AWACS_SOUND_CTRL
awacs_write_reg(sc, AWACS_SOUND_CTRL, sc->sc_soundctl);
awacs_write_reg(sc, AWACS_SOUND_CTRL, sc->sc_soundctl);
reason = awacs_read_reg(sc, AWACS_SOUND_CTRL);
awacs_write_reg(sc, AWACS_SOUND_CTRL, reason); /* clear interrupt */