1// SPDX-License-Identifier: GPL-2.0-only
2
3/*
4 * Copyright (c) Rajat Khandelwal <rajat.khandelwal@linux.intel.com>
5 *
6 * Maxim MAX30208 digital temperature sensor with 0.1°C accuracy
7 * (7-bit I2C slave address (0x50 - 0x53))
8 */
9
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>
16
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)
21
22#define MAX30208_FIFO_OVF_CNTR 0x06
23#define MAX30208_FIFO_DATA_CNTR 0x07
24#define MAX30208_FIFO_DATA 0x08
25
26#define MAX30208_FIFO_CONFIG 0x0a
27#define MAX30208_FIFO_CONFIG_RO BIT(1)
28
29#define MAX30208_SYSTEM_CTRL 0x0c
30#define MAX30208_SYSTEM_CTRL_RESET 0x01
31
32#define MAX30208_TEMP_SENSOR_SETUP 0x14
33#define MAX30208_TEMP_SENSOR_SETUP_CONV BIT(0)
34
35struct max30208_data {
36 struct i2c_client *client;
37 struct mutex lock; /* Lock to prevent concurrent reads of temperature readings */
38};
39
40static const struct iio_chan_spec max30208_channels[] = {
41 {
42 .type = IIO_TEMP,
43 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
44 },
45};
46
47/**
48 * max30208_request() - Request a reading
49 * @data: Struct comprising member elements of the device
50 *
51 * Requests a reading from the device and waits until the conversion is ready.
52 */
53static int max30208_request(struct max30208_data *data)
54{
55 /*
56 * Sensor can take up to 500 ms to respond so execute a total of
57 * 10 retries to give the device sufficient time.
58 */
59 int retries = 10;
60 u8 regval;
61 int ret;
62
63 ret = i2c_smbus_read_byte_data(client: data->client, MAX30208_TEMP_SENSOR_SETUP);
64 if (ret < 0)
65 return ret;
66
67 regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV;
68
69 ret = i2c_smbus_write_byte_data(client: data->client, MAX30208_TEMP_SENSOR_SETUP, value: regval);
70 if (ret)
71 return ret;
72
73 while (retries--) {
74 ret = i2c_smbus_read_byte_data(client: data->client, MAX30208_STATUS);
75 if (ret < 0)
76 return ret;
77
78 if (ret & MAX30208_STATUS_TEMP_RDY)
79 return 0;
80
81 msleep(msecs: 50);
82 }
83 dev_err(&data->client->dev, "Temperature conversion failed\n");
84
85 return -ETIMEDOUT;
86}
87
88static int max30208_update_temp(struct max30208_data *data)
89{
90 u8 data_count;
91 int ret;
92
93 mutex_lock(&data->lock);
94
95 ret = max30208_request(data);
96 if (ret)
97 goto unlock;
98
99 ret = i2c_smbus_read_byte_data(client: data->client, MAX30208_FIFO_OVF_CNTR);
100 if (ret < 0)
101 goto unlock;
102 else if (!ret) {
103 ret = i2c_smbus_read_byte_data(client: data->client, MAX30208_FIFO_DATA_CNTR);
104 if (ret < 0)
105 goto unlock;
106
107 data_count = ret;
108 } else
109 data_count = 1;
110
111 while (data_count) {
112 ret = i2c_smbus_read_word_swapped(client: data->client, MAX30208_FIFO_DATA);
113 if (ret < 0)
114 goto unlock;
115
116 data_count--;
117 }
118
119unlock:
120 mutex_unlock(lock: &data->lock);
121 return ret;
122}
123
124/**
125 * max30208_config_setup() - Set up FIFO configuration register
126 * @data: Struct comprising member elements of the device
127 *
128 * Sets the rollover bit to '1' to enable overwriting FIFO during overflow.
129 */
130static int max30208_config_setup(struct max30208_data *data)
131{
132 u8 regval;
133 int ret;
134
135 ret = i2c_smbus_read_byte_data(client: data->client, MAX30208_FIFO_CONFIG);
136 if (ret < 0)
137 return ret;
138
139 regval = ret | MAX30208_FIFO_CONFIG_RO;
140
141 ret = i2c_smbus_write_byte_data(client: data->client, MAX30208_FIFO_CONFIG, value: regval);
142 if (ret)
143 return ret;
144
145 return 0;
146}
147
148static int max30208_read(struct iio_dev *indio_dev,
149 struct iio_chan_spec const *chan,
150 int *val, int *val2, long mask)
151{
152 struct max30208_data *data = iio_priv(indio_dev);
153 int ret;
154
155 switch (mask) {
156 case IIO_CHAN_INFO_RAW:
157 ret = max30208_update_temp(data);
158 if (ret < 0)
159 return ret;
160
161 *val = sign_extend32(value: ret, index: 15);
162 return IIO_VAL_INT;
163
164 case IIO_CHAN_INFO_SCALE:
165 *val = 5;
166 return IIO_VAL_INT;
167
168 default:
169 return -EINVAL;
170 }
171}
172
173static const struct iio_info max30208_info = {
174 .read_raw = max30208_read,
175};
176
177static int max30208_probe(struct i2c_client *i2c)
178{
179 struct device *dev = &i2c->dev;
180 struct max30208_data *data;
181 struct iio_dev *indio_dev;
182 int ret;
183
184 indio_dev = devm_iio_device_alloc(parent: dev, sizeof_priv: sizeof(*data));
185 if (!indio_dev)
186 return -ENOMEM;
187
188 data = iio_priv(indio_dev);
189 data->client = i2c;
190 mutex_init(&data->lock);
191
192 indio_dev->name = "max30208";
193 indio_dev->channels = max30208_channels;
194 indio_dev->num_channels = ARRAY_SIZE(max30208_channels);
195 indio_dev->info = &max30208_info;
196 indio_dev->modes = INDIO_DIRECT_MODE;
197
198 ret = i2c_smbus_write_byte_data(client: data->client, MAX30208_SYSTEM_CTRL,
199 MAX30208_SYSTEM_CTRL_RESET);
200 if (ret) {
201 dev_err(dev, "Failure in performing reset\n");
202 return ret;
203 }
204
205 msleep(msecs: 50);
206
207 ret = max30208_config_setup(data);
208 if (ret)
209 return ret;
210
211 ret = devm_iio_device_register(dev, indio_dev);
212 if (ret) {
213 dev_err(dev, "Failed to register IIO device\n");
214 return ret;
215 }
216
217 return 0;
218}
219
220static const struct i2c_device_id max30208_id_table[] = {
221 { "max30208" },
222 { }
223};
224MODULE_DEVICE_TABLE(i2c, max30208_id_table);
225
226static const struct acpi_device_id max30208_acpi_match[] = {
227 { "MAX30208" },
228 { }
229};
230MODULE_DEVICE_TABLE(acpi, max30208_acpi_match);
231
232static const struct of_device_id max30208_of_match[] = {
233 { .compatible = "maxim,max30208" },
234 { }
235};
236MODULE_DEVICE_TABLE(of, max30208_of_match);
237
238static struct i2c_driver max30208_driver = {
239 .driver = {
240 .name = "max30208",
241 .of_match_table = max30208_of_match,
242 .acpi_match_table = max30208_acpi_match,
243 },
244 .probe = max30208_probe,
245 .id_table = max30208_id_table,
246};
247module_i2c_driver(max30208_driver);
248
249MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@linux.intel.com>");
250MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor");
251MODULE_LICENSE("GPL");
252

source code of linux/drivers/iio/temperature/max30208.c