// SPDX-License-Identifier: GPL-2.0
/*
* HMC425A and similar Gain Amplifiers
*
* Copyright 2020, 2024 Analog Devices Inc.
*/
#include <linux/bits.h>
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/kernel.h>
#include <linux/math.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/regulator/consumer.h>
#include <linux/sysfs.h>
/*
* The LTC6373 amplifier supports configuring gain using GPIO's with the following
* values (OUTPUT_V / INPUT_V): 0(shutdown), 0.25, 0.5, 1, 2, 4, 8, 16
*
* Except for the shutdown value, all can be converted to dB using 20 * log10(x)
* From here, it is observed that all values are multiples of the '2' gain setting,
* with the correspondent of 6.020dB.
*/
#define LTC6373_CONVERSION_CONSTANT 6020
#define LTC6373_MIN_GAIN_CODE 0x6
#define LTC6373_CONVERSION_MASK GENMASK(2, 0)
#define LTC6373_SHUTDOWN GENMASK(2, 0)
enum hmc425a_type {
ID_HMC425A,
ID_HMC540S,
ID_ADRF5740,
ID_LTC6373,
};
struct hmc425a_chip_info {
const char *name;
const struct iio_chan_spec *channels;
unsigned int num_channels;
unsigned int num_gpios;
int gain_min;
int gain_max;
int default_gain;
int powerdown_val;
bool has_powerdown;
int (*gain_dB_to_code)(int gain, int *code);
int (*code_to_gain_dB)(int code, int *val, int *val2);
};
struct hmc425a_state {
struct mutex lock; /* protect sensor state */
const struct hmc425a_chip_info *chip_info;
struct gpio_descs *gpios;
u32 gain;
bool powerdown;
};
static int gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code)
{
const struct hmc425a_chip_info *inf = st->chip_info;
int gain;
if (val < 0)
gain = (val * 1000) - (val2 / 1000);
else
gain = (val * 1000) + (val2 / 1000);
if (gain > inf->gain_max || gain < inf->gain_min)
return -EINVAL;
if (st->powerdown)
return -EPERM;
return st->chip_info->gain_dB_to_code(gain, code);
}
static int hmc425a_gain_dB_to_code(int gain, int *code)
{
*code = ~((abs(gain) / 500) & 0x3F);
return 0;
}
static int hmc540s_gain_dB_to_code(int gain, int *code)
{
*code = ~((abs(gain) / 1000) & 0xF);
return 0;
}
static int adrf5740_gain_dB_to_code(int gain, int *code)
{
int temp = (abs(gain) / 2000) & 0xF;
/* Bit [0-3]: 2dB 4dB 8dB 8dB */
*code = temp & BIT(3) ? temp | BIT(2) : temp;
return 0;
}
static int ltc6373_gain_dB_to_code(int gain, int *code)
{
*code = ~(DIV_ROUND_CLOSEST(gain, LTC6373_CONVERSION_CONSTANT) + 3)
& LTC6373_CONVERSION_MASK;
return 0;
}
static int code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2)
{
if (st->powerdown)
return -EPERM;
return st->chip_info->code_to_gain_dB(st->gain, val, val2);
}
static int hmc425a_code_to_gain_dB(int code, int *val, int *val2)
{
*val = (~code * -500) / 1000;
*val2 = ((~code * -500) % 1000) * 1000;
return 0;
}
static int hmc540s_code_to_gain_dB(int code, int *val, int *val2)
{
*val = (~code * -1000) / 1000;
*val2 = ((~code * -1000) % 1000) * 1000;
return 0;
}
static int adrf5740_code_to_gain_dB(int code, int *val, int *val2)
{
/*
* Bit [0-3]: 2dB 4dB 8dB 8dB
* When BIT(3) is set, unset BIT(2) and use 3 as double the place value
*/
code = code & BIT(3) ? code & ~BIT(2) : code;
*val = (code * -2000) / 1000;
*val2 = ((code * -2000) % 1000) * 1000;
return 0;
}
static int ltc6373_code_to_gain_dB(int code, int *val, int *val2)
{
int gain = ((~code & LTC6373_CONVERSION_MASK) - 3) *
LTC6373_CONVERSION_CONSTANT;
*val = gain / 1000;
*val2 = (gain % 1000) * 1000;
return 0;
}
static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
{
struct hmc425a_state *st = iio_priv(indio_dev);
DECLARE_BITMAP(values, BITS_PER_TYPE(value));
values[0] = value;
gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
NULL, values);
return 0;
}
static int hmc425a_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long m)
{
struct hmc425a_state *st = iio_priv(indio_dev);
int ret;
mutex_lock(&st->lock);
switch (m) {
case IIO_CHAN_INFO_HARDWAREGAIN:
ret = code_to_gain_dB(st, val, val2);
if (ret)
break;
ret = IIO_VAL_INT_PLUS_MICRO_DB;
break;
default:
ret = -EINVAL;
}
mutex_unlock(&st->lock);
return ret;
};
static int hmc425a_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int val,
int val2, long mask)
{
struct hmc425a_state *st = iio_priv(indio_dev);
int code = 0, ret;
mutex_lock(&st->lock);
switch (mask) {
case IIO_CHAN_INFO_HARDWAREGAIN:
ret = gain_dB_to_code(st, val, val2, &code);
if (ret)
break;
st->gain = code;
ret = hmc425a_write(indio_dev, st->gain);
break;
default:
ret = -EINVAL;
}
mutex_unlock(&st->lock);
return ret;
}
static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
long mask)
{
switch (mask) {
case IIO_CHAN_INFO_HARDWAREGAIN:
return IIO_VAL_INT_PLUS_MICRO_DB;
default:
return -EINVAL;
}
}
static const struct iio_info hmc425a_info = {
.read_raw = &hmc425a_read_raw,
.write_raw = &hmc425a_write_raw,
.write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
};
static ssize_t ltc6373_read_powerdown(struct iio_dev *indio_dev,
uintptr_t private,
const struct iio_chan_spec *chan,
char *buf)
{
struct hmc425a_state *st = iio_priv(indio_dev);
return sysfs_emit(buf, "%d\n", st->powerdown);
}
static ssize_t ltc6373_write_powerdown(struct iio_dev *indio_dev,
uintptr_t private,
const struct iio_chan_spec *chan,
const char *buf,
size_t len)
{
struct hmc425a_state *st = iio_priv(indio_dev);
bool powerdown;
int code, ret;
ret = kstrtobool(buf, &powerdown);
if (ret)
return ret;
mutex_lock(&st->lock);
st->powerdown = powerdown;
code = (powerdown) ? LTC6373_SHUTDOWN : st->gain;
hmc425a_write(indio_dev, code);
mutex_unlock(&st->lock);
return len;
}
static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = {
{
.name = "powerdown",
.read = ltc6373_read_powerdown,
.write = ltc6373_write_powerdown,
.shared = IIO_SEPARATE,
},
{}
};
#define HMC425A_CHAN(_channel) \
{ \
.type = IIO_VOLTAGE, \
.output = 1, \
.indexed = 1, \
.channel = _channel, \
.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
}
#define LTC6373_CHAN(_channel) \
{ \
.type = IIO_VOLTAGE, \
.output = 1, \
.indexed = 1, \
.channel = _channel, \
.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
.ext_info = ltc6373_ext_info, \
}
static const struct iio_chan_spec hmc425a_channels[] = {
HMC425A_CHAN(0),
};
static const struct iio_chan_spec ltc6373_channels[] = {
LTC6373_CHAN(0),
};
static const struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
[ID_HMC425A] = {
.name = "hmc425a",
.channels = hmc425a_channels,
.num_channels = ARRAY_SIZE(hmc425a_channels),
.num_gpios = 6,
.gain_min = -31500,
.gain_max = 0,
.default_gain = -0x40, /* set default gain -31.5db*/
.gain_dB_to_code = hmc425a_gain_dB_to_code,
.code_to_gain_dB = hmc425a_code_to_gain_dB,
},
[ID_HMC540S] = {
.name = "hmc540s",
.channels = hmc425a_channels,
.num_channels = ARRAY_SIZE(hmc425a_channels),
.num_gpios = 4,
.gain_min = -15000,
.gain_max = 0,
.default_gain = -0x10, /* set default gain -15.0db*/
.gain_dB_to_code = hmc540s_gain_dB_to_code,
.code_to_gain_dB = hmc540s_code_to_gain_dB,
},
[ID_ADRF5740] = {
.name = "adrf5740",
.channels = hmc425a_channels,
.num_channels = ARRAY_SIZE(hmc425a_channels),
.num_gpios = 4,
.gain_min = -22000,
.gain_max = 0,
.default_gain = 0xF, /* set default gain -22.0db*/
.gain_dB_to_code = adrf5740_gain_dB_to_code,
.code_to_gain_dB = adrf5740_code_to_gain_dB,
},
[ID_LTC6373] = {
.name = "ltc6373",
.channels = ltc6373_channels,
.num_channels = ARRAY_SIZE(ltc6373_channels),
.num_gpios = 3,
.gain_min = -12041, /* gain setting x0.25*/
.gain_max = 24082, /* gain setting x16 */
.default_gain = LTC6373_MIN_GAIN_CODE,
.powerdown_val = LTC6373_SHUTDOWN,
.has_powerdown = true,
.gain_dB_to_code = ltc6373_gain_dB_to_code,
.code_to_gain_dB = ltc6373_code_to_gain_dB,
},
};
static int hmc425a_probe(struct platform_device *pdev)
{
struct iio_dev *indio_dev;
struct hmc425a_state *st;
int ret;
indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
st->chip_info = device_get_match_data(&pdev->dev);
indio_dev->num_channels = st->chip_info->num_channels;
indio_dev->channels = st->chip_info->channels;
indio_dev->name = st->chip_info->name;
st->gain = st->chip_info->default_gain;
st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW);
if (IS_ERR(st->gpios))
return dev_err_probe(&pdev->dev, PTR_ERR(st->gpios),
"failed to get gpios\n");
if (st->gpios->ndescs != st->chip_info->num_gpios) {
dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
st->chip_info->num_gpios);
return -ENODEV;
}
ret = devm_regulator_get_enable(&pdev->dev, "vcc-supply");
if (ret)
return ret;
mutex_init(&st->lock);
indio_dev->info = &hmc425a_info;
indio_dev->modes = INDIO_DIRECT_MODE;
if (st->chip_info->has_powerdown) {
st->powerdown = true;
hmc425a_write(indio_dev, st->chip_info->powerdown_val);
} else {
/* Set default gain */
hmc425a_write(indio_dev, st->gain);
}
return devm_iio_device_register(&pdev->dev, indio_dev);
}
/* Match table for of_platform binding */
static const struct of_device_id hmc425a_of_match[] = {
{ .compatible = "adi,hmc425a",
.data = &hmc425a_chip_info_tbl[ID_HMC425A]},
{ .compatible = "adi,hmc540s",
.data = &hmc425a_chip_info_tbl[ID_HMC540S]},
{ .compatible = "adi,adrf5740",
.data = &hmc425a_chip_info_tbl[ID_ADRF5740]},
{ .compatible = "adi,ltc6373",
.data = &hmc425a_chip_info_tbl[ID_LTC6373]},
{}
};
MODULE_DEVICE_TABLE(of, hmc425a_of_match);
static struct platform_driver hmc425a_driver = {
.driver = {
.name = KBUILD_MODNAME,
.of_match_table = hmc425a_of_match,
},
.probe = hmc425a_probe,
};
module_platform_driver(hmc425a_driver);
MODULE_AUTHOR("Michael Hennerich <[email protected]>");
MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
MODULE_LICENSE("GPL v2");
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