PMC_SMI_EN
ioreg = bus_space_read_4(sc->sc_pmt, sc->sc_pmh, PMC_SMI_EN);
bus_space_write_4(sc->sc_pmt, sc->sc_pmh, PMC_SMI_EN, ioreg);
bus_space_read_4(sc->sc_pmt, sc->sc_pmh, PMC_SMI_EN));