media-devnode.h

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/*
 * Media device node
 *
 * Copyright (C) 2010 Nokia Corporation
 *
 * Contacts: Laurent Pinchart <[email protected]>
 *       Sakari Ailus <[email protected]>
 *
 * 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 {
    /* 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 */