MHU_CHAN_RX_HP
reg = bus_read_4(sc->res[0], MHU_CHAN_RX_HP + MHU_INTR_STAT);
bus_write_4(sc->res[0], MHU_CHAN_RX_HP + MHU_INTR_CLEAR,
offset = MHU_CHAN_RX_HP;