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 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  33 {
  34         fh->vdev = vdev;
  35         INIT_LIST_HEAD(&fh->list);
  36         set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  37         fh->prio = V4L2_PRIORITY_UNSET;
  38
  39         /*
  40          * fh->events only needs to be initialized if the driver
  41          * supports the VIDIOC_SUBSCRIBE_EVENT ioctl.
  42          */
  43         if (vdev->ioctl_ops && vdev->ioctl_ops->vidioc_subscribe_event)
  44                 return v4l2_event_init(fh);
  45
  46         fh->events = NULL;
  47
  48         return 0;
  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         if (test_bit(V4L2_FL_USE_FH_PRIO, &fh->vdev->flags))
  57                 v4l2_prio_open(fh->vdev->prio, &fh->prio);
  58         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  59         list_add(&fh->list, &fh->vdev->fh_list);
  60         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  61 }
  62 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  63
  64 int v4l2_fh_open(struct file *filp)
  65 {
  66         struct video_device *vdev = video_devdata(filp);
  67         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  68
  69         filp->private_data = fh;
  70         if (fh == NULL)
  71                 return -ENOMEM;
  72         v4l2_fh_init(fh, vdev);
  73         v4l2_fh_add(fh);
  74         return 0;
  75 }
  76 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  77
  78 void v4l2_fh_del(struct v4l2_fh *fh)
  79 {
  80         unsigned long flags;
  81
  82         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  83         list_del_init(&fh->list);
  84         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  85         if (test_bit(V4L2_FL_USE_FH_PRIO, &fh->vdev->flags))
  86                 v4l2_prio_close(fh->vdev->prio, fh->prio);
  87 }
  88 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  89
  90 void v4l2_fh_exit(struct v4l2_fh *fh)
  91 {
  92         if (fh->vdev == NULL)
  93                 return;
  94
  95         fh->vdev = NULL;
  96
  97         v4l2_event_free(fh);
  98 }
  99 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
 100
 101 int v4l2_fh_release(struct file *filp)
 102 {
 103         struct v4l2_fh *fh = filp->private_data;
 104
 105         if (fh) {
 106                 v4l2_fh_del(fh);
 107                 v4l2_fh_exit(fh);
 108                 kfree(fh);
 109         }
 110         return 0;
 111 }
 112 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 113
 114 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 115 {
 116         unsigned long flags;
 117         int is_singular;
 118
 119         if (fh == NULL || fh->vdev == NULL)
 120                 return 0;
 121         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 122         is_singular = list_is_singular(&fh->list);
 123         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 124         return is_singular;
 125 }
 126 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);