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 | */ |
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(client: 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(client: data->client, MAX30208_TEMP_SENSOR_SETUP, value: regval); |
71 | if (ret) |
72 | return ret; |
73 | |
74 | while (retries--) { |
75 | ret = i2c_smbus_read_byte_data(client: 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(msecs: 50); |
83 | } |
84 | dev_err(&data->client->dev, "Temperature conversion failed\n" ); |
85 | |
86 | return -ETIMEDOUT; |
87 | } |
88 | |
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(client: data->client, MAX30208_FIFO_OVF_CNTR); |
101 | if (ret < 0) |
102 | goto unlock; |
103 | else if (!ret) { |
104 | ret = i2c_smbus_read_byte_data(client: 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(client: data->client, MAX30208_FIFO_DATA); |
114 | if (ret < 0) |
115 | goto unlock; |
116 | |
117 | data_count--; |
118 | } |
119 | |
120 | unlock: |
121 | mutex_unlock(lock: &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 | */ |
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(client: 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(client: data->client, MAX30208_FIFO_CONFIG, value: regval); |
143 | if (ret) |
144 | return ret; |
145 | |
146 | return 0; |
147 | } |
148 | |
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(value: ret, index: 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 | |
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(parent: dev, sizeof_priv: 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(client: 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(msecs: 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 | |