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 
20 #include <linux/bitops.h>
21 #include <linux/slab.h>
22 #include <linux/export.h>
23 #include <media/v4l2-dev.h>
24 #include <media/v4l2-fh.h>
25 #include <media/v4l2-event.h>
26 #include <media/v4l2-ioctl.h>
27 #include <media/v4l2-mc.h>
28 
29 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
30 {
31 	fh->vdev = vdev;
32 	/* Inherit from video_device. May be overridden by the driver. */
33 	fh->ctrl_handler = vdev->ctrl_handler;
34 	INIT_LIST_HEAD(&fh->list);
35 	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
36 	/*
37 	 * determine_valid_ioctls() does not know if struct v4l2_fh
38 	 * is used by this driver, but here we do. So enable the
39 	 * prio ioctls here.
40 	 */
41 	set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
42 	set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
43 	fh->prio = V4L2_PRIORITY_UNSET;
44 	init_waitqueue_head(&fh->wait);
45 	INIT_LIST_HEAD(&fh->available);
46 	INIT_LIST_HEAD(&fh->subscribed);
47 	fh->sequence = -1;
48 	mutex_init(&fh->subscribe_lock);
49 }
50 EXPORT_SYMBOL_GPL(v4l2_fh_init);
51 
52 void v4l2_fh_add(struct v4l2_fh *fh)
53 {
54 	unsigned long flags;
55 
56 	v4l2_prio_open(fh->vdev->prio, &fh->prio);
57 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
58 	list_add(&fh->list, &fh->vdev->fh_list);
59 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
60 }
61 EXPORT_SYMBOL_GPL(v4l2_fh_add);
62 
63 int v4l2_fh_open(struct file *filp)
64 {
65 	struct video_device *vdev = video_devdata(filp);
66 	struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
67 
68 	filp->private_data = fh;
69 	if (fh == NULL)
70 		return -ENOMEM;
71 	v4l2_fh_init(fh, vdev);
72 	v4l2_fh_add(fh);
73 	return 0;
74 }
75 EXPORT_SYMBOL_GPL(v4l2_fh_open);
76 
77 void v4l2_fh_del(struct v4l2_fh *fh)
78 {
79 	unsigned long flags;
80 
81 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
82 	list_del_init(&fh->list);
83 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
84 	v4l2_prio_close(fh->vdev->prio, fh->prio);
85 }
86 EXPORT_SYMBOL_GPL(v4l2_fh_del);
87 
88 void v4l2_fh_exit(struct v4l2_fh *fh)
89 {
90 	if (fh->vdev == NULL)
91 		return;
92 	v4l_disable_media_source(fh->vdev);
93 	v4l2_event_unsubscribe_all(fh);
94 	mutex_destroy(&fh->subscribe_lock);
95 	fh->vdev = NULL;
96 }
97 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
98 
99 int v4l2_fh_release(struct file *filp)
100 {
101 	struct v4l2_fh *fh = filp->private_data;
102 
103 	if (fh) {
104 		v4l2_fh_del(fh);
105 		v4l2_fh_exit(fh);
106 		kfree(fh);
107 	}
108 	return 0;
109 }
110 EXPORT_SYMBOL_GPL(v4l2_fh_release);
111 
112 int v4l2_fh_is_singular(struct v4l2_fh *fh)
113 {
114 	unsigned long flags;
115 	int is_singular;
116 
117 	if (fh == NULL || fh->vdev == NULL)
118 		return 0;
119 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
120 	is_singular = list_is_singular(&fh->list);
121 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
122 	return is_singular;
123 }
124 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
125