summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/sht3x.c
blob: 370b57dafab75424e94bc4eb671939aa2377f0da (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
/* Sensirion SHT3x-DIS humidity and temperature sensor driver.
 * The SHT3x comes in many different versions, this driver is for the
 * I2C version only.
 *
 * Copyright (C) 2016 Sensirion AG, Switzerland
 * Author: David Frey <david.frey@sensirion.com>
 * Author: Pascal Sachs <pascal.sachs@sensirion.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#include <asm/page.h>
#include <linux/crc8.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/platform_data/sht3x.h>

/* commands (high precision mode) */
static const unsigned char sht3x_cmd_measure_blocking_hpm[]    = { 0x2c, 0x06 };
static const unsigned char sht3x_cmd_measure_nonblocking_hpm[] = { 0x24, 0x00 };

/* commands (low power mode) */
static const unsigned char sht3x_cmd_measure_blocking_lpm[]    = { 0x2c, 0x10 };
static const unsigned char sht3x_cmd_measure_nonblocking_lpm[] = { 0x24, 0x16 };

/* commands for periodic mode */
static const unsigned char sht3x_cmd_measure_periodic_mode[]   = { 0xe0, 0x00 };
static const unsigned char sht3x_cmd_break[]                   = { 0x30, 0x93 };

/* commands for heater control */
static const unsigned char sht3x_cmd_heater_on[]               = { 0x30, 0x6d };
static const unsigned char sht3x_cmd_heater_off[]              = { 0x30, 0x66 };

/* other commands */
static const unsigned char sht3x_cmd_read_status_reg[]         = { 0xf3, 0x2d };
static const unsigned char sht3x_cmd_clear_status_reg[]        = { 0x30, 0x41 };

/* delays for non-blocking i2c commands, both in us */
#define SHT3X_NONBLOCKING_WAIT_TIME_HPM  15000
#define SHT3X_NONBLOCKING_WAIT_TIME_LPM   4000

#define SHT3X_WORD_LEN         2
#define SHT3X_CMD_LENGTH       2
#define SHT3X_CRC8_LEN         1
#define SHT3X_RESPONSE_LENGTH  6
#define SHT3X_CRC8_POLYNOMIAL  0x31
#define SHT3X_CRC8_INIT        0xFF
#define SHT3X_MIN_TEMPERATURE  -45000
#define SHT3X_MAX_TEMPERATURE  130000
#define SHT3X_MIN_HUMIDITY     0
#define SHT3X_MAX_HUMIDITY     100000

enum sht3x_chips {
	sht3x,
	sts3x,
};

enum sht3x_limits {
	limit_max = 0,
	limit_max_hyst,
	limit_min,
	limit_min_hyst,
};

DECLARE_CRC8_TABLE(sht3x_crc8_table);

/* periodic measure commands (high precision mode) */
static const char periodic_measure_commands_hpm[][SHT3X_CMD_LENGTH] = {
	/* 0.5 measurements per second */
	{0x20, 0x32},
	/* 1 measurements per second */
	{0x21, 0x30},
	/* 2 measurements per second */
	{0x22, 0x36},
	/* 4 measurements per second */
	{0x23, 0x34},
	/* 10 measurements per second */
	{0x27, 0x37},
};

/* periodic measure commands (low power mode) */
static const char periodic_measure_commands_lpm[][SHT3X_CMD_LENGTH] = {
	/* 0.5 measurements per second */
	{0x20, 0x2f},
	/* 1 measurements per second */
	{0x21, 0x2d},
	/* 2 measurements per second */
	{0x22, 0x2b},
	/* 4 measurements per second */
	{0x23, 0x29},
	/* 10 measurements per second */
	{0x27, 0x2a},
};

struct sht3x_limit_commands {
	const char read_command[SHT3X_CMD_LENGTH];
	const char write_command[SHT3X_CMD_LENGTH];
};

static const struct sht3x_limit_commands limit_commands[] = {
	/* temp1_max, humidity1_max */
	[limit_max] = { {0xe1, 0x1f}, {0x61, 0x1d} },
	/* temp_1_max_hyst, humidity1_max_hyst */
	[limit_max_hyst] = { {0xe1, 0x14}, {0x61, 0x16} },
	/* temp1_min, humidity1_min */
	[limit_min] = { {0xe1, 0x02}, {0x61, 0x00} },
	/* temp_1_min_hyst, humidity1_min_hyst */
	[limit_min_hyst] = { {0xe1, 0x09}, {0x61, 0x0B} },
};

#define SHT3X_NUM_LIMIT_CMD  ARRAY_SIZE(limit_commands)

static const u16 mode_to_update_interval[] = {
	   0,
	2000,
	1000,
	 500,
	 250,
	 100,
};

struct sht3x_data {
	struct i2c_client *client;
	struct mutex i2c_lock; /* lock for sending i2c commands */
	struct mutex data_lock; /* lock for updating driver data */

	u8 mode;
	const unsigned char *command;
	u32 wait_time;			/* in us*/
	unsigned long last_update;	/* last update in periodic mode*/

	struct sht3x_platform_data setup;

	/*
	 * cached values for temperature and humidity and limits
	 * the limits arrays have the following order:
	 * max, max_hyst, min, min_hyst
	 */
	int temperature;
	int temperature_limits[SHT3X_NUM_LIMIT_CMD];
	u32 humidity;
	u32 humidity_limits[SHT3X_NUM_LIMIT_CMD];
};

static u8 get_mode_from_update_interval(u16 value)
{
	size_t index;
	u8 number_of_modes = ARRAY_SIZE(mode_to_update_interval);

	if (value == 0)
		return 0;

	/* find next faster update interval */
	for (index = 1; index < number_of_modes; index++) {
		if (mode_to_update_interval[index] <= value)
			return index;
	}

	return number_of_modes - 1;
}

static int sht3x_read_from_command(struct i2c_client *client,
				   struct sht3x_data *data,
				   const char *command,
				   char *buf, int length, u32 wait_time)
{
	int ret;

	mutex_lock(&data->i2c_lock);
	ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);

	if (ret != SHT3X_CMD_LENGTH) {
		ret = ret < 0 ? ret : -EIO;
		goto out;
	}

	if (wait_time)
		usleep_range(wait_time, wait_time + 1000);

	ret = i2c_master_recv(client, buf, length);
	if (ret != length) {
		ret = ret < 0 ? ret : -EIO;
		goto out;
	}

	ret = 0;
out:
	mutex_unlock(&data->i2c_lock);
	return ret;
}

static int sht3x_extract_temperature(u16 raw)
{
	/*
	 * From datasheet:
	 * T = -45 + 175 * ST / 2^16
	 * Adapted for integer fixed point (3 digit) arithmetic.
	 */
	return ((21875 * (int)raw) >> 13) - 45000;
}

static u32 sht3x_extract_humidity(u16 raw)
{
	/*
	 * From datasheet:
	 * RH = 100 * SRH / 2^16
	 * Adapted for integer fixed point (3 digit) arithmetic.
	 */
	return (12500 * (u32)raw) >> 13;
}

static struct sht3x_data *sht3x_update_client(struct device *dev)
{
	struct sht3x_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	u16 interval_ms = mode_to_update_interval[data->mode];
	unsigned long interval_jiffies = msecs_to_jiffies(interval_ms);
	unsigned char buf[SHT3X_RESPONSE_LENGTH];
	u16 val;
	int ret = 0;

	mutex_lock(&data->data_lock);
	/*
	 * Only update cached readings once per update interval in periodic
	 * mode. In single shot mode the sensor measures values on demand, so
	 * every time the sysfs interface is called, a measurement is triggered.
	 * In periodic mode however, the measurement process is handled
	 * internally by the sensor and reading out sensor values only makes
	 * sense if a new reading is available.
	 */
	if (time_after(jiffies, data->last_update + interval_jiffies)) {
		ret = sht3x_read_from_command(client, data, data->command, buf,
					      sizeof(buf), data->wait_time);
		if (ret)
			goto out;

		val = be16_to_cpup((__be16 *)buf);
		data->temperature = sht3x_extract_temperature(val);
		val = be16_to_cpup((__be16 *)(buf + 3));
		data->humidity = sht3x_extract_humidity(val);
		data->last_update = jiffies;
	}

out:
	mutex_unlock(&data->data_lock);
	if (ret)
		return ERR_PTR(ret);

	return data;
}

/* sysfs attributes */
static ssize_t temp1_input_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct sht3x_data *data = sht3x_update_client(dev);

	if (IS_ERR(data))
		return PTR_ERR(data);

	return sprintf(buf, "%d\n", data->temperature);
}

static ssize_t humidity1_input_show(struct device *dev,
				    struct device_attribute *attr, char *buf)
{
	struct sht3x_data *data = sht3x_update_client(dev);

	if (IS_ERR(data))
		return PTR_ERR(data);

	return sprintf(buf, "%u\n", data->humidity);
}

/*
 * limits_update must only be called from probe or with data_lock held
 */
static int limits_update(struct sht3x_data *data)
{
	int ret;
	u8 index;
	int temperature;
	u32 humidity;
	u16 raw;
	char buffer[SHT3X_RESPONSE_LENGTH];
	const struct sht3x_limit_commands *commands;
	struct i2c_client *client = data->client;

	for (index = 0; index < SHT3X_NUM_LIMIT_CMD; index++) {
		commands = &limit_commands[index];
		ret = sht3x_read_from_command(client, data,
					      commands->read_command, buffer,
					      SHT3X_RESPONSE_LENGTH, 0);

		if (ret)
			return ret;

		raw = be16_to_cpup((__be16 *)buffer);
		temperature = sht3x_extract_temperature((raw & 0x01ff) << 7);
		humidity = sht3x_extract_humidity(raw & 0xfe00);
		data->temperature_limits[index] = temperature;
		data->humidity_limits[index] = humidity;
	}

	return ret;
}

static ssize_t temp1_limit_show(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{
	struct sht3x_data *data = dev_get_drvdata(dev);
	u8 index = to_sensor_dev_attr(attr)->index;
	int temperature_limit = data->temperature_limits[index];

	return scnprintf(buf, PAGE_SIZE, "%d\n", temperature_limit);
}

static ssize_t humidity1_limit_show(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	struct sht3x_data *data = dev_get_drvdata(dev);
	u8 index = to_sensor_dev_attr(attr)->index;
	u32 humidity_limit = data->humidity_limits[index];

	return scnprintf(buf, PAGE_SIZE, "%u\n", humidity_limit);
}

/*
 * limit_store must only be called with data_lock held
 */
static size_t limit_store(struct device *dev,
			  size_t count,
			  u8 index,
			  int temperature,
			  u32 humidity)
{
	char buffer[SHT3X_CMD_LENGTH + SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
	char *position = buffer;
	int ret;
	u16 raw;
	struct sht3x_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	const struct sht3x_limit_commands *commands;

	commands = &limit_commands[index];

	memcpy(position, commands->write_command, SHT3X_CMD_LENGTH);
	position += SHT3X_CMD_LENGTH;
	/*
	 * ST = (T + 45) / 175 * 2^16
	 * SRH = RH / 100 * 2^16
	 * adapted for fixed point arithmetic and packed the same as
	 * in limit_show()
	 */
	raw = ((u32)(temperature + 45000) * 24543) >> (16 + 7);
	raw |= ((humidity * 42950) >> 16) & 0xfe00;

	*((__be16 *)position) = cpu_to_be16(raw);
	position += SHT3X_WORD_LEN;
	*position = crc8(sht3x_crc8_table,
			 position - SHT3X_WORD_LEN,
			 SHT3X_WORD_LEN,
			 SHT3X_CRC8_INIT);

	mutex_lock(&data->i2c_lock);
	ret = i2c_master_send(client, buffer, sizeof(buffer));
	mutex_unlock(&data->i2c_lock);

	if (ret != sizeof(buffer))
		return ret < 0 ? ret : -EIO;

	data->temperature_limits[index] = temperature;
	data->humidity_limits[index] = humidity;
	return count;
}

static ssize_t temp1_limit_store(struct device *dev,
				 struct device_attribute *attr,
				 const char *buf,
				 size_t count)
{
	int temperature;
	int ret;
	struct sht3x_data *data = dev_get_drvdata(dev);
	u8 index = to_sensor_dev_attr(attr)->index;

	ret = kstrtoint(buf, 0, &temperature);
	if (ret)
		return ret;

	temperature = clamp_val(temperature, SHT3X_MIN_TEMPERATURE,
				SHT3X_MAX_TEMPERATURE);
	mutex_lock(&data->data_lock);
	ret = limit_store(dev, count, index, temperature,
			  data->humidity_limits[index]);
	mutex_unlock(&data->data_lock);

	return ret;
}

static ssize_t humidity1_limit_store(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf,
				     size_t count)
{
	u32 humidity;
	int ret;
	struct sht3x_data *data = dev_get_drvdata(dev);
	u8 index = to_sensor_dev_attr(attr)->index;

	ret = kstrtou32(buf, 0, &humidity);
	if (ret)
		return ret;

	humidity = clamp_val(humidity, SHT3X_MIN_HUMIDITY, SHT3X_MAX_HUMIDITY);
	mutex_lock(&data->data_lock);
	ret = limit_store(dev, count, index, data->temperature_limits[index],
			  humidity);
	mutex_unlock(&data->data_lock);

	return ret;
}

static void sht3x_select_command(struct sht3x_data *data)
{
	/*
	 * In blocking mode (clock stretching mode) the I2C bus
	 * is blocked for other traffic, thus the call to i2c_master_recv()
	 * will wait until the data is ready. For non blocking mode, we
	 * have to wait ourselves.
	 */
	if (data->mode > 0) {
		data->command = sht3x_cmd_measure_periodic_mode;
		data->wait_time = 0;
	} else if (data->setup.blocking_io) {
		data->command = data->setup.high_precision ?
				sht3x_cmd_measure_blocking_hpm :
				sht3x_cmd_measure_blocking_lpm;
		data->wait_time = 0;
	} else {
		if (data->setup.high_precision) {
			data->command = sht3x_cmd_measure_nonblocking_hpm;
			data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_HPM;
		} else {
			data->command = sht3x_cmd_measure_nonblocking_lpm;
			data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_LPM;
		}
	}
}

static int status_register_read(struct device *dev,
				struct device_attribute *attr,
				char *buffer, int length)
{
	int ret;
	struct sht3x_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;

	ret = sht3x_read_from_command(client, data, sht3x_cmd_read_status_reg,
				      buffer, length, 0);

	return ret;
}

static ssize_t temp1_alarm_show(struct device *dev,
				struct device_attribute *attr,
				char *buf)
{
	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
	int ret;

	ret = status_register_read(dev, attr, buffer,
				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
	if (ret)
		return ret;

	return scnprintf(buf, PAGE_SIZE, "%d\n", !!(buffer[0] & 0x04));
}

static ssize_t humidity1_alarm_show(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
	int ret;

	ret = status_register_read(dev, attr, buffer,
				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
	if (ret)
		return ret;

	return scnprintf(buf, PAGE_SIZE, "%d\n", !!(buffer[0] & 0x08));
}

static ssize_t heater_enable_show(struct device *dev,
				  struct device_attribute *attr,
				  char *buf)
{
	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
	int ret;

	ret = status_register_read(dev, attr, buffer,
				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
	if (ret)
		return ret;

	return scnprintf(buf, PAGE_SIZE, "%d\n", !!(buffer[0] & 0x20));
}

static ssize_t heater_enable_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf,
				   size_t count)
{
	struct sht3x_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int ret;
	bool status;

	ret = kstrtobool(buf, &status);
	if (ret)
		return ret;

	mutex_lock(&data->i2c_lock);

	if (status)
		ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_on,
				      SHT3X_CMD_LENGTH);
	else
		ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_off,
				      SHT3X_CMD_LENGTH);

	mutex_unlock(&data->i2c_lock);

	return ret;
}

static ssize_t update_interval_show(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	struct sht3x_data *data = dev_get_drvdata(dev);

	return scnprintf(buf, PAGE_SIZE, "%u\n",
			 mode_to_update_interval[data->mode]);
}

static ssize_t update_interval_store(struct device *dev,
				     struct device_attribute *attr,
				     const char *buf,
				     size_t count)
{
	u16 update_interval;
	u8 mode;
	int ret;
	const char *command;
	struct sht3x_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;

	ret = kstrtou16(buf, 0, &update_interval);
	if (ret)
		return ret;

	mode = get_mode_from_update_interval(update_interval);

	mutex_lock(&data->data_lock);
	/* mode did not change */
	if (mode == data->mode) {
		mutex_unlock(&data->data_lock);
		return count;
	}

	mutex_lock(&data->i2c_lock);
	/*
	 * Abort periodic measure mode.
	 * To do any changes to the configuration while in periodic mode, we
	 * have to send a break command to the sensor, which then falls back
	 * to single shot (mode = 0).
	 */
	if (data->mode > 0) {
		ret = i2c_master_send(client, sht3x_cmd_break,
				      SHT3X_CMD_LENGTH);
		if (ret != SHT3X_CMD_LENGTH)
			goto out;
		data->mode = 0;
	}

	if (mode > 0) {
		if (data->setup.high_precision)
			command = periodic_measure_commands_hpm[mode - 1];
		else
			command = periodic_measure_commands_lpm[mode - 1];

		/* select mode */
		ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
		if (ret != SHT3X_CMD_LENGTH)
			goto out;
	}

	/* select mode and command */
	data->mode = mode;
	sht3x_select_command(data);

out:
	mutex_unlock(&data->i2c_lock);
	mutex_unlock(&data->data_lock);
	if (ret != SHT3X_CMD_LENGTH)
		return ret < 0 ? ret : -EIO;

	return count;
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, temp1_input_show, NULL, 0);
static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, humidity1_input_show,
			  NULL, 0);
static SENSOR_DEVICE_ATTR(temp1_max, S_IRUGO | S_IWUSR,
			  temp1_limit_show, temp1_limit_store,
			  limit_max);
static SENSOR_DEVICE_ATTR(humidity1_max, S_IRUGO | S_IWUSR,
			  humidity1_limit_show, humidity1_limit_store,
			  limit_max);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO | S_IWUSR,
			  temp1_limit_show, temp1_limit_store,
			  limit_max_hyst);
static SENSOR_DEVICE_ATTR(humidity1_max_hyst, S_IRUGO | S_IWUSR,
			  humidity1_limit_show, humidity1_limit_store,
			  limit_max_hyst);
static SENSOR_DEVICE_ATTR(temp1_min, S_IRUGO | S_IWUSR,
			  temp1_limit_show, temp1_limit_store,
			  limit_min);
static SENSOR_DEVICE_ATTR(humidity1_min, S_IRUGO | S_IWUSR,
			  humidity1_limit_show, humidity1_limit_store,
			  limit_min);
static SENSOR_DEVICE_ATTR(temp1_min_hyst, S_IRUGO | S_IWUSR,
			  temp1_limit_show, temp1_limit_store,
			  limit_min_hyst);
static SENSOR_DEVICE_ATTR(humidity1_min_hyst, S_IRUGO | S_IWUSR,
			  humidity1_limit_show, humidity1_limit_store,
			  limit_min_hyst);
static SENSOR_DEVICE_ATTR(temp1_alarm, S_IRUGO, temp1_alarm_show, NULL, 0);
static SENSOR_DEVICE_ATTR(humidity1_alarm, S_IRUGO, humidity1_alarm_show,
			  NULL, 0);
static SENSOR_DEVICE_ATTR(heater_enable, S_IRUGO | S_IWUSR,
			  heater_enable_show, heater_enable_store, 0);
static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
			  update_interval_show, update_interval_store, 0);

static struct attribute *sht3x_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_humidity1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_max.dev_attr.attr,
	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
	&sensor_dev_attr_humidity1_max.dev_attr.attr,
	&sensor_dev_attr_humidity1_max_hyst.dev_attr.attr,
	&sensor_dev_attr_temp1_min.dev_attr.attr,
	&sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
	&sensor_dev_attr_humidity1_min.dev_attr.attr,
	&sensor_dev_attr_humidity1_min_hyst.dev_attr.attr,
	&sensor_dev_attr_temp1_alarm.dev_attr.attr,
	&sensor_dev_attr_humidity1_alarm.dev_attr.attr,
	&sensor_dev_attr_heater_enable.dev_attr.attr,
	&sensor_dev_attr_update_interval.dev_attr.attr,
	NULL
};

static struct attribute *sts3x_attrs[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	NULL
};

ATTRIBUTE_GROUPS(sht3x);
ATTRIBUTE_GROUPS(sts3x);

static int sht3x_probe(struct i2c_client *client,
		       const struct i2c_device_id *id)
{
	int ret;
	struct sht3x_data *data;
	struct device *hwmon_dev;
	struct i2c_adapter *adap = client->adapter;
	struct device *dev = &client->dev;
	const struct attribute_group **attribute_groups;

	/*
	 * we require full i2c support since the sht3x uses multi-byte read and
	 * writes as well as multi-byte commands which are not supported by
	 * the smbus protocol
	 */
	if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
		return -ENODEV;

	ret = i2c_master_send(client, sht3x_cmd_clear_status_reg,
			      SHT3X_CMD_LENGTH);
	if (ret != SHT3X_CMD_LENGTH)
		return ret < 0 ? ret : -ENODEV;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->setup.blocking_io = false;
	data->setup.high_precision = true;
	data->mode = 0;
	data->last_update = jiffies - msecs_to_jiffies(3000);
	data->client = client;
	crc8_populate_msb(sht3x_crc8_table, SHT3X_CRC8_POLYNOMIAL);

	if (client->dev.platform_data)
		data->setup = *(struct sht3x_platform_data *)dev->platform_data;

	sht3x_select_command(data);

	mutex_init(&data->i2c_lock);
	mutex_init(&data->data_lock);

	/*
	 * An attempt to read limits register too early
	 * causes a NACK response from the chip.
	 * Waiting for an empirical delay of 500 us solves the issue.
	 */
	usleep_range(500, 600);

	ret = limits_update(data);
	if (ret)
		return ret;

	if (id->driver_data == sts3x)
		attribute_groups = sts3x_groups;
	else
		attribute_groups = sht3x_groups;

	hwmon_dev = devm_hwmon_device_register_with_groups(dev,
							   client->name,
							   data,
							   attribute_groups);

	if (IS_ERR(hwmon_dev))
		dev_dbg(dev, "unable to register hwmon device\n");

	return PTR_ERR_OR_ZERO(hwmon_dev);
}

/* device ID table */
static const struct i2c_device_id sht3x_ids[] = {
	{"sht3x", sht3x},
	{"sts3x", sts3x},
	{}
};

MODULE_DEVICE_TABLE(i2c, sht3x_ids);

static struct i2c_driver sht3x_i2c_driver = {
	.driver.name = "sht3x",
	.probe       = sht3x_probe,
	.id_table    = sht3x_ids,
};

module_i2c_driver(sht3x_i2c_driver);

MODULE_AUTHOR("David Frey <david.frey@sensirion.com>");
MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
MODULE_DESCRIPTION("Sensirion SHT3x humidity and temperature sensor driver");
MODULE_LICENSE("GPL");