PORT_HWVOL_MASTER
n = bus_space_read_1(sc->iot, sc->ioh, PORT_HWVOL_MASTER);
bus_space_write_1(sc->iot, sc->ioh, PORT_HWVOL_MASTER,
bus_space_write_1(sc->iot, sc->ioh, PORT_HWVOL_MASTER, MIDDLE_VOLUME);