+extern int tty_port_carrier_raised(struct tty_port *port);
+extern void tty_port_raise_dtr_rts(struct tty_port *port);
+extern void tty_port_hangup(struct tty_port *port);
+extern int tty_port_block_til_ready(struct tty_port *port,
+ struct tty_struct *tty, struct file *filp);
+extern int tty_port_close_start(struct tty_port *port,
+ struct tty_struct *tty, struct file *filp);
+extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);