LXR linux/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
  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        /*
  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}
  53EXPORT_SYMBOL_GPL(v4l2_fh_init);
  54
  55void 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}
  64EXPORT_SYMBOL_GPL(v4l2_fh_add);
  65
  66int 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}
  78EXPORT_SYMBOL_GPL(v4l2_fh_open);
  79
  80void 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}
  89EXPORT_SYMBOL_GPL(v4l2_fh_del);
  90
  91void 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}
  98EXPORT_SYMBOL_GPL(v4l2_fh_exit);
  99
 100int 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}
 111EXPORT_SYMBOL_GPL(v4l2_fh_release);
 112
 113int 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}
 125EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
 126