From 9d901e356c8d3640940cb72ff7969f03e85c2e95 Mon Sep 17 00:00:00 2001 From: Olivier Moysan Date: Tue, 15 Nov 2022 11:31:21 +0100 Subject: iio: adc: stm32-adc: smart calibration support 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 Reviewed-by: Fabrice Gasnier Link: https://lore.kernel.org/r/20221115103124.70074-2-olivier.moysan@foss.st.com Signed-off-by: Jonathan Cameron --- drivers/iio/adc/stm32-adc-core.h | 1 + drivers/iio/adc/stm32-adc.c | 108 +++++++++++++++++++-------------------- 2 files changed, 53 insertions(+), 56 deletions(-) (limited to 'drivers/iio') 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 @@ out: 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 @@ out: 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); -- cgit v1.2.3