drivers/media/video/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@maxwell.research.nokia.com>
   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 #include <media/v4l2-ctrls.h>
  29
  30 #include <linux/sched.h>
  31 #include <linux/slab.h>
  32 #include <linux/export.h>
  33
  34 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
  35 {
  36         idx += sev->first;
  37         return idx >= sev->elems ? idx - sev->elems : idx;
  38 }
  39
  40 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  41 {
  42         struct v4l2_kevent *kev;
  43         unsigned long flags;
  44
  45         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  46
  47         if (list_empty(&fh->available)) {
  48                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  49                 return -ENOENT;
  50         }
  51
  52         WARN_ON(fh->navailable == 0);
  53
  54         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  55         list_del(&kev->list);
  56         fh->navailable--;
  57
  58         kev->event.pending = fh->navailable;
  59         *event = kev->event;
  60         kev->sev->first = sev_pos(kev->sev, 1);
  61         kev->sev->in_use--;
  62
  63         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  64
  65         return 0;
  66 }
  67
  68 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  69                        int nonblocking)
  70 {
  71         int ret;
  72
  73         if (nonblocking)
  74                 return __v4l2_event_dequeue(fh, event);
  75
  76         /* Release the vdev lock while waiting */
  77         if (fh->vdev->lock)
  78                 mutex_unlock(fh->vdev->lock);
  79
  80         do {
  81                 ret = wait_event_interruptible(fh->wait,
  82                                                fh->navailable != 0);
  83                 if (ret < 0)
  84                         break;
  85
  86                 ret = __v4l2_event_dequeue(fh, event);
  87         } while (ret == -ENOENT);
  88
  89         if (fh->vdev->lock)
  90                 mutex_lock(fh->vdev->lock);
  91
  92         return ret;
  93 }
  94 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
  95
  96 /* Caller must hold fh->vdev->fh_lock! */
  97 static struct v4l2_subscribed_event *v4l2_event_subscribed(
  98                 struct v4l2_fh *fh, u32 type, u32 id)
  99 {
 100         struct v4l2_subscribed_event *sev;
 101
 102         assert_spin_locked(&fh->vdev->fh_lock);
 103
 104         list_for_each_entry(sev, &fh->subscribed, list)
 105                 if (sev->type == type && sev->id == id)
 106                         return sev;
 107
 108         return NULL;
 109 }
 110
 111 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 112                 const struct timespec *ts)
 113 {
 114         struct v4l2_subscribed_event *sev;
 115         struct v4l2_kevent *kev;
 116         bool copy_payload = true;
 117
 118         /* Are we subscribed? */
 119         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 120         if (sev == NULL)
 121                 return;
 122
 123         /*
 124          * If the event has been added to the fh->subscribed list, but its
 125          * add op has not completed yet elems will be 0, treat this as
 126          * not being subscribed.
 127          */
 128         if (!sev->elems)
 129                 return;
 130
 131         /* Increase event sequence number on fh. */
 132         fh->sequence++;
 133
 134         /* Do we have any free events? */
 135         if (sev->in_use == sev->elems) {
 136                 /* no, remove the oldest one */
 137                 kev = sev->events + sev_pos(sev, 0);
 138                 list_del(&kev->list);
 139                 sev->in_use--;
 140                 sev->first = sev_pos(sev, 1);
 141                 fh->navailable--;
 142                 if (sev->elems == 1) {
 143                         if (sev->ops && sev->ops->replace) {
 144                                 sev->ops->replace(&kev->event, ev);
 145                                 copy_payload = false;
 146                         }
 147                 } else if (sev->ops && sev->ops->merge) {
 148                         struct v4l2_kevent *second_oldest =
 149                                 sev->events + sev_pos(sev, 0);
 150                         sev->ops->merge(&kev->event, &second_oldest->event);
 151                 }
 152         }
 153
 154         /* Take one and fill it. */
 155         kev = sev->events + sev_pos(sev, sev->in_use);
 156         kev->event.type = ev->type;
 157         if (copy_payload)
 158                 kev->event.u = ev->u;
 159         kev->event.id = ev->id;
 160         kev->event.timestamp = *ts;
 161         kev->event.sequence = fh->sequence;
 162         sev->in_use++;
 163         list_add_tail(&kev->list, &fh->available);
 164
 165         fh->navailable++;
 166
 167         wake_up_all(&fh->wait);
 168 }
 169
 170 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 171 {
 172         struct v4l2_fh *fh;
 173         unsigned long flags;
 174         struct timespec timestamp;
 175
 176         ktime_get_ts(&timestamp);
 177
 178         spin_lock_irqsave(&vdev->fh_lock, flags);
 179
 180         list_for_each_entry(fh, &vdev->fh_list, list)
 181                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 182
 183         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 184 }
 185 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 186
 187 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 188 {
 189         unsigned long flags;
 190         struct timespec timestamp;
 191
 192         ktime_get_ts(&timestamp);
 193
 194         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 195         __v4l2_event_queue_fh(fh, ev, &timestamp);
 196         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 197 }
 198 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 199
 200 int v4l2_event_pending(struct v4l2_fh *fh)
 201 {
 202         return fh->navailable;
 203 }
 204 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 205
 206 static void ctrls_replace(struct v4l2_event *old, const struct v4l2_event *new)
 207 {
 208         u32 old_changes = old->u.ctrl.changes;
 209
 210         old->u.ctrl = new->u.ctrl;
 211         old->u.ctrl.changes |= old_changes;
 212 }
 213
 214 static void ctrls_merge(const struct v4l2_event *old, struct v4l2_event *new)
 215 {
 216         new->u.ctrl.changes |= old->u.ctrl.changes;
 217 }
 218
 219 static const struct v4l2_subscribed_event_ops ctrl_ops = {
 220         .replace = ctrls_replace,
 221         .merge = ctrls_merge,
 222 };
 223
 224 int v4l2_event_subscribe(struct v4l2_fh *fh,
 225                          struct v4l2_event_subscription *sub, unsigned elems,
 226                          const struct v4l2_subscribed_event_ops *ops)
 227 {
 228         struct v4l2_subscribed_event *sev, *found_ev;
 229         struct v4l2_ctrl *ctrl = NULL;
 230         unsigned long flags;
 231         unsigned i;
 232
 233         if (sub->type == V4L2_EVENT_ALL)
 234                 return -EINVAL;
 235
 236         if (elems < 1)
 237                 elems = 1;
 238         if (sub->type == V4L2_EVENT_CTRL) {
 239                 ctrl = v4l2_ctrl_find(fh->ctrl_handler, sub->id);
 240                 if (ctrl == NULL)
 241                         return -EINVAL;
 242         }
 243
 244         sev = kzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, GFP_KERNEL);
 245         if (!sev)
 246                 return -ENOMEM;
 247         for (i = 0; i < elems; i++)
 248                 sev->events[i].sev = sev;
 249         sev->type = sub->type;
 250         sev->id = sub->id;
 251         sev->flags = sub->flags;
 252         sev->fh = fh;
 253         sev->ops = ops;
 254         if (ctrl) {
 255                 sev->ops = &ctrl_ops;
 256         }
 257
 258         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 259         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 260         if (!found_ev)
 261                 list_add(&sev->list, &fh->subscribed);
 262         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 263
 264         if (found_ev) {
 265                 kfree(sev);
 266                 return 0; /* Already listening */
 267         }
 268
 269         if (sev->ops && sev->ops->add) {
 270                 int ret = sev->ops->add(sev);
 271                 if (ret) {
 272                         sev->ops = NULL;
 273                         v4l2_event_unsubscribe(fh, sub);
 274                         return ret;
 275                 }
 276         }
 277
 278         /* v4l2_ctrl_add_event uses a mutex, so do this outside the spin lock */
 279         if (ctrl)
 280                 v4l2_ctrl_add_event(ctrl, sev);
 281
 282         /* Mark as ready for use */
 283         sev->elems = elems;
 284
 285         return 0;
 286 }
 287 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 288
 289 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 290 {
 291         struct v4l2_event_subscription sub;
 292         struct v4l2_subscribed_event *sev;
 293         unsigned long flags;
 294
 295         do {
 296                 sev = NULL;
 297
 298                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 299                 if (!list_empty(&fh->subscribed)) {
 300                         sev = list_first_entry(&fh->subscribed,
 301                                         struct v4l2_subscribed_event, list);
 302                         sub.type = sev->type;
 303                         sub.id = sev->id;
 304                 }
 305                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 306                 if (sev)
 307                         v4l2_event_unsubscribe(fh, &sub);
 308         } while (sev);
 309 }
 310 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 311
 312 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 313                            struct v4l2_event_subscription *sub)
 314 {
 315         struct v4l2_subscribed_event *sev;
 316         unsigned long flags;
 317         int i;
 318
 319         if (sub->type == V4L2_EVENT_ALL) {
 320                 v4l2_event_unsubscribe_all(fh);
 321                 return 0;
 322         }
 323
 324         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 325
 326         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 327         if (sev != NULL) {
 328                 /* Remove any pending events for this subscription */
 329                 for (i = 0; i < sev->in_use; i++) {
 330                         list_del(&sev->events[sev_pos(sev, i)].list);
 331                         fh->navailable--;
 332                 }
 333                 list_del(&sev->list);
 334         }
 335
 336         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 337
 338         if (sev && sev->ops && sev->ops->del)
 339                 sev->ops->del(sev);
 340
 341         if (sev && sev->type == V4L2_EVENT_CTRL) {
 342                 struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);
 343
 344                 if (ctrl)
 345                         v4l2_ctrl_del_event(ctrl, sev);
 346         }
 347
 348         kfree(sev);
 349
 350         return 0;
 351 }
 352 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);