xadc_read_adc_reg
xadc_read_adc_reg(xadc, XADC_REG_THRESHOLD(i),
xadc_read_adc_reg(xadc, chan, &xadc->data[j]);
ret = xadc_read_adc_reg(xadc, XADC_REG_CONF2, &val16);
ret = xadc_read_adc_reg(xadc, chan->address, &val16);