[PATCH v2 04/14] iio: adc: stm32-adc: manage characterization voltage diversity

[Fabrice Gasnier]

From: Olivier Moysan <olivier.moysan at foss.st.com>

The characterization voltage used to calibrate vrefint depends
on SoC family. Add vref_charac_mv field in stm32_adc_cfg structure
to store the characterization voltage for each SoC, and use it
in Vref computation formula.

Signed-off-by: Olivier Moysan <olivier.moysan at foss.st.com>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier at foss.st.com>
---
Changes in v2:
- Andy's review comments: rename variable to vref_charac_mv (unit suffix).
  Drop the const attribute.
---
 drivers/iio/adc/stm32-adc.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 90f0e257e6d1..ddf74c674da6 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -43,7 +43,6 @@
 #define STM32_ADC_TIMEOUT_US		100000
 #define STM32_ADC_TIMEOUT	(msecs_to_jiffies(STM32_ADC_TIMEOUT_US / 1000))
 #define STM32_ADC_HW_STOP_DELAY_MS	100
-#define STM32_ADC_VREFINT_VOLTAGE	3300
 
 #define STM32_DMA_BUFFER_SIZE		PAGE_SIZE
 
@@ -211,6 +210,7 @@ struct stm32_adc;
  * @set_ovs:		routine to set oversampling configuration
  * @smp_cycles:		programmable sampling time (ADC clock cycles)
  * @ts_int_ch:		pointer to array of internal channels minimum sampling time in ns
+ * @vref_charac_mv:	Vref characterization voltage used to measure vrefint calibration value
  */
 struct stm32_adc_cfg {
 	const struct stm32_adc_regspec	*regs;
@@ -230,6 +230,7 @@ struct stm32_adc_cfg {
 	void (*set_ovs)(struct iio_dev *indio_dev, u32 ovs_idx);
 	const unsigned int *smp_cycles;
 	const unsigned int *ts_int_ch;
+	int vref_charac_mv;
 };
 
 /**
@@ -1615,7 +1616,7 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 		if (mask == IIO_CHAN_INFO_PROCESSED) {
 			if (*val == 0)
 				return -EINVAL;
-			*val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val;
+			*val = adc->cfg->vref_charac_mv * adc->vrefint.vrefint_cal / *val;
 		}
 
 		return ret;
@@ -2711,6 +2712,7 @@ static const struct stm32_adc_cfg stm32f4_adc_cfg = {
 	.stop_conv = stm32f4_adc_stop_conv,
 	.smp_cycles = stm32f4_adc_smp_cycles,
 	.irq_clear = stm32f4_adc_irq_clear,
+	.vref_charac_mv = 3300,
 };
 
 static const unsigned int stm32_adc_min_ts_h7[] = { 0, 0, 0, 4300, 9000 };
@@ -2732,6 +2734,7 @@ static const struct stm32_adc_cfg stm32h7_adc_cfg = {
 	.irq_clear = stm32h7_adc_irq_clear,
 	.ts_int_ch = stm32_adc_min_ts_h7,
 	.set_ovs = stm32h7_adc_set_ovs,
+	.vref_charac_mv = 3300,
 };
 
 static const unsigned int stm32_adc_min_ts_mp1[] = { 100, 100, 100, 4300, 9800 };
@@ -2754,6 +2757,7 @@ static const struct stm32_adc_cfg stm32mp1_adc_cfg = {
 	.irq_clear = stm32h7_adc_irq_clear,
 	.ts_int_ch = stm32_adc_min_ts_mp1,
 	.set_ovs = stm32h7_adc_set_ovs,
+	.vref_charac_mv = 3300,
 };
 
 static const unsigned int stm32_adc_min_ts_mp13[] = { 100, 0, 0, 4300, 9800 };
@@ -2772,6 +2776,7 @@ static const struct stm32_adc_cfg stm32mp13_adc_cfg = {
 	.irq_clear = stm32h7_adc_irq_clear,
 	.ts_int_ch = stm32_adc_min_ts_mp13,
 	.set_ovs = stm32mp13_adc_set_ovs,
+	.vref_charac_mv = 3300,
 };
 
 static const struct of_device_id stm32_adc_of_match[] = {

-- 
2.43.0