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         /*
 123          * If the event has been added to the fh->subscribed list, but its
 124          * add op has not completed yet elems will be 0, treat this as
 125          * not being subscribed.
 126          */
 127         if (!sev->elems)
 128                 return;
 129
 130         /* Increase event sequence number on fh. */
 131         fh->sequence++;
 132
 133         /* Do we have any free events? */
 134         if (sev->in_use == sev->elems) {
 135                 /* no, remove the oldest one */
 136                 kev = sev->events + sev_pos(sev, 0);
 137                 list_del(&kev->list);
 138                 sev->in_use--;
 139                 sev->first = sev_pos(sev, 1);
 140                 fh->navailable--;
 141                 if (sev->elems == 1) {
 142                         if (sev->ops && sev->ops->replace) {
 143                                 sev->ops->replace(&kev->event, ev);
 144                                 copy_payload = false;
 145                         }
 146                 } else if (sev->ops && sev->ops->merge) {
 147                         struct v4l2_kevent *second_oldest =
 148                                 sev->events + sev_pos(sev, 0);
 149                         sev->ops->merge(&kev->event, &second_oldest->event);
 150                 }
 151         }
 152
 153         /* Take one and fill it. */
 154         kev = sev->events + sev_pos(sev, sev->in_use);
 155         kev->event.type = ev->type;
 156         if (copy_payload)
 157                 kev->event.u = ev->u;
 158         kev->event.id = ev->id;
 159         kev->event.timestamp = *ts;
 160         kev->event.sequence = fh->sequence;
 161         sev->in_use++;
 162         list_add_tail(&kev->list, &fh->available);
 163
 164         fh->navailable++;
 165
 166         wake_up_all(&fh->wait);
 167 }
 168
 169 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 170 {
 171         struct v4l2_fh *fh;
 172         unsigned long flags;
 173         struct timespec timestamp;
 174
 175         if (vdev == NULL)
 176                 return;
 177
 178         ktime_get_ts(&timestamp);
 179
 180         spin_lock_irqsave(&vdev->fh_lock, flags);
 181
 182         list_for_each_entry(fh, &vdev->fh_list, list)
 183                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 184
 185         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 186 }
 187 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 188
 189 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 190 {
 191         unsigned long flags;
 192         struct timespec timestamp;
 193
 194         ktime_get_ts(&timestamp);
 195
 196         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 197         __v4l2_event_queue_fh(fh, ev, &timestamp);
 198         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 199 }
 200 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 201
 202 int v4l2_event_pending(struct v4l2_fh *fh)
 203 {
 204         return fh->navailable;
 205 }
 206 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 207
 208 int v4l2_event_subscribe(struct v4l2_fh *fh,
 209                          const struct v4l2_event_subscription *sub, unsigned elems,
 210                          const struct v4l2_subscribed_event_ops *ops)
 211 {
 212         struct v4l2_subscribed_event *sev, *found_ev;
 213         unsigned long flags;
 214         unsigned i;
 215
 216         if (sub->type == V4L2_EVENT_ALL)
 217                 return -EINVAL;
 218
 219         if (elems < 1)
 220                 elems = 1;
 221
 222         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 223         if (!sev)
 224                 return -ENOMEM;
 225         for (i = 0; i < elems; i++)
 226                 sev->events[i].sev = sev;
 227         sev->type = sub->type;
 228         sev->id = sub->id;
 229         sev->flags = sub->flags;
 230         sev->fh = fh;
 231         sev->ops = ops;
 232
 233         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 234         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 235         if (!found_ev)
 236                 list_add(&sev->list, &fh->subscribed);
 237         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 238
 239         if (found_ev) {
 240                 kfree(sev);
 241                 return 0; /* Already listening */
 242         }
 243
 244         if (sev->ops && sev->ops->add) {
 245                 int ret = sev->ops->add(sev, elems);
 246                 if (ret) {
 247                         sev->ops = NULL;
 248                         v4l2_event_unsubscribe(fh, sub);
 249                         return ret;
 250                 }
 251         }
 252
 253         /* Mark as ready for use */
 254         sev->elems = elems;
 255
 256         return 0;
 257 }
 258 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 259
 260 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 261 {
 262         struct v4l2_event_subscription sub;
 263         struct v4l2_subscribed_event *sev;
 264         unsigned long flags;
 265
 266         do {
 267                 sev = NULL;
 268
 269                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 270                 if (!list_empty(&fh->subscribed)) {
 271                         sev = list_first_entry(&fh->subscribed,
 272                                         struct v4l2_subscribed_event, list);
 273                         sub.type = sev->type;
 274                         sub.id = sev->id;
 275                 }
 276                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 277                 if (sev)
 278                         v4l2_event_unsubscribe(fh, &sub);
 279         } while (sev);
 280 }
 281 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 282
 283 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 284                            const struct v4l2_event_subscription *sub)
 285 {
 286         struct v4l2_subscribed_event *sev;
 287         unsigned long flags;
 288         int i;
 289
 290         if (sub->type == V4L2_EVENT_ALL) {
 291                 v4l2_event_unsubscribe_all(fh);
 292                 return 0;
 293         }
 294
 295         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 296
 297         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 298         if (sev != NULL) {
 299                 /* Remove any pending events for this subscription */
 300                 for (i = 0; i < sev->in_use; i++) {
 301                         list_del(&sev->events[sev_pos(sev, i)].list);
 302                         fh->navailable--;
 303                 }
 304                 list_del(&sev->list);
 305         }
 306
 307         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 308
 309         if (sev && sev->ops && sev->ops->del)
 310                 sev->ops->del(sev);
 311
 312         kfree(sev);
 313
 314         return 0;
 315 }
 316 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
 317
 318 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 319                                   struct v4l2_event_subscription *sub)
 320 {
 321         return v4l2_event_unsubscribe(fh, sub);
 322 }
 323 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
 324
 325 static void v4l2_event_src_replace(struct v4l2_event *old,
 326                                 const struct v4l2_event *new)
 327 {
 328         u32 old_changes = old->u.src_change.changes;
 329
 330         old->u.src_change = new->u.src_change;
 331         old->u.src_change.changes |= old_changes;
 332 }
 333
 334 static void v4l2_event_src_merge(const struct v4l2_event *old,
 335                                 struct v4l2_event *new)
 336 {
 337         new->u.src_change.changes |= old->u.src_change.changes;
 338 }
 339
 340 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
 341         .replace = v4l2_event_src_replace,
 342         .merge = v4l2_event_src_merge,
 343 };
 344
 345 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 346                                 const struct v4l2_event_subscription *sub)
 347 {
 348         if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
 349                 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
 350         return -EINVAL;
 351 }
 352 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
 353
 354 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 355                 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
 356 {
 357         return v4l2_src_change_event_subscribe(fh, sub);
 358 }
 359 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);