PIIX4_SMBHSTCNT_INTREN
tmp & ~PIIX4_SMBHSTCNT_INTREN);
tmp |= PIIX4_SMBHSTCNT_INTREN;
bus_write_1(sc->io_res, PIIX4_SMBHSTCNT, tmp & ~PIIX4_SMBHSTCNT_INTREN);