Do not erase previous configuration of the mode register when setting
the sampling frequency.
Signed-off-by: Ludovic Desroches <ludovic.desroc...@atmel.com>
---
drivers/iio/adc/at91-sama5d2_adc.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c
b/drivers/iio/adc/at91-sama5d2_adc.c
index 5bc038f..01ba106 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -66,8 +66,10 @@
#define AT91_SAMA5D2_MR_PRESCAL(v) ((v) <<
AT91_SAMA5D2_MR_PRESCAL_OFFSET)
#define AT91_SAMA5D2_MR_PRESCAL_OFFSET 8
#define AT91_SAMA5D2_MR_PRESCAL_MAX 0xff
+#define AT91_SAMA5D2_MR_PRESCAL_MASK GENMASK(15, 8)
/* Startup Time */
#define AT91_SAMA5D2_MR_STARTUP(v) ((v) << 16)
+#define AT91_SAMA5D2_MR_STARTUP_MASK GENMASK(19, 16)
/* Analog Change */
#define AT91_SAMA5D2_MR_ANACH BIT(23)
/* Tracking Time */
@@ -226,7 +228,7 @@ static unsigned at91_adc_startup_time(unsigned
startup_time_min,
static void at91_adc_setup_samp_freq(struct at91_adc_state *st, unsigned freq)
{
struct iio_dev *indio_dev = iio_priv_to_dev(st);
- unsigned f_per, prescal, startup;
+ unsigned f_per, prescal, startup, mr;
f_per = clk_get_rate(st->per_clk);
prescal = (f_per / (2 * freq)) - 1;
@@ -234,10 +236,11 @@ static void at91_adc_setup_samp_freq(struct
at91_adc_state *st, unsigned freq)
startup = at91_adc_startup_time(st->soc_info.startup_time,
freq / 1000);
- at91_adc_writel(st, AT91_SAMA5D2_MR,
- AT91_SAMA5D2_MR_TRANSFER(2)
- | AT91_SAMA5D2_MR_STARTUP(startup)
- | AT91_SAMA5D2_MR_PRESCAL(prescal));
+ mr = at91_adc_readl(st, AT91_SAMA5D2_MR);
+ mr &= ~(AT91_SAMA5D2_MR_STARTUP_MASK | AT91_SAMA5D2_MR_PRESCAL_MASK);
+ mr |= AT91_SAMA5D2_MR_STARTUP(startup);
+ mr |= AT91_SAMA5D2_MR_PRESCAL(prescal);
+ at91_adc_writel(st, AT91_SAMA5D2_MR, mr);
dev_dbg(&indio_dev->dev, "freq: %u, startup: %u, prescal: %u\n",
freq, startup, prescal);
@@ -444,6 +447,8 @@ static int at91_adc_probe(struct platform_device *pdev)
at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
at91_adc_writel(st, AT91_SAMA5D2_IDR, 0xffffffff);
+ /* Transfer field must be set to 2 according to the datasheet. */
+ at91_adc_writel(st, AT91_SAMA5D2_MR, AT91_SAMA5D2_MR_TRANSFER(2));
at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
--
2.5.0
