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iio: adc: stm32-adc: smart calibration support

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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@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20221115103124.70074-2-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Olivier Moysan 2022-11-15 11:31:21 +01:00 committed by Jonathan Cameron
parent f237cf1914
commit 9d901e356c
2 changed files with 53 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/iio/adc/stm32-adc-core.h
View File

@ -142,6 +142,7 @@
#define STM32H7_LINCALRDYW3 BIT(24) #define STM32H7_LINCALRDYW3 BIT(24)
#define STM32H7_LINCALRDYW2 BIT(23) #define STM32H7_LINCALRDYW2 BIT(23)
#define STM32H7_LINCALRDYW1 BIT(22) #define STM32H7_LINCALRDYW1 BIT(22)
#define STM32H7_LINCALRDYW_MASK GENMASK(27, 22)
#define STM32H7_ADCALLIN BIT(16) #define STM32H7_ADCALLIN BIT(16)
#define STM32H7_BOOST BIT(8) #define STM32H7_BOOST BIT(8)
#define STM32H7_ADSTP BIT(4) #define STM32H7_ADSTP BIT(4)

102
drivers/iio/adc/stm32-adc.c
View File

@ -119,16 +119,12 @@ struct stm32_adc_trig_info {
/** /**
* struct stm32_adc_calib - optional adc calibration data * 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 * @lincalfact: Linearity calibration factor
* @calibrated: Indicates calibration status * @lincal_saved: Indicates that linear calibration factors are saved
*/ */
struct stm32_adc_calib { struct stm32_adc_calib {
u32 calfact_s;
u32 calfact_d;
u32 lincalfact[STM32H7_LINCALFACT_NUM]; u32 lincalfact[STM32H7_LINCALFACT_NUM];
bool calibrated; bool lincal_saved;
}; };
/** /**
@ -165,8 +161,6 @@ struct stm32_adc_vrefint {
* @extsel: trigger selection register & bitfield * @extsel: trigger selection register & bitfield
* @res: resolution selection register & bitfield * @res: resolution selection register & bitfield
* @difsel: differential mode 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 * @smpr: smpr1 & smpr2 registers offset array
* @smp_bits: smpr1 & smpr2 index and bitfields * @smp_bits: smpr1 & smpr2 index and bitfields
* @or_vddcore: option register & vddcore bitfield * @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 extsel;
const struct stm32_adc_regs res; const struct stm32_adc_regs res;
const struct stm32_adc_regs difsel; 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 u32 smpr[2];
const struct stm32_adc_regs *smp_bits; const struct stm32_adc_regs *smp_bits;
const struct stm32_adc_regs or_vddcore; const struct stm32_adc_regs or_vddcore;
@ -525,10 +517,6 @@ static const struct stm32_adc_regspec stm32h7_adc_regspec = {
STM32H7_EXTSEL_SHIFT }, STM32H7_EXTSEL_SHIFT },
.res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT }, .res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT },
.difsel = { STM32H7_ADC_DIFSEL, STM32H7_DIFSEL_MASK}, .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 }, .smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
.smp_bits = stm32h7_smp_bits, .smp_bits = stm32h7_smp_bits,
}; };
@ -550,10 +538,6 @@ static const struct stm32_adc_regspec stm32mp13_adc_regspec = {
STM32H7_EXTSEL_SHIFT }, STM32H7_EXTSEL_SHIFT },
.res = { STM32H7_ADC_CFGR, STM32MP13_RES_MASK, STM32MP13_RES_SHIFT }, .res = { STM32H7_ADC_CFGR, STM32MP13_RES_MASK, STM32MP13_RES_SHIFT },
.difsel = { STM32MP13_ADC_DIFSEL, STM32MP13_DIFSEL_MASK}, .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 }, .smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
.smp_bits = stm32h7_smp_bits, .smp_bits = stm32h7_smp_bits,
.or_vddcore = { STM32MP13_ADC2_OR, STM32MP13_OP0 }, .or_vddcore = { STM32MP13_ADC2_OR, STM32MP13_OP0 },
@ -575,10 +559,6 @@ static const struct stm32_adc_regspec stm32mp1_adc_regspec = {
STM32H7_EXTSEL_SHIFT }, STM32H7_EXTSEL_SHIFT },
.res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT }, .res = { STM32H7_ADC_CFGR, STM32H7_RES_MASK, STM32H7_RES_SHIFT },
.difsel = { STM32H7_ADC_DIFSEL, STM32H7_DIFSEL_MASK}, .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 }, .smpr = { STM32H7_ADC_SMPR1, STM32H7_ADC_SMPR2 },
.smp_bits = stm32h7_smp_bits, .smp_bits = stm32h7_smp_bits,
.or_vddcore = { STM32MP1_ADC2_OR, STM32MP1_VDDCOREEN }, .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; int i, ret;
u32 lincalrdyw_mask, val; u32 lincalrdyw_mask, val;
if (!adc->cfg->has_linearcal)
goto skip_linearcal;
/* Read linearity calibration */ /* Read linearity calibration */
lincalrdyw_mask = STM32H7_LINCALRDYW6; lincalrdyw_mask = STM32H7_LINCALRDYW6;
for (i = STM32H7_LINCALFACT_NUM - 1; i >= 0; i--) { 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; lincalrdyw_mask >>= 1;
} }
adc->cal.lincal_saved = true;
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;
return 0; return 0;
} }
@ -1048,13 +1017,6 @@ static int stm32h7_adc_restore_selfcalib(struct iio_dev *indio_dev)
int i, ret; int i, ret;
u32 lincalrdyw_mask, val; 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; lincalrdyw_mask = STM32H7_LINCALRDYW6;
for (i = STM32H7_LINCALFACT_NUM - 1; i >= 0; i--) { 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 * stm32h7_adc_selfcalib() - Procedure to calibrate ADC
* @indio_dev: IIO device instance * @indio_dev: IIO device instance
* @do_lincal: linear calibration request flag
* Note: Must be called once ADC is out of power down. * 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); struct stm32_adc *adc = iio_priv(indio_dev);
int ret; int ret;
u32 msk = STM32H7_ADCALDIF; u32 msk = STM32H7_ADCALDIF;
u32 val; u32 val;
if (adc->cal.calibrated) if (adc->cfg->has_linearcal && do_lincal)
return true;
if (adc->cfg->has_linearcal)
msk |= STM32H7_ADCALLIN; msk |= STM32H7_ADCALLIN;
/* ADC must be disabled for calibration */ /* ADC must be disabled for calibration */
stm32h7_adc_disable(indio_dev); stm32h7_adc_disable(indio_dev);
@ -1172,6 +1135,33 @@ out:
return ret; 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. * stm32h7_adc_prepare() - Leave power down mode to enable ADC.
* @indio_dev: IIO device instance * @indio_dev: IIO device instance
@ -1186,16 +1176,20 @@ out:
static int stm32h7_adc_prepare(struct iio_dev *indio_dev) static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
{ {
struct stm32_adc *adc = iio_priv(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); ret = stm32h7_adc_exit_pwr_down(indio_dev);
if (ret) if (ret)
return 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) if (ret < 0)
goto pwr_dwn; goto pwr_dwn;
calib = ret;
stm32_adc_int_ch_enable(indio_dev); stm32_adc_int_ch_enable(indio_dev);
@ -1205,13 +1199,15 @@ static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
if (ret) if (ret)
goto ch_disable; goto ch_disable;
/* Either restore or read calibration result for future reference */ if (adc->cfg->has_linearcal) {
if (calib) if (!adc->cal.lincal_saved)
ret = stm32h7_adc_restore_selfcalib(indio_dev);
else
ret = stm32h7_adc_read_selfcalib(indio_dev); ret = stm32h7_adc_read_selfcalib(indio_dev);
else
ret = stm32h7_adc_restore_selfcalib(indio_dev);
if (ret) if (ret)
goto disable; goto disable;
}
if (adc->cfg->has_presel) if (adc->cfg->has_presel)
stm32_adc_writel(adc, STM32H7_ADC_PCSEL, adc->pcsel); stm32_adc_writel(adc, STM32H7_ADC_PCSEL, adc->pcsel);