ad5421_read
fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
fault = ad5421_read(indio_dev, AD5421_REG_FAULT);
ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);
ret = ad5421_read(indio_dev, AD5421_REG_OFFSET);
ret = ad5421_read(indio_dev, AD5421_REG_GAIN);
ret = ad5421_read(indio_dev, AD5421_REG_DAC_DATA);