iio: ad9523-1: Improve reported VCO frequency accuracy

To improve the accuracy of the reported VCO frequency perform all
multiplications before divisions. This reduces rounding errors and makes
sure the reported rates are accurate down to the last digit.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/frequency/ad9523.c

@@ -862,9 +862,11 @@ static int ad9523_setup(struct iio_dev *indio_dev)
 	if (ret < 0)
 		return ret;
 
-	st->vco_freq = (pdata->vcxo_freq * (pdata->pll2_freq_doubler_en ? 2 : 1)
-			/ pdata->pll2_r2_div) * AD9523_PLL2_FB_NDIV(pdata->
-			pll2_ndiv_a_cnt, pdata->pll2_ndiv_b_cnt);
+	st->vco_freq = div_u64((unsigned long long)pdata->vcxo_freq *
+			       (pdata->pll2_freq_doubler_en ? 2 : 1) *
+			       AD9523_PLL2_FB_NDIV(pdata->pll2_ndiv_a_cnt,
+						   pdata->pll2_ndiv_b_cnt),
+			       pdata->pll2_r2_div);
 
 	ret = ad9523_write(indio_dev, AD9523_PLL2_VCO_CTRL,
 		AD9523_PLL2_VCO_CALIBRATE);