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  * 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         ktime_get_ts(&timestamp);
 176
 177         spin_lock_irqsave(&vdev->fh_lock, flags);
 178
 179         list_for_each_entry(fh, &vdev->fh_list, list)
 180                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 181
 182         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 183 }
 184 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 185
 186 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 187 {
 188         unsigned long flags;
 189         struct timespec timestamp;
 190
 191         ktime_get_ts(&timestamp);
 192
 193         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 194         __v4l2_event_queue_fh(fh, ev, &timestamp);
 195         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 196 }
 197 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 198
 199 int v4l2_event_pending(struct v4l2_fh *fh)
 200 {
 201         return fh->navailable;
 202 }
 203 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 204
 205 int v4l2_event_subscribe(struct v4l2_fh *fh,
 206                          const struct v4l2_event_subscription *sub, unsigned elems,
 207                          const struct v4l2_subscribed_event_ops *ops)
 208 {
 209         struct v4l2_subscribed_event *sev, *found_ev;
 210         unsigned long flags;
 211         unsigned i;
 212
 213         if (sub->type == V4L2_EVENT_ALL)
 214                 return -EINVAL;
 215
 216         if (elems < 1)
 217                 elems = 1;
 218
 219         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 220         if (!sev)
 221                 return -ENOMEM;
 222         for (i = 0; i < elems; i++)
 223                 sev->events[i].sev = sev;
 224         sev->type = sub->type;
 225         sev->id = sub->id;
 226         sev->flags = sub->flags;
 227         sev->fh = fh;
 228         sev->ops = ops;
 229
 230         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 231         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 232         if (!found_ev)
 233                 list_add(&sev->list, &fh->subscribed);
 234         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 235
 236         if (found_ev) {
 237                 kfree(sev);
 238                 return 0; /* Already listening */
 239         }
 240
 241         if (sev->ops && sev->ops->add) {
 242                 int ret = sev->ops->add(sev, elems);
 243                 if (ret) {
 244                         sev->ops = NULL;
 245                         v4l2_event_unsubscribe(fh, sub);
 246                         return ret;
 247                 }
 248         }
 249
 250         /* Mark as ready for use */
 251         sev->elems = elems;
 252
 253         return 0;
 254 }
 255 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 256
 257 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 258 {
 259         struct v4l2_event_subscription sub;
 260         struct v4l2_subscribed_event *sev;
 261         unsigned long flags;
 262
 263         do {
 264                 sev = NULL;
 265
 266                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 267                 if (!list_empty(&fh->subscribed)) {
 268                         sev = list_first_entry(&fh->subscribed,
 269                                         struct v4l2_subscribed_event, list);
 270                         sub.type = sev->type;
 271                         sub.id = sev->id;
 272                 }
 273                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 274                 if (sev)
 275                         v4l2_event_unsubscribe(fh, &sub);
 276         } while (sev);
 277 }
 278 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 279
 280 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 281                            const struct v4l2_event_subscription *sub)
 282 {
 283         struct v4l2_subscribed_event *sev;
 284         unsigned long flags;
 285         int i;
 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                 /* Remove any pending events for this subscription */
 297                 for (i = 0; i < sev->in_use; i++) {
 298                         list_del(&sev->events[sev_pos(sev, i)].list);
 299                         fh->navailable--;
 300                 }
 301                 list_del(&sev->list);
 302         }
 303
 304         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 305
 306         if (sev && sev->ops && sev->ops->del)
 307                 sev->ops->del(sev);
 308
 309         kfree(sev);
 310
 311         return 0;
 312 }
 313 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);
 314
 315 int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
 316                                   struct v4l2_event_subscription *sub)
 317 {
 318         return v4l2_event_unsubscribe(fh, sub);
 319 }
 320 EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);