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_init(struct v4l2_fh *fh)
  36 {
  37         fh->events = kzalloc(sizeof(*fh->events), GFP_KERNEL);
  38         if (fh->events == NULL)
  39                 return -ENOMEM;
  40
  41         init_waitqueue_head(&fh->events->wait);
  42
  43         INIT_LIST_HEAD(&fh->events->free);
  44         INIT_LIST_HEAD(&fh->events->available);
  45         INIT_LIST_HEAD(&fh->events->subscribed);
  46
  47         fh->events->sequence = -1;
  48
  49         return 0;
  50 }
  51 EXPORT_SYMBOL_GPL(v4l2_event_init);
  52
  53 int v4l2_event_alloc(struct v4l2_fh *fh, unsigned int n)
  54 {
  55         struct v4l2_events *events = fh->events;
  56         unsigned long flags;
  57
  58         if (!events) {
  59                 WARN_ON(1);
  60                 return -ENOMEM;
  61         }
  62
  63         while (events->nallocated < n) {
  64                 struct v4l2_kevent *kev;
  65
  66                 kev = kzalloc(sizeof(*kev), GFP_KERNEL);
  67                 if (kev == NULL)
  68                         return -ENOMEM;
  69
  70                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  71                 list_add_tail(&kev->list, &events->free);
  72                 events->nallocated++;
  73                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  74         }
  75
  76         return 0;
  77 }
  78 EXPORT_SYMBOL_GPL(v4l2_event_alloc);
  79
  80 #define list_kfree(list, type, member)                          \
  81         while (!list_empty(list)) {                             \
  82                 type *hi;                                       \
  83                 hi = list_first_entry(list, type, member);      \
  84                 list_del(&hi->member);                          \
  85                 kfree(hi);                                      \
  86         }
  87
  88 void v4l2_event_free(struct v4l2_fh *fh)
  89 {
  90         struct v4l2_events *events = fh->events;
  91
  92         if (!events)
  93                 return;
  94
  95         list_kfree(&events->free, struct v4l2_kevent, list);
  96         list_kfree(&events->available, struct v4l2_kevent, list);
  97         v4l2_event_unsubscribe_all(fh);
  98
  99         kfree(events);
 100         fh->events = NULL;
 101 }
 102 EXPORT_SYMBOL_GPL(v4l2_event_free);
 103
 104 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
 105 {
 106         struct v4l2_events *events = fh->events;
 107         struct v4l2_kevent *kev;
 108         unsigned long flags;
 109
 110         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 111
 112         if (list_empty(&events->available)) {
 113                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 114                 return -ENOENT;
 115         }
 116
 117         WARN_ON(events->navailable == 0);
 118
 119         kev = list_first_entry(&events->available, struct v4l2_kevent, list);
 120         list_move(&kev->list, &events->free);
 121         events->navailable--;
 122
 123         kev->event.pending = events->navailable;
 124         *event = kev->event;
 125
 126         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 127
 128         return 0;
 129 }
 130
 131 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
 132                        int nonblocking)
 133 {
 134         struct v4l2_events *events = fh->events;
 135         int ret;
 136
 137         if (nonblocking)
 138                 return __v4l2_event_dequeue(fh, event);
 139
 140         /* Release the vdev lock while waiting */
 141         if (fh->vdev->lock)
 142                 mutex_unlock(fh->vdev->lock);
 143
 144         do {
 145                 ret = wait_event_interruptible(events->wait,
 146                                                events->navailable != 0);
 147                 if (ret < 0)
 148                         break;
 149
 150                 ret = __v4l2_event_dequeue(fh, event);
 151         } while (ret == -ENOENT);
 152
 153         if (fh->vdev->lock)
 154                 mutex_lock(fh->vdev->lock);
 155
 156         return ret;
 157 }
 158 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
 159
 160 /* Caller must hold fh->vdev->fh_lock! */
 161 static struct v4l2_subscribed_event *v4l2_event_subscribed(
 162                 struct v4l2_fh *fh, u32 type, u32 id)
 163 {
 164         struct v4l2_events *events = fh->events;
 165         struct v4l2_subscribed_event *sev;
 166
 167         assert_spin_locked(&fh->vdev->fh_lock);
 168
 169         list_for_each_entry(sev, &events->subscribed, list) {
 170                 if (sev->type == type && sev->id == id)
 171                         return sev;
 172         }
 173
 174         return NULL;
 175 }
 176
 177 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 178                 const struct timespec *ts)
 179 {
 180         struct v4l2_events *events = fh->events;
 181         struct v4l2_subscribed_event *sev;
 182         struct v4l2_kevent *kev;
 183
 184         /* Are we subscribed? */
 185         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 186         if (sev == NULL)
 187                 return;
 188
 189         /* Increase event sequence number on fh. */
 190         events->sequence++;
 191
 192         /* Do we have any free events? */
 193         if (list_empty(&events->free))
 194                 return;
 195
 196         /* Take one and fill it. */
 197         kev = list_first_entry(&events->free, struct v4l2_kevent, list);
 198         kev->event.type = ev->type;
 199         kev->event.u = ev->u;
 200         kev->event.id = ev->id;
 201         kev->event.timestamp = *ts;
 202         kev->event.sequence = events->sequence;
 203         list_move_tail(&kev->list, &events->available);
 204
 205         events->navailable++;
 206
 207         wake_up_all(&events->wait);
 208 }
 209
 210 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 211 {
 212         struct v4l2_fh *fh;
 213         unsigned long flags;
 214         struct timespec timestamp;
 215
 216         ktime_get_ts(&timestamp);
 217
 218         spin_lock_irqsave(&vdev->fh_lock, flags);
 219
 220         list_for_each_entry(fh, &vdev->fh_list, list) {
 221                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 222         }
 223
 224         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 225 }
 226 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 227
 228 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 229 {
 230         unsigned long flags;
 231         struct timespec timestamp;
 232
 233         ktime_get_ts(&timestamp);
 234
 235         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 236         __v4l2_event_queue_fh(fh, ev, &timestamp);
 237         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 238 }
 239 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 240
 241 int v4l2_event_pending(struct v4l2_fh *fh)
 242 {
 243         return fh->events->navailable;
 244 }
 245 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 246
 247 int v4l2_event_subscribe(struct v4l2_fh *fh,
 248                          struct v4l2_event_subscription *sub)
 249 {
 250         struct v4l2_events *events = fh->events;
 251         struct v4l2_subscribed_event *sev, *found_ev;
 252         struct v4l2_ctrl *ctrl = NULL;
 253         struct v4l2_ctrl_fh *ctrl_fh = NULL;
 254         unsigned long flags;
 255
 256         if (fh->events == NULL) {
 257                 WARN_ON(1);
 258                 return -ENOMEM;
 259         }
 260
 261         if (sub->type == V4L2_EVENT_CTRL) {
 262                 ctrl = v4l2_ctrl_find(fh->ctrl_handler, sub->id);
 263                 if (ctrl == NULL)
 264                         return -EINVAL;
 265         }
 266
 267         sev = kmalloc(sizeof(*sev), GFP_KERNEL);
 268         if (!sev)
 269                 return -ENOMEM;
 270         if (ctrl) {
 271                 ctrl_fh = kzalloc(sizeof(*ctrl_fh), GFP_KERNEL);
 272                 if (!ctrl_fh) {
 273                         kfree(sev);
 274                         return -ENOMEM;
 275                 }
 276                 ctrl_fh->fh = fh;
 277         }
 278
 279         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 280
 281         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 282         if (!found_ev) {
 283                 INIT_LIST_HEAD(&sev->list);
 284                 sev->type = sub->type;
 285                 sev->id = sub->id;
 286
 287                 list_add(&sev->list, &events->subscribed);
 288                 sev = NULL;
 289         }
 290
 291         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 292
 293         /* v4l2_ctrl_add_fh uses a mutex, so do this outside the spin lock */
 294         if (ctrl) {
 295                 if (found_ev)
 296                         kfree(ctrl_fh);
 297                 else
 298                         v4l2_ctrl_add_fh(fh->ctrl_handler, ctrl_fh, sub);
 299         }
 300
 301         kfree(sev);
 302
 303         return 0;
 304 }
 305 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 306
 307 static void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 308 {
 309         struct v4l2_events *events = fh->events;
 310         struct v4l2_event_subscription sub;
 311         struct v4l2_subscribed_event *sev;
 312         unsigned long flags;
 313
 314         do {
 315                 sev = NULL;
 316
 317                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 318                 if (!list_empty(&events->subscribed)) {
 319                         sev = list_first_entry(&events->subscribed,
 320                                         struct v4l2_subscribed_event, list);
 321                         sub.type = sev->type;
 322                         sub.id = sev->id;
 323                 }
 324                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 325                 if (sev)
 326                         v4l2_event_unsubscribe(fh, &sub);
 327         } while (sev);
 328 }
 329
 330 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 331                            struct v4l2_event_subscription *sub)
 332 {
 333         struct v4l2_subscribed_event *sev;
 334         unsigned long flags;
 335
 336         if (sub->type == V4L2_EVENT_ALL) {
 337                 v4l2_event_unsubscribe_all(fh);
 338                 return 0;
 339         }
 340
 341         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 342
 343         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 344         if (sev != NULL)
 345                 list_del(&sev->list);
 346
 347         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 348         if (sev->type == V4L2_EVENT_CTRL) {
 349                 struct v4l2_ctrl *ctrl = v4l2_ctrl_find(fh->ctrl_handler, sev->id);
 350
 351                 if (ctrl)
 352                         v4l2_ctrl_del_fh(ctrl, fh);
 353         }
 354
 355         kfree(sev);
 356
 357         return 0;
 358 }
 359 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe);