1 // SPDX-License-Identifier: GPL-2.0-only
4 * Copyright (c) Rajat Khandelwal <rajat.khandelwal@linux.intel.com>
6 * Maxim MAX30208 digital temperature sensor with 0.1°C accuracy
7 * (7-bit I2C slave address (0x50 - 0x53))
10 #include <linux/bitops.h>
11 #include <linux/delay.h>
12 #include <linux/iio/iio.h>
13 #include <linux/i2c.h>
14 #include <linux/module.h>
15 #include <linux/types.h>
17 #define MAX30208_STATUS 0x00
18 #define MAX30208_STATUS_TEMP_RDY BIT(0)
19 #define MAX30208_INT_ENABLE 0x01
20 #define MAX30208_INT_ENABLE_TEMP_RDY BIT(0)
22 #define MAX30208_FIFO_OVF_CNTR 0x06
23 #define MAX30208_FIFO_DATA_CNTR 0x07
24 #define MAX30208_FIFO_DATA 0x08
26 #define MAX30208_FIFO_CONFIG 0x0a
27 #define MAX30208_FIFO_CONFIG_RO BIT(1)
29 #define MAX30208_SYSTEM_CTRL 0x0c
30 #define MAX30208_SYSTEM_CTRL_RESET 0x01
32 #define MAX30208_TEMP_SENSOR_SETUP 0x14
33 #define MAX30208_TEMP_SENSOR_SETUP_CONV BIT(0)
35 struct max30208_data {
36 struct i2c_client *client;
37 struct iio_dev *indio_dev;
38 struct mutex lock; /* Lock to prevent concurrent reads of temperature readings */
41 static const struct iio_chan_spec max30208_channels[] = {
44 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
49 * max30208_request() - Request a reading
50 * @data: Struct comprising member elements of the device
52 * Requests a reading from the device and waits until the conversion is ready.
54 static int max30208_request(struct max30208_data *data)
57 * Sensor can take up to 500 ms to respond so execute a total of
58 * 10 retries to give the device sufficient time.
64 ret = i2c_smbus_read_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP);
68 regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV;
70 ret = i2c_smbus_write_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP, regval);
75 ret = i2c_smbus_read_byte_data(data->client, MAX30208_STATUS);
79 if (ret & MAX30208_STATUS_TEMP_RDY)
84 dev_err(&data->client->dev, "Temperature conversion failed\n");
89 static int max30208_update_temp(struct max30208_data *data)
94 mutex_lock(&data->lock);
96 ret = max30208_request(data);
100 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_OVF_CNTR);
104 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_DATA_CNTR);
113 ret = i2c_smbus_read_word_swapped(data->client, MAX30208_FIFO_DATA);
121 mutex_unlock(&data->lock);
126 * max30208_config_setup() - Set up FIFO configuration register
127 * @data: Struct comprising member elements of the device
129 * Sets the rollover bit to '1' to enable overwriting FIFO during overflow.
131 static int max30208_config_setup(struct max30208_data *data)
136 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_CONFIG);
140 regval = ret | MAX30208_FIFO_CONFIG_RO;
142 ret = i2c_smbus_write_byte_data(data->client, MAX30208_FIFO_CONFIG, regval);
149 static int max30208_read(struct iio_dev *indio_dev,
150 struct iio_chan_spec const *chan,
151 int *val, int *val2, long mask)
153 struct max30208_data *data = iio_priv(indio_dev);
157 case IIO_CHAN_INFO_RAW:
158 ret = max30208_update_temp(data);
162 *val = sign_extend32(ret, 15);
165 case IIO_CHAN_INFO_SCALE:
174 static const struct iio_info max30208_info = {
175 .read_raw = max30208_read,
178 static int max30208_probe(struct i2c_client *i2c)
180 struct device *dev = &i2c->dev;
181 struct max30208_data *data;
182 struct iio_dev *indio_dev;
185 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
189 data = iio_priv(indio_dev);
191 mutex_init(&data->lock);
193 indio_dev->name = "max30208";
194 indio_dev->channels = max30208_channels;
195 indio_dev->num_channels = ARRAY_SIZE(max30208_channels);
196 indio_dev->info = &max30208_info;
197 indio_dev->modes = INDIO_DIRECT_MODE;
199 ret = i2c_smbus_write_byte_data(data->client, MAX30208_SYSTEM_CTRL,
200 MAX30208_SYSTEM_CTRL_RESET);
202 dev_err(dev, "Failure in performing reset\n");
208 ret = max30208_config_setup(data);
212 ret = devm_iio_device_register(dev, indio_dev);
214 dev_err(dev, "Failed to register IIO device\n");
221 static const struct i2c_device_id max30208_id_table[] = {
225 MODULE_DEVICE_TABLE(i2c, max30208_id_table);
227 static const struct acpi_device_id max30208_acpi_match[] = {
231 MODULE_DEVICE_TABLE(acpi, max30208_acpi_match);
233 static const struct of_device_id max30208_of_match[] = {
234 { .compatible = "maxim,max30208" },
237 MODULE_DEVICE_TABLE(of, max30208_of_match);
239 static struct i2c_driver max30208_driver = {
242 .of_match_table = max30208_of_match,
243 .acpi_match_table = max30208_acpi_match,
245 .probe = max30208_probe,
246 .id_table = max30208_id_table,
248 module_i2c_driver(max30208_driver);
250 MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@linux.intel.com>");
251 MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor");
252 MODULE_LICENSE("GPL");