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 <[email protected]>
   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/mm.h>
  25 #include <linux/sched.h>
  26 #include <linux/slab.h>
  27 #include <linux/export.h>
  28
  29 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
  30 {
  31         idx += sev->first;
  32         return idx >= sev->elems ? idx - sev->elems : idx;
  33 }
  34
  35 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  36 {
  37         struct v4l2_kevent *kev;
  38         unsigned long flags;
  39
  40         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  41
  42         if (list_empty(&fh->available)) {
  43                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  44                 return -ENOENT;
  45         }
  46
  47         WARN_ON(fh->navailable == 0);
  48
  49         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  50         list_del(&kev->list);
  51         fh->navailable--;
  52
  53         kev->event.pending = fh->navailable;
  54         *event = kev->event;
  55         kev->sev->first = sev_pos(kev->sev, 1);
  56         kev->sev->in_use--;
  57
  58         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  59
  60         return 0;
  61 }
  62
  63 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  64                        int nonblocking)
  65 {
  66         int ret;
  67
  68         if (nonblocking)
  69                 return __v4l2_event_dequeue(fh, event);
  70
  71         /* Release the vdev lock while waiting */
  72         if (fh->vdev->lock)
  73                 mutex_unlock(fh->vdev->lock);
  74
  75         do {
  76                 ret = wait_event_interruptible(fh->wait,
  77                                                fh->navailable != 0);
  78                 if (ret < 0)
  79                         break;
  80
  81                 ret = __v4l2_event_dequeue(fh, event);
  82         } while (ret == -ENOENT);
  83
  84         if (fh->vdev->lock)
  85                 mutex_lock(fh->vdev->lock);
  86
  87         return ret;
  88 }
  89 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
  90
  91 /* Caller must hold fh->vdev->fh_lock! */
  92 static struct v4l2_subscribed_event *v4l2_event_subscribed(
  93                 struct v4l2_fh *fh, u32 type, u32 id)
  94 {
  95         struct v4l2_subscribed_event *sev;
  96
  97         assert_spin_locked(&fh->vdev->fh_lock);
  98
  99         list_for_each_entry(sev, &fh->subscribed, list)
 100                 if (sev->type == type && sev->id == id)
 101                         return sev;
 102
 103         return NULL;
 104 }
 105
 106 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 107                 const struct timespec *ts)
 108 {
 109         struct v4l2_subscribed_event *sev;
 110         struct v4l2_kevent *kev;
 111         bool copy_payload = true;
 112
 113         /* Are we subscribed? */
 114         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 115         if (sev == NULL)
 116                 return;
 117
 118         /* Increase event sequence number on fh. */
 119         fh->sequence++;
 120
 121         /* Do we have any free events? */
 122         if (sev->in_use == sev->elems) {
 123                 /* no, remove the oldest one */
 124                 kev = sev->events + sev_pos(sev, 0);
 125                 list_del(&kev->list);
 126                 sev->in_use--;
 127                 sev->first = sev_pos(sev, 1);
 128                 fh->navailable--;
 129                 if (sev->elems == 1) {
 130                         if (sev->ops && sev->ops->replace) {
 131                                 sev->ops->replace(&kev->event, ev);
 132                                 copy_payload = false;
 133                         }
 134                 } else if (sev->ops && sev->ops->merge) {
 135                         struct v4l2_kevent *second_oldest =
 136                                 sev->events + sev_pos(sev, 0);
 137                         sev->ops->merge(&kev->event, &second_oldest->event);
 138                 }
 139         }
 140
 141         /* Take one and fill it. */
 142         kev = sev->events + sev_pos(sev, sev->in_use);
 143         kev->event.type = ev->type;
 144         if (copy_payload)
 145                 kev->event.u = ev->u;
 146         kev->event.id = ev->id;
 147         kev->event.timestamp = *ts;
 148         kev->event.sequence = fh->sequence;
 149         sev->in_use++;
 150         list_add_tail(&kev->list, &fh->available);
 151
 152         fh->navailable++;
 153
 154         wake_up_all(&fh->wait);
 155 }
 156
 157 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 158 {
 159         struct v4l2_fh *fh;
 160         unsigned long flags;
 161         struct timespec timestamp;
 162
 163         if (vdev == NULL)
 164                 return;
 165
 166         ktime_get_ts(&timestamp);
 167
 168         spin_lock_irqsave(&vdev->fh_lock, flags);
 169
 170         list_for_each_entry(fh, &vdev->fh_list, list)
 171                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 172
 173         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 174 }
 175 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 176
 177 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 178 {
 179         unsigned long flags;
 180         struct timespec timestamp;
 181
 182         ktime_get_ts(&timestamp);
 183
 184         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 185         __v4l2_event_queue_fh(fh, ev, &timestamp);
 186         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 187 }
 188 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 189
 190 int v4l2_event_pending(struct v4l2_fh *fh)
 191 {
 192         return fh->navailable;
 193 }
 194 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 195
 196 static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
 197 {
 198         struct v4l2_fh *fh = sev->fh;
 199         unsigned int i;
 200
 201         lockdep_assert_held(&fh->subscribe_lock);
 202         assert_spin_locked(&fh->vdev->fh_lock);
 203
 204         /* Remove any pending events for this subscription */
 205         for (i = 0; i < sev->in_use; i++) {
 206                 list_del(&sev->events[sev_pos(sev, i)].list);
 207                 fh->navailable--;
 208         }
 209         list_del(&sev->list);
 210 }
 211
 212 int v4l2_event_subscribe(struct v4l2_fh *fh,
 213                          const struct v4l2_event_subscription *sub, unsigned elems,
 214                          const struct v4l2_subscribed_event_ops *ops)
 215 {
 216         struct v4l2_subscribed_event *sev, *found_ev;
 217         unsigned long flags;
 218         unsigned i;
 219         int ret = 0;
 220
 221         if (sub->type == V4L2_EVENT_ALL)
 222                 return -EINVAL;
 223
 224         if (elems < 1)
 225                 elems = 1;
 226
 227         sev = kvzalloc(struct_size(sev, events, 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->ops = ops;
 237         sev->elems = elems;
 238
 239         mutex_lock(&fh->subscribe_lock);
 240
 241         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 242         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 243         if (!found_ev)
 244                 list_add(&sev->list, &fh->subscribed);
 245         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 246
 247         if (found_ev) {
 248                 /* Already listening */
 249                 kvfree(sev);
 250         } else if (sev->ops && sev->ops->add) {
 251                 ret = sev->ops->add(sev, elems);
 252                 if (ret) {
 253                         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 254                         __v4l2_event_unsubscribe(sev);
 255                         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 256                         kvfree(sev);
 257                 }
 258         }
 259
 260         mutex_unlock(&fh->subscribe_lock);
 261
 262         return ret;
 263 }
 264 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 265
 266 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 267 {
 268         struct v4l2_event_subscription sub;
 269         struct v4l2_subscribed_event *sev;
 270         unsigned long flags;
 271
 272         do {
 273                 sev = NULL;
 274
 275                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 276                 if (!list_empty(&fh->subscribed)) {
 277                         sev = list_first_entry(&fh->subscribed,
 278                                         struct v4l2_subscribed_event, list);
 279                         sub.type = sev->type;
 280                         sub.id = sev->id;
 281                 }
 282                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 283                 if (sev)
 284                         v4l2_event_unsubscribe(fh, &sub);
 285         } while (sev);
 286 }
 287 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 288
 289 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 290                            const struct v4l2_event_subscription *sub)
 291 {
 292         struct v4l2_subscribed_event *sev;
 293         unsigned long flags;
 294
 295         if (sub->type == V4L2_EVENT_ALL) {
 296                 v4l2_event_unsubscribe_all(fh);
 297                 return 0;
 298         }
 299
 300         mutex_lock(&fh->subscribe_lock);
 301
 302         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 303
 304         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 305         if (sev != NULL)
 306                 __v4l2_event_unsubscribe(sev);
 307
 308         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 309
 310         if (sev && sev->ops && sev->ops->del)
 311                 sev->ops->del(sev);
 312
 313         mutex_unlock(&fh->subscribe_lock);
 314
 315         kvfree(sev);
 316
 317         return 0;
 318 }
 319 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
 320
 321 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 322                                   struct v4l2_event_subscription *sub)
 323 {
 324         return v4l2_event_unsubscribe(fh, sub);
 325 }
 326 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
 327
 328 static void v4l2_event_src_replace(struct v4l2_event *old,
 329                                 const struct v4l2_event *new)
 330 {
 331         u32 old_changes = old->u.src_change.changes;
 332
 333         old->u.src_change = new->u.src_change;
 334         old->u.src_change.changes |= old_changes;
 335 }
 336
 337 static void v4l2_event_src_merge(const struct v4l2_event *old,
 338                                 struct v4l2_event *new)
 339 {
 340         new->u.src_change.changes |= old->u.src_change.changes;
 341 }
 342
 343 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
 344         .replace = v4l2_event_src_replace,
 345         .merge = v4l2_event_src_merge,
 346 };
 347
 348 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 349                                 const struct v4l2_event_subscription *sub)
 350 {
 351         if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
 352                 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
 353         return -EINVAL;
 354 }
 355 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
 356
 357 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 358                 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
 359 {
 360         return v4l2_src_change_event_subscribe(fh, sub);
 361 }
 362 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);