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  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  22  * 02110-1301 USA
  23  */
  24
  25 #include <linux/bitops.h>
  26 #include <linux/slab.h>
  27 #include <linux/export.h>
  28 #include <media/v4l2-dev.h>
  29 #include <media/v4l2-fh.h>
  30 #include <media/v4l2-event.h>
  31 #include <media/v4l2-ioctl.h>
  32 #include <media/v4l2-mc.h>
  33
  34 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  35 {
  36         fh->vdev = vdev;
  37         /* Inherit from video_device. May be overridden by the driver. */
  38         fh->ctrl_handler = vdev->ctrl_handler;
  39         INIT_LIST_HEAD(&fh->list);
  40         set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  41         /*
  42          * determine_valid_ioctls() does not know if struct v4l2_fh
  43          * is used by this driver, but here we do. So enable the
  44          * prio ioctls here.
  45          */
  46         set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
  47         set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
  48         fh->prio = V4L2_PRIORITY_UNSET;
  49         init_waitqueue_head(&fh->wait);
  50         INIT_LIST_HEAD(&fh->available);
  51         INIT_LIST_HEAD(&fh->subscribed);
  52         fh->sequence = -1;
  53 }
  54 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  55
  56 void v4l2_fh_add(struct v4l2_fh *fh)
  57 {
  58         unsigned long flags;
  59
  60         v4l2_prio_open(fh->vdev->prio, &fh->prio);
  61         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  62         list_add(&fh->list, &fh->vdev->fh_list);
  63         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  64 }
  65 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  66
  67 int v4l2_fh_open(struct file *filp)
  68 {
  69         struct video_device *vdev = video_devdata(filp);
  70         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  71
  72         filp->private_data = fh;
  73         if (fh == NULL)
  74                 return -ENOMEM;
  75         v4l2_fh_init(fh, vdev);
  76         v4l2_fh_add(fh);
  77         return 0;
  78 }
  79 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  80
  81 void v4l2_fh_del(struct v4l2_fh *fh)
  82 {
  83         unsigned long flags;
  84
  85         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  86         list_del_init(&fh->list);
  87         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  88         v4l2_prio_close(fh->vdev->prio, fh->prio);
  89 }
  90 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  91
  92 void v4l2_fh_exit(struct v4l2_fh *fh)
  93 {
  94         if (fh->vdev == NULL)
  95                 return;
  96         v4l_disable_media_source(fh->vdev);
  97         v4l2_event_unsubscribe_all(fh);
  98         fh->vdev = NULL;
  99 }
 100 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
 101
 102 int v4l2_fh_release(struct file *filp)
 103 {
 104         struct v4l2_fh *fh = filp->private_data;
 105
 106         if (fh) {
 107                 v4l2_fh_del(fh);
 108                 v4l2_fh_exit(fh);
 109                 kfree(fh);
 110         }
 111         return 0;
 112 }
 113 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 114
 115 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 116 {
 117         unsigned long flags;
 118         int is_singular;
 119
 120         if (fh == NULL || fh->vdev == NULL)
 121                 return 0;
 122         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 123         is_singular = list_is_singular(&fh->list);
 124         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 125         return is_singular;
 126 }
 127 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);