PIIX4_SMBHSTDAT0
addr = bus_read_1(sc->io_res, PIIX4_SMBHSTDAT0);
*byte = bus_read_1(sc->io_res, PIIX4_SMBHSTDAT0);
bus_write_1(sc->io_res, PIIX4_SMBHSTDAT0, byte);
bus_write_1(sc->io_res, PIIX4_SMBHSTDAT0, word & 0xff);
*byte = bus_read_1(sc->io_res, PIIX4_SMBHSTDAT0);
*word = bus_read_1(sc->io_res, PIIX4_SMBHSTDAT0);
bus_write_1(sc->io_res, PIIX4_SMBHSTDAT0, count);
nread = bus_read_1(sc->io_res, PIIX4_SMBHSTDAT0);