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
  20 #include <media/v4l2-dev.h>
  21 #include <media/v4l2-fh.h>
  22 #include <media/v4l2-event.h>
  23
  24 #include <linux/mm.h>
  25 #include <linux/sched.h>
  26 #include <linux/slab.h>
  27 #include <linux/export.h>
  28
  29 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
  30 {
  31         idx += sev->first;
  32         return idx >= sev->elems ? idx - sev->elems : idx;
  33 }
  34
  35 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  36 {
  37         struct v4l2_kevent *kev;
  38         unsigned long flags;
  39
  40         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  41
  42         if (list_empty(&fh->available)) {
  43                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  44                 return -ENOENT;
  45         }
  46
  47         WARN_ON(fh->navailable == 0);
  48
  49         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  50         list_del(&kev->list);
  51         fh->navailable--;
  52
  53         kev->event.pending = fh->navailable;
  54         *event = kev->event;
  55         kev->sev->first = sev_pos(kev->sev, 1);
  56         kev->sev->in_use--;
  57
  58         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  59
  60         return 0;
  61 }
  62
  63 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  64                        int nonblocking)
  65 {
  66         int ret;
  67
  68         if (nonblocking)
  69                 return __v4l2_event_dequeue(fh, event);
  70
  71         /* Release the vdev lock while waiting */
  72         if (fh->vdev->lock)
  73                 mutex_unlock(fh->vdev->lock);
  74
  75         do {
  76                 ret = wait_event_interruptible(fh->wait,
  77                                                fh->navailable != 0);
  78                 if (ret < 0)
  79                         break;
  80
  81                 ret = __v4l2_event_dequeue(fh, event);
  82         } while (ret == -ENOENT);
  83
  84         if (fh->vdev->lock)
  85                 mutex_lock(fh->vdev->lock);
  86
  87         return ret;
  88 }
  89 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
  90
  91 /* Caller must hold fh->vdev->fh_lock! */
  92 static struct v4l2_subscribed_event *v4l2_event_subscribed(
  93                 struct v4l2_fh *fh, u32 type, u32 id)
  94 {
  95         struct v4l2_subscribed_event *sev;
  96
  97         assert_spin_locked(&fh->vdev->fh_lock);
  98
  99         list_for_each_entry(sev, &fh->subscribed, list)
 100                 if (sev->type == type && sev->id == id)
 101                         return sev;
 102
 103         return NULL;
 104 }
 105
 106 static void __v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev,
 107                 const struct timespec *ts)
 108 {
 109         struct v4l2_subscribed_event *sev;
 110         struct v4l2_kevent *kev;
 111         bool copy_payload = true;
 112
 113         /* Are we subscribed? */
 114         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 115         if (sev == NULL)
 116                 return;
 117
 118         /*
 119          * If the event has been added to the fh->subscribed list, but its
 120          * add op has not completed yet elems will be 0, treat this as
 121          * not being subscribed.
 122          */
 123         if (!sev->elems)
 124                 return;
 125
 126         /* Increase event sequence number on fh. */
 127         fh->sequence++;
 128
 129         /* Do we have any free events? */
 130         if (sev->in_use == sev->elems) {
 131                 /* no, remove the oldest one */
 132                 kev = sev->events + sev_pos(sev, 0);
 133                 list_del(&kev->list);
 134                 sev->in_use--;
 135                 sev->first = sev_pos(sev, 1);
 136                 fh->navailable--;
 137                 if (sev->elems == 1) {
 138                         if (sev->ops && sev->ops->replace) {
 139                                 sev->ops->replace(&kev->event, ev);
 140                                 copy_payload = false;
 141                         }
 142                 } else if (sev->ops && sev->ops->merge) {
 143                         struct v4l2_kevent *second_oldest =
 144                                 sev->events + sev_pos(sev, 0);
 145                         sev->ops->merge(&kev->event, &second_oldest->event);
 146                 }
 147         }
 148
 149         /* Take one and fill it. */
 150         kev = sev->events + sev_pos(sev, sev->in_use);
 151         kev->event.type = ev->type;
 152         if (copy_payload)
 153                 kev->event.u = ev->u;
 154         kev->event.id = ev->id;
 155         kev->event.timestamp = *ts;
 156         kev->event.sequence = fh->sequence;
 157         sev->in_use++;
 158         list_add_tail(&kev->list, &fh->available);
 159
 160         fh->navailable++;
 161
 162         wake_up_all(&fh->wait);
 163 }
 164
 165 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 166 {
 167         struct v4l2_fh *fh;
 168         unsigned long flags;
 169         struct timespec timestamp;
 170
 171         if (vdev == NULL)
 172                 return;
 173
 174         ktime_get_ts(&timestamp);
 175
 176         spin_lock_irqsave(&vdev->fh_lock, flags);
 177
 178         list_for_each_entry(fh, &vdev->fh_list, list)
 179                 __v4l2_event_queue_fh(fh, ev, &timestamp);
 180
 181         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 182 }
 183 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 184
 185 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 186 {
 187         unsigned long flags;
 188         struct timespec timestamp;
 189
 190         ktime_get_ts(&timestamp);
 191
 192         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 193         __v4l2_event_queue_fh(fh, ev, &timestamp);
 194         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 195 }
 196 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 197
 198 int v4l2_event_pending(struct v4l2_fh *fh)
 199 {
 200         return fh->navailable;
 201 }
 202 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 203
 204 int v4l2_event_subscribe(struct v4l2_fh *fh,
 205                          const struct v4l2_event_subscription *sub, unsigned elems,
 206                          const struct v4l2_subscribed_event_ops *ops)
 207 {
 208         struct v4l2_subscribed_event *sev, *found_ev;
 209         unsigned long flags;
 210         unsigned i;
 211
 212         if (sub->type == V4L2_EVENT_ALL)
 213                 return -EINVAL;
 214
 215         if (elems < 1)
 216                 elems = 1;
 217
 218         sev = kvzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems,
 219                        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                 kvfree(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         kvfree(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);
 321
 322 static void v4l2_event_src_replace(struct v4l2_event *old,
 323                                 const struct v4l2_event *new)
 324 {
 325         u32 old_changes = old->u.src_change.changes;
 326
 327         old->u.src_change = new->u.src_change;
 328         old->u.src_change.changes |= old_changes;
 329 }
 330
 331 static void v4l2_event_src_merge(const struct v4l2_event *old,
 332                                 struct v4l2_event *new)
 333 {
 334         new->u.src_change.changes |= old->u.src_change.changes;
 335 }
 336
 337 static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
 338         .replace = v4l2_event_src_replace,
 339         .merge = v4l2_event_src_merge,
 340 };
 341
 342 int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
 343                                 const struct v4l2_event_subscription *sub)
 344 {
 345         if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
 346                 return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
 347         return -EINVAL;
 348 }
 349 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
 350
 351 int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
 352                 struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
 353 {
 354         return v4l2_src_change_event_subscribe(fh, sub);
 355 }
 356 EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);