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
  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         /*
  41          * determine_valid_ioctls() does not know if struct v4l2_fh
  42          * is used by this driver, but here we do. So enable the
  43          * prio ioctls here.
  44          */
  45         set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
  46         set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
  47         fh->prio = V4L2_PRIORITY_UNSET;
  48         init_waitqueue_head(&fh->wait);
  49         INIT_LIST_HEAD(&fh->available);
  50         INIT_LIST_HEAD(&fh->subscribed);
  51         fh->sequence = -1;
  52 }
  53 EXPORT_SYMBOL_GPL(v4l2_fh_init);
  54
  55 void v4l2_fh_add(struct v4l2_fh *fh)
  56 {
  57         unsigned long flags;
  58
  59         v4l2_prio_open(fh->vdev->prio, &fh->prio);
  60         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  61         list_add(&fh->list, &fh->vdev->fh_list);
  62         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  63 }
  64 EXPORT_SYMBOL_GPL(v4l2_fh_add);
  65
  66 int v4l2_fh_open(struct file *filp)
  67 {
  68         struct video_device *vdev = video_devdata(filp);
  69         struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
  70
  71         filp->private_data = fh;
  72         if (fh == NULL)
  73                 return -ENOMEM;
  74         v4l2_fh_init(fh, vdev);
  75         v4l2_fh_add(fh);
  76         return 0;
  77 }
  78 EXPORT_SYMBOL_GPL(v4l2_fh_open);
  79
  80 void v4l2_fh_del(struct v4l2_fh *fh)
  81 {
  82         unsigned long flags;
  83
  84         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
  85         list_del_init(&fh->list);
  86         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
  87         v4l2_prio_close(fh->vdev->prio, fh->prio);
  88 }
  89 EXPORT_SYMBOL_GPL(v4l2_fh_del);
  90
  91 void v4l2_fh_exit(struct v4l2_fh *fh)
  92 {
  93         if (fh->vdev == NULL)
  94                 return;
  95         v4l2_event_unsubscribe_all(fh);
  96         fh->vdev = NULL;
  97 }
  98 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  99
 100 int v4l2_fh_release(struct file *filp)
 101 {
 102         struct v4l2_fh *fh = filp->private_data;
 103
 104         if (fh) {
 105                 v4l2_fh_del(fh);
 106                 v4l2_fh_exit(fh);
 107                 kfree(fh);
 108         }
 109         return 0;
 110 }
 111 EXPORT_SYMBOL_GPL(v4l2_fh_release);
 112
 113 int v4l2_fh_is_singular(struct v4l2_fh *fh)
 114 {
 115         unsigned long flags;
 116         int is_singular;
 117
 118         if (fh == NULL || fh->vdev == NULL)
 119                 return 0;
 120         spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 121         is_singular = list_is_singular(&fh->list);
 122         spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 123         return is_singular;
 124 }
 125 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);