mirror of
https://github.com/torvalds/linux.git
synced 2024-11-05 03:21:32 +00:00
cf4b9211b5
The media_devnode structure provides support for registering and unregistering character devices using a dynamic major number. Reference counting is handled internally, making device drivers easier to write without having to solve the open/disconnect race condition issue over and over again. The code is based on video/v4l2-dev.c. [mchehab@redhat.com: Remove linux/smp_lock.h include to not break compilation on bisect] Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
98 lines
2.9 KiB
C
98 lines
2.9 KiB
C
/*
|
|
* Media device node
|
|
*
|
|
* Copyright (C) 2010 Nokia Corporation
|
|
*
|
|
* Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
|
|
* Sakari Ailus <sakari.ailus@iki.fi>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*
|
|
* --
|
|
*
|
|
* Common functions for media-related drivers to register and unregister media
|
|
* device nodes.
|
|
*/
|
|
|
|
#ifndef _MEDIA_DEVNODE_H
|
|
#define _MEDIA_DEVNODE_H
|
|
|
|
#include <linux/poll.h>
|
|
#include <linux/fs.h>
|
|
#include <linux/device.h>
|
|
#include <linux/cdev.h>
|
|
|
|
/*
|
|
* Flag to mark the media_devnode struct as registered. Drivers must not touch
|
|
* this flag directly, it will be set and cleared by media_devnode_register and
|
|
* media_devnode_unregister.
|
|
*/
|
|
#define MEDIA_FLAG_REGISTERED 0
|
|
|
|
struct media_file_operations {
|
|
struct module *owner;
|
|
ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
|
|
ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
|
|
unsigned int (*poll) (struct file *, struct poll_table_struct *);
|
|
long (*ioctl) (struct file *, unsigned int, unsigned long);
|
|
int (*open) (struct file *);
|
|
int (*release) (struct file *);
|
|
};
|
|
|
|
/**
|
|
* struct media_devnode - Media device node
|
|
* @parent: parent device
|
|
* @minor: device node minor number
|
|
* @flags: flags, combination of the MEDIA_FLAG_* constants
|
|
*
|
|
* This structure represents a media-related device node.
|
|
*
|
|
* The @parent is a physical device. It must be set by core or device drivers
|
|
* before registering the node.
|
|
*/
|
|
struct media_devnode {
|
|
/* device ops */
|
|
const struct media_file_operations *fops;
|
|
|
|
/* sysfs */
|
|
struct device dev; /* media device */
|
|
struct cdev cdev; /* character device */
|
|
struct device *parent; /* device parent */
|
|
|
|
/* device info */
|
|
int minor;
|
|
unsigned long flags; /* Use bitops to access flags */
|
|
|
|
/* callbacks */
|
|
void (*release)(struct media_devnode *mdev);
|
|
};
|
|
|
|
/* dev to media_devnode */
|
|
#define to_media_devnode(cd) container_of(cd, struct media_devnode, dev)
|
|
|
|
int __must_check media_devnode_register(struct media_devnode *mdev);
|
|
void media_devnode_unregister(struct media_devnode *mdev);
|
|
|
|
static inline struct media_devnode *media_devnode_data(struct file *filp)
|
|
{
|
|
return filp->private_data;
|
|
}
|
|
|
|
static inline int media_devnode_is_registered(struct media_devnode *mdev)
|
|
{
|
|
return test_bit(MEDIA_FLAG_REGISTERED, &mdev->flags);
|
|
}
|
|
|
|
#endif /* _MEDIA_DEVNODE_H */
|