drivers/media/video/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@maxwell.research.nokia.com>
   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 <media/v4l2-dev.h>
  28 #include <media/v4l2-fh.h>
  29 #include <media/v4l2-event.h>
  30 #include <media/v4l2-ioctl.h>
  31
  32 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  33 {
  34         fh->vdev = vdev;
  35         /* Inherit from video_device. May be overridden by the driver. */
  36         fh->ctrl_handler = vdev->ctrl_handler;
  37         INIT_LIST_HEAD(&fh->list);
  38         set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  39         fh->prio = V4L2_PRIORITY_UNSET;
  40         init_waitqueue_head(&fh->wait);
  41         INIT_LIST_HEAD(&fh->available);
  42         INIT_LIST_HEAD(&fh->subscribed);
  43         fh->sequence = -1;
  44 }
  45 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  46
  47 void v4l2_fh_add(struct v4l2_fh *fh)
  48 {
  49         unsigned long flags;
  50
  51         if (test_bit(V4L2_FL_USE_FH_PRIO, &fh->vdev->flags))
  52                 v4l2_prio_open(fh->vdev->prio, &fh->prio);
  53         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  54         list_add(&fh->list, &fh->vdev->fh_list);
  55         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  56 }
  57 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  58
  59 int v4l2_fh_open(struct file *filp)
  60 {
  61         struct video_device *vdev = video_devdata(filp);
  62         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  63
  64         filp->private_data = fh;
  65         if (fh == NULL)
  66                 return -ENOMEM;
  67         v4l2_fh_init(fh, vdev);
  68         v4l2_fh_add(fh);
  69         return 0;
  70 }
  71 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  72
  73 void v4l2_fh_del(struct v4l2_fh *fh)
  74 {
  75         unsigned long flags;
  76
  77         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  78         list_del_init(&fh->list);
  79         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  80         if (test_bit(V4L2_FL_USE_FH_PRIO, &fh->vdev->flags))
  81                 v4l2_prio_close(fh->vdev->prio, fh->prio);
  82 }
  83 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  84
  85 void v4l2_fh_exit(struct v4l2_fh *fh)
  86 {
  87         if (fh->vdev == NULL)
  88                 return;
  89         v4l2_event_unsubscribe_all(fh);
  90         fh->vdev = NULL;
  91 }
  92 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  93
  94 int v4l2_fh_release(struct file *filp)
  95 {
  96         struct v4l2_fh *fh = filp->private_data;
  97
  98         if (fh) {
  99                 v4l2_fh_del(fh);
 100                 v4l2_fh_exit(fh);
 101                 kfree(fh);
 102         }
 103         return 0;
 104 }
 105 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 106
 107 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 108 {
 109         unsigned long flags;
 110         int is_singular;
 111
 112         if (fh == NULL || fh->vdev == NULL)
 113                 return 0;
 114         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 115         is_singular = list_is_singular(&fh->list);
 116         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 117         return is_singular;
 118 }
 119 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);