IRQB
bus_space_write_1(sc->sc_tag, sc->sc_handle, IRQB, 0);
bus_space_write_1(sc->sc_tag, sc->sc_handle, IRQB, DISABLEHALFIRQ);
IRQB, DISABLEHALFIRQ);
bus_space_write_1(sc->sc_tag, sc->sc_handle, IRQB, 0);