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linux/drivers/iio/adc/ad7191.c
Alisa-Dariana Roman 2e3ae10c35 iio: adc: ad7191: add AD7191 
AD7191 is a pin-programmable, ultra-low noise 24-bit sigma-delta ADC
designed for precision bridge sensor measurements. It features two
differential analog input channels, selectable output rates,
programmable gain, internal temperature sensor and simultaneous
50Hz/60Hz rejection.

Signed-off-by: Alisa-Dariana Roman <alisa.roman@analog.com>
Reviewed-by: David Lechner<dlechner@baylibre.com>
Link: https://patch.msgid.link/20250228141327.262488-3-alisa.roman@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2025-03-11 19:08:56 +00:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* AD7191 ADC driver
*
* Copyright 2025 Analog Devices Inc.
*/
#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/interrupt.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <linux/types.h>
#include <linux/units.h>
#include <linux/iio/adc/ad_sigma_delta.h>
#include <linux/iio/iio.h>
#define ad_sigma_delta_to_ad7191(sigmad) \
container_of((sigmad), struct ad7191_state, sd)
#define AD7191_TEMP_CODES_PER_DEGREE 2815
#define AD7191_CHAN_MASK BIT(0)
#define AD7191_TEMP_MASK BIT(1)
enum ad7191_channel {
AD7191_CH_AIN1_AIN2,
AD7191_CH_AIN3_AIN4,
AD7191_CH_TEMP,
};
/*
* NOTE:
* The AD7191 features a dual-use data out ready DOUT/RDY output.
* In order to avoid contentions on the SPI bus, it's therefore necessary
* to use SPI bus locking.
*
* The DOUT/RDY output must also be wired to an interrupt-capable GPIO.
*
* The SPI controller's chip select must be connected to the PDOWN pin
* of the ADC. When CS (PDOWN) is high, it powers down the device and
* resets the internal circuitry.
*/
struct ad7191_state {
struct ad_sigma_delta sd;
struct mutex lock; /* Protect device state */
struct gpio_descs *odr_gpios;
struct gpio_descs *pga_gpios;
struct gpio_desc *temp_gpio;
struct gpio_desc *chan_gpio;
u16 int_vref_mv;
const u32 (*scale_avail)[2];
size_t scale_avail_size;
u32 scale_index;
const u32 *samp_freq_avail;
size_t samp_freq_avail_size;
u32 samp_freq_index;
struct clk *mclk;
};
static int ad7191_set_channel(struct ad_sigma_delta *sd, unsigned int address)
{
struct ad7191_state *st = ad_sigma_delta_to_ad7191(sd);
u8 temp_gpio_val, chan_gpio_val;
if (!FIELD_FIT(AD7191_CHAN_MASK | AD7191_TEMP_MASK, address))
return -EINVAL;
chan_gpio_val = FIELD_GET(AD7191_CHAN_MASK, address);
temp_gpio_val = FIELD_GET(AD7191_TEMP_MASK, address);
gpiod_set_value(st->chan_gpio, chan_gpio_val);
gpiod_set_value(st->temp_gpio, temp_gpio_val);
return 0;
}
static int ad7191_set_cs(struct ad_sigma_delta *sigma_delta, int assert)
{
struct spi_transfer t = {
.len = 0,
.cs_change = assert,
};
struct spi_message m;
spi_message_init_with_transfers(&m, &t, 1);
return spi_sync_locked(sigma_delta->spi, &m);
}
static int ad7191_set_mode(struct ad_sigma_delta *sd,
enum ad_sigma_delta_mode mode)
{
struct ad7191_state *st = ad_sigma_delta_to_ad7191(sd);
switch (mode) {
case AD_SD_MODE_CONTINUOUS:
case AD_SD_MODE_SINGLE:
return ad7191_set_cs(&st->sd, 1);
case AD_SD_MODE_IDLE:
return ad7191_set_cs(&st->sd, 0);
default:
return -EINVAL;
}
}
static const struct ad_sigma_delta_info ad7191_sigma_delta_info = {
.set_channel = ad7191_set_channel,
.set_mode = ad7191_set_mode,
.has_registers = false,
};
static int ad7191_init_regulators(struct iio_dev *indio_dev)
{
struct ad7191_state *st = iio_priv(indio_dev);
struct device *dev = &st->sd.spi->dev;
int ret;
ret = devm_regulator_get_enable(dev, "avdd");
if (ret)
return dev_err_probe(dev, ret, "Failed to enable specified AVdd supply\n");
ret = devm_regulator_get_enable(dev, "dvdd");
if (ret)
return dev_err_probe(dev, ret, "Failed to enable specified DVdd supply\n");
ret = devm_regulator_get_enable_read_voltage(dev, "vref");
if (ret < 0)
return dev_err_probe(dev, ret, "Failed to get Vref voltage\n");
st->int_vref_mv = ret / 1000;
return 0;
}
static int ad7191_config_setup(struct iio_dev *indio_dev)
{
struct ad7191_state *st = iio_priv(indio_dev);
struct device *dev = &st->sd.spi->dev;
/* Sampling frequencies in Hz, see Table 5 */
static const u32 samp_freq[4] = { 120, 60, 50, 10 };
/* Gain options, see Table 7 */
const u32 gain[4] = { 1, 8, 64, 128 };
static u32 scale_buffer[4][2];
int odr_value, odr_index = 0, pga_value, pga_index = 0, i, ret;
u64 scale_uv;
st->samp_freq_index = 0;
st->scale_index = 0;
ret = device_property_read_u32(dev, "adi,odr-value", &odr_value);
if (ret && ret != -EINVAL)
return dev_err_probe(dev, ret, "Failed to get odr value.\n");
if (ret == -EINVAL) {
st->odr_gpios = devm_gpiod_get_array(dev, "odr", GPIOD_OUT_LOW);
if (IS_ERR(st->odr_gpios))
return dev_err_probe(dev, PTR_ERR(st->odr_gpios),
"Failed to get odr gpios.\n");
if (st->odr_gpios->ndescs != 2)
return dev_err_probe(dev, -EINVAL, "Expected 2 odr gpio pins.\n");
st->samp_freq_avail = samp_freq;
st->samp_freq_avail_size = ARRAY_SIZE(samp_freq);
} else {
for (i = 0; i < ARRAY_SIZE(samp_freq); i++) {
if (odr_value != samp_freq[i])
continue;
odr_index = i;
break;
}
st->samp_freq_avail = &samp_freq[odr_index];
st->samp_freq_avail_size = 1;
st->odr_gpios = NULL;
}
mutex_lock(&st->lock);
for (i = 0; i < ARRAY_SIZE(scale_buffer); i++) {
scale_uv = ((u64)st->int_vref_mv * NANO) >>
(indio_dev->channels[0].scan_type.realbits - 1);
do_div(scale_uv, gain[i]);
scale_buffer[i][1] = do_div(scale_uv, NANO);
scale_buffer[i][0] = scale_uv;
}
mutex_unlock(&st->lock);
ret = device_property_read_u32(dev, "adi,pga-value", &pga_value);
if (ret && ret != -EINVAL)
return dev_err_probe(dev, ret, "Failed to get pga value.\n");
if (ret == -EINVAL) {
st->pga_gpios = devm_gpiod_get_array(dev, "pga", GPIOD_OUT_LOW);
if (IS_ERR(st->pga_gpios))
return dev_err_probe(dev, PTR_ERR(st->pga_gpios),
"Failed to get pga gpios.\n");
if (st->pga_gpios->ndescs != 2)
return dev_err_probe(dev, -EINVAL, "Expected 2 pga gpio pins.\n");
st->scale_avail = scale_buffer;
st->scale_avail_size = ARRAY_SIZE(scale_buffer);
} else {
for (i = 0; i < ARRAY_SIZE(gain); i++) {
if (pga_value != gain[i])
continue;
pga_index = i;
break;
}
st->scale_avail = &scale_buffer[pga_index];
st->scale_avail_size = 1;
st->pga_gpios = NULL;
}
st->temp_gpio = devm_gpiod_get(dev, "temp", GPIOD_OUT_LOW);
if (IS_ERR(st->temp_gpio))
return dev_err_probe(dev, PTR_ERR(st->temp_gpio),
"Failed to get temp gpio.\n");
st->chan_gpio = devm_gpiod_get(dev, "chan", GPIOD_OUT_LOW);
if (IS_ERR(st->chan_gpio))
return dev_err_probe(dev, PTR_ERR(st->chan_gpio),
"Failed to get chan gpio.\n");
return 0;
}
static int ad7191_clock_setup(struct ad7191_state *st)
{
struct device *dev = &st->sd.spi->dev;
st->mclk = devm_clk_get_optional_enabled(dev, "mclk");
if (IS_ERR(st->mclk))
return dev_err_probe(dev, PTR_ERR(st->mclk),
"Failed to get mclk.\n");
return 0;
}
static int ad7191_setup(struct iio_dev *indio_dev)
{
struct ad7191_state *st = iio_priv(indio_dev);
int ret;
ret = ad7191_init_regulators(indio_dev);
if (ret)
return ret;
ret = ad7191_config_setup(indio_dev);
if (ret)
return ret;
return ad7191_clock_setup(st);
}
static int ad7191_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long m)
{
struct ad7191_state *st = iio_priv(indio_dev);
switch (m) {
case IIO_CHAN_INFO_RAW:
return ad_sigma_delta_single_conversion(indio_dev, chan, val);
case IIO_CHAN_INFO_SCALE:
switch (chan->type) {
case IIO_VOLTAGE: {
guard(mutex)(&st->lock);
*val = st->scale_avail[st->scale_index][0];
*val2 = st->scale_avail[st->scale_index][1];
return IIO_VAL_INT_PLUS_NANO;
}
case IIO_TEMP:
*val = 0;
*val2 = NANO / AD7191_TEMP_CODES_PER_DEGREE;
return IIO_VAL_INT_PLUS_NANO;
default:
return -EINVAL;
}
case IIO_CHAN_INFO_OFFSET:
*val = -(1 << (chan->scan_type.realbits - 1));
switch (chan->type) {
case IIO_VOLTAGE:
return IIO_VAL_INT;
case IIO_TEMP:
*val -= 273 * AD7191_TEMP_CODES_PER_DEGREE;
return IIO_VAL_INT;
default:
return -EINVAL;
}
case IIO_CHAN_INFO_SAMP_FREQ:
*val = st->samp_freq_avail[st->samp_freq_index];
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static int ad7191_set_gain(struct ad7191_state *st, int gain_index)
{
DECLARE_BITMAP(bitmap, 2) = { };
st->scale_index = gain_index;
bitmap_write(bitmap, gain_index, 0, 2);
return gpiod_multi_set_value_cansleep(st->pga_gpios, bitmap);
}
static int ad7191_set_samp_freq(struct ad7191_state *st, int samp_freq_index)
{
DECLARE_BITMAP(bitmap, 2) = {};
st->samp_freq_index = samp_freq_index;
bitmap_write(bitmap, samp_freq_index, 0, 2);
return gpiod_multi_set_value_cansleep(st->odr_gpios, bitmap);
}
static int __ad7191_write_raw(struct ad7191_state *st,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
int i;
switch (mask) {
case IIO_CHAN_INFO_SCALE: {
if (!st->pga_gpios)
return -EPERM;
guard(mutex)(&st->lock);
for (i = 0; i < st->scale_avail_size; i++) {
if (val2 == st->scale_avail[i][1])
return ad7191_set_gain(st, i);
}
return -EINVAL;
}
case IIO_CHAN_INFO_SAMP_FREQ: {
if (!st->odr_gpios)
return -EPERM;
guard(mutex)(&st->lock);
for (i = 0; i < st->samp_freq_avail_size; i++) {
if (val == st->samp_freq_avail[i])
return ad7191_set_samp_freq(st, i);
}
return -EINVAL;
}
default:
return -EINVAL;
}
}
static int ad7191_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int val, int val2,
long mask)
{
struct ad7191_state *st = iio_priv(indio_dev);
int ret;
if (!iio_device_claim_direct(indio_dev))
return -EBUSY;
ret = __ad7191_write_raw(st, chan, val, val2, mask);
iio_device_release_direct(indio_dev);
return ret;
}
static int ad7191_write_raw_get_fmt(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, long mask)
{
switch (mask) {
case IIO_CHAN_INFO_SCALE:
return IIO_VAL_INT_PLUS_NANO;
case IIO_CHAN_INFO_SAMP_FREQ:
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static int ad7191_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, const int **vals,
int *type, int *length, long mask)
{
struct ad7191_state *st = iio_priv(indio_dev);
switch (mask) {
case IIO_CHAN_INFO_SCALE:
*vals = (int *)st->scale_avail;
*type = IIO_VAL_INT_PLUS_NANO;
*length = st->scale_avail_size * 2;
return IIO_AVAIL_LIST;
case IIO_CHAN_INFO_SAMP_FREQ:
*vals = (int *)st->samp_freq_avail;
*type = IIO_VAL_INT;
*length = st->samp_freq_avail_size;
return IIO_AVAIL_LIST;
}
return -EINVAL;
}
static const struct iio_info ad7191_info = {
.read_raw = ad7191_read_raw,
.write_raw = ad7191_write_raw,
.write_raw_get_fmt = ad7191_write_raw_get_fmt,
.read_avail = ad7191_read_avail,
.validate_trigger = ad_sd_validate_trigger,
};
static const struct iio_chan_spec ad7191_channels[] = {
{
.type = IIO_TEMP,
.address = AD7191_CH_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_OFFSET) |
BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
.scan_type = {
.sign = 'u',
.realbits = 24,
.storagebits = 32,
.endianness = IIO_BE,
},
},
{
.type = IIO_VOLTAGE,
.differential = 1,
.indexed = 1,
.channel = 1,
.channel2 = 2,
.address = AD7191_CH_AIN1_AIN2,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_OFFSET) |
BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
.scan_index = 1,
.scan_type = {
.sign = 'u',
.realbits = 24,
.storagebits = 32,
.endianness = IIO_BE,
},
},
{
.type = IIO_VOLTAGE,
.differential = 1,
.indexed = 1,
.channel = 3,
.channel2 = 4,
.address = AD7191_CH_AIN3_AIN4,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_OFFSET) |
BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),
.scan_index = 2,
.scan_type = {
.sign = 'u',
.realbits = 24,
.storagebits = 32,
.endianness = IIO_BE,
},
},
IIO_CHAN_SOFT_TIMESTAMP(3),
};
static int ad7191_probe(struct spi_device *spi)
{
struct device *dev = &spi->dev;
struct ad7191_state *st;
struct iio_dev *indio_dev;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
ret = devm_mutex_init(dev, &st->lock);
if (ret)
return ret;
indio_dev->name = "ad7191";
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = ad7191_channels;
indio_dev->num_channels = ARRAY_SIZE(ad7191_channels);
indio_dev->info = &ad7191_info;
ret = ad_sd_init(&st->sd, indio_dev, spi, &ad7191_sigma_delta_info);
if (ret)
return ret;
ret = devm_ad_sd_setup_buffer_and_trigger(dev, indio_dev);
if (ret)
return ret;
ret = ad7191_setup(indio_dev);
if (ret)
return ret;
return devm_iio_device_register(dev, indio_dev);
}
static const struct of_device_id ad7191_of_match[] = {
{ .compatible = "adi,ad7191", },
{ }
};
MODULE_DEVICE_TABLE(of, ad7191_of_match);
static const struct spi_device_id ad7191_id_table[] = {
{ "ad7191" },
{ }
};
MODULE_DEVICE_TABLE(spi, ad7191_id_table);
static struct spi_driver ad7191_driver = {
.driver = {
.name = "ad7191",
.of_match_table = ad7191_of_match,
},
.probe = ad7191_probe,
.id_table = ad7191_id_table,
};
module_spi_driver(ad7191_driver);
MODULE_AUTHOR("Alisa-Dariana Roman <alisa.roman@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7191 ADC");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("IIO_AD_SIGMA_DELTA");
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