PIIX4_SMBSLVCNT
bus_write_1(sc->io_res, PIIX4_SMBSLVCNT, PIIX4_SMBSLVCNT_ALTEN);
bus_write_1(sc->io_res, PIIX4_SMBSLVCNT, 0);
slvcnt = bus_read_1(sc->io_res, PIIX4_SMBSLVCNT);
bus_write_1(sc->io_res, PIIX4_SMBSLVCNT,
bus_write_1(sc->io_res, PIIX4_SMBSLVCNT,
bus_write_1(sc->io_res, PIIX4_SMBSLVCNT,
bus_write_1(sc->io_res, PIIX4_SMBSLVCNT, PIIX4_SMBSLVCNT_ALTEN);