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Linux 6.13-rc6
[linux.git] / drivers / hwmon / sht4x.c
blob6c9b776237c236c059bd0f307aa580c6ab84acb3
1 // SPDX-License-Identifier: GPL-2.0-only
2
3 /*
4 * Copyright (c) Linumiz 2021
5 *
6 * sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor
7 *
8 * Author: Navin Sankar Velliangiri <navin@linumiz.com>
9 */
10
11 #include <linux/crc8.h>
12 #include <linux/delay.h>
13 #include <linux/hwmon.h>
14 #include <linux/hwmon-sysfs.h>
15 #include <linux/i2c.h>
16 #include <linux/jiffies.h>
17 #include <linux/module.h>
18
19 /*
20 * Poll intervals (in milliseconds)
21 */
22 #define SHT4X_MIN_POLL_INTERVAL 2000
23
24 /*
25 * I2C command delays (in microseconds)
26 */
27 #define SHT4X_MEAS_DELAY_HPM 8200 /* see t_MEAS,h in datasheet */
28 #define SHT4X_DELAY_EXTRA 10000
29
30 /*
31 * Command Bytes
32 */
33 #define SHT4X_CMD_MEASURE_HPM 0b11111101
34 #define SHT4X_CMD_RESET 0b10010100
35 #define SHT4X_CMD_HEATER_20_1 0b00011110
36 #define SHT4X_CMD_HEATER_20_01 0b00010101
37 #define SHT4X_CMD_HEATER_110_1 0b00101111
38 #define SHT4X_CMD_HEATER_110_01 0b00100100
39 #define SHT4X_CMD_HEATER_200_1 0b00111001
40 #define SHT4X_CMD_HEATER_200_01 0b00110010
41
42 #define SHT4X_CMD_LEN 1
43 #define SHT4X_CRC8_LEN 1
44 #define SHT4X_WORD_LEN 2
45 #define SHT4X_RESPONSE_LENGTH 6
46 #define SHT4X_CRC8_POLYNOMIAL 0x31
47 #define SHT4X_CRC8_INIT 0xff
48 #define SHT4X_MIN_TEMPERATURE -45000
49 #define SHT4X_MAX_TEMPERATURE 125000
50 #define SHT4X_MIN_HUMIDITY 0
51 #define SHT4X_MAX_HUMIDITY 100000
52
53 DECLARE_CRC8_TABLE(sht4x_crc8_table);
54
55 /**
56 * struct sht4x_data - All the data required to operate an SHT4X chip
57 * @client: the i2c client associated with the SHT4X
58 * @lock: a mutex that is used to prevent parallel access to the i2c client
59 * @heating_complete: the time that the last heating finished
60 * @data_pending: true if and only if there are measurements to retrieve after heating
61 * @heater_power: the power at which the heater will be started
62 * @heater_time: the time for which the heater will remain turned on
63 * @valid: validity of fields below
64 * @update_interval: the minimum poll interval
65 * @last_updated: the previous time that the SHT4X was polled
66 * @temperature: the latest temperature value received from the SHT4X
67 * @humidity: the latest humidity value received from the SHT4X
68 */
69 struct sht4x_data {
70 struct i2c_client *client;
71 struct mutex lock; /* atomic read data updates */
72 unsigned long heating_complete; /* in jiffies */
73 bool data_pending;
74 u32 heater_power; /* in milli-watts */
75 u32 heater_time; /* in milli-seconds */
76 bool valid; /* validity of fields below */
77 long update_interval; /* in milli-seconds */
78 long last_updated; /* in jiffies */
79 s32 temperature;
80 s32 humidity;
81 };
82
83 /**
84 * sht4x_read_values() - read and parse the raw data from the SHT4X
85 * @data: the struct sht4x_data to use for the lock
86 * Return: 0 if successful, -ERRNO if not
87 */
88 static int sht4x_read_values(struct sht4x_data *data)
89 {
90 int ret = 0;
91 u16 t_ticks, rh_ticks;
92 unsigned long next_update;
93 struct i2c_client *client = data->client;
94 u8 crc;
95 u8 cmd[SHT4X_CMD_LEN] = {SHT4X_CMD_MEASURE_HPM};
96 u8 raw_data[SHT4X_RESPONSE_LENGTH];
97 unsigned long curr_jiffies;
98
99 mutex_lock(&data->lock);
100
101 curr_jiffies = jiffies;
102 if (time_before(curr_jiffies, data->heating_complete))
103 msleep(jiffies_to_msecs(data->heating_complete - curr_jiffies));
104
105 if (data->data_pending &&
106 time_before(jiffies, data->heating_complete + data->update_interval)) {
107 data->data_pending = false;
108 } else {
109 next_update = data->last_updated +
110 msecs_to_jiffies(data->update_interval);
111
112 if (data->valid && time_before_eq(jiffies, next_update))
113 goto unlock;
114
115 ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
116 if (ret < 0)
117 goto unlock;
118
119 usleep_range(SHT4X_MEAS_DELAY_HPM, SHT4X_MEAS_DELAY_HPM + SHT4X_DELAY_EXTRA);
120 }
121
122 ret = i2c_master_recv(client, raw_data, SHT4X_RESPONSE_LENGTH);
123 if (ret != SHT4X_RESPONSE_LENGTH) {
124 if (ret >= 0)
125 ret = -ENODATA;
126 goto unlock;
127 }
128
129 t_ticks = raw_data[0] << 8 | raw_data[1];
130 rh_ticks = raw_data[3] << 8 | raw_data[4];
131
132 crc = crc8(sht4x_crc8_table, &raw_data[0], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
133 if (crc != raw_data[2]) {
134 dev_err(&client->dev, "data integrity check failed\n");
135 ret = -EIO;
136 goto unlock;
137 }
138
139 crc = crc8(sht4x_crc8_table, &raw_data[3], SHT4X_WORD_LEN, CRC8_INIT_VALUE);
140 if (crc != raw_data[5]) {
141 dev_err(&client->dev, "data integrity check failed\n");
142 ret = -EIO;
143 goto unlock;
144 }
145
146 data->temperature = ((21875 * (int32_t)t_ticks) >> 13) - 45000;
147 data->humidity = ((15625 * (int32_t)rh_ticks) >> 13) - 6000;
148 data->last_updated = jiffies;
149 data->valid = true;
150 ret = 0;
151
152 unlock:
153 mutex_unlock(&data->lock);
154 return ret;
155 }
156
157 static ssize_t sht4x_interval_write(struct sht4x_data *data, long val)
158 {
159 data->update_interval = clamp_val(val, SHT4X_MIN_POLL_INTERVAL, INT_MAX);
160
161 return 0;
162 }
163
164 /* sht4x_interval_read() - read the minimum poll interval in milliseconds */
165 static size_t sht4x_interval_read(struct sht4x_data *data, long *val)
166 {
167 *val = data->update_interval;
168 return 0;
169 }
170
171 /* sht4x_temperature1_read() - read the temperature in millidegrees */
172 static int sht4x_temperature1_read(struct sht4x_data *data, long *val)
173 {
174 int ret;
175
176 ret = sht4x_read_values(data);
177 if (ret < 0)
178 return ret;
179
180 *val = data->temperature;
181
182 return 0;
183 }
184
185 /* sht4x_humidity1_read() - read a relative humidity in millipercent */
186 static int sht4x_humidity1_read(struct sht4x_data *data, long *val)
187 {
188 int ret;
189
190 ret = sht4x_read_values(data);
191 if (ret < 0)
192 return ret;
193
194 *val = data->humidity;
195
196 return 0;
197 }
198
199 static umode_t sht4x_hwmon_visible(const void *data,
200 enum hwmon_sensor_types type,
201 u32 attr, int channel)
202 {
203 switch (type) {
204 case hwmon_temp:
205 case hwmon_humidity:
206 return 0444;
207 case hwmon_chip:
208 return 0644;
209 default:
210 return 0;
211 }
212 }
213
214 static int sht4x_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
215 u32 attr, int channel, long *val)
216 {
217 struct sht4x_data *data = dev_get_drvdata(dev);
218
219 switch (type) {
220 case hwmon_temp:
221 return sht4x_temperature1_read(data, val);
222 case hwmon_humidity:
223 return sht4x_humidity1_read(data, val);
224 case hwmon_chip:
225 return sht4x_interval_read(data, val);
226 default:
227 return -EOPNOTSUPP;
228 }
229 }
230
231 static int sht4x_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
232 u32 attr, int channel, long val)
233 {
234 struct sht4x_data *data = dev_get_drvdata(dev);
235
236 switch (type) {
237 case hwmon_chip:
238 return sht4x_interval_write(data, val);
239 default:
240 return -EOPNOTSUPP;
241 }
242 }
243
244 static ssize_t heater_enable_show(struct device *dev,
245 struct device_attribute *attr,
246 char *buf)
247 {
248 struct sht4x_data *data = dev_get_drvdata(dev);
249
250 return sysfs_emit(buf, "%u\n", time_before(jiffies, data->heating_complete));
251 }
252
253 static ssize_t heater_enable_store(struct device *dev,
254 struct device_attribute *attr,
255 const char *buf,
256 size_t count)
257 {
258 struct sht4x_data *data = dev_get_drvdata(dev);
259 bool status;
260 ssize_t ret;
261 u8 cmd;
262 u32 heating_time_bound;
263
264 ret = kstrtobool(buf, &status);
265 if (ret)
266 return ret;
267 if (!status)
268 return -EINVAL;
269
270 if (data->heater_time == 100) {
271 if (data->heater_power == 20)
272 cmd = SHT4X_CMD_HEATER_20_01;
273 else if (data->heater_power == 110)
274 cmd = SHT4X_CMD_HEATER_110_01;
275 else /* data->heater_power == 200 */
276 cmd = SHT4X_CMD_HEATER_200_01;
277
278 heating_time_bound = 110;
279 } else { /* data->heater_time == 1000 */
280 if (data->heater_power == 20)
281 cmd = SHT4X_CMD_HEATER_20_1;
282 else if (data->heater_power == 110)
283 cmd = SHT4X_CMD_HEATER_110_1;
284 else /* data->heater_power == 200 */
285 cmd = SHT4X_CMD_HEATER_200_1;
286
287 heating_time_bound = 1100;
288 }
289
290 mutex_lock(&data->lock);
291
292 if (time_before(jiffies, data->heating_complete)) {
293 ret = -EBUSY;
294 goto unlock;
295 }
296
297 ret = i2c_master_send(data->client, &cmd, SHT4X_CMD_LEN);
298 if (ret < 0)
299 goto unlock;
300
301 data->heating_complete = jiffies + msecs_to_jiffies(heating_time_bound);
302 data->data_pending = true;
303 unlock:
304 mutex_unlock(&data->lock);
305 return ret;
306 }
307
308 static ssize_t heater_power_show(struct device *dev,
309 struct device_attribute *attr,
310 char *buf)
311 {
312 struct sht4x_data *data = dev_get_drvdata(dev);
313
314 return sysfs_emit(buf, "%u\n", data->heater_power);
315 }
316
317 static ssize_t heater_power_store(struct device *dev,
318 struct device_attribute *attr,
319 const char *buf,
320 size_t count)
321 {
322 struct sht4x_data *data = dev_get_drvdata(dev);
323 u32 power;
324 ssize_t ret;
325
326 ret = kstrtou32(buf, 10, &power);
327 if (ret)
328 return ret;
329
330 if (power != 20 && power != 110 && power != 200)
331 return -EINVAL;
332
333 data->heater_power = power;
334
335 return count;
336 }
337
338 static ssize_t heater_time_show(struct device *dev,
339 struct device_attribute *attr,
340 char *buf)
341 {
342 struct sht4x_data *data = dev_get_drvdata(dev);
343
344 return sysfs_emit(buf, "%u\n", data->heater_time);
345 }
346
347 static ssize_t heater_time_store(struct device *dev,
348 struct device_attribute *attr,
349 const char *buf,
350 size_t count)
351 {
352 struct sht4x_data *data = dev_get_drvdata(dev);
353 u32 time;
354 ssize_t ret;
355
356 ret = kstrtou32(buf, 10, &time);
357 if (ret)
358 return ret;
359
360 if (time != 100 && time != 1000)
361 return -EINVAL;
362
363 data->heater_time = time;
364
365 return count;
366 }
367
368 static DEVICE_ATTR_RW(heater_enable);
369 static DEVICE_ATTR_RW(heater_power);
370 static DEVICE_ATTR_RW(heater_time);
371
372 static struct attribute *sht4x_attrs[] = {
373 &dev_attr_heater_enable.attr,
374 &dev_attr_heater_power.attr,
375 &dev_attr_heater_time.attr,
376 NULL
377 };
378
379 ATTRIBUTE_GROUPS(sht4x);
380
381 static const struct hwmon_channel_info * const sht4x_info[] = {
382 HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
383 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
384 HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
385 NULL,
386 };
387
388 static const struct hwmon_ops sht4x_hwmon_ops = {
389 .is_visible = sht4x_hwmon_visible,
390 .read = sht4x_hwmon_read,
391 .write = sht4x_hwmon_write,
392 };
393
394 static const struct hwmon_chip_info sht4x_chip_info = {
395 .ops = &sht4x_hwmon_ops,
396 .info = sht4x_info,
397 };
398
399 static int sht4x_probe(struct i2c_client *client)
400 {
401 struct device *device = &client->dev;
402 struct device *hwmon_dev;
403 struct sht4x_data *data;
404 u8 cmd[] = {SHT4X_CMD_RESET};
405 int ret;
406
407 /*
408 * we require full i2c support since the sht4x uses multi-byte read and
409 * writes as well as multi-byte commands which are not supported by
410 * the smbus protocol
411 */
412 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
413 return -EOPNOTSUPP;
414
415 data = devm_kzalloc(device, sizeof(*data), GFP_KERNEL);
416 if (!data)
417 return -ENOMEM;
418
419 data->update_interval = SHT4X_MIN_POLL_INTERVAL;
420 data->client = client;
421 data->heater_power = 200;
422 data->heater_time = 1000;
423 data->heating_complete = jiffies;
424
425 mutex_init(&data->lock);
426
427 crc8_populate_msb(sht4x_crc8_table, SHT4X_CRC8_POLYNOMIAL);
428
429 ret = i2c_master_send(client, cmd, SHT4X_CMD_LEN);
430 if (ret < 0)
431 return ret;
432 if (ret != SHT4X_CMD_LEN)
433 return -EIO;
434
435 hwmon_dev = devm_hwmon_device_register_with_info(device,
436 client->name,
437 data,
438 &sht4x_chip_info,
439 sht4x_groups);
440
441 return PTR_ERR_OR_ZERO(hwmon_dev);
442 }
443
444 static const struct i2c_device_id sht4x_id[] = {
445 { "sht4x" },
446 { },
447 };
448 MODULE_DEVICE_TABLE(i2c, sht4x_id);
449
450 static const struct of_device_id sht4x_of_match[] = {
451 { .compatible = "sensirion,sht4x" },
452 { }
453 };
454 MODULE_DEVICE_TABLE(of, sht4x_of_match);
455
456 static struct i2c_driver sht4x_driver = {
457 .driver = {
458 .name = "sht4x",
459 .of_match_table = sht4x_of_match,
460 },
461 .probe = sht4x_probe,
462 .id_table = sht4x_id,
463 };
464
465 module_i2c_driver(sht4x_driver);
466
467 MODULE_AUTHOR("Navin Sankar Velliangiri <navin@linumiz.com>");
468 MODULE_DESCRIPTION("Sensirion SHT4x humidity and temperature sensor driver");
469 MODULE_LICENSE("GPL v2");
Linux Kernel