PB_CTS4
at91pio_in(sc->sc_piob, PB_CTS4);
at91pio_per(sc->sc_piob, PB_CTS4, -1);
sc->sc_cts_ih = at91pio_intr_establish(sc->sc_piob, PB_CTS4,
at91pio_intr_disestablish(sc->sc_piob, PB_CTS4, sc->sc_cts_ih);
if (!(PIOB_READ(PIO_PDSR) & (1U << PB_CTS4))) {