static void rs_wait_until_sent(struct tty_struct *tty, int timeout);
static int rs_write(struct tty_struct * tty, int from_user,
const unsigned char *buf, int count);
static void rs_wait_until_sent(struct tty_struct *tty, int timeout);
static int rs_write(struct tty_struct * tty, int from_user,
const unsigned char *buf, int count);