1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* Sensirion SHTC1 humidity and temperature sensor driver |
3 | * |
4 | * Copyright (C) 2014 Sensirion AG, Switzerland |
5 | * Author: Johannes Winkelmann <johannes.winkelmann@sensirion.com> |
6 | */ |
7 | |
8 | #include <linux/module.h> |
9 | #include <linux/init.h> |
10 | #include <linux/slab.h> |
11 | #include <linux/i2c.h> |
12 | #include <linux/hwmon.h> |
13 | #include <linux/hwmon-sysfs.h> |
14 | #include <linux/err.h> |
15 | #include <linux/delay.h> |
16 | #include <linux/platform_data/shtc1.h> |
17 | #include <linux/of.h> |
18 | |
19 | /* commands (high precision mode) */ |
20 | static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 }; |
21 | static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 }; |
22 | |
23 | /* commands (low precision mode) */ |
24 | static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 }; |
25 | static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c }; |
26 | |
27 | /* command for reading the ID register */ |
28 | static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 }; |
29 | |
30 | /* |
31 | * constants for reading the ID register |
32 | * SHTC1: 0x0007 with mask 0x003f |
33 | * SHTW1: 0x0007 with mask 0x003f |
34 | * SHTC3: 0x0807 with mask 0x083f |
35 | */ |
36 | #define SHTC3_ID 0x0807 |
37 | #define SHTC3_ID_MASK 0x083f |
38 | #define SHTC1_ID 0x0007 |
39 | #define SHTC1_ID_MASK 0x003f |
40 | |
41 | /* delays for non-blocking i2c commands, both in us */ |
42 | #define SHTC1_NONBLOCKING_WAIT_TIME_HPM 14400 |
43 | #define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1000 |
44 | #define SHTC3_NONBLOCKING_WAIT_TIME_HPM 12100 |
45 | #define SHTC3_NONBLOCKING_WAIT_TIME_LPM 800 |
46 | |
47 | #define SHTC1_CMD_LENGTH 2 |
48 | #define SHTC1_RESPONSE_LENGTH 6 |
49 | |
50 | enum shtcx_chips { |
51 | shtc1, |
52 | shtc3, |
53 | }; |
54 | |
55 | struct shtc1_data { |
56 | struct i2c_client *client; |
57 | struct mutex update_lock; |
58 | bool valid; |
59 | unsigned long last_updated; /* in jiffies */ |
60 | |
61 | const unsigned char *command; |
62 | unsigned int nonblocking_wait_time; /* in us */ |
63 | |
64 | struct shtc1_platform_data setup; |
65 | enum shtcx_chips chip; |
66 | |
67 | int temperature; /* 1000 * temperature in dgr C */ |
68 | int humidity; /* 1000 * relative humidity in %RH */ |
69 | }; |
70 | |
71 | static int shtc1_update_values(struct i2c_client *client, |
72 | struct shtc1_data *data, |
73 | char *buf, int bufsize) |
74 | { |
75 | int ret = i2c_master_send(client, buf: data->command, SHTC1_CMD_LENGTH); |
76 | if (ret != SHTC1_CMD_LENGTH) { |
77 | dev_err(&client->dev, "failed to send command: %d\n" , ret); |
78 | return ret < 0 ? ret : -EIO; |
79 | } |
80 | |
81 | /* |
82 | * In blocking mode (clock stretching mode) the I2C bus |
83 | * is blocked for other traffic, thus the call to i2c_master_recv() |
84 | * will wait until the data is ready. For non blocking mode, we |
85 | * have to wait ourselves. |
86 | */ |
87 | if (!data->setup.blocking_io) |
88 | usleep_range(min: data->nonblocking_wait_time, |
89 | max: data->nonblocking_wait_time + 1000); |
90 | |
91 | ret = i2c_master_recv(client, buf, count: bufsize); |
92 | if (ret != bufsize) { |
93 | dev_err(&client->dev, "failed to read values: %d\n" , ret); |
94 | return ret < 0 ? ret : -EIO; |
95 | } |
96 | |
97 | return 0; |
98 | } |
99 | |
100 | /* sysfs attributes */ |
101 | static struct shtc1_data *shtc1_update_client(struct device *dev) |
102 | { |
103 | struct shtc1_data *data = dev_get_drvdata(dev); |
104 | struct i2c_client *client = data->client; |
105 | unsigned char buf[SHTC1_RESPONSE_LENGTH]; |
106 | int val; |
107 | int ret = 0; |
108 | |
109 | mutex_lock(&data->update_lock); |
110 | |
111 | if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) { |
112 | ret = shtc1_update_values(client, data, buf, bufsize: sizeof(buf)); |
113 | if (ret) |
114 | goto out; |
115 | |
116 | /* |
117 | * From datasheet: |
118 | * T = -45 + 175 * ST / 2^16 |
119 | * RH = 100 * SRH / 2^16 |
120 | * |
121 | * Adapted for integer fixed point (3 digit) arithmetic. |
122 | */ |
123 | val = be16_to_cpup(p: (__be16 *)buf); |
124 | data->temperature = ((21875 * val) >> 13) - 45000; |
125 | val = be16_to_cpup(p: (__be16 *)(buf + 3)); |
126 | data->humidity = ((12500 * val) >> 13); |
127 | |
128 | data->last_updated = jiffies; |
129 | data->valid = true; |
130 | } |
131 | |
132 | out: |
133 | mutex_unlock(lock: &data->update_lock); |
134 | |
135 | return ret == 0 ? data : ERR_PTR(error: ret); |
136 | } |
137 | |
138 | static ssize_t temp1_input_show(struct device *dev, |
139 | struct device_attribute *attr, |
140 | char *buf) |
141 | { |
142 | struct shtc1_data *data = shtc1_update_client(dev); |
143 | if (IS_ERR(ptr: data)) |
144 | return PTR_ERR(ptr: data); |
145 | |
146 | return sprintf(buf, fmt: "%d\n" , data->temperature); |
147 | } |
148 | |
149 | static ssize_t humidity1_input_show(struct device *dev, |
150 | struct device_attribute *attr, char *buf) |
151 | { |
152 | struct shtc1_data *data = shtc1_update_client(dev); |
153 | if (IS_ERR(ptr: data)) |
154 | return PTR_ERR(ptr: data); |
155 | |
156 | return sprintf(buf, fmt: "%d\n" , data->humidity); |
157 | } |
158 | |
159 | static DEVICE_ATTR_RO(temp1_input); |
160 | static DEVICE_ATTR_RO(humidity1_input); |
161 | |
162 | static struct attribute *shtc1_attrs[] = { |
163 | &dev_attr_temp1_input.attr, |
164 | &dev_attr_humidity1_input.attr, |
165 | NULL |
166 | }; |
167 | |
168 | ATTRIBUTE_GROUPS(shtc1); |
169 | |
170 | static void shtc1_select_command(struct shtc1_data *data) |
171 | { |
172 | if (data->setup.high_precision) { |
173 | data->command = data->setup.blocking_io ? |
174 | shtc1_cmd_measure_blocking_hpm : |
175 | shtc1_cmd_measure_nonblocking_hpm; |
176 | data->nonblocking_wait_time = (data->chip == shtc1) ? |
177 | SHTC1_NONBLOCKING_WAIT_TIME_HPM : |
178 | SHTC3_NONBLOCKING_WAIT_TIME_HPM; |
179 | } else { |
180 | data->command = data->setup.blocking_io ? |
181 | shtc1_cmd_measure_blocking_lpm : |
182 | shtc1_cmd_measure_nonblocking_lpm; |
183 | data->nonblocking_wait_time = (data->chip == shtc1) ? |
184 | SHTC1_NONBLOCKING_WAIT_TIME_LPM : |
185 | SHTC3_NONBLOCKING_WAIT_TIME_LPM; |
186 | } |
187 | } |
188 | |
189 | static const struct i2c_device_id shtc1_id[]; |
190 | |
191 | static int shtc1_probe(struct i2c_client *client) |
192 | { |
193 | int ret; |
194 | u16 id_reg; |
195 | char id_reg_buf[2]; |
196 | struct shtc1_data *data; |
197 | struct device *hwmon_dev; |
198 | enum shtcx_chips chip = i2c_match_id(id: shtc1_id, client)->driver_data; |
199 | struct i2c_adapter *adap = client->adapter; |
200 | struct device *dev = &client->dev; |
201 | struct device_node *np = dev->of_node; |
202 | |
203 | if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) { |
204 | dev_err(dev, "plain i2c transactions not supported\n" ); |
205 | return -ENODEV; |
206 | } |
207 | |
208 | ret = i2c_master_send(client, buf: shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH); |
209 | if (ret != SHTC1_CMD_LENGTH) { |
210 | dev_err(dev, "could not send read_id_reg command: %d\n" , ret); |
211 | return ret < 0 ? ret : -ENODEV; |
212 | } |
213 | ret = i2c_master_recv(client, buf: id_reg_buf, count: sizeof(id_reg_buf)); |
214 | if (ret != sizeof(id_reg_buf)) { |
215 | dev_err(dev, "could not read ID register: %d\n" , ret); |
216 | return -ENODEV; |
217 | } |
218 | |
219 | id_reg = be16_to_cpup(p: (__be16 *)id_reg_buf); |
220 | if (chip == shtc3) { |
221 | if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) { |
222 | dev_err(dev, "SHTC3 ID register does not match\n" ); |
223 | return -ENODEV; |
224 | } |
225 | } else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) { |
226 | dev_err(dev, "SHTC1 ID register does not match\n" ); |
227 | return -ENODEV; |
228 | } |
229 | |
230 | data = devm_kzalloc(dev, size: sizeof(*data), GFP_KERNEL); |
231 | if (!data) |
232 | return -ENOMEM; |
233 | |
234 | data->setup.blocking_io = false; |
235 | data->setup.high_precision = true; |
236 | data->client = client; |
237 | data->chip = chip; |
238 | |
239 | if (np) { |
240 | data->setup.blocking_io = of_property_read_bool(np, propname: "sensirion,blocking-io" ); |
241 | data->setup.high_precision = !of_property_read_bool(np, propname: "sensicon,low-precision" ); |
242 | } else { |
243 | if (client->dev.platform_data) |
244 | data->setup = *(struct shtc1_platform_data *)dev->platform_data; |
245 | } |
246 | |
247 | shtc1_select_command(data); |
248 | mutex_init(&data->update_lock); |
249 | |
250 | hwmon_dev = devm_hwmon_device_register_with_groups(dev, |
251 | name: client->name, |
252 | drvdata: data, |
253 | groups: shtc1_groups); |
254 | if (IS_ERR(ptr: hwmon_dev)) |
255 | dev_dbg(dev, "unable to register hwmon device\n" ); |
256 | |
257 | return PTR_ERR_OR_ZERO(ptr: hwmon_dev); |
258 | } |
259 | |
260 | /* device ID table */ |
261 | static const struct i2c_device_id shtc1_id[] = { |
262 | { "shtc1" , shtc1 }, |
263 | { "shtw1" , shtc1 }, |
264 | { "shtc3" , shtc3 }, |
265 | { } |
266 | }; |
267 | MODULE_DEVICE_TABLE(i2c, shtc1_id); |
268 | |
269 | static const struct of_device_id shtc1_of_match[] = { |
270 | { .compatible = "sensirion,shtc1" }, |
271 | { .compatible = "sensirion,shtw1" }, |
272 | { .compatible = "sensirion,shtc3" }, |
273 | { } |
274 | }; |
275 | MODULE_DEVICE_TABLE(of, shtc1_of_match); |
276 | |
277 | static struct i2c_driver shtc1_i2c_driver = { |
278 | .driver = { |
279 | .name = "shtc1" , |
280 | .of_match_table = shtc1_of_match, |
281 | }, |
282 | .probe = shtc1_probe, |
283 | .id_table = shtc1_id, |
284 | }; |
285 | |
286 | module_i2c_driver(shtc1_i2c_driver); |
287 | |
288 | MODULE_AUTHOR("Johannes Winkelmann <johannes.winkelmann@sensirion.com>" ); |
289 | MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver" ); |
290 | MODULE_LICENSE("GPL" ); |
291 | |