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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * v4l2-fh.c
   4  *
   5  * V4L2 file handles.
   6  *
   7  * Copyright (C) 2009--2010 Nokia Corporation.
   8  *
   9  * Contact: Sakari Ailus <sakari.ailus@iki.fi>
  10  */
  11
  12 #include <linux/bitops.h>
  13 #include <linux/slab.h>
  14 #include <linux/export.h>
  15 #include <media/v4l2-dev.h>
  16 #include <media/v4l2-fh.h>
  17 #include <media/v4l2-event.h>
  18 #include <media/v4l2-ioctl.h>
  19 #include <media/v4l2-mc.h>
  20
  21 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  22 {
  23         fh->vdev = vdev;
  24         /* Inherit from video_device. May be overridden by the driver. */
  25         fh->ctrl_handler = vdev->ctrl_handler;
  26         INIT_LIST_HEAD(&fh->list);
  27         set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  28         /*
  29          * determine_valid_ioctls() does not know if struct v4l2_fh
  30          * is used by this driver, but here we do. So enable the
  31          * prio ioctls here.
  32          */
  33         set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
  34         set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
  35         fh->prio = V4L2_PRIORITY_UNSET;
  36         init_waitqueue_head(&fh->wait);
  37         INIT_LIST_HEAD(&fh->available);
  38         INIT_LIST_HEAD(&fh->subscribed);
  39         fh->sequence = -1;
  40         mutex_init(&fh->subscribe_lock);
  41 }
  42 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  43
  44 void v4l2_fh_add(struct v4l2_fh *fh)
  45 {
  46         unsigned long flags;
  47
  48         v4l2_prio_open(fh->vdev->prio, &fh->prio);
  49         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  50         list_add(&fh->list, &fh->vdev->fh_list);
  51         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  52 }
  53 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  54
  55 int v4l2_fh_open(struct file *filp)
  56 {
  57         struct video_device *vdev = video_devdata(filp);
  58         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  59
  60         filp->private_data = fh;
  61         if (fh == NULL)
  62                 return -ENOMEM;
  63         v4l2_fh_init(fh, vdev);
  64         v4l2_fh_add(fh);
  65         return 0;
  66 }
  67 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  68
  69 void v4l2_fh_del(struct v4l2_fh *fh)
  70 {
  71         unsigned long flags;
  72
  73         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  74         list_del_init(&fh->list);
  75         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  76         v4l2_prio_close(fh->vdev->prio, fh->prio);
  77 }
  78 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  79
  80 void v4l2_fh_exit(struct v4l2_fh *fh)
  81 {
  82         if (fh->vdev == NULL)
  83                 return;
  84         v4l_disable_media_source(fh->vdev);
  85         v4l2_event_unsubscribe_all(fh);
  86         mutex_destroy(&fh->subscribe_lock);
  87         fh->vdev = NULL;
  88 }
  89 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  90
  91 int v4l2_fh_release(struct file *filp)
  92 {
  93         struct v4l2_fh *fh = filp->private_data;
  94
  95         if (fh) {
  96                 v4l2_fh_del(fh);
  97                 v4l2_fh_exit(fh);
  98                 kfree(fh);
  99         }
 100         return 0;
 101 }
 102 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 103
 104 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 105 {
 106         unsigned long flags;
 107         int is_singular;
 108
 109         if (fh == NULL || fh->vdev == NULL)
 110                 return 0;
 111         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 112         is_singular = list_is_singular(&fh->list);
 113         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 114         return is_singular;
 115 }
 116 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);