TPM_INT_STATUS
bus_space_write_4(sc->sc_bt, sc->sc_bh, TPM_INT_STATUS,
bus_space_read_4(sc->sc_bt, sc->sc_bh, TPM_INT_STATUS));
r = bus_space_read_4(sc->sc_bt, sc->sc_bh, TPM_INT_STATUS);
bus_space_write_4(sc->sc_bt, sc->sc_bh, TPM_INT_STATUS, r);