diff options
Diffstat (limited to 'drivers/iio/temperature/max30208.c')
| -rw-r--r-- | drivers/iio/temperature/max30208.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/drivers/iio/temperature/max30208.c b/drivers/iio/temperature/max30208.c new file mode 100644 index 000000000000..c85c21474711 --- /dev/null +++ b/drivers/iio/temperature/max30208.c @@ -0,0 +1,252 @@ +// 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"); |