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)
 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}
 53EXPORT_SYMBOL_GPL(v4l2_fh_add);
 54
 55int 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}
 67EXPORT_SYMBOL_GPL(v4l2_fh_open);
 68
 69void 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}
 78EXPORT_SYMBOL_GPL(v4l2_fh_del);
 79
 80void 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}
 89EXPORT_SYMBOL_GPL(v4l2_fh_exit);
 90
 91int 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		filp->private_data = NULL;
100	}
101	return 0;
102}
103EXPORT_SYMBOL_GPL(v4l2_fh_release);
104
105int v4l2_fh_is_singular(struct v4l2_fh *fh)
106{
107	unsigned long flags;
108	int is_singular;
109
110	if (fh == NULL || fh->vdev == NULL)
111		return 0;
112	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
113	is_singular = list_is_singular(&fh->list);
114	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
115	return is_singular;
116}
117EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);