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
  33 static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
  34
  35 int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n)
  36 {
  37         unsigned long flags;
  38
  39         while (fh->nallocated < n) {
  40                 struct v4l2_kevent *kev;
  41
  42                 kev = kzalloc(sizeof(*kev), GFP_KERNEL);
  43                 if (kev == NULL)
  44                         return -ENOMEM;
  45
  46                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  47                 list_add_tail(&kev->list, &fh->free);
  48                 fh->nallocated++;
  49                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  50         }
  51
  52         return 0;
  53 }
  54 EXPORT_SYMBOL_GPL(v4l2_event_alloc);
  55
  56 #define list_kfree(list, type, member)                          \
  57         while (!list_empty(list)) {                             \
  58                 type *hi;                                       \
  59                 hi = list_first_entry(list, type, member);      \
  60                 list_del(&hi->member);                          \
  61                 kfree(hi);                                      \
  62         }
  63
  64 void v4l2_event_free(struct v4l2_fh *fh)
  65 {
  66         list_kfree(&fh->free, struct v4l2_kevent, list);
  67         list_kfree(&fh->available, struct v4l2_kevent, list);
  68         v4l2_event_unsubscribe_all(fh);
  69 }
  70 EXPORT_SYMBOL_GPL(v4l2_event_free);
  71
  72 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  73 {
  74         struct v4l2_kevent *kev;
  75         unsigned long flags;
  76
  77         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  78
  79         if (list_empty(&fh->available)) {
  80                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  81                 return -ENOENT;
  82         }
  83
  84         WARN_ON(fh->navailable == 0);
  85
  86         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  87         list_move(&kev->list, &fh->free);
  88         fh->navailable--;
  89
  90         kev->event.pending = fh->navailable;
  91         *event = kev->event;
  92
  93         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  94
  95         return 0;
  96 }
  97
  98 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  99                        int nonblocking)
 100 {
 101         int ret;
 102
 103         if (nonblocking)
 104                 return __v4l2_event_dequeue(fh, event);
 105
 106         /* Release the vdev lock while waiting */
 107         if (fh->vdev->lock)
 108                 mutex_unlock(fh->vdev->lock);
 109
 110         do {
 111                 ret = wait_event_interruptible(fh->wait,
 112                                                fh->navailable != 0);
 113                 if (ret < 0)
 114                         break;
 115
 116                 ret = __v4l2_event_dequeue(fh, event);
 117         } while (ret == -ENOENT);
 118
 119         if (fh->vdev->lock)
 120                 mutex_lock(fh->vdev->lock);
 121
 122         return ret;
 123 }
 124 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
 125
 126 /* Caller must hold fh->vdev->fh_lock! */
 127 static struct v4l2_subscribed_event *v4l2_event_subscribed(
 128                 struct v4l2_fh *fh, u32 type, u32 id)
 129 {
 130         struct v4l2_subscribed_event *sev;
 131
 132         assert_spin_locked(&fh->vdev->fh_lock);
 133
 134         list_for_each_entry(sev, &fh->subscribed, list) {
 135                 if (sev->type == type && sev->id == id)
 136                         return sev;
 137         }
 138
 139         return NULL;
 140 }
 141
 142 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 143                 const struct timespec *ts)
 144 {
 145         struct v4l2_subscribed_event *sev;
 146         struct v4l2_kevent *kev;
 147
 148         /* Are we subscribed? */
 149         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 150         if (sev == NULL)
 151                 return;
 152
 153         /* Increase event sequence number on fh. */
 154         fh->sequence++;
 155
 156         /* Do we have any free events? */
 157         if (list_empty(&fh->free))
 158                 return;
 159
 160         /* Take one and fill it. */
 161         kev = list_first_entry(&fh->free, struct v4l2_kevent, list);
 162         kev->event.type = ev->type;
 163         kev->event.u = ev->u;
 164         kev->event.id = ev->id;
 165         kev->event.timestamp = *ts;
 166         kev->event.sequence = fh->sequence;
 167         list_move_tail(&kev->list, &fh->available);
 168
 169         fh->navailable++;
 170
 171         wake_up_all(&fh->wait);
 172 }
 173
 174 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 175 {
 176         struct v4l2_fh *fh;
 177         unsigned long flags;
 178         struct timespec timestamp;
 179
 180         ktime_get_ts(&timestamp);
 181
 182         spin_lock_irqsave(&vdev->fh_lock, flags);
 183
 184         list_for_each_entry(fh, &vdev->fh_list, list) {
 185                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 186         }
 187
 188         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 189 }
 190 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 191
 192 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 193 {
 194         unsigned long flags;
 195         struct timespec timestamp;
 196
 197         ktime_get_ts(&timestamp);
 198
 199         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 200         __v4l2_event_queue_fh(fh, ev, &timestamp);
 201         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 202 }
 203 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 204
 205 int v4l2_event_pending(struct v4l2_fh *fh)
 206 {
 207         return fh->navailable;
 208 }
 209 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 210
 211 int v4l2_event_subscribe(struct v4l2_fh *fh,
 212                          struct v4l2_event_subscription *sub)
 213 {
 214         struct v4l2_subscribed_event *sev, *found_ev;
 215         struct v4l2_ctrl *ctrl = NULL;
 216         unsigned long flags;
 217
 218         if (sub->type == V4L2_EVENT_CTRL) {
 219                 ctrl = v4l2_ctrl_find(fh->ctrl_handler, sub->id);
 220                 if (ctrl == NULL)
 221                         return -EINVAL;
 222         }
 223
 224         sev = kzalloc(sizeof(*sev), GFP_KERNEL);
 225         if (!sev)
 226                 return -ENOMEM;
 227
 228         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 229
 230         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 231         if (!found_ev) {
 232                 INIT_LIST_HEAD(&sev->list);
 233                 sev->type = sub->type;
 234                 sev->id = sub->id;
 235                 sev->fh = fh;
 236                 sev->flags = sub->flags;
 237
 238                 list_add(&sev->list, &fh->subscribed);
 239         }
 240
 241         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 242
 243         /* v4l2_ctrl_add_fh uses a mutex, so do this outside the spin lock */
 244         if (found_ev)
 245                 kfree(sev);
 246         else if (ctrl)
 247                 v4l2_ctrl_add_event(ctrl, sev);
 248
 249         return 0;
 250 }
 251 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 252
 253 static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 254 {
 255         struct v4l2_event_subscription sub;
 256         struct v4l2_subscribed_event *sev;
 257         unsigned long flags;
 258
 259         do {
 260                 sev = NULL;
 261
 262                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 263                 if (!list_empty(&fh->subscribed)) {
 264                         sev = list_first_entry(&fh->subscribed,
 265                                         struct v4l2_subscribed_event, list);
 266                         sub.type = sev->type;
 267                         sub.id = sev->id;
 268                 }
 269                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 270                 if (sev)
 271                         v4l2_event_unsubscribe(fh, &sub);
 272         } while (sev);
 273 }
 274
 275 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 276                            struct v4l2_event_subscription *sub)
 277 {
 278         struct v4l2_subscribed_event *sev;
 279         unsigned long flags;
 280
 281         if (sub->type == V4L2_EVENT_ALL) {
 282                 v4l2_event_unsubscribe_all(fh);
 283                 return 0;
 284         }
 285
 286         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 287
 288         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 289         if (sev != NULL) {
 290                 list_del(&sev->list);
 291                 sev->fh = NULL;
 292         }
 293
 294         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 295         if (sev && sev->type == V4L2_EVENT_CTRL) {
 296                 struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);
 297
 298                 if (ctrl)
 299                         v4l2_ctrl_del_event(ctrl, sev);
 300         }
 301
 302         kfree(sev);
 303
 304         return 0;
 305 }
 306 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);