1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * v4l2-fh.c
4  *
5  * V4L2 file handles.
6  *
7  * Copyright (C) 2009--2010 Nokia Corporation.
8  *
9  * Contact: Sakari Ailus <sakari.ailus@iki.fi>
10  */
11 
12 #include <linux/bitops.h>
13 #include <linux/slab.h>
14 #include <linux/export.h>
15 #include <media/v4l2-dev.h>
16 #include <media/v4l2-fh.h>
17 #include <media/v4l2-event.h>
18 #include <media/v4l2-ioctl.h>
19 #include <media/v4l2-mc.h>
20 
21 void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
22 {
23 	fh->vdev = vdev;
24 	/* Inherit from video_device. May be overridden by the driver. */
25 	fh->ctrl_handler = vdev->ctrl_handler;
26 	INIT_LIST_HEAD(&fh->list);
27 	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
28 	/*
29 	 * determine_valid_ioctls() does not know if struct v4l2_fh
30 	 * is used by this driver, but here we do. So enable the
31 	 * prio ioctls here.
32 	 */
33 	set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
34 	set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
35 	fh->prio = V4L2_PRIORITY_UNSET;
36 	init_waitqueue_head(&fh->wait);
37 	INIT_LIST_HEAD(&fh->available);
38 	INIT_LIST_HEAD(&fh->subscribed);
39 	fh->sequence = -1;
40 	mutex_init(&fh->subscribe_lock);
41 }
42 EXPORT_SYMBOL_GPL(v4l2_fh_init);
43 
44 void v4l2_fh_add(struct v4l2_fh *fh)
45 {
46 	unsigned long flags;
47 
48 	v4l2_prio_open(fh->vdev->prio, &fh->prio);
49 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
50 	list_add(&fh->list, &fh->vdev->fh_list);
51 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
52 }
53 EXPORT_SYMBOL_GPL(v4l2_fh_add);
54 
55 int v4l2_fh_open(struct file *filp)
56 {
57 	struct video_device *vdev = video_devdata(filp);
58 	struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
59 
60 	filp->private_data = fh;
61 	if (fh == NULL)
62 		return -ENOMEM;
63 	v4l2_fh_init(fh, vdev);
64 	v4l2_fh_add(fh);
65 	return 0;
66 }
67 EXPORT_SYMBOL_GPL(v4l2_fh_open);
68 
69 void v4l2_fh_del(struct v4l2_fh *fh)
70 {
71 	unsigned long flags;
72 
73 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
74 	list_del_init(&fh->list);
75 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
76 	v4l2_prio_close(fh->vdev->prio, fh->prio);
77 }
78 EXPORT_SYMBOL_GPL(v4l2_fh_del);
79 
80 void v4l2_fh_exit(struct v4l2_fh *fh)
81 {
82 	if (fh->vdev == NULL)
83 		return;
84 	v4l_disable_media_source(fh->vdev);
85 	v4l2_event_unsubscribe_all(fh);
86 	mutex_destroy(&fh->subscribe_lock);
87 	fh->vdev = NULL;
88 }
89 EXPORT_SYMBOL_GPL(v4l2_fh_exit);
90 
91 int v4l2_fh_release(struct file *filp)
92 {
93 	struct v4l2_fh *fh = filp->private_data;
94 
95 	if (fh) {
96 		v4l2_fh_del(fh);
97 		v4l2_fh_exit(fh);
98 		kfree(fh);
99 	}
100 	return 0;
101 }
102 EXPORT_SYMBOL_GPL(v4l2_fh_release);
103 
104 int v4l2_fh_is_singular(struct v4l2_fh *fh)
105 {
106 	unsigned long flags;
107 	int is_singular;
108 
109 	if (fh == NULL || fh->vdev == NULL)
110 		return 0;
111 	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
112 	is_singular = list_is_singular(&fh->list);
113 	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
114 	return is_singular;
115 }
116 EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
117