static int if_tiocmget(struct tty_struct *tty, struct file *file);
static int if_tiocmset(struct tty_struct *tty, struct file *file,
unsigned int set, unsigned int clear);
static int if_write(struct tty_struct *tty,
const unsigned char *buf, int count);
static int if_tiocmget(struct tty_struct *tty, struct file *file);
static int if_tiocmset(struct tty_struct *tty, struct file *file,
unsigned int set, unsigned int clear);
static int if_write(struct tty_struct *tty,
const unsigned char *buf, int count);