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/debugfs.h>
 14#include <linux/delay.h>
 15#include <linux/err.h>
 16#include <linux/hwmon.h>
 17#include <linux/hwmon-sysfs.h>
 18#include <linux/i2c.h>
 19#include <linux/init.h>
 20#include <linux/kernel.h>
 21#include <linux/module.h>
 22#include <linux/slab.h>
 23#include <linux/jiffies.h>
 24
 25/* commands (high repeatability mode) */
 26static const unsigned char sht3x_cmd_measure_single_hpm[] = { 0x24, 0x00 };
 27
 28/* commands (medium repeatability mode) */
 29static const unsigned char sht3x_cmd_measure_single_mpm[] = { 0x24, 0x0b };
 30
 31/* commands (low repeatability mode) */
 32static const unsigned char sht3x_cmd_measure_single_lpm[] = { 0x24, 0x16 };
 33
 34/* commands for periodic mode */
 35static const unsigned char sht3x_cmd_measure_periodic_mode[]   = { 0xe0, 0x00 };
 36static const unsigned char sht3x_cmd_break[]                   = { 0x30, 0x93 };
 37
 38/* commands for heater control */
 39static const unsigned char sht3x_cmd_heater_on[]               = { 0x30, 0x6d };
 40static const unsigned char sht3x_cmd_heater_off[]              = { 0x30, 0x66 };
 41
 42/* other commands */
 43static const unsigned char sht3x_cmd_read_status_reg[]         = { 0xf3, 0x2d };
 44static const unsigned char sht3x_cmd_clear_status_reg[]        = { 0x30, 0x41 };
 45static const unsigned char sht3x_cmd_read_serial_number[]      = { 0x37, 0x80 };
 46
 47/* delays for single-shot mode i2c commands, both in us */
 48#define SHT3X_SINGLE_WAIT_TIME_HPM  15000
 49#define SHT3X_SINGLE_WAIT_TIME_MPM   6000
 50#define SHT3X_SINGLE_WAIT_TIME_LPM   4000
 51
 52#define SHT3X_WORD_LEN         2
 53#define SHT3X_CMD_LENGTH       2
 54#define SHT3X_CRC8_LEN         1
 55#define SHT3X_RESPONSE_LENGTH  6
 56#define SHT3X_CRC8_POLYNOMIAL  0x31
 57#define SHT3X_CRC8_INIT        0xFF
 58#define SHT3X_MIN_TEMPERATURE  -45000
 59#define SHT3X_MAX_TEMPERATURE  130000
 60#define SHT3X_MIN_HUMIDITY     0
 61#define SHT3X_MAX_HUMIDITY     100000
 62
 63enum sht3x_chips {
 64	sht3x,
 65	sts3x,
 66};
 67
 68enum sht3x_limits {
 69	limit_max = 0,
 70	limit_max_hyst,
 71	limit_min,
 72	limit_min_hyst,
 73};
 74
 75enum sht3x_repeatability {
 76	low_repeatability,
 77	medium_repeatability,
 78	high_repeatability,
 79};
 80
 81DECLARE_CRC8_TABLE(sht3x_crc8_table);
 82
 83/* periodic measure commands (high repeatability mode) */
 84static const char periodic_measure_commands_hpm[][SHT3X_CMD_LENGTH] = {
 85	/* 0.5 measurements per second */
 86	{0x20, 0x32},
 87	/* 1 measurements per second */
 88	{0x21, 0x30},
 89	/* 2 measurements per second */
 90	{0x22, 0x36},
 91	/* 4 measurements per second */
 92	{0x23, 0x34},
 93	/* 10 measurements per second */
 94	{0x27, 0x37},
 95};
 96
 97/* periodic measure commands (medium repeatability) */
 98static const char periodic_measure_commands_mpm[][SHT3X_CMD_LENGTH] = {
 99	/* 0.5 measurements per second */
100	{0x20, 0x24},
101	/* 1 measurements per second */
102	{0x21, 0x26},
103	/* 2 measurements per second */
104	{0x22, 0x20},
105	/* 4 measurements per second */
106	{0x23, 0x22},
107	/* 10 measurements per second */
108	{0x27, 0x21},
109};
110
111/* periodic measure commands (low repeatability mode) */
112static const char periodic_measure_commands_lpm[][SHT3X_CMD_LENGTH] = {
113	/* 0.5 measurements per second */
114	{0x20, 0x2f},
115	/* 1 measurements per second */
116	{0x21, 0x2d},
117	/* 2 measurements per second */
118	{0x22, 0x2b},
119	/* 4 measurements per second */
120	{0x23, 0x29},
121	/* 10 measurements per second */
122	{0x27, 0x2a},
123};
124
125struct sht3x_limit_commands {
126	const char read_command[SHT3X_CMD_LENGTH];
127	const char write_command[SHT3X_CMD_LENGTH];
128};
129
130static const struct sht3x_limit_commands limit_commands[] = {
131	/* temp1_max, humidity1_max */
132	[limit_max] = { {0xe1, 0x1f}, {0x61, 0x1d} },
133	/* temp_1_max_hyst, humidity1_max_hyst */
134	[limit_max_hyst] = { {0xe1, 0x14}, {0x61, 0x16} },
135	/* temp1_min, humidity1_min */
136	[limit_min] = { {0xe1, 0x02}, {0x61, 0x00} },
137	/* temp_1_min_hyst, humidity1_min_hyst */
138	[limit_min_hyst] = { {0xe1, 0x09}, {0x61, 0x0B} },
139};
140
141#define SHT3X_NUM_LIMIT_CMD  ARRAY_SIZE(limit_commands)
142
143static const u16 mode_to_update_interval[] = {
144	   0,
145	2000,
146	1000,
147	 500,
148	 250,
149	 100,
150};
151
152static const struct hwmon_channel_info * const sht3x_channel_info[] = {
153	HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
154	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN |
155				HWMON_T_MIN_HYST | HWMON_T_MAX |
156				HWMON_T_MAX_HYST | HWMON_T_ALARM),
157	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT | HWMON_H_MIN |
158				HWMON_H_MIN_HYST | HWMON_H_MAX |
159				HWMON_H_MAX_HYST | HWMON_H_ALARM),
160	NULL,
161};
162
163struct sht3x_data {
164	struct i2c_client *client;
165	enum sht3x_chips chip_id;
166	struct mutex i2c_lock; /* lock for sending i2c commands */
167	struct mutex data_lock; /* lock for updating driver data */
168
169	u8 mode;
170	const unsigned char *command;
171	u32 wait_time;			/* in us*/
172	unsigned long last_update;	/* last update in periodic mode*/
173	enum sht3x_repeatability repeatability;
174	u32 serial_number;
175
176	/*
177	 * cached values for temperature and humidity and limits
178	 * the limits arrays have the following order:
179	 * max, max_hyst, min, min_hyst
180	 */
181	int temperature;
182	int temperature_limits[SHT3X_NUM_LIMIT_CMD];
183	u32 humidity;
184	u32 humidity_limits[SHT3X_NUM_LIMIT_CMD];
185};
186
187static u8 get_mode_from_update_interval(u16 value)
188{
189	size_t index;
190	u8 number_of_modes = ARRAY_SIZE(mode_to_update_interval);
191
192	if (value == 0)
193		return 0;
194
195	/* find next faster update interval */
196	for (index = 1; index < number_of_modes; index++) {
197		if (mode_to_update_interval[index] <= value)
198			return index;
199	}
200
201	return number_of_modes - 1;
202}
203
204static int sht3x_read_from_command(struct i2c_client *client,
205				   struct sht3x_data *data,
206				   const char *command,
207				   char *buf, int length, u32 wait_time)
208{
209	int ret;
210
211	mutex_lock(&data->i2c_lock);
212	ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
213
214	if (ret != SHT3X_CMD_LENGTH) {
215		ret = ret < 0 ? ret : -EIO;
216		goto out;
217	}
218
219	if (wait_time)
220		usleep_range(wait_time, wait_time + 1000);
221
222	ret = i2c_master_recv(client, buf, length);
223	if (ret != length) {
224		ret = ret < 0 ? ret : -EIO;
225		goto out;
226	}
227
228	ret = 0;
229out:
230	mutex_unlock(&data->i2c_lock);
231	return ret;
232}
233
234static int sht3x_extract_temperature(u16 raw)
235{
236	/*
237	 * From datasheet:
238	 * T = -45 + 175 * ST / 2^16
239	 * Adapted for integer fixed point (3 digit) arithmetic.
240	 */
241	return ((21875 * (int)raw) >> 13) - 45000;
242}
243
244static u32 sht3x_extract_humidity(u16 raw)
245{
246	/*
247	 * From datasheet:
248	 * RH = 100 * SRH / 2^16
249	 * Adapted for integer fixed point (3 digit) arithmetic.
250	 */
251	return (12500 * (u32)raw) >> 13;
252}
253
254static struct sht3x_data *sht3x_update_client(struct device *dev)
255{
256	struct sht3x_data *data = dev_get_drvdata(dev);
257	struct i2c_client *client = data->client;
258	u16 interval_ms = mode_to_update_interval[data->mode];
259	unsigned long interval_jiffies = msecs_to_jiffies(interval_ms);
260	unsigned char buf[SHT3X_RESPONSE_LENGTH];
261	u16 val;
262	int ret = 0;
263
264	mutex_lock(&data->data_lock);
265	/*
266	 * Only update cached readings once per update interval in periodic
267	 * mode. In single shot mode the sensor measures values on demand, so
268	 * every time the sysfs interface is called, a measurement is triggered.
269	 * In periodic mode however, the measurement process is handled
270	 * internally by the sensor and reading out sensor values only makes
271	 * sense if a new reading is available.
272	 */
273	if (time_after(jiffies, data->last_update + interval_jiffies)) {
274		ret = sht3x_read_from_command(client, data, data->command, buf,
275					      sizeof(buf), data->wait_time);
276		if (ret)
277			goto out;
278
279		val = be16_to_cpup((__be16 *)buf);
280		data->temperature = sht3x_extract_temperature(val);
281		val = be16_to_cpup((__be16 *)(buf + 3));
282		data->humidity = sht3x_extract_humidity(val);
283		data->last_update = jiffies;
284	}
285
286out:
287	mutex_unlock(&data->data_lock);
288	if (ret)
289		return ERR_PTR(ret);
290
291	return data;
292}
293
294static int temp1_input_read(struct device *dev, long *temp)
295{
296	struct sht3x_data *data = sht3x_update_client(dev);
297
298	if (IS_ERR(data))
299		return PTR_ERR(data);
300
301	*temp = data->temperature;
302	return 0;
303}
304
305static int humidity1_input_read(struct device *dev, long *humidity)
306{
307	struct sht3x_data *data = sht3x_update_client(dev);
308
309	if (IS_ERR(data))
310		return PTR_ERR(data);
311
312	*humidity = data->humidity;
313	return 0;
314}
315
316/*
317 * limits_update must only be called from probe or with data_lock held
318 */
319static int limits_update(struct sht3x_data *data)
320{
321	int ret;
322	u8 index;
323	int temperature;
324	u32 humidity;
325	u16 raw;
326	char buffer[SHT3X_RESPONSE_LENGTH];
327	const struct sht3x_limit_commands *commands;
328	struct i2c_client *client = data->client;
329
330	for (index = 0; index < SHT3X_NUM_LIMIT_CMD; index++) {
331		commands = &limit_commands[index];
332		ret = sht3x_read_from_command(client, data,
333					      commands->read_command, buffer,
334					      SHT3X_RESPONSE_LENGTH, 0);
335
336		if (ret)
337			return ret;
338
339		raw = be16_to_cpup((__be16 *)buffer);
340		temperature = sht3x_extract_temperature((raw & 0x01ff) << 7);
341		humidity = sht3x_extract_humidity(raw & 0xfe00);
342		data->temperature_limits[index] = temperature;
343		data->humidity_limits[index] = humidity;
344	}
345
346	return ret;
347}
348
349static int temp1_limit_read(struct device *dev, int index)
350{
351	struct sht3x_data *data = dev_get_drvdata(dev);
352
353	return data->temperature_limits[index];
354}
355
356static int humidity1_limit_read(struct device *dev, int index)
357{
358	struct sht3x_data *data = dev_get_drvdata(dev);
359
360	return data->humidity_limits[index];
361}
362
363/*
364 * limit_write must only be called with data_lock held
365 */
366static size_t limit_write(struct device *dev,
367			  u8 index,
368			  int temperature,
369			  u32 humidity)
370{
371	char buffer[SHT3X_CMD_LENGTH + SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
372	char *position = buffer;
373	int ret;
374	u16 raw;
375	struct sht3x_data *data = dev_get_drvdata(dev);
376	struct i2c_client *client = data->client;
377	const struct sht3x_limit_commands *commands;
378
379	commands = &limit_commands[index];
380
381	memcpy(position, commands->write_command, SHT3X_CMD_LENGTH);
382	position += SHT3X_CMD_LENGTH;
383	/*
384	 * ST = (T + 45) / 175 * 2^16
385	 * SRH = RH / 100 * 2^16
386	 * adapted for fixed point arithmetic and packed the same as
387	 * in limit_read()
388	 */
389	raw = ((u32)(temperature + 45000) * 24543) >> (16 + 7);
390	raw |= ((humidity * 42950) >> 16) & 0xfe00;
391
392	*((__be16 *)position) = cpu_to_be16(raw);
393	position += SHT3X_WORD_LEN;
394	*position = crc8(sht3x_crc8_table,
395			 position - SHT3X_WORD_LEN,
396			 SHT3X_WORD_LEN,
397			 SHT3X_CRC8_INIT);
398
399	mutex_lock(&data->i2c_lock);
400	ret = i2c_master_send(client, buffer, sizeof(buffer));
401	mutex_unlock(&data->i2c_lock);
402
403	if (ret != sizeof(buffer))
404		return ret < 0 ? ret : -EIO;
405
406	data->temperature_limits[index] = temperature;
407	data->humidity_limits[index] = humidity;
408
409	return 0;
410}
411
412static int temp1_limit_write(struct device *dev, int index, int val)
413{
414	int temperature;
415	int ret;
416	struct sht3x_data *data = dev_get_drvdata(dev);
417
418	temperature = clamp_val(val, SHT3X_MIN_TEMPERATURE,
419				SHT3X_MAX_TEMPERATURE);
420	mutex_lock(&data->data_lock);
421	ret = limit_write(dev, index, temperature,
422			  data->humidity_limits[index]);
423	mutex_unlock(&data->data_lock);
424
425	return ret;
426}
427
428static int humidity1_limit_write(struct device *dev, int index, int val)
429{
430	u32 humidity;
431	int ret;
432	struct sht3x_data *data = dev_get_drvdata(dev);
433
434	humidity = clamp_val(val, SHT3X_MIN_HUMIDITY, SHT3X_MAX_HUMIDITY);
435	mutex_lock(&data->data_lock);
436	ret = limit_write(dev, index, data->temperature_limits[index],
437			  humidity);
438	mutex_unlock(&data->data_lock);
439
440	return ret;
441}
442
443static void sht3x_select_command(struct sht3x_data *data)
444{
445	/*
446	 * For single-shot mode, only non blocking mode is support,
447	 * we have to wait ourselves for result.
448	 */
449	if (data->mode > 0) {
450		data->command = sht3x_cmd_measure_periodic_mode;
451		data->wait_time = 0;
452	} else {
453		if (data->repeatability == high_repeatability) {
454			data->command = sht3x_cmd_measure_single_hpm;
455			data->wait_time = SHT3X_SINGLE_WAIT_TIME_HPM;
456		} else if (data->repeatability ==  medium_repeatability) {
457			data->command = sht3x_cmd_measure_single_mpm;
458			data->wait_time = SHT3X_SINGLE_WAIT_TIME_MPM;
459		} else {
460			data->command = sht3x_cmd_measure_single_lpm;
461			data->wait_time = SHT3X_SINGLE_WAIT_TIME_LPM;
462		}
463	}
464}
465
466static int status_register_read(struct device *dev,
467				char *buffer, int length)
468{
469	int ret;
470	struct sht3x_data *data = dev_get_drvdata(dev);
471	struct i2c_client *client = data->client;
472
473	ret = sht3x_read_from_command(client, data, sht3x_cmd_read_status_reg,
474				      buffer, length, 0);
475
476	return ret;
477}
478
479static int temp1_alarm_read(struct device *dev)
480{
481	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
482	int ret;
483
484	ret = status_register_read(dev, buffer,
485				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
486	if (ret)
487		return ret;
488
489	return !!(buffer[0] & 0x04);
490}
491
492static int humidity1_alarm_read(struct device *dev)
493{
494	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
495	int ret;
496
497	ret = status_register_read(dev, buffer,
498				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
499	if (ret)
500		return ret;
501
502	return !!(buffer[0] & 0x08);
503}
504
505static ssize_t heater_enable_show(struct device *dev,
506				  struct device_attribute *attr,
507				  char *buf)
508{
509	char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
510	int ret;
511
512	ret = status_register_read(dev, buffer,
513				   SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
514	if (ret)
515		return ret;
516
517	return sysfs_emit(buf, "%d\n", !!(buffer[0] & 0x20));
518}
519
520static ssize_t heater_enable_store(struct device *dev,
521				   struct device_attribute *attr,
522				   const char *buf,
523				   size_t count)
524{
525	struct sht3x_data *data = dev_get_drvdata(dev);
526	struct i2c_client *client = data->client;
527	int ret;
528	bool status;
529
530	ret = kstrtobool(buf, &status);
531	if (ret)
532		return ret;
533
534	mutex_lock(&data->i2c_lock);
535
536	if (status)
537		ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_on,
538				      SHT3X_CMD_LENGTH);
539	else
540		ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_off,
541				      SHT3X_CMD_LENGTH);
542
543	mutex_unlock(&data->i2c_lock);
544
545	return ret;
546}
547
548static int update_interval_read(struct device *dev)
549{
550	struct sht3x_data *data = dev_get_drvdata(dev);
551
552	return mode_to_update_interval[data->mode];
553}
554
555static int update_interval_write(struct device *dev, int val)
556{
557	u8 mode;
558	int ret;
559	const char *command;
560	struct sht3x_data *data = dev_get_drvdata(dev);
561	struct i2c_client *client = data->client;
562
563	mode = get_mode_from_update_interval(val);
564
565	mutex_lock(&data->data_lock);
566	/* mode did not change */
567	if (mode == data->mode) {
568		mutex_unlock(&data->data_lock);
569		return 0;
570	}
571
572	mutex_lock(&data->i2c_lock);
573	/*
574	 * Abort periodic measure mode.
575	 * To do any changes to the configuration while in periodic mode, we
576	 * have to send a break command to the sensor, which then falls back
577	 * to single shot (mode = 0).
578	 */
579	if (data->mode > 0) {
580		ret = i2c_master_send(client, sht3x_cmd_break,
581				      SHT3X_CMD_LENGTH);
582		if (ret != SHT3X_CMD_LENGTH)
583			goto out;
584		data->mode = 0;
585	}
586
587	if (mode > 0) {
588		if (data->repeatability == high_repeatability)
589			command = periodic_measure_commands_hpm[mode - 1];
590		else if (data->repeatability == medium_repeatability)
591			command = periodic_measure_commands_mpm[mode - 1];
592		else
593			command = periodic_measure_commands_lpm[mode - 1];
594
595		/* select mode */
596		ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
597		if (ret != SHT3X_CMD_LENGTH)
598			goto out;
599	}
600
601	/* select mode and command */
602	data->mode = mode;
603	sht3x_select_command(data);
604
605out:
606	mutex_unlock(&data->i2c_lock);
607	mutex_unlock(&data->data_lock);
608	if (ret != SHT3X_CMD_LENGTH)
609		return ret < 0 ? ret : -EIO;
610
611	return 0;
612}
613
614static ssize_t repeatability_show(struct device *dev,
615				  struct device_attribute *attr,
616				  char *buf)
617{
618	struct sht3x_data *data = dev_get_drvdata(dev);
619
620	return sysfs_emit(buf, "%d\n", data->repeatability);
621}
622
623static ssize_t repeatability_store(struct device *dev,
624				   struct device_attribute *attr,
625				   const char *buf,
626				   size_t count)
627{
628	int ret;
629	u8 val;
630
631	struct sht3x_data *data = dev_get_drvdata(dev);
632
633	ret = kstrtou8(buf, 0, &val);
634	if (ret)
635		return ret;
636
637	if (val > 2)
638		return -EINVAL;
639
640	data->repeatability = val;
641
642	return count;
643}
644
645static SENSOR_DEVICE_ATTR_RW(heater_enable, heater_enable, 0);
646static SENSOR_DEVICE_ATTR_RW(repeatability, repeatability, 0);
647
648static struct attribute *sht3x_attrs[] = {
649	&sensor_dev_attr_heater_enable.dev_attr.attr,
650	&sensor_dev_attr_repeatability.dev_attr.attr,
651	NULL
652};
653
654ATTRIBUTE_GROUPS(sht3x);
655
656static umode_t sht3x_is_visible(const void *data, enum hwmon_sensor_types type,
657				u32 attr, int channel)
658{
659	const struct sht3x_data *chip_data = data;
660
661	switch (type) {
662	case hwmon_chip:
663		switch (attr) {
664		case hwmon_chip_update_interval:
665			return 0644;
666		default:
667			break;
668		}
669		break;
670	case hwmon_temp:
671		switch (attr) {
672		case hwmon_temp_input:
673		case hwmon_temp_alarm:
674			return 0444;
675		case hwmon_temp_max:
676		case hwmon_temp_max_hyst:
677		case hwmon_temp_min:
678		case hwmon_temp_min_hyst:
679			return 0644;
680		default:
681			break;
682		}
683		break;
684	case hwmon_humidity:
685		if (chip_data->chip_id == sts3x)
686			break;
687		switch (attr) {
688		case hwmon_humidity_input:
689		case hwmon_humidity_alarm:
690			return 0444;
691		case hwmon_humidity_max:
692		case hwmon_humidity_max_hyst:
693		case hwmon_humidity_min:
694		case hwmon_humidity_min_hyst:
695			return 0644;
696		default:
697			break;
698		}
699		break;
700	default:
701		break;
702	}
703
704	return 0;
705}
706
707static int sht3x_read(struct device *dev, enum hwmon_sensor_types type,
708		      u32 attr, int channel, long *val)
709{
710	enum sht3x_limits index;
711	int ret;
712
713	switch (type) {
714	case hwmon_chip:
715		switch (attr) {
716		case hwmon_chip_update_interval:
717			*val = update_interval_read(dev);
718			break;
719		default:
720			return -EOPNOTSUPP;
721		}
722		break;
723	case hwmon_temp:
724		switch (attr) {
725		case hwmon_temp_input:
726			return temp1_input_read(dev, val);
727		case hwmon_temp_alarm:
728			ret = temp1_alarm_read(dev);
729			if (ret < 0)
730				return ret;
731			*val = ret;
732			break;
733		case hwmon_temp_max:
734			index = limit_max;
735			*val = temp1_limit_read(dev, index);
736			break;
737		case hwmon_temp_max_hyst:
738			index = limit_max_hyst;
739			*val = temp1_limit_read(dev, index);
740			break;
741		case hwmon_temp_min:
742			index = limit_min;
743			*val = temp1_limit_read(dev, index);
744			break;
745		case hwmon_temp_min_hyst:
746			index = limit_min_hyst;
747			*val = temp1_limit_read(dev, index);
748			break;
749		default:
750			return -EOPNOTSUPP;
751		}
752		break;
753	case hwmon_humidity:
754		switch (attr) {
755		case hwmon_humidity_input:
756			return humidity1_input_read(dev, val);
757		case hwmon_humidity_alarm:
758			ret = humidity1_alarm_read(dev);
759			if (ret < 0)
760				return ret;
761			*val = ret;
762			break;
763		case hwmon_humidity_max:
764			index = limit_max;
765			*val = humidity1_limit_read(dev, index);
766			break;
767		case hwmon_humidity_max_hyst:
768			index = limit_max_hyst;
769			*val = humidity1_limit_read(dev, index);
770			break;
771		case hwmon_humidity_min:
772			index = limit_min;
773			*val = humidity1_limit_read(dev, index);
774			break;
775		case hwmon_humidity_min_hyst:
776			index = limit_min_hyst;
777			*val = humidity1_limit_read(dev, index);
778			break;
779		default:
780			return -EOPNOTSUPP;
781		}
782		break;
783	default:
784		return -EOPNOTSUPP;
785	}
786
787	return 0;
788}
789
790static int sht3x_write(struct device *dev, enum hwmon_sensor_types type,
791		       u32 attr, int channel, long val)
792{
793	enum sht3x_limits index;
794
795	switch (type) {
796	case hwmon_chip:
797		switch (attr) {
798		case hwmon_chip_update_interval:
799			return update_interval_write(dev, val);
800		default:
801			return -EOPNOTSUPP;
802		}
803	case hwmon_temp:
804		switch (attr) {
805		case hwmon_temp_max:
806			index = limit_max;
807			break;
808		case hwmon_temp_max_hyst:
809			index = limit_max_hyst;
810			break;
811		case hwmon_temp_min:
812			index = limit_min;
813			break;
814		case hwmon_temp_min_hyst:
815			index = limit_min_hyst;
816			break;
817		default:
818			return -EOPNOTSUPP;
819		}
820		return temp1_limit_write(dev, index, val);
821	case hwmon_humidity:
822		switch (attr) {
823		case hwmon_humidity_max:
824			index = limit_max;
825			break;
826		case hwmon_humidity_max_hyst:
827			index = limit_max_hyst;
828			break;
829		case hwmon_humidity_min:
830			index = limit_min;
831			break;
832		case hwmon_humidity_min_hyst:
833			index = limit_min_hyst;
834			break;
835		default:
836			return -EOPNOTSUPP;
837		}
838		return humidity1_limit_write(dev, index, val);
839	default:
840		return -EOPNOTSUPP;
841	}
842}
843
844static void sht3x_serial_number_read(struct sht3x_data *data)
845{
846	int ret;
847	char buffer[SHT3X_RESPONSE_LENGTH];
848	struct i2c_client *client = data->client;
849
850	ret = sht3x_read_from_command(client, data,
851				      sht3x_cmd_read_serial_number,
852				      buffer,
853				      SHT3X_RESPONSE_LENGTH, 0);
854	if (ret)
855		return;
856
857	data->serial_number = (buffer[0] << 24) | (buffer[1] << 16) |
858			      (buffer[3] << 8) | buffer[4];
859
860	debugfs_create_u32("serial_number", 0444, client->debugfs, &data->serial_number);
861}
862
863static const struct hwmon_ops sht3x_ops = {
864	.is_visible = sht3x_is_visible,
865	.read = sht3x_read,
866	.write = sht3x_write,
867};
868
869static const struct hwmon_chip_info sht3x_chip_info = {
870	.ops = &sht3x_ops,
871	.info = sht3x_channel_info,
872};
873
874static int sht3x_probe(struct i2c_client *client)
875{
876	int ret;
877	struct sht3x_data *data;
878	struct device *hwmon_dev;
879	struct i2c_adapter *adap = client->adapter;
880	struct device *dev = &client->dev;
881
882	/*
883	 * we require full i2c support since the sht3x uses multi-byte read and
884	 * writes as well as multi-byte commands which are not supported by
885	 * the smbus protocol
886	 */
887	if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
888		return -ENODEV;
889
890	ret = i2c_master_send(client, sht3x_cmd_clear_status_reg,
891			      SHT3X_CMD_LENGTH);
892	if (ret != SHT3X_CMD_LENGTH)
893		return ret < 0 ? ret : -ENODEV;
894
895	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
896	if (!data)
897		return -ENOMEM;
898
899	data->repeatability = high_repeatability;
900	data->mode = 0;
901	data->last_update = jiffies - msecs_to_jiffies(3000);
902	data->client = client;
903	data->chip_id = (uintptr_t)i2c_get_match_data(client);
904	crc8_populate_msb(sht3x_crc8_table, SHT3X_CRC8_POLYNOMIAL);
905
906	sht3x_select_command(data);
907
908	mutex_init(&data->i2c_lock);
909	mutex_init(&data->data_lock);
910
911	/*
912	 * An attempt to read limits register too early
913	 * causes a NACK response from the chip.
914	 * Waiting for an empirical delay of 500 us solves the issue.
915	 */
916	usleep_range(500, 600);
917
918	ret = limits_update(data);
919	if (ret)
920		return ret;
921
922	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
923							 &sht3x_chip_info, sht3x_groups);
924	if (IS_ERR(hwmon_dev))
925		return PTR_ERR(hwmon_dev);
926
927	sht3x_serial_number_read(data);
928
929	return 0;
930}
931
932/* device ID table */
933static const struct i2c_device_id sht3x_ids[] = {
934	{"sht3x", sht3x},
935	{"sts3x", sts3x},
936	{}
937};
938
939MODULE_DEVICE_TABLE(i2c, sht3x_ids);
940
941static struct i2c_driver sht3x_i2c_driver = {
942	.driver.name = "sht3x",
943	.probe       = sht3x_probe,
944	.id_table    = sht3x_ids,
945};
946module_i2c_driver(sht3x_i2c_driver);
947
948MODULE_AUTHOR("David Frey <david.frey@sensirion.com>");
949MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
950MODULE_DESCRIPTION("Sensirion SHT3x humidity and temperature sensor driver");
951MODULE_LICENSE("GPL");