iio: adc: stm32-dfsdm: fix sample rate for div2 spi clock

When channel clk source is set to "CLKOUT_F" or "CLKOUT_R" (e.g. div2),
sample rate is currently set to half the requested value.

Fixes: eca949800d2d ("IIO: ADC: add stm32 DFSDM support for PDM
microphone")

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Acked-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index dc911b6fedd6..b28a716a23b2 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -771,7 +771,7 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
         struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
         struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
         struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[chan->channel];
-        unsigned int spi_freq = adc->spi_freq;
+        unsigned int spi_freq;
         int ret = -EINVAL;
 
         switch (mask) {
@@ -785,8 +785,18 @@ static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
         case IIO_CHAN_INFO_SAMP_FREQ:
                 if (!val)
                         return -EINVAL;
-                if (ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
+
+                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;
+                }
 
                 if (spi_freq % val)
                         dev_warn(&indio_dev->dev,