = sub->type;
 237         sev->id = sub->id;
 238         sev->flags = sub->flags;
 239         sev->fh = fh;
 240         sev->ops = ops;
 241         sev->elems = elems;
 242
 243         mutex_lock(&fh->subscribe_lock);
 244
 245         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 246         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 247         if (!found_ev)
 248                 list_add(&sev->list, &fh->subscribed);
 249         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 250
 251         if (found_ev) {
 252                 /* Already listening */
 253                 kfree(sev);
 254         } else if (sev->ops && sev->ops->add) {
 255                 ret = sev->ops->add(sev, elems);
 256                 if (ret) {
 257                         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 258                         __v4l2_event_unsubscribe(sev);
 259                         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 260                         kfree(sev);
 261                 }
 262         }
 263
 264         mutex_unlock(&fh->subscribe_lock);
 265
 266         return ret;
 267 }
 268 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 269
 270 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 271 {
 272         struct v4l2_event_subscription sub;
 273         struct v4l2_subscribed_event *sev;
 274         unsigned long flags;
 275
 276         do {
 277                 sev = NULL;
 278
 279                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 280                 if (!list_empty(&fh->subscribed)) {
 281                         sev = list_first_entry(&fh->subscribed,
 282                                         struct v4l2_subscribed_event, list);
 283                         sub.type = sev->type;
 284                         sub.id = sev->id;
 285                 }
 286                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 287                 if (sev)
 288                         v4l2_event_unsubscribe(fh, &sub);
 289         } while (sev);
 290 }
 291 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 292
 293 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 294                            const struct v4l2_event_subscription *sub)
 295 {
 296         struct v4l2_subscribed_event *sev;
 297         unsigned long flags;
 298
 299         if (sub->type == V4L2_EVENT_ALL) {
 300                 v4l2_event_unsubscribe_all(fh);
 301                 return 0;
 302         }
 303
 304         mutex_lock(&fh->subscribe_lock);
 305
 306         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 307
 308         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 309         if (sev != NULL)
 310                 __v4l2_event_unsubscribe(sev);
 311
 312         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 313
 314         if (sev && sev->ops && sev->ops->del)
 315                 sev->ops->del(sev);
 316
 317         kfree(sev);
 318         mutex_unlock(&fh->subscribe_lock);
 319
 320         return 0;
 321 }
 322 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
 323
 324 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 325                                   struct v4l2_event_subscription *sub)
 326 {
 327         return v4l2_event_unsubscribe(fh, sub);
 328 }
 329 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
 330
 331 static void v4l2_event_src_replace(struct v4l2_event *old,
 332                                 const struct v4l2_event *new)
 333 {
 334         u32 old_changes = old->u.src_change.changes;
 335
 336         old->u.src_change = new->u.src_change;
 337         old->u.src_change.changes |= old_changes;
 338 }
 339
 340 static void v4l2_event_src_merge(const struct v4l2_event *old,
 341                                 struct v4l2_event *new)
 342 {
 343         new->u.src_change.changes |= old->u.src_change.changes;
 344 }
 345
 346 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
 347         .replace = v4l2_event_src_replace,
 348         .merge = v4l2_event_src_merge,
 349 };
 350
 351 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 352                                 const struct v4l2_event_subscription *sub)
 353 {
 354         if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
 355                 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
 356         return -EINVAL;
 357 }
 358 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
 359
 360 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 361                 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
 362 {
 363         return v4l2_src_change_event_subscribe(fh, sub);
 364 }
 365 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);