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linux/drivers/iio/amplifiers/ada4250.c
Antoniu Miclaus 28b4c30bfa iio: amplifiers: ada4250: add support for ADA4250 
The ADA4250 is an instrumentation amplifier with SPI/pin-strap
progammable gains that is optimized for ultra-low power systems.
With a minimum supply voltage of 1.7V, 26uA of quiescent current,
a shutdown mode, a sleep mode, and a fast wake up settling time,
ADA4250 can be power cycled on a battery powered system for even
futher savings.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Link: https://lore.kernel.org/r/20220223120112.8067-2-antoniu.miclaus@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2022-02-27 12:06:25 +00:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* ADA4250 driver
*
* Copyright 2022 Analog Devices Inc.
*/
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/device.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#include <asm/unaligned.h>
/* ADA4250 Register Map */
#define ADA4250_REG_GAIN_MUX 0x00
#define ADA4250_REG_REFBUF_EN 0x01
#define ADA4250_REG_RESET 0x02
#define ADA4250_REG_SNSR_CAL_VAL 0x04
#define ADA4250_REG_SNSR_CAL_CNFG 0x05
#define ADA4250_REG_DIE_REV 0x18
#define ADA4250_REG_CHIP_ID 0x19
/* ADA4250_REG_GAIN_MUX Map */
#define ADA4250_GAIN_MUX_MSK GENMASK(2, 0)
/* ADA4250_REG_REFBUF Map */
#define ADA4250_REFBUF_MSK BIT(0)
/* ADA4250_REG_RESET Map */
#define ADA4250_RESET_MSK BIT(0)
/* ADA4250_REG_SNSR_CAL_VAL Map */
#define ADA4250_CAL_CFG_BIAS_MSK GENMASK(7, 0)
/* ADA4250_REG_SNSR_CAL_CNFG Bit Definition */
#define ADA4250_BIAS_SET_MSK GENMASK(3, 2)
#define ADA4250_RANGE_SET_MSK GENMASK(1, 0)
/* Miscellaneous definitions */
#define ADA4250_CHIP_ID 0x4250
#define ADA4250_RANGE1 0
#define ADA4250_RANGE4 3
/* ADA4250 current bias set */
enum ada4250_current_bias {
ADA4250_BIAS_DISABLED,
ADA4250_BIAS_BANDGAP,
ADA4250_BIAS_AVDD,
};
struct ada4250_state {
struct spi_device *spi;
struct regmap *regmap;
struct regulator *reg;
/* Protect against concurrent accesses to the device and data content */
struct mutex lock;
u8 bias;
u8 gain;
int offset_uv;
bool refbuf_en;
};
/* ADA4250 Current Bias Source Settings: Disabled, Bandgap Reference, AVDD */
static const int calibbias_table[] = {0, 1, 2};
/* ADA4250 Gain (V/V) values: 1, 2, 4, 8, 16, 32, 64, 128 */
static const int hwgain_table[] = {1, 2, 4, 8, 16, 32, 64, 128};
static const struct regmap_config ada4250_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.read_flag_mask = BIT(7),
.max_register = 0x1A,
};
static int ada4250_set_offset_uv(struct iio_dev *indio_dev,
const struct iio_chan_spec *chan,
int offset_uv)
{
struct ada4250_state *st = iio_priv(indio_dev);
int i, ret, x[8], max_vos, min_vos, voltage_v, vlsb = 0;
u8 offset_raw, range = ADA4250_RANGE1;
u32 lsb_coeff[6] = {1333, 2301, 4283, 8289, 16311, 31599};
if (st->bias == 0 || st->bias == 3)
return -EINVAL;
voltage_v = regulator_get_voltage(st->reg);
voltage_v = DIV_ROUND_CLOSEST(voltage_v, 1000000);
if (st->bias == ADA4250_BIAS_AVDD)
x[0] = voltage_v;
else
x[0] = 5;
x[1] = 126 * (x[0] - 1);
for (i = 0; i < 6; i++)
x[i + 2] = DIV_ROUND_CLOSEST(x[1] * 1000, lsb_coeff[i]);
if (st->gain == 0)
return -EINVAL;
/*
* Compute Range and Voltage per LSB for the Sensor Offset Calibration
* Example of computation for Range 1 and Range 2 (Curren Bias Set = AVDD):
* Range 1 Range 2
* Gain | Max Vos(mV) | LSB(mV) | Max Vos(mV) | LSB(mV) |
* 2 | X1*127 | X1=0.126(AVDD-1) | X1*3*127 | X1*3 |
* 4 | X2*127 | X2=X1/1.3333 | X2*3*127 | X2*3 |
* 8 | X3*127 | X3=X1/2.301 | X3*3*127 | X3*3 |
* 16 | X4*127 | X4=X1/4.283 | X4*3*127 | X4*3 |
* 32 | X5*127 | X5=X1/8.289 | X5*3*127 | X5*3 |
* 64 | X6*127 | X6=X1/16.311 | X6*3*127 | X6*3 |
* 128 | X7*127 | X7=X1/31.599 | X7*3*127 | X7*3 |
*/
for (i = ADA4250_RANGE1; i <= ADA4250_RANGE4; i++) {
max_vos = x[st->gain] * 127 * ((1 << (i + 1)) - 1);
min_vos = -1 * max_vos;
if (offset_uv > min_vos && offset_uv < max_vos) {
range = i;
vlsb = x[st->gain] * ((1 << (i + 1)) - 1);
break;
}
}
if (vlsb <= 0)
return -EINVAL;
offset_raw = DIV_ROUND_CLOSEST(abs(offset_uv), vlsb);
mutex_lock(&st->lock);
ret = regmap_update_bits(st->regmap, ADA4250_REG_SNSR_CAL_CNFG,
ADA4250_RANGE_SET_MSK,
FIELD_PREP(ADA4250_RANGE_SET_MSK, range));
if (ret)
goto exit;
st->offset_uv = offset_raw * vlsb;
/*
* To set the offset calibration value, use bits [6:0] and bit 7 as the
* polarity bit (set to "0" for a negative offset and "1" for a positive
* offset).
*/
if (offset_uv < 0) {
offset_raw |= BIT(7);
st->offset_uv *= (-1);
}
ret = regmap_write(st->regmap, ADA4250_REG_SNSR_CAL_VAL, offset_raw);
exit:
mutex_unlock(&st->lock);
return ret;
}
static int ada4250_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long info)
{
struct ada4250_state *st = iio_priv(indio_dev);
int ret;
switch (info) {
case IIO_CHAN_INFO_HARDWAREGAIN:
ret = regmap_read(st->regmap, ADA4250_REG_GAIN_MUX, val);
if (ret)
return ret;
*val = BIT(*val);
return IIO_VAL_INT;
case IIO_CHAN_INFO_OFFSET:
*val = st->offset_uv;
return IIO_VAL_INT;
case IIO_CHAN_INFO_CALIBBIAS:
ret = regmap_read(st->regmap, ADA4250_REG_SNSR_CAL_CNFG, val);
if (ret)
return ret;
*val = FIELD_GET(ADA4250_BIAS_SET_MSK, *val);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = 1;
*val2 = 1000000;
return IIO_VAL_FRACTIONAL;
default:
return -EINVAL;
}
}
static int ada4250_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long info)
{
struct ada4250_state *st = iio_priv(indio_dev);
int ret;
switch (info) {
case IIO_CHAN_INFO_HARDWAREGAIN:
ret = regmap_write(st->regmap, ADA4250_REG_GAIN_MUX,
FIELD_PREP(ADA4250_GAIN_MUX_MSK, ilog2(val)));
if (ret)
return ret;
st->gain = ilog2(val);
return ret;
case IIO_CHAN_INFO_OFFSET:
return ada4250_set_offset_uv(indio_dev, chan, val);
case IIO_CHAN_INFO_CALIBBIAS:
ret = regmap_update_bits(st->regmap, ADA4250_REG_SNSR_CAL_CNFG,
ADA4250_BIAS_SET_MSK,
FIELD_PREP(ADA4250_BIAS_SET_MSK, val));
if (ret)
return ret;
st->bias = val;
return ret;
default:
return -EINVAL;
}
}
static int ada4250_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
const int **vals, int *type, int *length,
long mask)
{
switch (mask) {
case IIO_CHAN_INFO_CALIBBIAS:
*vals = calibbias_table;
*type = IIO_VAL_INT;
*length = ARRAY_SIZE(calibbias_table);
return IIO_AVAIL_LIST;
case IIO_CHAN_INFO_HARDWAREGAIN:
*vals = hwgain_table;
*type = IIO_VAL_INT;
*length = ARRAY_SIZE(hwgain_table);
return IIO_AVAIL_LIST;
default:
return -EINVAL;
}
}
static int ada4250_reg_access(struct iio_dev *indio_dev,
unsigned int reg,
unsigned int write_val,
unsigned int *read_val)
{
struct ada4250_state *st = iio_priv(indio_dev);
if (read_val)
return regmap_read(st->regmap, reg, read_val);
else
return regmap_write(st->regmap, reg, write_val);
}
static const struct iio_info ada4250_info = {
.read_raw = ada4250_read_raw,
.write_raw = ada4250_write_raw,
.read_avail = &ada4250_read_avail,
.debugfs_reg_access = &ada4250_reg_access,
};
static const struct iio_chan_spec ada4250_channels[] = {
{
.type = IIO_VOLTAGE,
.output = 1,
.indexed = 1,
.channel = 0,
.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
BIT(IIO_CHAN_INFO_OFFSET) |
BIT(IIO_CHAN_INFO_CALIBBIAS) |
BIT(IIO_CHAN_INFO_SCALE),
.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBBIAS) |
BIT(IIO_CHAN_INFO_HARDWAREGAIN),
}
};
static void ada4250_reg_disable(void *data)
{
regulator_disable(data);
}
static int ada4250_init(struct ada4250_state *st)
{
int ret;
u16 chip_id;
u8 data[2] __aligned(8) = {};
struct spi_device *spi = st->spi;
st->refbuf_en = device_property_read_bool(&spi->dev, "adi,refbuf-enable");
st->reg = devm_regulator_get(&spi->dev, "avdd");
if (IS_ERR(st->reg))
return dev_err_probe(&spi->dev, PTR_ERR(st->reg),
"failed to get the AVDD voltage\n");
ret = regulator_enable(st->reg);
if (ret) {
dev_err(&spi->dev, "Failed to enable specified AVDD supply\n");
return ret;
}
ret = devm_add_action_or_reset(&spi->dev, ada4250_reg_disable, st->reg);
if (ret)
return ret;
ret = regmap_write(st->regmap, ADA4250_REG_RESET,
FIELD_PREP(ADA4250_RESET_MSK, 1));
if (ret)
return ret;
ret = regmap_bulk_read(st->regmap, ADA4250_REG_CHIP_ID, data, 2);
if (ret)
return ret;
chip_id = get_unaligned_le16(data);
if (chip_id != ADA4250_CHIP_ID) {
dev_err(&spi->dev, "Invalid chip ID.\n");
return -EINVAL;
}
return regmap_write(st->regmap, ADA4250_REG_REFBUF_EN,
FIELD_PREP(ADA4250_REFBUF_MSK, st->refbuf_en));
}
static int ada4250_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct regmap *regmap;
struct ada4250_state *st;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
regmap = devm_regmap_init_spi(spi, &ada4250_regmap_config);
if (IS_ERR(regmap))
return PTR_ERR(regmap);
st = iio_priv(indio_dev);
st->regmap = regmap;
st->spi = spi;
indio_dev->info = &ada4250_info;
indio_dev->name = "ada4250";
indio_dev->channels = ada4250_channels;
indio_dev->num_channels = ARRAY_SIZE(ada4250_channels);
mutex_init(&st->lock);
ret = ada4250_init(st);
if (ret) {
dev_err(&spi->dev, "ADA4250 init failed\n");
return ret;
}
return devm_iio_device_register(&spi->dev, indio_dev);
}
static const struct spi_device_id ada4250_id[] = {
{ "ada4250", 0 },
{}
};
MODULE_DEVICE_TABLE(spi, ada4250_id);
static const struct of_device_id ada4250_of_match[] = {
{ .compatible = "adi,ada4250" },
{},
};
MODULE_DEVICE_TABLE(of, ada4250_of_match);
static struct spi_driver ada4250_driver = {
.driver = {
.name = "ada4250",
.of_match_table = ada4250_of_match,
},
.probe = ada4250_probe,
.id_table = ada4250_id,
};
module_spi_driver(ada4250_driver);
MODULE_AUTHOR("Antoniu Miclaus <antoniu.miclaus@analog.com");
MODULE_DESCRIPTION("Analog Devices ADA4250");
MODULE_LICENSE("GPL v2");
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