drivers/media/v4l2-core/v4l2-fh.c

Source file repositories/reference/linux-study-clean/drivers/media/v4l2-core/v4l2-fh.c

File Facts

System
Linux kernel
Corpus path
drivers/media/v4l2-core/v4l2-fh.c
Extension
.c
Size
2853 bytes
Lines
120
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-only
/*
 * v4l2-fh.c
 *
 * V4L2 file handles.
 *
 * Copyright (C) 2009--2010 Nokia Corporation.
 *
 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
 */

#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <media/v4l2-dev.h>
#include <media/v4l2-fh.h>
#include <media/v4l2-event.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-mc.h>

void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
{
	fh->vdev = vdev;
	/* Inherit from video_device. May be overridden by the driver. */
	fh->ctrl_handler = vdev->ctrl_handler;
	INIT_LIST_HEAD(&fh->list);
	set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
	/*
	 * determine_valid_ioctls() does not know if struct v4l2_fh
	 * is used by this driver, but here we do. So enable the
	 * prio ioctls here.
	 */
	set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
	set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
	fh->prio = V4L2_PRIORITY_UNSET;
	init_waitqueue_head(&fh->wait);
	INIT_LIST_HEAD(&fh->available);
	INIT_LIST_HEAD(&fh->subscribed);
	fh->sequence = -1;
	mutex_init(&fh->subscribe_lock);
}
EXPORT_SYMBOL_GPL(v4l2_fh_init);

void v4l2_fh_add(struct v4l2_fh *fh, struct file *filp)
{
	unsigned long flags;

	filp->private_data = fh;

	v4l2_prio_open(fh->vdev->prio, &fh->prio);
	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
	list_add(&fh->list, &fh->vdev->fh_list);
	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
}
EXPORT_SYMBOL_GPL(v4l2_fh_add);

int v4l2_fh_open(struct file *filp)
{
	struct video_device *vdev = video_devdata(filp);
	struct v4l2_fh *fh = kzalloc_obj(*fh);

	if (fh == NULL)
		return -ENOMEM;
	v4l2_fh_init(fh, vdev);
	v4l2_fh_add(fh, filp);
	return 0;
}
EXPORT_SYMBOL_GPL(v4l2_fh_open);

void v4l2_fh_del(struct v4l2_fh *fh, struct file *filp)
{
	unsigned long flags;

	spin_lock_irqsave(&fh->vdev->fh_lock, flags);
	list_del_init(&fh->list);
	spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
	v4l2_prio_close(fh->vdev->prio, fh->prio);

	filp->private_data = NULL;
}
EXPORT_SYMBOL_GPL(v4l2_fh_del);

void v4l2_fh_exit(struct v4l2_fh *fh)
{
	if (fh->vdev == NULL)
		return;
	v4l_disable_media_source(fh->vdev);
	v4l2_event_unsubscribe_all(fh);
	mutex_destroy(&fh->subscribe_lock);
	fh->vdev = NULL;

Annotation

Implementation Notes