#ifndef _LINUX_TTY_DRIVER_H
#define _LINUX_TTY_DRIVER_H

/*
 * This structure defines the interface between the low-level tty
 * driver and the tty routines.  The following routines can be
 * defined; unless noted otherwise, they are optional, and can be
 * filled in with a null pointer.
 *
 * struct tty_struct * (*lookup)(struct tty_driver *self, int idx)
 *
 *	Return the tty device corresponding to idx, NULL if there is not
 *	one currently in use and an ERR_PTR value on error. Called under
 *	tty_mutex (for now!)
 *
 *	Optional method. Default behaviour is to use the ttys array
 *
 * int (*install)(struct tty_driver *self, struct tty_struct *tty)
 *
 *	Install a new tty into the tty driver internal tables. Used in
 *	conjunction with lookup and remove methods.
 *
 *	Optional method. Default behaviour is to use the ttys array
 *
 * void (*remove)(struct tty_driver *self, struct tty_struct *tty)
 *
 *	Remove a closed tty from the tty driver internal tables. Used in
 *	conjunction with lookup and remove methods.
 *
 *	Optional method. Default behaviour is to use the ttys array
 *
 * int  (*open)(struct tty_struct * tty, struct file * filp);
 *
 * 	This routine is called when a particular tty device is opened.
 * 	This routine is mandatory; if this routine is not filled in,
 * 	the attempted open will fail with ENODEV.
 *
 *	Required method.
 *     
 * void (*close)(struct tty_struct * tty, struct file * filp);
 *
 * 	This routine is called when a particular tty device is closed.
 *
 *	Required method.
 *
 * void (*shutdown)(struct tty_struct * tty);
 *
 * 	This routine is called synchronously when a particular tty device
 *	is closed for the last time freeing up the resources.