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 <media/v4l2-dev.h>
  27 #include <media/v4l2-fh.h>
  28 #include <media/v4l2-event.h>
  29 #include <media/v4l2-ioctl.h>
  30
  31 int v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
  32 {
  33         fh->vdev = vdev;
  34         INIT_LIST_HEAD(&fh->list);
  35         set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
  36
  37         /*
  38          * fh->events only needs to be initialized if the driver
  39          * supports the VIDIOC_SUBSCRIBE_EVENT ioctl.
  40          */
  41         if (vdev->ioctl_ops && vdev->ioctl_ops->vidioc_subscribe_event)
  42                 return v4l2_event_init(fh);
  43
  44         fh->events = NULL;
  45
  46         return 0;
  47 }
  48 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  49
  50 void v4l2_fh_add(struct v4l2_fh *fh)
  51 {
  52         unsigned long flags;
  53
  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 void v4l2_fh_del(struct v4l2_fh *fh)
  61 {
  62         unsigned long flags;
  63
  64         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  65         list_del_init(&fh->list);
  66         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  67 }
  68 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  69
  70 void v4l2_fh_exit(struct v4l2_fh *fh)
  71 {
  72         if (fh->vdev == NULL)
  73                 return;
  74
  75         fh->vdev = NULL;
  76
  77         v4l2_event_free(fh);
  78 }
  79 EXPORT_SYMBOL_GPL(v4l2_fh_exit);