AD_DMA_WAV
reg = ad1889_readw(chip, AD_DMA_WAV);
ad1889_writew(chip, AD_DMA_WAV, reg);
ad1889_readw(chip, AD_DMA_WAV);
ad1889_writew(chip, AD_DMA_WAV, AD_DMA_LOOP | AD_DMA_IM_CNT);