treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157
[sfrench/cifs-2.6.git] / drivers / hwmon / sht3x.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Sensirion SHT3x-DIS humidity and temperature sensor driver.
3  * The SHT3x comes in many different versions, this driver is for the
4  * I2C version only.
5  *
6  * Copyright (C) 2016 Sensirion AG, Switzerland
7  * Author: David Frey <david.frey@sensirion.com>
8  * Author: Pascal Sachs <pascal.sachs@sensirion.com>
9  */
10
11 #include <asm/page.h>
12 #include <linux/crc8.h>
13 #include <linux/delay.h>
14 #include <linux/err.h>
15 #include <linux/hwmon.h>
16 #include <linux/hwmon-sysfs.h>
17 #include <linux/i2c.h>
18 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <linux/jiffies.h>
23 #include <linux/platform_data/sht3x.h>
24
25 /* commands (high precision mode) */
26 static const unsigned char sht3x_cmd_measure_blocking_hpm[]    = { 0x2c, 0x06 };
27 static const unsigned char sht3x_cmd_measure_nonblocking_hpm[] = { 0x24, 0x00 };
28
29 /* commands (low power mode) */
30 static const unsigned char sht3x_cmd_measure_blocking_lpm[]    = { 0x2c, 0x10 };
31 static const unsigned char sht3x_cmd_measure_nonblocking_lpm[] = { 0x24, 0x16 };
32
33 /* commands for periodic mode */
34 static const unsigned char sht3x_cmd_measure_periodic_mode[]   = { 0xe0, 0x00 };
35 static const unsigned char sht3x_cmd_break[]                   = { 0x30, 0x93 };
36
37 /* commands for heater control */
38 static const unsigned char sht3x_cmd_heater_on[]               = { 0x30, 0x6d };
39 static const unsigned char sht3x_cmd_heater_off[]              = { 0x30, 0x66 };
40
41 /* other commands */
42 static const unsigned char sht3x_cmd_read_status_reg[]         = { 0xf3, 0x2d };
43 static const unsigned char sht3x_cmd_clear_status_reg[]        = { 0x30, 0x41 };
44
45 /* delays for non-blocking i2c commands, both in us */
46 #define SHT3X_NONBLOCKING_WAIT_TIME_HPM  15000
47 #define SHT3X_NONBLOCKING_WAIT_TIME_LPM   4000
48
49 #define SHT3X_WORD_LEN         2
50 #define SHT3X_CMD_LENGTH       2
51 #define SHT3X_CRC8_LEN         1
52 #define SHT3X_RESPONSE_LENGTH  6
53 #define SHT3X_CRC8_POLYNOMIAL  0x31
54 #define SHT3X_CRC8_INIT        0xFF
55 #define SHT3X_MIN_TEMPERATURE  -45000
56 #define SHT3X_MAX_TEMPERATURE  130000
57 #define SHT3X_MIN_HUMIDITY     0
58 #define SHT3X_MAX_HUMIDITY     100000
59
60 enum sht3x_chips {
61         sht3x,
62         sts3x,
63 };
64
65 enum sht3x_limits {
66         limit_max = 0,
67         limit_max_hyst,
68         limit_min,
69         limit_min_hyst,
70 };
71
72 DECLARE_CRC8_TABLE(sht3x_crc8_table);
73
74 /* periodic measure commands (high precision mode) */
75 static const char periodic_measure_commands_hpm[][SHT3X_CMD_LENGTH] = {
76         /* 0.5 measurements per second */
77         {0x20, 0x32},
78         /* 1 measurements per second */
79         {0x21, 0x30},
80         /* 2 measurements per second */
81         {0x22, 0x36},
82         /* 4 measurements per second */
83         {0x23, 0x34},
84         /* 10 measurements per second */
85         {0x27, 0x37},
86 };
87
88 /* periodic measure commands (low power mode) */
89 static const char periodic_measure_commands_lpm[][SHT3X_CMD_LENGTH] = {
90         /* 0.5 measurements per second */
91         {0x20, 0x2f},
92         /* 1 measurements per second */
93         {0x21, 0x2d},
94         /* 2 measurements per second */
95         {0x22, 0x2b},
96         /* 4 measurements per second */
97         {0x23, 0x29},
98         /* 10 measurements per second */
99         {0x27, 0x2a},
100 };
101
102 struct sht3x_limit_commands {
103         const char read_command[SHT3X_CMD_LENGTH];
104         const char write_command[SHT3X_CMD_LENGTH];
105 };
106
107 static const struct sht3x_limit_commands limit_commands[] = {
108         /* temp1_max, humidity1_max */
109         [limit_max] = { {0xe1, 0x1f}, {0x61, 0x1d} },
110         /* temp_1_max_hyst, humidity1_max_hyst */
111         [limit_max_hyst] = { {0xe1, 0x14}, {0x61, 0x16} },
112         /* temp1_min, humidity1_min */
113         [limit_min] = { {0xe1, 0x02}, {0x61, 0x00} },
114         /* temp_1_min_hyst, humidity1_min_hyst */
115         [limit_min_hyst] = { {0xe1, 0x09}, {0x61, 0x0B} },
116 };
117
118 #define SHT3X_NUM_LIMIT_CMD  ARRAY_SIZE(limit_commands)
119
120 static const u16 mode_to_update_interval[] = {
121            0,
122         2000,
123         1000,
124          500,
125          250,
126          100,
127 };
128
129 struct sht3x_data {
130         struct i2c_client *client;
131         struct mutex i2c_lock; /* lock for sending i2c commands */
132         struct mutex data_lock; /* lock for updating driver data */
133
134         u8 mode;
135         const unsigned char *command;
136         u32 wait_time;                  /* in us*/
137         unsigned long last_update;      /* last update in periodic mode*/
138
139         struct sht3x_platform_data setup;
140
141         /*
142          * cached values for temperature and humidity and limits
143          * the limits arrays have the following order:
144          * max, max_hyst, min, min_hyst
145          */
146         int temperature;
147         int temperature_limits[SHT3X_NUM_LIMIT_CMD];
148         u32 humidity;
149         u32 humidity_limits[SHT3X_NUM_LIMIT_CMD];
150 };
151
152 static u8 get_mode_from_update_interval(u16 value)
153 {
154         size_t index;
155         u8 number_of_modes = ARRAY_SIZE(mode_to_update_interval);
156
157         if (value == 0)
158                 return 0;
159
160         /* find next faster update interval */
161         for (index = 1; index < number_of_modes; index++) {
162                 if (mode_to_update_interval[index] <= value)
163                         return index;
164         }
165
166         return number_of_modes - 1;
167 }
168
169 static int sht3x_read_from_command(struct i2c_client *client,
170                                    struct sht3x_data *data,
171                                    const char *command,
172                                    char *buf, int length, u32 wait_time)
173 {
174         int ret;
175
176         mutex_lock(&data->i2c_lock);
177         ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
178
179         if (ret != SHT3X_CMD_LENGTH) {
180                 ret = ret < 0 ? ret : -EIO;
181                 goto out;
182         }
183
184         if (wait_time)
185                 usleep_range(wait_time, wait_time + 1000);
186
187         ret = i2c_master_recv(client, buf, length);
188         if (ret != length) {
189                 ret = ret < 0 ? ret : -EIO;
190                 goto out;
191         }
192
193         ret = 0;
194 out:
195         mutex_unlock(&data->i2c_lock);
196         return ret;
197 }
198
199 static int sht3x_extract_temperature(u16 raw)
200 {
201         /*
202          * From datasheet:
203          * T = -45 + 175 * ST / 2^16
204          * Adapted for integer fixed point (3 digit) arithmetic.
205          */
206         return ((21875 * (int)raw) >> 13) - 45000;
207 }
208
209 static u32 sht3x_extract_humidity(u16 raw)
210 {
211         /*
212          * From datasheet:
213          * RH = 100 * SRH / 2^16
214          * Adapted for integer fixed point (3 digit) arithmetic.
215          */
216         return (12500 * (u32)raw) >> 13;
217 }
218
219 static struct sht3x_data *sht3x_update_client(struct device *dev)
220 {
221         struct sht3x_data *data = dev_get_drvdata(dev);
222         struct i2c_client *client = data->client;
223         u16 interval_ms = mode_to_update_interval[data->mode];
224         unsigned long interval_jiffies = msecs_to_jiffies(interval_ms);
225         unsigned char buf[SHT3X_RESPONSE_LENGTH];
226         u16 val;
227         int ret = 0;
228
229         mutex_lock(&data->data_lock);
230         /*
231          * Only update cached readings once per update interval in periodic
232          * mode. In single shot mode the sensor measures values on demand, so
233          * every time the sysfs interface is called, a measurement is triggered.
234          * In periodic mode however, the measurement process is handled
235          * internally by the sensor and reading out sensor values only makes
236          * sense if a new reading is available.
237          */
238         if (time_after(jiffies, data->last_update + interval_jiffies)) {
239                 ret = sht3x_read_from_command(client, data, data->command, buf,
240                                               sizeof(buf), data->wait_time);
241                 if (ret)
242                         goto out;
243
244                 val = be16_to_cpup((__be16 *)buf);
245                 data->temperature = sht3x_extract_temperature(val);
246                 val = be16_to_cpup((__be16 *)(buf + 3));
247                 data->humidity = sht3x_extract_humidity(val);
248                 data->last_update = jiffies;
249         }
250
251 out:
252         mutex_unlock(&data->data_lock);
253         if (ret)
254                 return ERR_PTR(ret);
255
256         return data;
257 }
258
259 /* sysfs attributes */
260 static ssize_t temp1_input_show(struct device *dev,
261                                 struct device_attribute *attr, char *buf)
262 {
263         struct sht3x_data *data = sht3x_update_client(dev);
264
265         if (IS_ERR(data))
266                 return PTR_ERR(data);
267
268         return sprintf(buf, "%d\n", data->temperature);
269 }
270
271 static ssize_t humidity1_input_show(struct device *dev,
272                                     struct device_attribute *attr, char *buf)
273 {
274         struct sht3x_data *data = sht3x_update_client(dev);
275
276         if (IS_ERR(data))
277                 return PTR_ERR(data);
278
279         return sprintf(buf, "%u\n", data->humidity);
280 }
281
282 /*
283  * limits_update must only be called from probe or with data_lock held
284  */
285 static int limits_update(struct sht3x_data *data)
286 {
287         int ret;
288         u8 index;
289         int temperature;
290         u32 humidity;
291         u16 raw;
292         char buffer[SHT3X_RESPONSE_LENGTH];
293         const struct sht3x_limit_commands *commands;
294         struct i2c_client *client = data->client;
295
296         for (index = 0; index < SHT3X_NUM_LIMIT_CMD; index++) {
297                 commands = &limit_commands[index];
298                 ret = sht3x_read_from_command(client, data,
299                                               commands->read_command, buffer,
300                                               SHT3X_RESPONSE_LENGTH, 0);
301
302                 if (ret)
303                         return ret;
304
305                 raw = be16_to_cpup((__be16 *)buffer);
306                 temperature = sht3x_extract_temperature((raw & 0x01ff) << 7);
307                 humidity = sht3x_extract_humidity(raw & 0xfe00);
308                 data->temperature_limits[index] = temperature;
309                 data->humidity_limits[index] = humidity;
310         }
311
312         return ret;
313 }
314
315 static ssize_t temp1_limit_show(struct device *dev,
316                                 struct device_attribute *attr,
317                                 char *buf)
318 {
319         struct sht3x_data *data = dev_get_drvdata(dev);
320         u8 index = to_sensor_dev_attr(attr)->index;
321         int temperature_limit = data->temperature_limits[index];
322
323         return scnprintf(buf, PAGE_SIZE, "%d\n", temperature_limit);
324 }
325
326 static ssize_t humidity1_limit_show(struct device *dev,
327                                     struct device_attribute *attr,
328                                     char *buf)
329 {
330         struct sht3x_data *data = dev_get_drvdata(dev);
331         u8 index = to_sensor_dev_attr(attr)->index;
332         u32 humidity_limit = data->humidity_limits[index];
333
334         return scnprintf(buf, PAGE_SIZE, "%u\n", humidity_limit);
335 }
336
337 /*
338  * limit_store must only be called with data_lock held
339  */
340 static size_t limit_store(struct device *dev,
341                           size_t count,
342                           u8 index,
343                           int temperature,
344                           u32 humidity)
345 {
346         char buffer[SHT3X_CMD_LENGTH + SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
347         char *position = buffer;
348         int ret;
349         u16 raw;
350         struct sht3x_data *data = dev_get_drvdata(dev);
351         struct i2c_client *client = data->client;
352         const struct sht3x_limit_commands *commands;
353
354         commands = &limit_commands[index];
355
356         memcpy(position, commands->write_command, SHT3X_CMD_LENGTH);
357         position += SHT3X_CMD_LENGTH;
358         /*
359          * ST = (T + 45) / 175 * 2^16
360          * SRH = RH / 100 * 2^16
361          * adapted for fixed point arithmetic and packed the same as
362          * in limit_show()
363          */
364         raw = ((u32)(temperature + 45000) * 24543) >> (16 + 7);
365         raw |= ((humidity * 42950) >> 16) & 0xfe00;
366
367         *((__be16 *)position) = cpu_to_be16(raw);
368         position += SHT3X_WORD_LEN;
369         *position = crc8(sht3x_crc8_table,
370                          position - SHT3X_WORD_LEN,
371                          SHT3X_WORD_LEN,
372                          SHT3X_CRC8_INIT);
373
374         mutex_lock(&data->i2c_lock);
375         ret = i2c_master_send(client, buffer, sizeof(buffer));
376         mutex_unlock(&data->i2c_lock);
377
378         if (ret != sizeof(buffer))
379                 return ret < 0 ? ret : -EIO;
380
381         data->temperature_limits[index] = temperature;
382         data->humidity_limits[index] = humidity;
383         return count;
384 }
385
386 static ssize_t temp1_limit_store(struct device *dev,
387                                  struct device_attribute *attr,
388                                  const char *buf,
389                                  size_t count)
390 {
391         int temperature;
392         int ret;
393         struct sht3x_data *data = dev_get_drvdata(dev);
394         u8 index = to_sensor_dev_attr(attr)->index;
395
396         ret = kstrtoint(buf, 0, &temperature);
397         if (ret)
398                 return ret;
399
400         temperature = clamp_val(temperature, SHT3X_MIN_TEMPERATURE,
401                                 SHT3X_MAX_TEMPERATURE);
402         mutex_lock(&data->data_lock);
403         ret = limit_store(dev, count, index, temperature,
404                           data->humidity_limits[index]);
405         mutex_unlock(&data->data_lock);
406
407         return ret;
408 }
409
410 static ssize_t humidity1_limit_store(struct device *dev,
411                                      struct device_attribute *attr,
412                                      const char *buf,
413                                      size_t count)
414 {
415         u32 humidity;
416         int ret;
417         struct sht3x_data *data = dev_get_drvdata(dev);
418         u8 index = to_sensor_dev_attr(attr)->index;
419
420         ret = kstrtou32(buf, 0, &humidity);
421         if (ret)
422                 return ret;
423
424         humidity = clamp_val(humidity, SHT3X_MIN_HUMIDITY, SHT3X_MAX_HUMIDITY);
425         mutex_lock(&data->data_lock);
426         ret = limit_store(dev, count, index, data->temperature_limits[index],
427                           humidity);
428         mutex_unlock(&data->data_lock);
429
430         return ret;
431 }
432
433 static void sht3x_select_command(struct sht3x_data *data)
434 {
435         /*
436          * In blocking mode (clock stretching mode) the I2C bus
437          * is blocked for other traffic, thus the call to i2c_master_recv()
438          * will wait until the data is ready. For non blocking mode, we
439          * have to wait ourselves.
440          */
441         if (data->mode > 0) {
442                 data->command = sht3x_cmd_measure_periodic_mode;
443                 data->wait_time = 0;
444         } else if (data->setup.blocking_io) {
445                 data->command = data->setup.high_precision ?
446                                 sht3x_cmd_measure_blocking_hpm :
447                                 sht3x_cmd_measure_blocking_lpm;
448                 data->wait_time = 0;
449         } else {
450                 if (data->setup.high_precision) {
451                         data->command = sht3x_cmd_measure_nonblocking_hpm;
452                         data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_HPM;
453                 } else {
454                         data->command = sht3x_cmd_measure_nonblocking_lpm;
455                         data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_LPM;
456                 }
457         }
458 }
459
460 static int status_register_read(struct device *dev,
461                                 struct device_attribute *attr,
462                                 char *buffer, int length)
463 {
464         int ret;
465         struct sht3x_data *data = dev_get_drvdata(dev);
466         struct i2c_client *client = data->client;
467
468         ret = sht3x_read_from_command(client, data, sht3x_cmd_read_status_reg,
469                                       buffer, length, 0);
470
471         return ret;
472 }
473
474 static ssize_t temp1_alarm_show(struct device *dev,
475                                 struct device_attribute *attr,
476                                 char *buf)
477 {
478         char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
479         int ret;
480
481         ret = status_register_read(dev, attr, buffer,
482                                    SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
483         if (ret)
484                 return ret;
485
486         return scnprintf(buf, PAGE_SIZE, "%d\n", !!(buffer[0] & 0x04));
487 }
488
489 static ssize_t humidity1_alarm_show(struct device *dev,
490                                     struct device_attribute *attr,
491                                     char *buf)
492 {
493         char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
494         int ret;
495
496         ret = status_register_read(dev, attr, buffer,
497                                    SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
498         if (ret)
499                 return ret;
500
501         return scnprintf(buf, PAGE_SIZE, "%d\n", !!(buffer[0] & 0x08));
502 }
503
504 static ssize_t heater_enable_show(struct device *dev,
505                                   struct device_attribute *attr,
506                                   char *buf)
507 {
508         char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
509         int ret;
510
511         ret = status_register_read(dev, attr, buffer,
512                                    SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
513         if (ret)
514                 return ret;
515
516         return scnprintf(buf, PAGE_SIZE, "%d\n", !!(buffer[0] & 0x20));
517 }
518
519 static ssize_t heater_enable_store(struct device *dev,
520                                    struct device_attribute *attr,
521                                    const char *buf,
522                                    size_t count)
523 {
524         struct sht3x_data *data = dev_get_drvdata(dev);
525         struct i2c_client *client = data->client;
526         int ret;
527         bool status;
528
529         ret = kstrtobool(buf, &status);
530         if (ret)
531                 return ret;
532
533         mutex_lock(&data->i2c_lock);
534
535         if (status)
536                 ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_on,
537                                       SHT3X_CMD_LENGTH);
538         else
539                 ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_off,
540                                       SHT3X_CMD_LENGTH);
541
542         mutex_unlock(&data->i2c_lock);
543
544         return ret;
545 }
546
547 static ssize_t update_interval_show(struct device *dev,
548                                     struct device_attribute *attr,
549                                     char *buf)
550 {
551         struct sht3x_data *data = dev_get_drvdata(dev);
552
553         return scnprintf(buf, PAGE_SIZE, "%u\n",
554                          mode_to_update_interval[data->mode]);
555 }
556
557 static ssize_t update_interval_store(struct device *dev,
558                                      struct device_attribute *attr,
559                                      const char *buf,
560                                      size_t count)
561 {
562         u16 update_interval;
563         u8 mode;
564         int ret;
565         const char *command;
566         struct sht3x_data *data = dev_get_drvdata(dev);
567         struct i2c_client *client = data->client;
568
569         ret = kstrtou16(buf, 0, &update_interval);
570         if (ret)
571                 return ret;
572
573         mode = get_mode_from_update_interval(update_interval);
574
575         mutex_lock(&data->data_lock);
576         /* mode did not change */
577         if (mode == data->mode) {
578                 mutex_unlock(&data->data_lock);
579                 return count;
580         }
581
582         mutex_lock(&data->i2c_lock);
583         /*
584          * Abort periodic measure mode.
585          * To do any changes to the configuration while in periodic mode, we
586          * have to send a break command to the sensor, which then falls back
587          * to single shot (mode = 0).
588          */
589         if (data->mode > 0) {
590                 ret = i2c_master_send(client, sht3x_cmd_break,
591                                       SHT3X_CMD_LENGTH);
592                 if (ret != SHT3X_CMD_LENGTH)
593                         goto out;
594                 data->mode = 0;
595         }
596
597         if (mode > 0) {
598                 if (data->setup.high_precision)
599                         command = periodic_measure_commands_hpm[mode - 1];
600                 else
601                         command = periodic_measure_commands_lpm[mode - 1];
602
603                 /* select mode */
604                 ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
605                 if (ret != SHT3X_CMD_LENGTH)
606                         goto out;
607         }
608
609         /* select mode and command */
610         data->mode = mode;
611         sht3x_select_command(data);
612
613 out:
614         mutex_unlock(&data->i2c_lock);
615         mutex_unlock(&data->data_lock);
616         if (ret != SHT3X_CMD_LENGTH)
617                 return ret < 0 ? ret : -EIO;
618
619         return count;
620 }
621
622 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp1_input, 0);
623 static SENSOR_DEVICE_ATTR_RO(humidity1_input, humidity1_input, 0);
624 static SENSOR_DEVICE_ATTR_RW(temp1_max, temp1_limit, limit_max);
625 static SENSOR_DEVICE_ATTR_RW(humidity1_max, humidity1_limit, limit_max);
626 static SENSOR_DEVICE_ATTR_RW(temp1_max_hyst, temp1_limit, limit_max_hyst);
627 static SENSOR_DEVICE_ATTR_RW(humidity1_max_hyst, humidity1_limit,
628                              limit_max_hyst);
629 static SENSOR_DEVICE_ATTR_RW(temp1_min, temp1_limit, limit_min);
630 static SENSOR_DEVICE_ATTR_RW(humidity1_min, humidity1_limit, limit_min);
631 static SENSOR_DEVICE_ATTR_RW(temp1_min_hyst, temp1_limit, limit_min_hyst);
632 static SENSOR_DEVICE_ATTR_RW(humidity1_min_hyst, humidity1_limit,
633                              limit_min_hyst);
634 static SENSOR_DEVICE_ATTR_RO(temp1_alarm, temp1_alarm, 0);
635 static SENSOR_DEVICE_ATTR_RO(humidity1_alarm, humidity1_alarm, 0);
636 static SENSOR_DEVICE_ATTR_RW(heater_enable, heater_enable, 0);
637 static SENSOR_DEVICE_ATTR_RW(update_interval, update_interval, 0);
638
639 static struct attribute *sht3x_attrs[] = {
640         &sensor_dev_attr_temp1_input.dev_attr.attr,
641         &sensor_dev_attr_humidity1_input.dev_attr.attr,
642         &sensor_dev_attr_temp1_max.dev_attr.attr,
643         &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
644         &sensor_dev_attr_humidity1_max.dev_attr.attr,
645         &sensor_dev_attr_humidity1_max_hyst.dev_attr.attr,
646         &sensor_dev_attr_temp1_min.dev_attr.attr,
647         &sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
648         &sensor_dev_attr_humidity1_min.dev_attr.attr,
649         &sensor_dev_attr_humidity1_min_hyst.dev_attr.attr,
650         &sensor_dev_attr_temp1_alarm.dev_attr.attr,
651         &sensor_dev_attr_humidity1_alarm.dev_attr.attr,
652         &sensor_dev_attr_heater_enable.dev_attr.attr,
653         &sensor_dev_attr_update_interval.dev_attr.attr,
654         NULL
655 };
656
657 static struct attribute *sts3x_attrs[] = {
658         &sensor_dev_attr_temp1_input.dev_attr.attr,
659         NULL
660 };
661
662 ATTRIBUTE_GROUPS(sht3x);
663 ATTRIBUTE_GROUPS(sts3x);
664
665 static int sht3x_probe(struct i2c_client *client,
666                        const struct i2c_device_id *id)
667 {
668         int ret;
669         struct sht3x_data *data;
670         struct device *hwmon_dev;
671         struct i2c_adapter *adap = client->adapter;
672         struct device *dev = &client->dev;
673         const struct attribute_group **attribute_groups;
674
675         /*
676          * we require full i2c support since the sht3x uses multi-byte read and
677          * writes as well as multi-byte commands which are not supported by
678          * the smbus protocol
679          */
680         if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
681                 return -ENODEV;
682
683         ret = i2c_master_send(client, sht3x_cmd_clear_status_reg,
684                               SHT3X_CMD_LENGTH);
685         if (ret != SHT3X_CMD_LENGTH)
686                 return ret < 0 ? ret : -ENODEV;
687
688         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
689         if (!data)
690                 return -ENOMEM;
691
692         data->setup.blocking_io = false;
693         data->setup.high_precision = true;
694         data->mode = 0;
695         data->last_update = jiffies - msecs_to_jiffies(3000);
696         data->client = client;
697         crc8_populate_msb(sht3x_crc8_table, SHT3X_CRC8_POLYNOMIAL);
698
699         if (client->dev.platform_data)
700                 data->setup = *(struct sht3x_platform_data *)dev->platform_data;
701
702         sht3x_select_command(data);
703
704         mutex_init(&data->i2c_lock);
705         mutex_init(&data->data_lock);
706
707         /*
708          * An attempt to read limits register too early
709          * causes a NACK response from the chip.
710          * Waiting for an empirical delay of 500 us solves the issue.
711          */
712         usleep_range(500, 600);
713
714         ret = limits_update(data);
715         if (ret)
716                 return ret;
717
718         if (id->driver_data == sts3x)
719                 attribute_groups = sts3x_groups;
720         else
721                 attribute_groups = sht3x_groups;
722
723         hwmon_dev = devm_hwmon_device_register_with_groups(dev,
724                                                            client->name,
725                                                            data,
726                                                            attribute_groups);
727
728         if (IS_ERR(hwmon_dev))
729                 dev_dbg(dev, "unable to register hwmon device\n");
730
731         return PTR_ERR_OR_ZERO(hwmon_dev);
732 }
733
734 /* device ID table */
735 static const struct i2c_device_id sht3x_ids[] = {
736         {"sht3x", sht3x},
737         {"sts3x", sts3x},
738         {}
739 };
740
741 MODULE_DEVICE_TABLE(i2c, sht3x_ids);
742
743 static struct i2c_driver sht3x_i2c_driver = {
744         .driver.name = "sht3x",
745         .probe       = sht3x_probe,
746         .id_table    = sht3x_ids,
747 };
748
749 module_i2c_driver(sht3x_i2c_driver);
750
751 MODULE_AUTHOR("David Frey <david.frey@sensirion.com>");
752 MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
753 MODULE_DESCRIPTION("Sensirion SHT3x humidity and temperature sensor driver");
754 MODULE_LICENSE("GPL");