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
  20 #include <media/v4l2-dev.h>
  21 #include <media/v4l2-fh.h>
  22 #include <media/v4l2-event.h>
  23
  24 #include <linux/sched.h>
  25 #include <linux/slab.h>
  26 #include <linux/export.h>
  27
  28 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
  29 {
  30         idx += sev->first;
  31         return idx >= sev->elems ? idx - sev->elems : idx;
  32 }
  33
  34 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  35 {
  36         struct v4l2_kevent *kev;
  37         unsigned long flags;
  38
  39         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  40
  41         if (list_empty(&fh->available)) {
  42                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  43                 return -ENOENT;
  44         }
  45
  46         WARN_ON(fh->navailable == 0);
  47
  48         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  49         list_del(&kev->list);
  50         fh->navailable--;
  51
  52         kev->event.pending = fh->navailable;
  53         *event = kev->event;
  54         kev->sev->first = sev_pos(kev->sev, 1);
  55         kev->sev->in_use--;
  56
  57         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  58
  59         return 0;
  60 }
  61
  62 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  63                        int nonblocking)
  64 {
  65         int ret;
  66
  67         if (nonblocking)
  68                 return __v4l2_event_dequeue(fh, event);
  69
  70         /* Release the vdev lock while waiting */
  71         if (fh->vdev->lock)
  72                 mutex_unlock(fh->vdev->lock);
  73
  74         do {
  75                 ret = wait_event_interruptible(fh->wait,
  76                                                fh->navailable != 0);
  77                 if (ret < 0)
  78                         break;
  79
  80                 ret = __v4l2_event_dequeue(fh, event);
  81         } while (ret == -ENOENT);
  82
  83         if (fh->vdev->lock)
  84                 mutex_lock(fh->vdev->lock);
  85
  86         return ret;
  87 }
  88 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
  89
  90 /* Caller must hold fh->vdev->fh_lock! */
  91 static struct v4l2_subscribed_event *v4l2_event_subscribed(
  92                 struct v4l2_fh *fh, u32 type, u32 id)
  93 {
  94         struct v4l2_subscribed_event *sev;
  95
  96         assert_spin_locked(&fh->vdev->fh_lock);
  97
  98         list_for_each_entry(sev, &fh->subscribed, list)
  99                 if (sev->type == type && sev->id == id)
 100                         return sev;
 101
 102         return NULL;
 103 }
 104
 105 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 106                 const struct timespec *ts)
 107 {
 108         struct v4l2_subscribed_event *sev;
 109         struct v4l2_kevent *kev;
 110         bool copy_payload = true;
 111
 112         /* Are we subscribed? */
 113         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 114         if (sev == NULL)
 115                 return;
 116
 117         /*
 118          * If the event has been added to the fh->subscribed list, but its
 119          * add op has not completed yet elems will be 0, treat this as
 120          * not being subscribed.
 121          */
 122         if (!sev->elems)
 123                 return;
 124
 125         /* Increase event sequence number on fh. */
 126         fh->sequence++;
 127
 128         /* Do we have any free events? */
 129         if (sev->in_use == sev->elems) {
 130                 /* no, remove the oldest one */
 131                 kev = sev->events + sev_pos(sev, 0);
 132                 list_del(&kev->list);
 133                 sev->in_use--;
 134                 sev->first = sev_pos(sev, 1);
 135                 fh->navailable--;
 136                 if (sev->elems == 1) {
 137                         if (sev->ops && sev->ops->replace) {
 138                                 sev->ops->replace(&kev->event, ev);
 139                                 copy_payload = false;
 140                         }
 141                 } else if (sev->ops && sev->ops->merge) {
 142                         struct v4l2_kevent *second_oldest =
 143                                 sev->events + sev_pos(sev, 0);
 144                         sev->ops->merge(&kev->event, &second_oldest->event);
 145                 }
 146         }
 147
 148         /* Take one and fill it. */
 149         kev = sev->events + sev_pos(sev, sev->in_use);
 150         kev->event.type = ev->type;
 151         if (copy_payload)
 152                 kev->event.u = ev->u;
 153         kev->event.id = ev->id;
 154         kev->event.timestamp = *ts;
 155         kev->event.sequence = fh->sequence;
 156         sev->in_use++;
 157         list_add_tail(&kev->list, &fh->available);
 158
 159         fh->navailable++;
 160
 161         wake_up_all(&fh->wait);
 162 }
 163
 164 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 165 {
 166         struct v4l2_fh *fh;
 167         unsigned long flags;
 168         struct timespec timestamp;
 169
 170         if (vdev == NULL)
 171                 return;
 172
 173         ktime_get_ts(&timestamp);
 174
 175         spin_lock_irqsave(&vdev->fh_lock, flags);
 176
 177         list_for_each_entry(fh, &vdev->fh_list, list)
 178                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 179
 180         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 181 }
 182 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 183
 184 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 185 {
 186         unsigned long flags;
 187         struct timespec timestamp;
 188
 189         ktime_get_ts(&timestamp);
 190
 191         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 192         __v4l2_event_queue_fh(fh, ev, &timestamp);
 193         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 194 }
 195 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 196
 197 int v4l2_event_pending(struct v4l2_fh *fh)
 198 {
 199         return fh->navailable;
 200 }
 201 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 202
 203 int v4l2_event_subscribe(struct v4l2_fh *fh,
 204                          const struct v4l2_event_subscription *sub, unsigned elems,
 205                          const struct v4l2_subscribed_event_ops *ops)
 206 {
 207         struct v4l2_subscribed_event *sev, *found_ev;
 208         unsigned long flags;
 209         unsigned i;
 210
 211         if (sub->type == V4L2_EVENT_ALL)
 212                 return -EINVAL;
 213
 214         if (elems < 1)
 215                 elems = 1;
 216
 217         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 218         if (!sev)
 219                 return -ENOMEM;
 220         for (i = 0; i < elems; i++)
 221                 sev->events[i].sev = sev;
 222         sev->type = sub->type;
 223         sev->id = sub->id;
 224         sev->flags = sub->flags;
 225         sev->fh = fh;
 226         sev->ops = ops;
 227
 228         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 229         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 230         if (!found_ev)
 231                 list_add(&sev->list, &fh->subscribed);
 232         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 233
 234         if (found_ev) {
 235                 kfree(sev);
 236                 return 0; /* Already listening */
 237         }
 238
 239         if (sev->ops && sev->ops->add) {
 240                 int ret = sev->ops->add(sev, elems);
 241                 if (ret) {
 242                         sev->ops = NULL;
 243                         v4l2_event_unsubscribe(fh, sub);
 244                         return ret;
 245                 }
 246         }
 247
 248         /* Mark as ready for use */
 249         sev->elems = elems;
 250
 251         return 0;
 252 }
 253 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 254
 255 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 256 {
 257         struct v4l2_event_subscription sub;
 258         struct v4l2_subscribed_event *sev;
 259         unsigned long flags;
 260
 261         do {
 262                 sev = NULL;
 263
 264                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 265                 if (!list_empty(&fh->subscribed)) {
 266                         sev = list_first_entry(&fh->subscribed,
 267                                         struct v4l2_subscribed_event, list);
 268                         sub.type = sev->type;
 269                         sub.id = sev->id;
 270                 }
 271                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 272                 if (sev)
 273                         v4l2_event_unsubscribe(fh, &sub);
 274         } while (sev);
 275 }
 276 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 277
 278 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 279                            const struct v4l2_event_subscription *sub)
 280 {
 281         struct v4l2_subscribed_event *sev;
 282         unsigned long flags;
 283         int i;
 284
 285         if (sub->type == V4L2_EVENT_ALL) {
 286                 v4l2_event_unsubscribe_all(fh);
 287                 return 0;
 288         }
 289
 290         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 291
 292         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 293         if (sev != NULL) {
 294                 /* Remove any pending events for this subscription */
 295                 for (i = 0; i < sev->in_use; i++) {
 296                         list_del(&sev->events[sev_pos(sev, i)].list);
 297                         fh->navailable--;
 298                 }
 299                 list_del(&sev->list);
 300         }
 301
 302         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 303
 304         if (sev && sev->ops && sev->ops->del)
 305                 sev->ops->del(sev);
 306
 307         kfree(sev);
 308
 309         return 0;
 310 }
 311 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
 312
 313 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 314                                   struct v4l2_event_subscription *sub)
 315 {
 316         return v4l2_event_unsubscribe(fh, sub);
 317 }
 318 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
 319
 320 static void v4l2_event_src_replace(struct v4l2_event *old,
 321                                 const struct v4l2_event *new)
 322 {
 323         u32 old_changes = old->u.src_change.changes;
 324
 325         old->u.src_change = new->u.src_change;
 326         old->u.src_change.changes |= old_changes;
 327 }
 328
 329 static void v4l2_event_src_merge(const struct v4l2_event *old,
 330                                 struct v4l2_event *new)
 331 {
 332         new->u.src_change.changes |= old->u.src_change.changes;
 333 }
 334
 335 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
 336         .replace = v4l2_event_src_replace,
 337         .merge = v4l2_event_src_merge,
 338 };
 339
 340 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 341                                 const struct v4l2_event_subscription *sub)
 342 {
 343         if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
 344                 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
 345         return -EINVAL;
 346 }
 347 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
 348
 349 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 350                 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
 351 {
 352         return v4l2_src_change_event_subscribe(fh, sub);
 353 }
 354 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);