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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) Rajat Khandelwal <rajat.khandelwal@linux.intel.com>
*
* Maxim MAX30208 digital temperature sensor with 0.1°C accuracy
* (7-bit I2C slave address (0x50 - 0x53))
*/
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/iio/iio.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/types.h>
#define MAX30208_STATUS 0x00
#define MAX30208_STATUS_TEMP_RDY BIT(0)
#define MAX30208_INT_ENABLE 0x01
#define MAX30208_INT_ENABLE_TEMP_RDY BIT(0)
#define MAX30208_FIFO_OVF_CNTR 0x06
#define MAX30208_FIFO_DATA_CNTR 0x07
#define MAX30208_FIFO_DATA 0x08
#define MAX30208_FIFO_CONFIG 0x0a
#define MAX30208_FIFO_CONFIG_RO BIT(1)
#define MAX30208_SYSTEM_CTRL 0x0c
#define MAX30208_SYSTEM_CTRL_RESET 0x01
#define MAX30208_TEMP_SENSOR_SETUP 0x14
#define MAX30208_TEMP_SENSOR_SETUP_CONV BIT(0)
struct max30208_data {
struct i2c_client *client;
struct iio_dev *indio_dev;
struct mutex lock; /* Lock to prevent concurrent reads of temperature readings */
};
static const struct iio_chan_spec max30208_channels[] = {
{
.type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
},
};
/**
* max30208_request() - Request a reading
* @data: Struct comprising member elements of the device
*
* Requests a reading from the device and waits until the conversion is ready.
*/
static int max30208_request(struct max30208_data *data)
{
/*
* Sensor can take up to 500 ms to respond so execute a total of
* 10 retries to give the device sufficient time.
*/
int retries = 10;
u8 regval;
int ret;
ret = i2c_smbus_read_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP);
if (ret < 0)
return ret;
regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV;
ret = i2c_smbus_write_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP, regval);
if (ret)
return ret;
while (retries--) {
ret = i2c_smbus_read_byte_data(data->client, MAX30208_STATUS);
if (ret < 0)
return ret;
if (ret & MAX30208_STATUS_TEMP_RDY)
return 0;
msleep(50);
}
dev_err(&data->client->dev, "Temperature conversion failed\n");
return -ETIMEDOUT;
}
static int max30208_update_temp(struct max30208_data *data)
{
u8 data_count;
int ret;
mutex_lock(&data->lock);
ret = max30208_request(data);
if (ret)
goto unlock;
ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_OVF_CNTR);
if (ret < 0)
goto unlock;
else if (!ret) {
ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_DATA_CNTR);
if (ret < 0)
goto unlock;
data_count = ret;
} else
data_count = 1;
while (data_count) {
ret = i2c_smbus_read_word_swapped(data->client, MAX30208_FIFO_DATA);
if (ret < 0)
goto unlock;
data_count--;
}
unlock:
mutex_unlock(&data->lock);
return ret;
}
/**
* max30208_config_setup() - Set up FIFO configuration register
* @data: Struct comprising member elements of the device
*
* Sets the rollover bit to '1' to enable overwriting FIFO during overflow.
*/
static int max30208_config_setup(struct max30208_data *data)
{
u8 regval;
int ret;
ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_CONFIG);
if (ret < 0)
return ret;
regval = ret | MAX30208_FIFO_CONFIG_RO;
ret = i2c_smbus_write_byte_data(data->client, MAX30208_FIFO_CONFIG, regval);
if (ret)
return ret;
return 0;
}
static int max30208_read(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct max30208_data *data = iio_priv(indio_dev);
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = max30208_update_temp(data);
if (ret < 0)
return ret;
*val = sign_extend32(ret, 15);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = 5;
return IIO_VAL_INT;
default:
return -EINVAL;
}
}
static const struct iio_info max30208_info = {
.read_raw = max30208_read,
};
static int max30208_probe(struct i2c_client *i2c)
{
struct device *dev = &i2c->dev;
struct max30208_data *data;
struct iio_dev *indio_dev;
int ret;
indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
if (!indio_dev)
return -ENOMEM;
data = iio_priv(indio_dev);
data->client = i2c;
mutex_init(&data->lock);
indio_dev->name = "max30208";
indio_dev->channels = max30208_channels;
indio_dev->num_channels = ARRAY_SIZE(max30208_channels);
indio_dev->info = &max30208_info;
indio_dev->modes = INDIO_DIRECT_MODE;
ret = i2c_smbus_write_byte_data(data->client, MAX30208_SYSTEM_CTRL,
MAX30208_SYSTEM_CTRL_RESET);
if (ret) {
dev_err(dev, "Failure in performing reset\n");
return ret;
}
msleep(50);
ret = max30208_config_setup(data);
if (ret)
return ret;
ret = devm_iio_device_register(dev, indio_dev);
if (ret) {
dev_err(dev, "Failed to register IIO device\n");
return ret;
}
return 0;
}
static const struct i2c_device_id max30208_id_table[] = {
{ "max30208" },
{ }
};
MODULE_DEVICE_TABLE(i2c, max30208_id_table);
static const struct acpi_device_id max30208_acpi_match[] = {
{ "MAX30208" },
{ }
};
MODULE_DEVICE_TABLE(acpi, max30208_acpi_match);
static const struct of_device_id max30208_of_match[] = {
{ .compatible = "maxim,max30208" },
{ }
};
MODULE_DEVICE_TABLE(of, max30208_of_match);
static struct i2c_driver max30208_driver = {
.driver = {
.name = "max30208",
.of_match_table = max30208_of_match,
.acpi_match_table = max30208_acpi_match,
},
.probe_new = max30208_probe,
.id_table = max30208_id_table,
};
module_i2c_driver(max30208_driver);
MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@linux.intel.com>");
MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor");
MODULE_LICENSE("GPL");