drivers/media/v4l2-core/v4l2-event.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * v4l2-event.c
   4  *
   5  * V4L2 events.
   6  *
   7  * Copyright (C) 2009--2010 Nokia Corporation.
   8  *
   9  * Contact: Sakari Ailus <sakari.ailus@iki.fi>
  10  */
  11
  12 #include <media/v4l2-dev.h>
  13 #include <media/v4l2-fh.h>
  14 #include <media/v4l2-event.h>
  15
  16 #include <linux/mm.h>
  17 #include <linux/sched.h>
  18 #include <linux/slab.h>
  19 #include <linux/export.h>
  20
  21 static unsigned sev_pos(const struct v4l2_subscribed_event *sev, unsigned idx)
  22 {
  23         idx += sev->first;
  24         return idx >= sev->elems ? idx - sev->elems : idx;
  25 }
  26
  27 static int __v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event)
  28 {
  29         struct v4l2_kevent *kev;
  30         struct timespec64 ts;
  31         unsigned long flags;
  32
  33         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  34
  35         if (list_empty(&fh->available)) {
  36                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  37                 return -ENOENT;
  38         }
  39
  40         WARN_ON(fh->navailable == 0);
  41
  42         kev = list_first_entry(&fh->available, struct v4l2_kevent, list);
  43         list_del(&kev->list);
  44         fh->navailable--;
  45
  46         kev->event.pending = fh->navailable;
  47         *event = kev->event;
  48         ts = ns_to_timespec64(kev->ts);
  49         event->timestamp.tv_sec = ts.tv_sec;
  50         event->timestamp.tv_nsec = ts.tv_nsec;
  51         kev->sev->first = sev_pos(kev->sev, 1);
  52         kev->sev->in_use--;
  53
  54         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  55
  56         return 0;
  57 }
  58
  59 int v4l2_event_dequeue(struct v4l2_fh *fh, struct v4l2_event *event,
  60                        int nonblocking)
  61 {
  62         int ret;
  63
  64         if (nonblocking)
  65                 return __v4l2_event_dequeue(fh, event);
  66
  67         /* Release the vdev lock while waiting */
  68         if (fh->vdev->lock)
  69                 mutex_unlock(fh->vdev->lock);
  70
  71         do {
  72                 ret = wait_event_interruptible(fh->wait,
  73                                                fh->navailable != 0);
  74                 if (ret < 0)
  75                         break;
  76
  77                 ret = __v4l2_event_dequeue(fh, event);
  78         } while (ret == -ENOENT);
  79
  80         if (fh->vdev->lock)
  81                 mutex_lock(fh->vdev->lock);
  82
  83         return ret;
  84 }
  85 EXPORT_SYMBOL_GPL(v4l2_event_dequeue);
  86
  87 /* Caller must hold fh->vdev->fh_lock! */
  88 static struct v4l2_subscribed_event *v4l2_event_subscribed(
  89                 struct v4l2_fh *fh, u32 type, u32 id)
  90 {
  91         struct v4l2_subscribed_event *sev;
  92
  93         assert_spin_locked(&fh->vdev->fh_lock);
  94
  95         list_for_each_entry(sev, &fh->subscribed, list)
  96                 if (sev->type == type && sev->id == id)
  97                         return sev;
  98
  99         return NULL;
 100 }
 101
 102 static void __v4l2_event_queue_fh(struct v4l2_fh *fh,
 103                                   const struct v4l2_event *ev, u64 ts)
 104 {
 105         struct v4l2_subscribed_event *sev;
 106         struct v4l2_kevent *kev;
 107         bool copy_payload = true;
 108
 109         /* Are we subscribed? */
 110         sev = v4l2_event_subscribed(fh, ev->type, ev->id);
 111         if (sev == NULL)
 112                 return;
 113
 114         /* Increase event sequence number on fh. */
 115         fh->sequence++;
 116
 117         /* Do we have any free events? */
 118         if (sev->in_use == sev->elems) {
 119                 /* no, remove the oldest one */
 120                 kev = sev->events + sev_pos(sev, 0);
 121                 list_del(&kev->list);
 122                 sev->in_use--;
 123                 sev->first = sev_pos(sev, 1);
 124                 fh->navailable--;
 125                 if (sev->elems == 1) {
 126                         if (sev->ops && sev->ops->replace) {
 127                                 sev->ops->replace(&kev->event, ev);
 128                                 copy_payload = false;
 129                         }
 130                 } else if (sev->ops && sev->ops->merge) {
 131                         struct v4l2_kevent *second_oldest =
 132                                 sev->events + sev_pos(sev, 0);
 133                         sev->ops->merge(&kev->event, &second_oldest->event);
 134                 }
 135         }
 136
 137         /* Take one and fill it. */
 138         kev = sev->events + sev_pos(sev, sev->in_use);
 139         kev->event.type = ev->type;
 140         if (copy_payload)
 141                 kev->event.u = ev->u;
 142         kev->event.id = ev->id;
 143         kev->ts = ts;
 144         kev->event.sequence = fh->sequence;
 145         sev->in_use++;
 146         list_add_tail(&kev->list, &fh->available);
 147
 148         fh->navailable++;
 149
 150         wake_up_all(&fh->wait);
 151 }
 152
 153 void v4l2_event_queue(struct video_device *vdev, const struct v4l2_event *ev)
 154 {
 155         struct v4l2_fh *fh;
 156         unsigned long flags;
 157         u64 ts;
 158
 159         if (vdev == NULL)
 160                 return;
 161
 162         ts = ktime_get_ns();
 163
 164         spin_lock_irqsave(&vdev->fh_lock, flags);
 165
 166         list_for_each_entry(fh, &vdev->fh_list, list)
 167                 __v4l2_event_queue_fh(fh, ev, ts);
 168
 169         spin_unlock_irqrestore(&vdev->fh_lock, flags);
 170 }
 171 EXPORT_SYMBOL_GPL(v4l2_event_queue);
 172
 173 void v4l2_event_queue_fh(struct v4l2_fh *fh, const struct v4l2_event *ev)
 174 {
 175         unsigned long flags;
 176         u64 ts = ktime_get_ns();
 177
 178         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 179         __v4l2_event_queue_fh(fh, ev, ts);
 180         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 181 }
 182 EXPORT_SYMBOL_GPL(v4l2_event_queue_fh);
 183
 184 int v4l2_event_pending(struct v4l2_fh *fh)
 185 {
 186         return fh->navailable;
 187 }
 188 EXPORT_SYMBOL_GPL(v4l2_event_pending);
 189
 190 static void __v4l2_event_unsubscribe(struct v4l2_subscribed_event *sev)
 191 {
 192         struct v4l2_fh *fh = sev->fh;
 193         unsigned int i;
 194
 195         lockdep_assert_held(&fh->subscribe_lock);
 196         assert_spin_locked(&fh->vdev->fh_lock);
 197
 198         /* Remove any pending events for this subscription */
 199         for (i = 0; i < sev->in_use; i++) {
 200                 list_del(&sev->events[sev_pos(sev, i)].list);
 201                 fh->navailable--;
 202         }
 203         list_del(&sev->list);
 204 }
 205
 206 int v4l2_event_subscribe(struct v4l2_fh *fh,
 207                          const struct v4l2_event_subscription *sub, unsigned elems,
 208                          const struct v4l2_subscribed_event_ops *ops)
 209 {
 210         struct v4l2_subscribed_event *sev, *found_ev;
 211         unsigned long flags;
 212         unsigned i;
 213         int ret = 0;
 214
 215         if (sub->type == V4L2_EVENT_ALL)
 216                 return -EINVAL;
 217
 218         if (elems < 1)
 219                 elems = 1;
 220
 221         sev = kvzalloc(struct_size(sev, events, elems), GFP_KERNEL);
 222         if (!sev)
 223                 return -ENOMEM;
 224         for (i = 0; i < elems; i++)
 225                 sev->events[i].sev = sev;
 226         sev->type = sub->type;
 227         sev->id = sub->id;
 228         sev->flags = sub->flags;
 229         sev->fh = fh;
 230         sev->ops = ops;
 231         sev->elems = elems;
 232
 233         mutex_lock(&fh->subscribe_lock);
 234
 235         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 236         found_ev = v4l2_event_subscribed(fh, sub->type, sub->id);
 237         if (!found_ev)
 238                 list_add(&sev->list, &fh->subscribed);
 239         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 240
 241         if (found_ev) {
 242                 /* Already listening */
 243                 kvfree(sev);
 244         } else if (sev->ops && sev->ops->add) {
 245                 ret = sev->ops->add(sev, elems);
 246                 if (ret) {
 247                         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 248                         __v4l2_event_unsubscribe(sev);
 249                         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 250                         kvfree(sev);
 251                 }
 252         }
 253
 254         mutex_unlock(&fh->subscribe_lock);
 255
 256         return ret;
 257 }
 258 EXPORT_SYMBOL_GPL(v4l2_event_subscribe);
 259
 260 void v4l2_event_unsubscribe_all(struct v4l2_fh *fh)
 261 {
 262         struct v4l2_event_subscription sub;
 263         struct v4l2_subscribed_event *sev;
 264         unsigned long flags;
 265
 266         do {
 267                 sev = NULL;
 268
 269                 spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 270                 if (!list_empty(&fh->subscribed)) {
 271                         sev = list_first_entry(&fh->subscribed,
 272                                         struct v4l2_subscribed_event, list);
 273                         sub.type = sev->type;
 274                         sub.id = sev->id;
 275                 }
 276                 spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 277                 if (sev)
 278                         v4l2_event_unsubscribe(fh, &sub);
 279         } while (sev);
 280 }
 281 EXPORT_SYMBOL_GPL(v4l2_event_unsubscribe_all);
 282
 283 int v4l2_event_unsubscribe(struct v4l2_fh *fh,
 284                            const struct v4l2_event_subscription *sub)
 285 {
 286         struct v4l2_subscribed_event *sev;
 287         unsigned long flags;
 288
 289         if (sub->type == V4L2_EVENT_ALL) {
 290                 v4l2_event_unsubscribe_all(fh);
 291                 return 0;
 292         }
 293
 294         mutex_lock(&fh->subscribe_lock);
 295
 296         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 297
 298         sev = v4l2_event_subscribed(fh, sub->type, sub->id);
 299         if (sev != NULL)
 300                 __v4l2_event_unsubscribe(sev);
 301
 302         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 303
 304         if (sev && sev->ops && sev->ops->del)
 305                 sev->ops->del(sev);
 306
 307         mutex_unlock(&fh->subscribe_lock);
 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);