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

   1 /*
   2  * v4l2-fh.c
   3  *
   4  * V4L2 file handles.
   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 <linux/bitops.h>
  21 #include <linux/slab.h>
  22 #include <linux/export.h>
  23 #include <media/v4l2-dev.h>
  24 #include <media/v4l2-fh.h>
  25 #include <media/v4l2-event.h>
  26 #include <media/v4l2-ioctl.h>
  27 #include <media/v4l2-mc.h>
  28
  29 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  30 {
  31         fh->vdev = vdev;
  32         /* Inherit from video_device. May be overridden by the driver. */
  33         fh->ctrl_handler = vdev->ctrl_handler;
  34         INIT_LIST_HEAD(&fh->list);
  35         set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  36         /*
  37          * determine_valid_ioctls() does not know if struct v4l2_fh
  38          * is used by this driver, but here we do. So enable the
  39          * prio ioctls here.
  40          */
  41         set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
  42         set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
  43         fh->prio = V4L2_PRIORITY_UNSET;
  44         init_waitqueue_head(&fh->wait);
  45         INIT_LIST_HEAD(&fh->available);
  46         INIT_LIST_HEAD(&fh->subscribed);
  47         fh->sequence = -1;
  48 }
  49 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  50
  51 void v4l2_fh_add(struct v4l2_fh *fh)
  52 {
  53         unsigned long flags;
  54
  55         v4l2_prio_open(fh->vdev->prio, &fh->prio);
  56         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  57         list_add(&fh->list, &fh->vdev->fh_list);
  58         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  59 }
  60 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  61
  62 int v4l2_fh_open(struct file *filp)
  63 {
  64         struct video_device *vdev = video_devdata(filp);
  65         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  66
  67         filp->private_data = fh;
  68         if (fh == NULL)
  69                 return -ENOMEM;
  70         v4l2_fh_init(fh, vdev);
  71         v4l2_fh_add(fh);
  72         return 0;
  73 }
  74 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  75
  76 void v4l2_fh_del(struct v4l2_fh *fh)
  77 {
  78         unsigned long flags;
  79
  80         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  81         list_del_init(&fh->list);
  82         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  83         v4l2_prio_close(fh->vdev->prio, fh->prio);
  84 }
  85 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  86
  87 void v4l2_fh_exit(struct v4l2_fh *fh)
  88 {
  89         if (fh->vdev == NULL)
  90                 return;
  91         v4l_disable_media_source(fh->vdev);
  92         v4l2_event_unsubscribe_all(fh);
  93         fh->vdev = NULL;
  94 }
  95 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  96
  97 int v4l2_fh_release(struct file *filp)
  98 {
  99         struct v4l2_fh *fh = filp->private_data;
 100
 101         if (fh) {
 102                 v4l2_fh_del(fh);
 103                 v4l2_fh_exit(fh);
 104                 kfree(fh);
 105         }
 106         return 0;
 107 }
 108 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 109
 110 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 111 {
 112         unsigned long flags;
 113         int is_singular;
 114
 115         if (fh == NULL || fh->vdev == NULL)
 116                 return 0;
 117         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 118         is_singular = list_is_singular(&fh->list);
 119         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 120         return is_singular;
 121 }
 122 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);