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iio: adc: stm32-adc: add vrefint calibration support

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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 <olivier.moysan@foss.st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20211014131228.4692-7-olivier.moysan@foss.st.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Olivier Moysan 2021-10-14 15:12:27 +02:00 committed by Jonathan Cameron
parent aec6e0d8f0
commit 0e346b2cfa
1 changed files with 68 additions and 6 deletions
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74
drivers/iio/adc/stm32-adc.c
View file

@ -21,6 +21,7 @@
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
@ -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[] = {