summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/sht3x.c
blob: c0d02fbcdb76c25e52a6a4b0da66320458c516c5 (plain)
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
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
// SPDX-License-Identifier: GPL-2.0-or-later
/* 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>
 */

#include <asm/page.h>
#include <linux/crc8.h>
#include <linux/debugfs.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>

/* commands (high repeatability mode) */
static const unsigned char sht3x_cmd_measure_single_hpm[] = { 0x24, 0x00 };

/* commands (medium repeatability mode) */
static const unsigned char sht3x_cmd_measure_single_mpm[] = { 0x24, 0x0b };

/* commands (low repeatability mode) */
static const unsigned char sht3x_cmd_measure_single_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 };
static const unsigned char sht3x_cmd_read_serial_number[]      = { 0x37, 0x80 };

static struct dentry *debugfs;

/* delays for single-shot mode i2c commands, both in us */
#define SHT3X_SINGLE_WAIT_TIME_HPM  15000
#define SHT3X_SINGLE_WAIT_TIME_MPM   6000
#define SHT3X_SINGLE_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,
};

enum sht3x_repeatability {
	low_repeatability,
	medium_repeatability,
	high_repeatability,
};

DECLARE_CRC8_TABLE(sht3x_crc8_table);

/* periodic measure commands (high repeatability 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 (medium repeatability) */
static const char periodic_measure_commands_mpm[][SHT3X_CMD_LENGTH] = {
	/* 0.5 measurements per second */
	{0x20, 0x24},
	/* 1 measurements per second */
	{0x21, 0x26},
	/* 2 measurements per second */
	{0x22, 0x20},
	/* 4 measurements per second */
	{0x23, 0x22},
	/* 10 measurements per second */
	{0x27, 0x21},
};

/* periodic measure commands (low repeatability 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,
};

static const struct hwmon_channel_info * const sht3x_channel_info[] = {
	HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN |
				HWMON_T_MIN_HYST | HWMON_T_MAX |
				HWMON_T_MAX_HYST | HWMON_T_ALARM),
	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT | HWMON_H_MIN |
				HWMON_H_MIN_HYST | HWMON_H_MAX |
				HWMON_H_MAX_HYST | HWMON_H_ALARM),
	NULL,
};

struct sht3x_data {
	struct i2c_client *client;
	enum sht3x_chips chip_id;
	struct mutex i2c_lock; /* lock for sending i2c commands */
	struct mutex data_lock; /* lock for updating driver data */
	struct dentry *sensor_dir;

	u8 mode;
	const unsigned char *command;
	u32 wait_time;			/* in us*/
	unsigned long last_update;	/* last update in periodic mode*/
	enum sht3x_repeatability repeatability;
	u32 serial_number;

	/*
	 * 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;
}

static int temp1_input_read(struct device *dev)
{
	struct sht3x_data *data = sht3x_update_client(dev);

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

	return data->temperature;
}

static int humidity1_input_read(struct device *dev)
{
	struct sht3x_data *data = sht3x_update_client(dev);

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

	return 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 int temp1_limit_read(struct device *dev, int index)
{
	struct sht3x_data *data = dev_get_drvdata(dev);

	return data->temperature_limits[index];
}

static int humidity1_limit_read(struct device *dev, int index)
{
	struct sht3x_data *data = dev_get_drvdata(dev);

	return data->humidity_limits[index];
}

/*
 * limit_write must only be called with data_lock held
 */
static size_t limit_write(struct device *dev,
			  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_read()
	 */
	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 0;
}

static int temp1_limit_write(struct device *dev, int index, int val)
{
	int temperature;
	int ret;
	struct sht3x_data *data = dev_get_drvdata(dev);

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

	return ret;
}

static int humidity1_limit_write(struct device *dev, int index, int val)
{
	u32 humidity;
	int ret;
	struct sht3x_data *data = dev_get_drvdata(dev);

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

	return ret;
}

static void sht3x_select_command(struct sht3x_data *data)
{
	/*
	 * For single-shot mode, only non blocking mode is support,
	 * we have to wait ourselves for result.
	 */
	if (data->mode > 0) {
		data->command = sht3x_cmd_measure_periodic_mode;
		data->wait_time = 0;
	} else {
		if (data->repeatability == high_repeatability) {
			data->command = sht3x_cmd_measure_single_hpm;
			data->wait_time = SHT3X_SINGLE_WAIT_TIME_HPM;
		} else if (data->repeatability ==  medium_repeatability) {
			data->command = sht3x_cmd_measure_single_mpm;
			data->wait_time = SHT3X_SINGLE_WAIT_TIME_MPM;
		} else {
			data->command = sht3x_cmd_measure_single_lpm;
			data->wait_time = SHT3X_SINGLE_WAIT_TIME_LPM;
		}
	}
}

static int status_register_read(struct device *dev,
				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 int temp1_alarm_read(struct device *dev)
{
	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
	int ret;

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

	return !!(buffer[0] & 0x04);
}

static int humidity1_alarm_read(struct device *dev)
{
	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
	int ret;

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

	return !!(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, buffer,
				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
	if (ret)
		return ret;

	return sysfs_emit(buf, "%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 int update_interval_read(struct device *dev)
{
	struct sht3x_data *data = dev_get_drvdata(dev);

	return mode_to_update_interval[data->mode];
}

static int update_interval_write(struct device *dev, int val)
{
	u8 mode;
	int ret;
	const char *command;
	struct sht3x_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;

	mode = get_mode_from_update_interval(val);

	mutex_lock(&data->data_lock);
	/* mode did not change */
	if (mode == data->mode) {
		mutex_unlock(&data->data_lock);
		return 0;
	}

	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->repeatability == high_repeatability)
			command = periodic_measure_commands_hpm[mode - 1];
		else if (data->repeatability == medium_repeatability)
			command = periodic_measure_commands_mpm[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 0;
}

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

	return sysfs_emit(buf, "%d\n", data->repeatability);
}

static ssize_t repeatability_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf,
				   size_t count)
{
	int ret;
	u8 val;

	struct sht3x_data *data = dev_get_drvdata(dev);

	ret = kstrtou8(buf, 0, &val);
	if (ret)
		return ret;

	if (val > 2)
		return -EINVAL;

	data->repeatability = val;

	return count;
}

static SENSOR_DEVICE_ATTR_RW(heater_enable, heater_enable, 0);
static SENSOR_DEVICE_ATTR_RW(repeatability, repeatability, 0);

static struct attribute *sht3x_attrs[] = {
	&sensor_dev_attr_heater_enable.dev_attr.attr,
	&sensor_dev_attr_repeatability.dev_attr.attr,
	NULL
};

ATTRIBUTE_GROUPS(sht3x);

static umode_t sht3x_is_visible(const void *data, enum hwmon_sensor_types type,
				u32 attr, int channel)
{
	const struct sht3x_data *chip_data = data;

	switch (type) {
	case hwmon_chip:
		switch (attr) {
		case hwmon_chip_update_interval:
			return 0644;
		default:
			break;
		}
		break;
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
		case hwmon_temp_alarm:
			return 0444;
		case hwmon_temp_max:
		case hwmon_temp_max_hyst:
		case hwmon_temp_min:
		case hwmon_temp_min_hyst:
			return 0644;
		default:
			break;
		}
		break;
	case hwmon_humidity:
		if (chip_data->chip_id == sts3x)
			break;
		switch (attr) {
		case hwmon_humidity_input:
		case hwmon_humidity_alarm:
			return 0444;
		case hwmon_humidity_max:
		case hwmon_humidity_max_hyst:
		case hwmon_humidity_min:
		case hwmon_humidity_min_hyst:
			return 0644;
		default:
			break;
		}
		break;
	default:
		break;
	}

	return 0;
}

static int sht3x_read(struct device *dev, enum hwmon_sensor_types type,
		      u32 attr, int channel, long *val)
{
	enum sht3x_limits index;

	switch (type) {
	case hwmon_chip:
		switch (attr) {
		case hwmon_chip_update_interval:
			*val = update_interval_read(dev);
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
			*val = temp1_input_read(dev);
			break;
		case hwmon_temp_alarm:
			*val = temp1_alarm_read(dev);
			break;
		case hwmon_temp_max:
			index = limit_max;
			*val = temp1_limit_read(dev, index);
			break;
		case hwmon_temp_max_hyst:
			index = limit_max_hyst;
			*val = temp1_limit_read(dev, index);
			break;
		case hwmon_temp_min:
			index = limit_min;
			*val = temp1_limit_read(dev, index);
			break;
		case hwmon_temp_min_hyst:
			index = limit_min_hyst;
			*val = temp1_limit_read(dev, index);
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	case hwmon_humidity:
		switch (attr) {
		case hwmon_humidity_input:
			*val = humidity1_input_read(dev);
			break;
		case hwmon_humidity_alarm:
			*val = humidity1_alarm_read(dev);
			break;
		case hwmon_humidity_max:
			index = limit_max;
			*val = humidity1_limit_read(dev, index);
			break;
		case hwmon_humidity_max_hyst:
			index = limit_max_hyst;
			*val = humidity1_limit_read(dev, index);
			break;
		case hwmon_humidity_min:
			index = limit_min;
			*val = humidity1_limit_read(dev, index);
			break;
		case hwmon_humidity_min_hyst:
			index = limit_min_hyst;
			*val = humidity1_limit_read(dev, index);
			break;
		default:
			return -EOPNOTSUPP;
		}
		break;
	default:
		return -EOPNOTSUPP;
	}

	return 0;
}

static int sht3x_write(struct device *dev, enum hwmon_sensor_types type,
		       u32 attr, int channel, long val)
{
	enum sht3x_limits index;

	switch (type) {
	case hwmon_chip:
		switch (attr) {
		case hwmon_chip_update_interval:
			return update_interval_write(dev, val);
		default:
			return -EOPNOTSUPP;
		}
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_max:
			index = limit_max;
			break;
		case hwmon_temp_max_hyst:
			index = limit_max_hyst;
			break;
		case hwmon_temp_min:
			index = limit_min;
			break;
		case hwmon_temp_min_hyst:
			index = limit_min_hyst;
			break;
		default:
			return -EOPNOTSUPP;
		}
		return temp1_limit_write(dev, index, val);
	case hwmon_humidity:
		switch (attr) {
		case hwmon_humidity_max:
			index = limit_max;
			break;
		case hwmon_humidity_max_hyst:
			index = limit_max_hyst;
			break;
		case hwmon_humidity_min:
			index = limit_min;
			break;
		case hwmon_humidity_min_hyst:
			index = limit_min_hyst;
			break;
		default:
			return -EOPNOTSUPP;
		}
		return humidity1_limit_write(dev, index, val);
	default:
		return -EOPNOTSUPP;
	}
}

static void sht3x_debugfs_init(struct sht3x_data *data)
{
	char name[32];

	snprintf(name, sizeof(name), "i2c%u-%02x",
		 data->client->adapter->nr, data->client->addr);
	data->sensor_dir = debugfs_create_dir(name, debugfs);
	debugfs_create_u32("serial_number", 0444,
			   data->sensor_dir, &data->serial_number);
}

static void sht3x_debugfs_remove(void *sensor_dir)
{
	debugfs_remove_recursive(sensor_dir);
}

static int sht3x_serial_number_read(struct sht3x_data *data)
{
	int ret;
	char buffer[SHT3X_RESPONSE_LENGTH];
	struct i2c_client *client = data->client;

	ret = sht3x_read_from_command(client, data,
				      sht3x_cmd_read_serial_number,
				      buffer,
				      SHT3X_RESPONSE_LENGTH, 0);
	if (ret)
		return ret;

	data->serial_number = (buffer[0] << 24) | (buffer[1] << 16) |
			      (buffer[3] << 8) | buffer[4];
	return ret;
}

static const struct hwmon_ops sht3x_ops = {
	.is_visible = sht3x_is_visible,
	.read = sht3x_read,
	.write = sht3x_write,
};

static const struct hwmon_chip_info sht3x_chip_info = {
	.ops = &sht3x_ops,
	.info = sht3x_channel_info,
};

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

MODULE_DEVICE_TABLE(i2c, sht3x_ids);

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

	/*
	 * 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->repeatability = high_repeatability;
	data->mode = 0;
	data->last_update = jiffies - msecs_to_jiffies(3000);
	data->client = client;
	data->chip_id = i2c_match_id(sht3x_ids, client)->driver_data;
	crc8_populate_msb(sht3x_crc8_table, SHT3X_CRC8_POLYNOMIAL);

	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;

	ret = sht3x_serial_number_read(data);
	if (ret) {
		dev_dbg(dev, "unable to read serial number\n");
	} else {
		sht3x_debugfs_init(data);
		ret = devm_add_action_or_reset(dev,
					       sht3x_debugfs_remove,
					       data->sensor_dir);
		if (ret)
			return ret;
	}

	hwmon_dev = devm_hwmon_device_register_with_info(dev,
							 client->name,
							 data,
							 &sht3x_chip_info,
							 sht3x_groups);

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

	return PTR_ERR_OR_ZERO(hwmon_dev);
}

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

static int __init sht3x_init(void)
{
	debugfs = debugfs_create_dir("sht3x", NULL);
	return i2c_add_driver(&sht3x_i2c_driver);
}
module_init(sht3x_init);

static void __exit sht3x_cleanup(void)
{
	debugfs_remove_recursive(debugfs);
	i2c_del_driver(&sht3x_i2c_driver);
}
module_exit(sht3x_cleanup);

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");