iio: adc: stm32-dfsdm: adapt sampling rate to oversampling ratio

Update sampling rate when oversampling ratio is changed
through the IIO ABI.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stm32-dfsdm-adc.c

@@ -1221,14 +1221,32 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
 	unsigned int spi_freq;
 	int ret = -EINVAL;
 
+	switch (ch->src) {
+	case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL:
+		spi_freq = adc->dfsdm->spi_master_freq;
+		break;
+	case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING:
+	case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING:
+		spi_freq = adc->dfsdm->spi_master_freq / 2;
+		break;
+	default:
+		spi_freq = adc->spi_freq;
+	}
+
 	switch (mask) {
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
+
 		ret = stm32_dfsdm_compute_all_osrs(indio_dev, val);
-		if (!ret)
+		if (!ret) {
+			dev_dbg(&indio_dev->dev,
+				"Sampling rate changed from (%u) to (%u)\n",
+				adc->sample_freq, spi_freq / val);
 			adc->oversamp = val;
+			adc->sample_freq = spi_freq / val;
+		}
 		iio_device_release_direct_mode(indio_dev);
 		return ret;
 
@@ -1240,18 +1258,6 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
 		if (ret)
 			return ret;
 
-		switch (ch->src) {
-		case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL:
-			spi_freq = adc->dfsdm->spi_master_freq;
-			break;
-		case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING:
-		case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING:
-			spi_freq = adc->dfsdm->spi_master_freq / 2;
-			break;
-		default:
-			spi_freq = adc->spi_freq;
-		}
-
 		ret = dfsdm_adc_set_samp_freq(indio_dev, val, spi_freq);
 		iio_device_release_direct_mode(indio_dev);
 		return ret;