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// SPDX-License-Identifier: GPL-2.0-only
/*
* ADS1100 - Texas Instruments Analog-to-Digital Converter
*
* Copyright (c) 2023, Topic Embedded Products
*
* Datasheet: https://www.ti.com/lit/gpn/ads1100
* IIO driver for ADS1100 and ADS1000 ADC 16-bit I2C
*/
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/property.h>
#include <linux/pm_runtime.h>
#include <linux/regulator/consumer.h>
#include <linux/units.h>
#include <linux/iio/iio.h>
#include <linux/iio/types.h>
/* The ADS1100 has a single byte config register */
/* Conversion in progress bit */
#define ADS1100_CFG_ST_BSY BIT(7)
/* Single conversion bit */
#define ADS1100_CFG_SC BIT(4)
/* Data rate */
#define ADS1100_DR_MASK GENMASK(3, 2)
/* Gain */
#define ADS1100_PGA_MASK GENMASK(1, 0)
#define ADS1100_CONTINUOUS 0
#define ADS1100_SINGLESHOT ADS1100_CFG_SC
#define ADS1100_SLEEP_DELAY_MS 2000
static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
struct ads1100_data {
struct i2c_client *client;
struct regulator *reg_vdd;
struct mutex lock;
int scale_avail[2 * 4]; /* 4 gain settings */
u8 config;
bool supports_data_rate; /* Only the ADS1100 can select the rate */
};
static const struct iio_chan_spec ads1100_channel = {
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
.info_mask_shared_by_all =
BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
.info_mask_shared_by_all_available =
BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
.scan_type = {
.sign = 's',
.realbits = 16,
.storagebits = 16,
.endianness = IIO_CPU,
},
.datasheet_name = "AIN",
};
static int ads1100_set_config_bits(struct ads1100_data *data, u8 mask, u8 value)
{
int ret;
u8 config = (data->config & ~mask) | (value & mask);
if (data->config == config)
return 0; /* Already done */
ret = i2c_master_send(data->client, &config, 1);
if (ret < 0)
return ret;
data->config = config;
return 0;
};
static int ads1100_data_bits(struct ads1100_data *data)
{
return ads1100_data_rate_bits[FIELD_GET(ADS1100_DR_MASK, data->config)];
}
static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
{
int ret;
__be16 buffer;
s16 value;
if (chan != 0)
return -EINVAL;
ret = pm_runtime_resume_and_get(&data->client->dev);
if (ret < 0)
return ret;
ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
pm_runtime_mark_last_busy(&data->client->dev);
pm_runtime_put_autosuspend(&data->client->dev);
if (ret < 0) {
dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
return ret;
}
/* Value is always 16-bit 2's complement */
value = be16_to_cpu(buffer);
/* Shift result to compensate for bit resolution vs. sample rate */
value <<= 16 - ads1100_data_bits(data);
*val = sign_extend32(value, 15);
return 0;
}
static int ads1100_set_scale(struct ads1100_data *data, int val, int val2)
{
int microvolts;
int gain;
/* With Vdd between 2.7 and 5V, the scale is always below 1 */
if (val)
return -EINVAL;
if (!val2)
return -EINVAL;
microvolts = regulator_get_voltage(data->reg_vdd);
/*
* val2 is in 'micro' units, n = val2 / 1000000
* result must be millivolts, d = microvolts / 1000
* the full-scale value is d/n, corresponds to 2^15,
* hence the gain = (d / n) >> 15, factoring out the 1000 and moving the
* bitshift so everything fits in 32-bits yields this formula.
*/
gain = DIV_ROUND_CLOSEST(microvolts, BIT(15)) * MILLI / val2;
if (gain < BIT(0) || gain > BIT(3))
return -EINVAL;
ads1100_set_config_bits(data, ADS1100_PGA_MASK, ffs(gain) - 1);
return 0;
}
static int ads1100_set_data_rate(struct ads1100_data *data, int chan, int rate)
{
unsigned int i;
unsigned int size;
size = data->supports_data_rate ? ARRAY_SIZE(ads1100_data_rate) : 1;
for (i = 0; i < size; i++) {
if (ads1100_data_rate[i] == rate)
return ads1100_set_config_bits(data, ADS1100_DR_MASK,
FIELD_PREP(ADS1100_DR_MASK, i));
}
return -EINVAL;
}
static int ads1100_get_vdd_millivolts(struct ads1100_data *data)
{
return regulator_get_voltage(data->reg_vdd) / (MICRO / MILLI);
}
static void ads1100_calc_scale_avail(struct ads1100_data *data)
{
int millivolts = ads1100_get_vdd_millivolts(data);
unsigned int i;
for (i = 0; i < ARRAY_SIZE(data->scale_avail) / 2; i++) {
data->scale_avail[i * 2 + 0] = millivolts;
data->scale_avail[i * 2 + 1] = 15 + i;
}
}
static int ads1100_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
const int **vals, int *type, int *length,
long mask)
{
struct ads1100_data *data = iio_priv(indio_dev);
if (chan->type != IIO_VOLTAGE)
return -EINVAL;
switch (mask) {
case IIO_CHAN_INFO_SAMP_FREQ:
*type = IIO_VAL_INT;
*vals = ads1100_data_rate;
if (data->supports_data_rate)
*length = ARRAY_SIZE(ads1100_data_rate);
else
*length = 1;
return IIO_AVAIL_LIST;
case IIO_CHAN_INFO_SCALE:
*type = IIO_VAL_FRACTIONAL_LOG2;
*vals = data->scale_avail;
*length = ARRAY_SIZE(data->scale_avail);
return IIO_AVAIL_LIST;
default:
return -EINVAL;
}
}
static int ads1100_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int *val,
int *val2, long mask)
{
int ret;
struct ads1100_data *data = iio_priv(indio_dev);
mutex_lock(&data->lock);
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
break;
ret = ads1100_get_adc_result(data, chan->address, val);
if (ret >= 0)
ret = IIO_VAL_INT;
iio_device_release_direct_mode(indio_dev);
break;
case IIO_CHAN_INFO_SCALE:
/* full-scale is the supply voltage in millivolts */
*val = ads1100_get_vdd_millivolts(data);
*val2 = 15 + FIELD_GET(ADS1100_PGA_MASK, data->config);
ret = IIO_VAL_FRACTIONAL_LOG2;
break;
case IIO_CHAN_INFO_SAMP_FREQ:
*val = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK,
data->config)];
ret = IIO_VAL_INT;
break;
default:
ret = -EINVAL;
break;
}
mutex_unlock(&data->lock);
return ret;
}
static int ads1100_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan, int val,
int val2, long mask)
{
struct ads1100_data *data = iio_priv(indio_dev);
int ret;
mutex_lock(&data->lock);
switch (mask) {
case IIO_CHAN_INFO_SCALE:
ret = ads1100_set_scale(data, val, val2);
break;
case IIO_CHAN_INFO_SAMP_FREQ:
ret = ads1100_set_data_rate(data, chan->address, val);
break;
default:
ret = -EINVAL;
break;
}
mutex_unlock(&data->lock);
return ret;
}
static const struct iio_info ads1100_info = {
.read_avail = ads1100_read_avail,
.read_raw = ads1100_read_raw,
.write_raw = ads1100_write_raw,
};
static int ads1100_setup(struct ads1100_data *data)
{
int ret;
u8 buffer[3];
/* Setup continuous sampling mode at 8sps */
buffer[0] = ADS1100_DR_MASK | ADS1100_CONTINUOUS;
ret = i2c_master_send(data->client, buffer, 1);
if (ret < 0)
return ret;
ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
if (ret < 0)
return ret;
/* Config register returned in third byte, strip away the busy status */
data->config = buffer[2] & ~ADS1100_CFG_ST_BSY;
/* Detect the sample rate capability by checking the DR bits */
data->supports_data_rate = FIELD_GET(ADS1100_DR_MASK, buffer[2]) != 0;
return 0;
}
static void ads1100_reg_disable(void *reg)
{
regulator_disable(reg);
}
static void ads1100_disable_continuous(void *data)
{
ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
}
static int ads1100_probe(struct i2c_client *client)
{
struct iio_dev *indio_dev;
struct ads1100_data *data;
struct device *dev = &client->dev;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
dev_set_drvdata(dev, data);
data->client = client;
mutex_init(&data->lock);
indio_dev->name = "ads1100";
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->channels = &ads1100_channel;
indio_dev->num_channels = 1;
indio_dev->info = &ads1100_info;
data->reg_vdd = devm_regulator_get(dev, "vdd");
if (IS_ERR(data->reg_vdd))
return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
"Failed to get vdd regulator\n");
ret = regulator_enable(data->reg_vdd);
if (ret < 0)
return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
"Failed to enable vdd regulator\n");
ret = devm_add_action_or_reset(dev, ads1100_reg_disable, data->reg_vdd);
if (ret)
return ret;
ret = ads1100_setup(data);
if (ret)
return dev_err_probe(dev, ret,
"Failed to communicate with device\n");
ret = devm_add_action_or_reset(dev, ads1100_disable_continuous, data);
if (ret)
return ret;
ads1100_calc_scale_avail(data);
pm_runtime_set_autosuspend_delay(dev, ADS1100_SLEEP_DELAY_MS);
pm_runtime_use_autosuspend(dev);
pm_runtime_set_active(dev);
ret = devm_pm_runtime_enable(dev);
if (ret)
return dev_err_probe(dev, ret, "Failed to enable pm_runtime\n");
ret = devm_iio_device_register(dev, indio_dev);
if (ret)
return dev_err_probe(dev, ret,
"Failed to register IIO device\n");
return 0;
}
static int ads1100_runtime_suspend(struct device *dev)
{
struct ads1100_data *data = dev_get_drvdata(dev);
ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
regulator_disable(data->reg_vdd);
return 0;
}
static int ads1100_runtime_resume(struct device *dev)
{
struct ads1100_data *data = dev_get_drvdata(dev);
int ret;
ret = regulator_enable(data->reg_vdd);
if (ret) {
dev_err(&data->client->dev, "Failed to enable Vdd\n");
return ret;
}
/*
* We'll always change the mode bit in the config register, so there is
* no need here to "force" a write to the config register. If the device
* has been power-cycled, we'll re-write its config register now.
*/
return ads1100_set_config_bits(data, ADS1100_CFG_SC,
ADS1100_CONTINUOUS);
}
static DEFINE_RUNTIME_DEV_PM_OPS(ads1100_pm_ops,
ads1100_runtime_suspend,
ads1100_runtime_resume,
NULL);
static const struct i2c_device_id ads1100_id[] = {
{ "ads1100" },
{ "ads1000" },
{ }
};
MODULE_DEVICE_TABLE(i2c, ads1100_id);
static const struct of_device_id ads1100_of_match[] = {
{.compatible = "ti,ads1100" },
{.compatible = "ti,ads1000" },
{ }
};
MODULE_DEVICE_TABLE(of, ads1100_of_match);
static struct i2c_driver ads1100_driver = {
.driver = {
.name = "ads1100",
.of_match_table = ads1100_of_match,
.pm = pm_ptr(&ads1100_pm_ops),
},
.probe_new = ads1100_probe,
.id_table = ads1100_id,
};
module_i2c_driver(ads1100_driver);
MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
MODULE_DESCRIPTION("Texas Instruments ADS1100 ADC driver");
MODULE_LICENSE("GPL");
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