[PATCH 1/3] iio: adc: stm32-adc: smart calibration support
Olivier Moysan
olivier.moysan at foss.st.com
Tue Nov 15 02:31:21 PST 2022
Add smart calibration support for STM32MP1.
- STM32MP15x: both linear & offset calibration are supported
- STM32MP13x: Only offset calibration is supported
Linear calibration:
Linear calibration is SoC dependent and does not change over time
so it can be done only once.
Linear calibration may have already been done in u-boot.
Skip calibration execution if calibration data are already available.
Save calibration factors in private data and restore them from private
data on next ADC start.
Offset calibration:
This calibration may vary over time, depending on temperature or voltage.
Run offset single-ended and differential calibration on each ADC start,
as it is not time consuming. This calibration do not need to be saved.
So, remove calfact_s and calfact_d value and bitfields that are no
longer used.
Signed-off-by: Olivier Moysan <olivier.moysan at foss.st.com>
---
drivers/iio/adc/stm32-adc-core.h | 1 +
drivers/iio/adc/stm32-adc.c | 108 +++++++++++++++----------------
2 files changed, 53 insertions(+), 56 deletions(-)
diff --git a/drivers/iio/adc/stm32-adc-core.h b/drivers/iio/adc/stm32-adc-core.h
index 9d6dfa1c03fa..73b2c2e91c08 100644
--- a/drivers/iio/adc/stm32-adc-core.h
+++ b/drivers/iio/adc/stm32-adc-core.h
@@ -142,6 +142,7 @@
#define STM32H7_LINCALRDYW3 BIT(24)
#define STM32H7_LINCALRDYW2 BIT(23)
#define STM32H7_LINCALRDYW1 BIT(22)
+#define STM32H7_LINCALRDYW_MASK GENMASK(27, 22)
#define STM32H7_ADCALLIN BIT(16)
#define STM32H7_BOOST BIT(8)
#define STM32H7_ADSTP BIT(4)
diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 8d03d21a33d6..2b2b55eb130e 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -119,16 +119,12 @@ struct stm32_adc_trig_info {
/**
* struct stm32_adc_calib - optional adc calibration data
- * @calfact_s: Calibration offset for single ended channels
- * @calfact_d: Calibration offset in differential
* @lincalfact: Linearity calibration factor
- * @calibrated: Indicates calibration status
+ * @lincal_saved: Indicates that linear calibration factors are saved
*/
struct stm32_adc_calib {
- u32 calfact_s;
- u32 calfact_d;
u32 lincalfact[STM32H7_LINCALFACT_NUM];
- bool calibrated;
+ bool lincal_saved;
};
/**
@@ -165,8 +161,6 @@ struct stm32_adc_vrefint {
* @extsel: trigger selection register & bitfield
* @res: resolution selection register & bitfield
* @difsel: differential mode selection register & bitfield
- * @calfact_s: single-ended calibration factors register & bitfield
- * @calfact_d: differential calibration factors register & bitfield
* @smpr: smpr1 & smpr2 registers offset array
* @smp_bits: smpr1 & smpr2 index and bitfields
* @or_vddcore: option register & vddcore bitfield
@@ -186,8 +180,6 @@ struct stm32_adc_regspec {
const struct stm32_adc_regs extsel;
const struct stm32_adc_regs res;
const struct stm32_adc_regs difsel;
- const struct stm32_adc_regs calfact_s;
- const struct stm32_adc_regs calfact_d;
const u32 smpr[2];
const struct stm32_adc_regs *smp_bits;
const struct stm32_adc_regs or_vddcore;
@@ -525,10 +517,6 @@ static const struct stm32_adc_regspec stm32h7_adc_regspec = {
STM32H7_EXTSEL_SHIFT },
.res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT },
.difsel = { STM32H7_ADC_DIFSEL, STM32H7_DIFSEL_MASK},
- .calfact_s = { STM32H7_ADC_CALFACT, STM32H7_CALFACT_S_MASK,
- STM32H7_CALFACT_S_SHIFT },
- .calfact_d = { STM32H7_ADC_CALFACT, STM32H7_CALFACT_D_MASK,
- STM32H7_CALFACT_D_SHIFT },
.smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
.smp_bits = stm32h7_smp_bits,
};
@@ -550,10 +538,6 @@ static const struct stm32_adc_regspec stm32mp13_adc_regspec = {
STM32H7_EXTSEL_SHIFT },
.res = { STM32H7_ADC_CFGR, STM32MP13_RES_MASK, STM32MP13_RES_SHIFT },
.difsel = { STM32MP13_ADC_DIFSEL, STM32MP13_DIFSEL_MASK},
- .calfact_s = { STM32MP13_ADC_CALFACT, STM32MP13_CALFACT_S_MASK,
- STM32MP13_CALFACT_S_SHIFT },
- .calfact_d = { STM32MP13_ADC_CALFACT, STM32MP13_CALFACT_D_MASK,
- STM32MP13_CALFACT_D_SHIFT },
.smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
.smp_bits = stm32h7_smp_bits,
.or_vddcore = { STM32MP13_ADC2_OR, STM32MP13_OP0 },
@@ -575,10 +559,6 @@ static const struct stm32_adc_regspec stm32mp1_adc_regspec = {
STM32H7_EXTSEL_SHIFT },
.res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT },
.difsel = { STM32H7_ADC_DIFSEL, STM32H7_DIFSEL_MASK},
- .calfact_s = { STM32H7_ADC_CALFACT, STM32H7_CALFACT_S_MASK,
- STM32H7_CALFACT_S_SHIFT },
- .calfact_d = { STM32H7_ADC_CALFACT, STM32H7_CALFACT_D_MASK,
- STM32H7_CALFACT_D_SHIFT },
.smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
.smp_bits = stm32h7_smp_bits,
.or_vddcore = { STM32MP1_ADC2_OR, STM32MP1_VDDCOREEN },
@@ -1000,9 +980,6 @@ static int stm32h7_adc_read_selfcalib(struct iio_dev *indio_dev)
int i, ret;
u32 lincalrdyw_mask, val;
- if (!adc->cfg->has_linearcal)
- goto skip_linearcal;
-
/* Read linearity calibration */
lincalrdyw_mask = STM32H7_LINCALRDYW6;
for (i = STM32H7_LINCALFACT_NUM - 1; i >= 0; i--) {
@@ -1024,15 +1001,7 @@ static int stm32h7_adc_read_selfcalib(struct iio_dev *indio_dev)
lincalrdyw_mask >>= 1;
}
-
-skip_linearcal:
- /* Read offset calibration */
- val = stm32_adc_readl(adc, adc->cfg->regs->calfact_s.reg);
- adc->cal.calfact_s = (val & adc->cfg->regs->calfact_s.mask);
- adc->cal.calfact_s >>= adc->cfg->regs->calfact_s.shift;
- adc->cal.calfact_d = (val & adc->cfg->regs->calfact_d.mask);
- adc->cal.calfact_d >>= adc->cfg->regs->calfact_d.shift;
- adc->cal.calibrated = true;
+ adc->cal.lincal_saved = true;
return 0;
}
@@ -1048,13 +1017,6 @@ static int stm32h7_adc_restore_selfcalib(struct iio_dev *indio_dev)
int i, ret;
u32 lincalrdyw_mask, val;
- val = (adc->cal.calfact_s << adc->cfg->regs->calfact_s.shift) |
- (adc->cal.calfact_d << adc->cfg->regs->calfact_d.shift);
- stm32_adc_writel(adc, adc->cfg->regs->calfact_s.reg, val);
-
- if (!adc->cfg->has_linearcal)
- return 0;
-
lincalrdyw_mask = STM32H7_LINCALRDYW6;
for (i = STM32H7_LINCALFACT_NUM - 1; i >= 0; i--) {
/*
@@ -1116,19 +1078,20 @@ static int stm32h7_adc_restore_selfcalib(struct iio_dev *indio_dev)
/**
* stm32h7_adc_selfcalib() - Procedure to calibrate ADC
* @indio_dev: IIO device instance
+ * @do_lincal: linear calibration request flag
* Note: Must be called once ADC is out of power down.
+ *
+ * Run offset calibration unconditionally.
+ * Run linear calibration if requested & supported.
*/
-static int stm32h7_adc_selfcalib(struct iio_dev *indio_dev)
+static int stm32h7_adc_selfcalib(struct iio_dev *indio_dev, int do_lincal)
{
struct stm32_adc *adc = iio_priv(indio_dev);
int ret;
u32 msk = STM32H7_ADCALDIF;
u32 val;
- if (adc->cal.calibrated)
- return true;
-
- if (adc->cfg->has_linearcal)
+ if (adc->cfg->has_linearcal && do_lincal)
msk |= STM32H7_ADCALLIN;
/* ADC must be disabled for calibration */
stm32h7_adc_disable(indio_dev);
@@ -1172,6 +1135,33 @@ static int stm32h7_adc_selfcalib(struct iio_dev *indio_dev)
return ret;
}
+/**
+ * stm32h7_adc_check_selfcalib() - Check linear calibration status
+ * @indio_dev: IIO device instance
+ *
+ * Used to check if linear calibration has been done.
+ * Return true if linear calibration factors are already saved in private data
+ * or if a linear calibration has been done at boot stage.
+ */
+static int stm32h7_adc_check_selfcalib(struct iio_dev *indio_dev)
+{
+ struct stm32_adc *adc = iio_priv(indio_dev);
+ u32 val;
+
+ if (adc->cal.lincal_saved)
+ return true;
+
+ /*
+ * Check if linear calibration factors are available in ADC registers,
+ * by checking that all LINCALRDYWx bits are set.
+ */
+ val = stm32_adc_readl(adc, STM32H7_ADC_CR) & STM32H7_LINCALRDYW_MASK;
+ if (val == STM32H7_LINCALRDYW_MASK)
+ return true;
+
+ return false;
+}
+
/**
* stm32h7_adc_prepare() - Leave power down mode to enable ADC.
* @indio_dev: IIO device instance
@@ -1186,16 +1176,20 @@ static int stm32h7_adc_selfcalib(struct iio_dev *indio_dev)
static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
{
struct stm32_adc *adc = iio_priv(indio_dev);
- int calib, ret;
+ int lincal_done = false;
+ int ret;
ret = stm32h7_adc_exit_pwr_down(indio_dev);
if (ret)
return ret;
- ret = stm32h7_adc_selfcalib(indio_dev);
+ if (adc->cfg->has_linearcal)
+ lincal_done = stm32h7_adc_check_selfcalib(indio_dev);
+
+ /* Always run offset calibration. Run linear calibration only once */
+ ret = stm32h7_adc_selfcalib(indio_dev, !lincal_done);
if (ret < 0)
goto pwr_dwn;
- calib = ret;
stm32_adc_int_ch_enable(indio_dev);
@@ -1205,13 +1199,15 @@ static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
if (ret)
goto ch_disable;
- /* Either restore or read calibration result for future reference */
- if (calib)
- ret = stm32h7_adc_restore_selfcalib(indio_dev);
- else
- ret = stm32h7_adc_read_selfcalib(indio_dev);
- if (ret)
- goto disable;
+ if (adc->cfg->has_linearcal) {
+ if (!adc->cal.lincal_saved)
+ ret = stm32h7_adc_read_selfcalib(indio_dev);
+ else
+ ret = stm32h7_adc_restore_selfcalib(indio_dev);
+
+ if (ret)
+ goto disable;
+ }
if (adc->cfg->has_presel)
stm32_adc_writel(adc, STM32H7_ADC_PCSEL, adc->pcsel);
--
2.25.1
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