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         mutex_init(&fh->subscribe_lock);
  49 }
  50 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  51
  52 void v4l2_fh_add(struct v4l2_fh *fh)
  53 {
  54         unsigned long flags;
  55
  56         v4l2_prio_open(fh->vdev->prio, &fh->prio);
  57         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  58         list_add(&fh->list, &fh->vdev->fh_list);
  59         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  60 }
  61 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  62
  63 int v4l2_fh_open(struct file *filp)
  64 {
  65         struct video_device *vdev = video_devdata(filp);
  66         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  67
  68         filp->private_data = fh;
  69         if (fh == NULL)
  70                 return -ENOMEM;
  71         v4l2_fh_init(fh, vdev);
  72         v4l2_fh_add(fh);
  73         return 0;
  74 }
  75 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  76
  77 void v4l2_fh_del(struct v4l2_fh *fh)
  78 {
  79         unsigned long flags;
  80
  81         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  82         list_del_init(&fh->list);
  83         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  84         v4l2_prio_close(fh->vdev->prio, fh->prio);
  85 }
  86 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  87
  88 void v4l2_fh_exit(struct v4l2_fh *fh)
  89 {
  90         if (fh->vdev == NULL)
  91                 return;
  92         v4l_disable_media_source(fh->vdev);
  93         v4l2_event_unsubscribe_all(fh);
  94         mutex_destroy(&fh->subscribe_lock);
  95         fh->vdev = NULL;
  96 }
  97 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  98
  99 int v4l2_fh_release(struct file *filp)
 100 {
 101         struct v4l2_fh *fh = filp->private_data;
 102
 103         if (fh) {
 104                 v4l2_fh_del(fh);
 105                 v4l2_fh_exit(fh);
 106                 kfree(fh);
 107         }
 108         return 0;
 109 }
 110 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 111
 112 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 113 {
 114         unsigned long flags;
 115         int is_singular;
 116
 117         if (fh == NULL || fh->vdev == NULL)
 118                 return 0;
 119         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 120         is_singular = list_is_singular(&fh->list);
 121         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 122         return is_singular;
 123 }
 124 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);