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