ADS131E08_NUM_STATUS_BYTES
u8 rx_buf[ADS131E08_NUM_STATUS_BYTES +
st->readback_len = ADS131E08_NUM_STATUS_BYTES +
src = st->rx_buf + ADS131E08_NUM_STATUS_BYTES +
src = st->rx_buf + ADS131E08_NUM_STATUS_BYTES + chn * num_bytes;