DU_IMR
duart->base[DU_IMR] = duart->imr;
duart->base[DU_IMR] = duart->imr;
sc->sc_duart->base[DU_IMR] = sc->sc_duart->imr;
dp->base[DU_IMR] = dp->imr;
dp->base[DU_IMR] = dp->imr;
duart_base[DU_IMR] = duart->imr = 0;
sc->sc_qr. qr_imr = DU_IMR;
sc->sc_qr.qr_cstrt = DU_IMR;