RTC_PORT
bus_space_write_1(sc->sc_bst, sc->sc_bsh, RTC_PORT, READ_CLOCK);
bus_space_write_1(sc->sc_bst, sc->sc_bsh, RTC_PORT, 0);
bus_space_write_1(sc->sc_bst, sc->sc_bsh, RTC_PORT, SET_CLOCK);
bus_space_write_1(sc->sc_bst, sc->sc_bsh, RTC_PORT, 0);