LXR linux/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
  33void 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}
  46EXPORT_SYMBOL_GPL(v4l2_fh_init);
  47
  48void 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}
  58EXPORT_SYMBOL_GPL(v4l2_fh_add);
  59
  60int 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}
  72EXPORT_SYMBOL_GPL(v4l2_fh_open);
  73
  74void 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}
  84EXPORT_SYMBOL_GPL(v4l2_fh_del);
  85
  86void 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}
  93EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  94
  95int 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}
 106EXPORT_SYMBOL_GPL(v4l2_fh_release);
 107
 108int 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}
 120EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
 121