From: Olivier Moysan Date: Thu, 14 Oct 2021 13:12:27 +0000 (+0200) Subject: iio: adc: stm32-adc: add vrefint calibration support X-Git-Tag: microblaze-v5.18~595^2~15^2~10 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=0e346b2cfa855d6e6990dbdb220983fbf2bb0b92;p=linux-2.6-microblaze.git iio: adc: stm32-adc: add vrefint calibration support Add support of vrefint calibration. If a channel is labeled as vrefint, get vrefint calibration from non volatile memory for this channel. vrefint channel is exposed as a processed channel returning the actual value of vrefp: vrefp = 3.3 x vrefint_cal / vrefint_data A conversion on vrefint channel allows to update scale factor according to vrefint deviation, compared to vrefint calibration value. Signed-off-by: Olivier Moysan Reviewed-by: Fabrice Gasnier Link: https://lore.kernel.org/r/20211014131228.4692-7-olivier.moysan@foss.st.com Signed-off-by: Jonathan Cameron --- diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c index 943ca03f4d31..5269bb87d094 100644 --- a/drivers/iio/adc/stm32-adc.c +++ b/drivers/iio/adc/stm32-adc.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -41,6 +42,7 @@ #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 @@ -137,6 +139,16 @@ struct stm32_adc_regs { int shift; }; +/** + * struct stm32_adc_vrefint - stm32 ADC internal reference voltage data + * @vrefint_cal: vrefint calibration value from nvmem + * @vrefint_data: vrefint actual value + */ +struct stm32_adc_vrefint { + u32 vrefint_cal; + u32 vrefint_data; +}; + /** * struct stm32_adc_regspec - stm32 registers definition * @dr: data register offset @@ -186,6 +198,7 @@ struct stm32_adc; * @unprepare: optional unprepare routine (disable, power-down) * @irq_clear: routine to clear irqs * @smp_cycles: programmable sampling time (ADC clock cycles) + * @ts_vrefint_ns: vrefint minimum sampling time in ns */ struct stm32_adc_cfg { const struct stm32_adc_regspec *regs; @@ -199,6 +212,7 @@ struct stm32_adc_cfg { void (*unprepare)(struct iio_dev *); void (*irq_clear)(struct iio_dev *indio_dev, u32 msk); const unsigned int *smp_cycles; + const unsigned int ts_vrefint_ns; }; /** @@ -223,6 +237,7 @@ struct stm32_adc_cfg { * @pcsel: bitmask to preselect channels on some devices * @smpr_val: sampling time settings (e.g. smpr1 / smpr2) * @cal: optional calibration data on some devices + * @vrefint: internal reference voltage data * @chan_name: channel name array * @num_diff: number of differential channels * @int_ch: internal channel indexes array @@ -248,6 +263,7 @@ struct stm32_adc { u32 pcsel; u32 smpr_val[2]; struct stm32_adc_calib cal; + struct stm32_adc_vrefint vrefint; char chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ]; u32 num_diff; int int_ch[STM32_ADC_INT_CH_NB]; @@ -1339,6 +1355,7 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev, switch (mask) { case IIO_CHAN_INFO_RAW: + case IIO_CHAN_INFO_PROCESSED: ret = iio_device_claim_direct_mode(indio_dev); if (ret) return ret; @@ -1346,6 +1363,10 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev, ret = stm32_adc_single_conv(indio_dev, chan, val); else ret = -EINVAL; + + if (mask == IIO_CHAN_INFO_PROCESSED && adc->vrefint.vrefint_cal) + *val = STM32_ADC_VREFINT_VOLTAGE * adc->vrefint.vrefint_cal / *val; + iio_device_release_direct_mode(indio_dev); return ret; @@ -1815,7 +1836,10 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev, chan->datasheet_name = name; chan->scan_index = scan_index; chan->indexed = 1; - chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); + if (chan->channel == adc->int_ch[STM32_ADC_INT_CH_VREFINT]) + chan->info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED); + else + chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW); chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET); chan->scan_type.sign = 'u'; @@ -1917,6 +1941,36 @@ static int stm32_adc_legacy_chan_init(struct iio_dev *indio_dev, return scan_index; } +static int stm32_adc_populate_int_ch(struct iio_dev *indio_dev, const char *ch_name, + int chan) +{ + struct stm32_adc *adc = iio_priv(indio_dev); + u16 vrefint; + int i, ret; + + for (i = 0; i < STM32_ADC_INT_CH_NB; i++) { + if (!strncmp(stm32_adc_ic[i].name, ch_name, STM32_ADC_CH_SZ)) { + adc->int_ch[i] = chan; + + if (stm32_adc_ic[i].idx != STM32_ADC_INT_CH_VREFINT) + continue; + + /* Get calibration data for vrefint channel */ + ret = nvmem_cell_read_u16(&indio_dev->dev, "vrefint", &vrefint); + if (ret && ret != -ENOENT) { + return dev_err_probe(&indio_dev->dev, ret, + "nvmem access error\n"); + } + if (ret == -ENOENT) + dev_dbg(&indio_dev->dev, "vrefint calibration not found\n"); + else + adc->vrefint.vrefint_cal = vrefint; + } + } + + return 0; +} + static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev, struct stm32_adc *adc, struct iio_chan_spec *channels) @@ -1925,7 +1979,7 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev, const struct stm32_adc_info *adc_info = adc->cfg->adc_info; struct device_node *child; const char *name; - int val, scan_index = 0, ret, i; + int val, scan_index = 0, ret; bool differential; u32 vin[2]; @@ -1945,10 +1999,9 @@ static int stm32_adc_generic_chan_init(struct iio_dev *indio_dev, return -EINVAL; } strncpy(adc->chan_name[val], name, STM32_ADC_CH_SZ); - for (i = 0; i < STM32_ADC_INT_CH_NB; i++) { - if (!strncmp(stm32_adc_ic[i].name, name, STM32_ADC_CH_SZ)) - adc->int_ch[i] = val; - } + ret = stm32_adc_populate_int_ch(indio_dev, name, val); + if (ret) + goto err; } else if (ret != -EINVAL) { dev_err(&indio_dev->dev, "Invalid label %d\n", ret); goto err; @@ -2055,6 +2108,14 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping) */ of_property_read_u32_index(node, "st,min-sample-time-nsecs", i, &smp); + + /* + * For vrefint channel, ensure that the sampling time cannot + * be lower than the one specified in the datasheet + */ + if (channels[i].channel == adc->int_ch[STM32_ADC_INT_CH_VREFINT]) + smp = max(smp, adc->cfg->ts_vrefint_ns); + /* Prepare sampling time settings */ stm32_adc_smpr_init(adc, channels[i].channel, smp); } @@ -2361,6 +2422,7 @@ static const struct stm32_adc_cfg stm32mp1_adc_cfg = { .unprepare = stm32h7_adc_unprepare, .smp_cycles = stm32h7_adc_smp_cycles, .irq_clear = stm32h7_adc_irq_clear, + .ts_vrefint_ns = 4300, }; static const struct of_device_id stm32_adc_of_match[] = {