v4l2-fh.c

  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
 21void 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}
 42EXPORT_SYMBOL_GPL(v4l2_fh_init);
 43
 44void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp)
 45{
 46	unsigned long flags;
 47
 48	filp->private_data = fh;
 49
 50	v4l2_prio_open(fh->vdev->prio, &fh->prio);
 51	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 52	list_add(&fh->list, &fh->vdev->fh_list);
 53	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 54}
 55EXPORT_SYMBOL_GPL(v4l2_fh_add);
 56
 57int v4l2_fh_open(struct file *filp)
 58{
 59	struct video_device *vdev = video_devdata(filp);
 60	struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
 61
 62	if (fh == NULL)
 63		return -ENOMEM;
 64	v4l2_fh_init(fh, vdev);
 65	v4l2_fh_add(fh, filp);
 66	return 0;
 67}
 68EXPORT_SYMBOL_GPL(v4l2_fh_open);
 69
 70void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp)
 71{
 72	unsigned long flags;
 73
 74	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
 75	list_del_init(&fh->list);
 76	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
 77	v4l2_prio_close(fh->vdev->prio, fh->prio);
 78
 79	filp->private_data = NULL;
 80}
 81EXPORT_SYMBOL_GPL(v4l2_fh_del);
 82
 83void v4l2_fh_exit(struct v4l2_fh *fh)
 84{
 85	if (fh->vdev == NULL)
 86		return;
 87	v4l_disable_media_source(fh->vdev);
 88	v4l2_event_unsubscribe_all(fh);
 89	mutex_destroy(&fh->subscribe_lock);
 90	fh->vdev = NULL;
 91}
 92EXPORT_SYMBOL_GPL(v4l2_fh_exit);
 93
 94int v4l2_fh_release(struct file *filp)
 95{
 96	struct v4l2_fh *fh = file_to_v4l2_fh(filp);
 97
 98	if (fh) {
 99		v4l2_fh_del(fh, filp);
100		v4l2_fh_exit(fh);
101		kfree(fh);
102	}
103	return 0;
104}
105EXPORT_SYMBOL_GPL(v4l2_fh_release);
106
107int v4l2_fh_is_singular(struct v4l2_fh *fh)
108{
109	unsigned long flags;
110	int is_singular;
111
112	if (fh == NULL || fh->vdev == NULL)
113		return 0;
114	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
115	is_singular = list_is_singular(&fh->list);
116	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
117	return is_singular;
118}
119EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);