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#include <media/v4l2-mc.h>
 33
 34void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
 35{
 36	fh->vdev = vdev;
 37	/* Inherit from video_device. May be overridden by the driver. */
 38	fh->ctrl_handler = vdev->ctrl_handler;
 39	INIT_LIST_HEAD(&fh->list);
 40	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
 41	/*
 42	 * determine_valid_ioctls() does not know if struct v4l2_fh
 43	 * is used by this driver, but here we do. So enable the
 44	 * prio ioctls here.
 45	 */
 46	set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
 47	set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
 48	fh->prio = V4L2_PRIORITY_UNSET;
 49	init_waitqueue_head(&fh->wait);
 50	INIT_LIST_HEAD(&fh->available);
 51	INIT_LIST_HEAD(&fh->subscribed);
 52	fh->sequence = -1;
 53}
 54EXPORT_SYMBOL_GPL(v4l2_fh_init);
 55
 56void v4l2_fh_add(struct v4l2_fh *fh)
 57{
 58	unsigned long flags;
 59
 60	v4l2_prio_open(fh->vdev->prio, &fh->prio);
 61	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 62	list_add(&fh->list, &fh->vdev->fh_list);
 63	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 64}
 65EXPORT_SYMBOL_GPL(v4l2_fh_add);
 66
 67int v4l2_fh_open(struct file *filp)
 68{
 69	struct video_device *vdev = video_devdata(filp);
 70	struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
 71
 72	filp->private_data = fh;
 73	if (fh == NULL)
 74		return -ENOMEM;
 75	v4l2_fh_init(fh, vdev);
 76	v4l2_fh_add(fh);
 77	return 0;
 78}
 79EXPORT_SYMBOL_GPL(v4l2_fh_open);
 80
 81void v4l2_fh_del(struct v4l2_fh *fh)
 82{
 83	unsigned long flags;
 84
 85	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 86	list_del_init(&fh->list);
 87	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 88	v4l2_prio_close(fh->vdev->prio, fh->prio);
 89}
 90EXPORT_SYMBOL_GPL(v4l2_fh_del);
 91
 92void v4l2_fh_exit(struct v4l2_fh *fh)
 93{
 94	if (fh->vdev == NULL)
 95		return;
 96	v4l_disable_media_source(fh->vdev);
 97	v4l2_event_unsubscribe_all(fh);
 98	fh->vdev = NULL;
 99}
100EXPORT_SYMBOL_GPL(v4l2_fh_exit);
101
102int v4l2_fh_release(struct file *filp)
103{
104	struct v4l2_fh *fh = filp->private_data;
105
106	if (fh) {
107		v4l2_fh_del(fh);
108		v4l2_fh_exit(fh);
109		kfree(fh);
110	}
111	return 0;
112}
113EXPORT_SYMBOL_GPL(v4l2_fh_release);
114
115int v4l2_fh_is_singular(struct v4l2_fh *fh)
116{
117	unsigned long flags;
118	int is_singular;
119
120	if (fh == NULL || fh->vdev == NULL)
121		return 0;
122	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
123	is_singular = list_is_singular(&fh->list);
124	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
125	return is_singular;
126}
127EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);