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
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 */
39 };
40
41 static const struct iio_chan_spec max30208_channels[] = {
42 {
43 .type = IIO_TEMP,
44 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
45 },
46 };
47
48 /**
49 * max30208_request() - Request a reading
50 * @data: Struct comprising member elements of the device
51 *
52 * Requests a reading from the device and waits until the conversion is ready.
53 */
max30208_request(struct max30208_data * data)54 static int max30208_request(struct max30208_data *data)
55 {
56 /*
57 * Sensor can take up to 500 ms to respond so execute a total of
58 * 10 retries to give the device sufficient time.
59 */
60 int retries = 10;
61 u8 regval;
62 int ret;
63
64 ret = i2c_smbus_read_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP);
65 if (ret < 0)
66 return ret;
67
68 regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV;
69
70 ret = i2c_smbus_write_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP, regval);
71 if (ret)
72 return ret;
73
74 while (retries--) {
75 ret = i2c_smbus_read_byte_data(data->client, MAX30208_STATUS);
76 if (ret < 0)
77 return ret;
78
79 if (ret & MAX30208_STATUS_TEMP_RDY)
80 return 0;
81
82 msleep(50);
83 }
84 dev_err(&data->client->dev, "Temperature conversion failed\n");
85
86 return -ETIMEDOUT;
87 }
88
max30208_update_temp(struct max30208_data * data)89 static int max30208_update_temp(struct max30208_data *data)
90 {
91 u8 data_count;
92 int ret;
93
94 mutex_lock(&data->lock);
95
96 ret = max30208_request(data);
97 if (ret)
98 goto unlock;
99
100 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_OVF_CNTR);
101 if (ret < 0)
102 goto unlock;
103 else if (!ret) {
104 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_DATA_CNTR);
105 if (ret < 0)
106 goto unlock;
107
108 data_count = ret;
109 } else
110 data_count = 1;
111
112 while (data_count) {
113 ret = i2c_smbus_read_word_swapped(data->client, MAX30208_FIFO_DATA);
114 if (ret < 0)
115 goto unlock;
116
117 data_count--;
118 }
119
120 unlock:
121 mutex_unlock(&data->lock);
122 return ret;
123 }
124
125 /**
126 * max30208_config_setup() - Set up FIFO configuration register
127 * @data: Struct comprising member elements of the device
128 *
129 * Sets the rollover bit to '1' to enable overwriting FIFO during overflow.
130 */
max30208_config_setup(struct max30208_data * data)131 static int max30208_config_setup(struct max30208_data *data)
132 {
133 u8 regval;
134 int ret;
135
136 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_CONFIG);
137 if (ret < 0)
138 return ret;
139
140 regval = ret | MAX30208_FIFO_CONFIG_RO;
141
142 ret = i2c_smbus_write_byte_data(data->client, MAX30208_FIFO_CONFIG, regval);
143 if (ret)
144 return ret;
145
146 return 0;
147 }
148
max30208_read(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)149 static int max30208_read(struct iio_dev *indio_dev,
150 struct iio_chan_spec const *chan,
151 int *val, int *val2, long mask)
152 {
153 struct max30208_data *data = iio_priv(indio_dev);
154 int ret;
155
156 switch (mask) {
157 case IIO_CHAN_INFO_RAW:
158 ret = max30208_update_temp(data);
159 if (ret < 0)
160 return ret;
161
162 *val = sign_extend32(ret, 15);
163 return IIO_VAL_INT;
164
165 case IIO_CHAN_INFO_SCALE:
166 *val = 5;
167 return IIO_VAL_INT;
168
169 default:
170 return -EINVAL;
171 }
172 }
173
174 static const struct iio_info max30208_info = {
175 .read_raw = max30208_read,
176 };
177
max30208_probe(struct i2c_client * i2c)178 static int max30208_probe(struct i2c_client *i2c)
179 {
180 struct device *dev = &i2c->dev;
181 struct max30208_data *data;
182 struct iio_dev *indio_dev;
183 int ret;
184
185 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
186 if (!indio_dev)
187 return -ENOMEM;
188
189 data = iio_priv(indio_dev);
190 data->client = i2c;
191 mutex_init(&data->lock);
192
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;
198
199 ret = i2c_smbus_write_byte_data(data->client, MAX30208_SYSTEM_CTRL,
200 MAX30208_SYSTEM_CTRL_RESET);
201 if (ret) {
202 dev_err(dev, "Failure in performing reset\n");
203 return ret;
204 }
205
206 msleep(50);
207
208 ret = max30208_config_setup(data);
209 if (ret)
210 return ret;
211
212 ret = devm_iio_device_register(dev, indio_dev);
213 if (ret) {
214 dev_err(dev, "Failed to register IIO device\n");
215 return ret;
216 }
217
218 return 0;
219 }
220
221 static const struct i2c_device_id max30208_id_table[] = {
222 { "max30208" },
223 { }
224 };
225 MODULE_DEVICE_TABLE(i2c, max30208_id_table);
226
227 static const struct acpi_device_id max30208_acpi_match[] = {
228 { "MAX30208" },
229 { }
230 };
231 MODULE_DEVICE_TABLE(acpi, max30208_acpi_match);
232
233 static const struct of_device_id max30208_of_match[] = {
234 { .compatible = "maxim,max30208" },
235 { }
236 };
237 MODULE_DEVICE_TABLE(of, max30208_of_match);
238
239 static struct i2c_driver max30208_driver = {
240 .driver = {
241 .name = "max30208",
242 .of_match_table = max30208_of_match,
243 .acpi_match_table = max30208_acpi_match,
244 },
245 .probe = max30208_probe,
246 .id_table = max30208_id_table,
247 };
248 module_i2c_driver(max30208_driver);
249
250 MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@linux.intel.com>");
251 MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor");
252 MODULE_LICENSE("GPL");
253
