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