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// SPDX-License-Identifier: GPL-2.0
/*
* Driver for the DFRobot SEN0322 oxygen sensor.
*
* Datasheet:
* https://wiki.dfrobot.com/Gravity_I2C_Oxygen_Sensor_SKU_SEN0322
*
* Possible I2C slave addresses:
* 0x70
* 0x71
* 0x72
* 0x73
*
* Copyright (C) 2025 Tóth János <gomba007@gmail.com>
*/
#include <linux/i2c.h>
#include <linux/regmap.h>
#include <linux/iio/iio.h>
#define SEN0322_REG_DATA 0x03
#define SEN0322_REG_COEFF 0x0A
struct sen0322 {
struct regmap *regmap;
};
static int sen0322_read_data(struct sen0322 *sen0322)
{
u8 data[3] = { };
int ret;
ret = regmap_bulk_read(sen0322->regmap, SEN0322_REG_DATA, data,
sizeof(data));
if (ret < 0)
return ret;
/*
* The actual value in the registers is:
* val = data[0] + data[1] / 10 + data[2] / 100
* but it is multiplied by 100 here to avoid floating-point math
* and the scale is divided by 100 to compensate this.
*/
return data[0] * 100 + data[1] * 10 + data[2];
}
static int sen0322_read_scale(struct sen0322 *sen0322, int *num, int *den)
{
u32 val;
int ret;
ret = regmap_read(sen0322->regmap, SEN0322_REG_COEFF, &val);
if (ret < 0)
return ret;
if (val) {
*num = val;
*den = 100000; /* Coeff is scaled by 1000 at calibration. */
} else { /* The device is not calibrated, using the factory-defaults. */
*num = 209; /* Oxygen content in the atmosphere is 20.9%. */
*den = 120000; /* Output of the sensor at 20.9% is 120 uA. */
}
dev_dbg(regmap_get_device(sen0322->regmap), "scale: %d/%d\n",
*num, *den);
return 0;
}
static int sen0322_read_raw(struct iio_dev *iio_dev,
const struct iio_chan_spec *chan,
int *val, int *val2, long mask)
{
struct sen0322 *sen0322 = iio_priv(iio_dev);
int ret;
if (chan->type != IIO_CONCENTRATION)
return -EINVAL;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = sen0322_read_data(sen0322);
if (ret < 0)
return ret;
*val = ret;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
ret = sen0322_read_scale(sen0322, val, val2);
if (ret < 0)
return ret;
return IIO_VAL_FRACTIONAL;
default:
return -EINVAL;
}
}
static const struct iio_info sen0322_info = {
.read_raw = sen0322_read_raw,
};
static const struct regmap_config sen0322_regmap_conf = {
.reg_bits = 8,
.val_bits = 8,
};
static const struct iio_chan_spec sen0322_channel = {
.type = IIO_CONCENTRATION,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
};
static int sen0322_probe(struct i2c_client *client)
{
struct sen0322 *sen0322;
struct iio_dev *iio_dev;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
return -ENODEV;
iio_dev = devm_iio_device_alloc(&client->dev, sizeof(*sen0322));
if (!iio_dev)
return -ENOMEM;
sen0322 = iio_priv(iio_dev);
sen0322->regmap = devm_regmap_init_i2c(client, &sen0322_regmap_conf);
if (IS_ERR(sen0322->regmap))
return PTR_ERR(sen0322->regmap);
iio_dev->info = &sen0322_info;
iio_dev->name = "sen0322";
iio_dev->channels = &sen0322_channel;
iio_dev->num_channels = 1;
iio_dev->modes = INDIO_DIRECT_MODE;
return devm_iio_device_register(&client->dev, iio_dev);
}
static const struct of_device_id sen0322_of_match[] = {
{ .compatible = "dfrobot,sen0322" },
{ }
};
MODULE_DEVICE_TABLE(of, sen0322_of_match);
static struct i2c_driver sen0322_driver = {
.driver = {
.name = "sen0322",
.of_match_table = sen0322_of_match,
},
.probe = sen0322_probe,
};
module_i2c_driver(sen0322_driver);
MODULE_AUTHOR("Tóth János <gomba007@gmail.com>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SEN0322 oxygen sensor driver");
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