root/include/linux/phonedev.h

#ifndef __LINUX_PHONEDEV_H
#define __LINUX_PHONEDEV_H

#include <linux/types.h>

#ifdef __KERNEL__

#include <linux/poll.h>

struct phone_device {
        struct phone_device *next;
        const struct file_operations *f_op;
        int (*open) (struct phone_device *, struct file *);
        int board;              /* Device private index */
        int minor;
};

extern int phonedev_init(void);
#define PHONE_MAJOR     100
extern int phone_register_device(struct phone_device *, int unit);
#define PHONE_UNIT_ANY  -1
extern void phone_unregister_device(struct phone_device *);

#endif
#endif