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
6 * Copyright (C) 2016 Sensirion AG, Switzerland
7 * Author: David Frey <david.frey@sensirion.com>
8 * Author: Pascal Sachs <pascal.sachs@sensirion.com>
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>
24 /* commands (high repeatability mode) */
25 static const unsigned char sht3x_cmd_measure_single_hpm[] = { 0x24, 0x00 };
27 /* commands (medium repeatability mode) */
28 static const unsigned char sht3x_cmd_measure_single_mpm[] = { 0x24, 0x0b };
30 /* commands (low repeatability mode) */
31 static const unsigned char sht3x_cmd_measure_single_lpm[] = { 0x24, 0x16 };
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 };
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 };
42 static const unsigned char sht3x_cmd_read_status_reg[] = { 0xf3, 0x2d };
43 static const unsigned char sht3x_cmd_clear_status_reg[] = { 0x30, 0x41 };
45 /* delays for single-shot mode i2c commands, both in us */
46 #define SHT3X_SINGLE_WAIT_TIME_HPM 15000
47 #define SHT3X_SINGLE_WAIT_TIME_MPM 6000
48 #define SHT3X_SINGLE_WAIT_TIME_LPM 4000
50 #define SHT3X_WORD_LEN 2
51 #define SHT3X_CMD_LENGTH 2
52 #define SHT3X_CRC8_LEN 1
53 #define SHT3X_RESPONSE_LENGTH 6
54 #define SHT3X_CRC8_POLYNOMIAL 0x31
55 #define SHT3X_CRC8_INIT 0xFF
56 #define SHT3X_MIN_TEMPERATURE -45000
57 #define SHT3X_MAX_TEMPERATURE 130000
58 #define SHT3X_MIN_HUMIDITY 0
59 #define SHT3X_MAX_HUMIDITY 100000
73 enum sht3x_repeatability {
79 DECLARE_CRC8_TABLE(sht3x_crc8_table);
81 /* periodic measure commands (high repeatability mode) */
82 static const char periodic_measure_commands_hpm[][SHT3X_CMD_LENGTH] = {
83 /* 0.5 measurements per second */
85 /* 1 measurements per second */
87 /* 2 measurements per second */
89 /* 4 measurements per second */
91 /* 10 measurements per second */
95 /* periodic measure commands (medium repeatability) */
96 static const char periodic_measure_commands_mpm[][SHT3X_CMD_LENGTH] = {
97 /* 0.5 measurements per second */
99 /* 1 measurements per second */
101 /* 2 measurements per second */
103 /* 4 measurements per second */
105 /* 10 measurements per second */
109 /* periodic measure commands (low repeatability mode) */
110 static const char periodic_measure_commands_lpm[][SHT3X_CMD_LENGTH] = {
111 /* 0.5 measurements per second */
113 /* 1 measurements per second */
115 /* 2 measurements per second */
117 /* 4 measurements per second */
119 /* 10 measurements per second */
123 struct sht3x_limit_commands {
124 const char read_command[SHT3X_CMD_LENGTH];
125 const char write_command[SHT3X_CMD_LENGTH];
128 static const struct sht3x_limit_commands limit_commands[] = {
129 /* temp1_max, humidity1_max */
130 [limit_max] = { {0xe1, 0x1f}, {0x61, 0x1d} },
131 /* temp_1_max_hyst, humidity1_max_hyst */
132 [limit_max_hyst] = { {0xe1, 0x14}, {0x61, 0x16} },
133 /* temp1_min, humidity1_min */
134 [limit_min] = { {0xe1, 0x02}, {0x61, 0x00} },
135 /* temp_1_min_hyst, humidity1_min_hyst */
136 [limit_min_hyst] = { {0xe1, 0x09}, {0x61, 0x0B} },
139 #define SHT3X_NUM_LIMIT_CMD ARRAY_SIZE(limit_commands)
141 static const u16 mode_to_update_interval[] = {
150 static const struct hwmon_channel_info * const sht3x_channel_info[] = {
151 HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
152 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN |
153 HWMON_T_MIN_HYST | HWMON_T_MAX |
154 HWMON_T_MAX_HYST | HWMON_T_ALARM),
155 HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT | HWMON_H_MIN |
156 HWMON_H_MIN_HYST | HWMON_H_MAX |
157 HWMON_H_MAX_HYST | HWMON_H_ALARM),
162 struct i2c_client *client;
163 enum sht3x_chips chip_id;
164 struct mutex i2c_lock; /* lock for sending i2c commands */
165 struct mutex data_lock; /* lock for updating driver data */
168 const unsigned char *command;
169 u32 wait_time; /* in us*/
170 unsigned long last_update; /* last update in periodic mode*/
171 enum sht3x_repeatability repeatability;
174 * cached values for temperature and humidity and limits
175 * the limits arrays have the following order:
176 * max, max_hyst, min, min_hyst
179 int temperature_limits[SHT3X_NUM_LIMIT_CMD];
181 u32 humidity_limits[SHT3X_NUM_LIMIT_CMD];
184 static u8 get_mode_from_update_interval(u16 value)
187 u8 number_of_modes = ARRAY_SIZE(mode_to_update_interval);
192 /* find next faster update interval */
193 for (index = 1; index < number_of_modes; index++) {
194 if (mode_to_update_interval[index] <= value)
198 return number_of_modes - 1;
201 static int sht3x_read_from_command(struct i2c_client *client,
202 struct sht3x_data *data,
204 char *buf, int length, u32 wait_time)
208 mutex_lock(&data->i2c_lock);
209 ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
211 if (ret != SHT3X_CMD_LENGTH) {
212 ret = ret < 0 ? ret : -EIO;
217 usleep_range(wait_time, wait_time + 1000);
219 ret = i2c_master_recv(client, buf, length);
221 ret = ret < 0 ? ret : -EIO;
227 mutex_unlock(&data->i2c_lock);
231 static int sht3x_extract_temperature(u16 raw)
235 * T = -45 + 175 * ST / 2^16
236 * Adapted for integer fixed point (3 digit) arithmetic.
238 return ((21875 * (int)raw) >> 13) - 45000;
241 static u32 sht3x_extract_humidity(u16 raw)
245 * RH = 100 * SRH / 2^16
246 * Adapted for integer fixed point (3 digit) arithmetic.
248 return (12500 * (u32)raw) >> 13;
251 static struct sht3x_data *sht3x_update_client(struct device *dev)
253 struct sht3x_data *data = dev_get_drvdata(dev);
254 struct i2c_client *client = data->client;
255 u16 interval_ms = mode_to_update_interval[data->mode];
256 unsigned long interval_jiffies = msecs_to_jiffies(interval_ms);
257 unsigned char buf[SHT3X_RESPONSE_LENGTH];
261 mutex_lock(&data->data_lock);
263 * Only update cached readings once per update interval in periodic
264 * mode. In single shot mode the sensor measures values on demand, so
265 * every time the sysfs interface is called, a measurement is triggered.
266 * In periodic mode however, the measurement process is handled
267 * internally by the sensor and reading out sensor values only makes
268 * sense if a new reading is available.
270 if (time_after(jiffies, data->last_update + interval_jiffies)) {
271 ret = sht3x_read_from_command(client, data, data->command, buf,
272 sizeof(buf), data->wait_time);
276 val = be16_to_cpup((__be16 *)buf);
277 data->temperature = sht3x_extract_temperature(val);
278 val = be16_to_cpup((__be16 *)(buf + 3));
279 data->humidity = sht3x_extract_humidity(val);
280 data->last_update = jiffies;
284 mutex_unlock(&data->data_lock);
291 static int temp1_input_read(struct device *dev)
293 struct sht3x_data *data = sht3x_update_client(dev);
296 return PTR_ERR(data);
298 return data->temperature;
301 static int humidity1_input_read(struct device *dev)
303 struct sht3x_data *data = sht3x_update_client(dev);
306 return PTR_ERR(data);
308 return data->humidity;
312 * limits_update must only be called from probe or with data_lock held
314 static int limits_update(struct sht3x_data *data)
321 char buffer[SHT3X_RESPONSE_LENGTH];
322 const struct sht3x_limit_commands *commands;
323 struct i2c_client *client = data->client;
325 for (index = 0; index < SHT3X_NUM_LIMIT_CMD; index++) {
326 commands = &limit_commands[index];
327 ret = sht3x_read_from_command(client, data,
328 commands->read_command, buffer,
329 SHT3X_RESPONSE_LENGTH, 0);
334 raw = be16_to_cpup((__be16 *)buffer);
335 temperature = sht3x_extract_temperature((raw & 0x01ff) << 7);
336 humidity = sht3x_extract_humidity(raw & 0xfe00);
337 data->temperature_limits[index] = temperature;
338 data->humidity_limits[index] = humidity;
344 static int temp1_limit_read(struct device *dev, int index)
346 struct sht3x_data *data = dev_get_drvdata(dev);
348 return data->temperature_limits[index];
351 static int humidity1_limit_read(struct device *dev, int index)
353 struct sht3x_data *data = dev_get_drvdata(dev);
355 return data->humidity_limits[index];
359 * limit_write must only be called with data_lock held
361 static size_t limit_write(struct device *dev,
366 char buffer[SHT3X_CMD_LENGTH + SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
367 char *position = buffer;
370 struct sht3x_data *data = dev_get_drvdata(dev);
371 struct i2c_client *client = data->client;
372 const struct sht3x_limit_commands *commands;
374 commands = &limit_commands[index];
376 memcpy(position, commands->write_command, SHT3X_CMD_LENGTH);
377 position += SHT3X_CMD_LENGTH;
379 * ST = (T + 45) / 175 * 2^16
380 * SRH = RH / 100 * 2^16
381 * adapted for fixed point arithmetic and packed the same as
384 raw = ((u32)(temperature + 45000) * 24543) >> (16 + 7);
385 raw |= ((humidity * 42950) >> 16) & 0xfe00;
387 *((__be16 *)position) = cpu_to_be16(raw);
388 position += SHT3X_WORD_LEN;
389 *position = crc8(sht3x_crc8_table,
390 position - SHT3X_WORD_LEN,
394 mutex_lock(&data->i2c_lock);
395 ret = i2c_master_send(client, buffer, sizeof(buffer));
396 mutex_unlock(&data->i2c_lock);
398 if (ret != sizeof(buffer))
399 return ret < 0 ? ret : -EIO;
401 data->temperature_limits[index] = temperature;
402 data->humidity_limits[index] = humidity;
407 static int temp1_limit_write(struct device *dev, int index, int val)
411 struct sht3x_data *data = dev_get_drvdata(dev);
413 temperature = clamp_val(val, SHT3X_MIN_TEMPERATURE,
414 SHT3X_MAX_TEMPERATURE);
415 mutex_lock(&data->data_lock);
416 ret = limit_write(dev, index, temperature,
417 data->humidity_limits[index]);
418 mutex_unlock(&data->data_lock);
423 static int humidity1_limit_write(struct device *dev, int index, int val)
427 struct sht3x_data *data = dev_get_drvdata(dev);
429 humidity = clamp_val(val, SHT3X_MIN_HUMIDITY, SHT3X_MAX_HUMIDITY);
430 mutex_lock(&data->data_lock);
431 ret = limit_write(dev, index, data->temperature_limits[index],
433 mutex_unlock(&data->data_lock);
438 static void sht3x_select_command(struct sht3x_data *data)
441 * For single-shot mode, only non blocking mode is support,
442 * we have to wait ourselves for result.
444 if (data->mode > 0) {
445 data->command = sht3x_cmd_measure_periodic_mode;
448 if (data->repeatability == high_repeatability) {
449 data->command = sht3x_cmd_measure_single_hpm;
450 data->wait_time = SHT3X_SINGLE_WAIT_TIME_HPM;
451 } else if (data->repeatability == medium_repeatability) {
452 data->command = sht3x_cmd_measure_single_mpm;
453 data->wait_time = SHT3X_SINGLE_WAIT_TIME_MPM;
455 data->command = sht3x_cmd_measure_single_lpm;
456 data->wait_time = SHT3X_SINGLE_WAIT_TIME_LPM;
461 static int status_register_read(struct device *dev,
462 char *buffer, int length)
465 struct sht3x_data *data = dev_get_drvdata(dev);
466 struct i2c_client *client = data->client;
468 ret = sht3x_read_from_command(client, data, sht3x_cmd_read_status_reg,
474 static int temp1_alarm_read(struct device *dev)
476 char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
479 ret = status_register_read(dev, buffer,
480 SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
484 return !!(buffer[0] & 0x04);
487 static int humidity1_alarm_read(struct device *dev)
489 char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
492 ret = status_register_read(dev, buffer,
493 SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
497 return !!(buffer[0] & 0x08);
500 static ssize_t heater_enable_show(struct device *dev,
501 struct device_attribute *attr,
504 char buffer[SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
507 ret = status_register_read(dev, buffer,
508 SHT3X_WORD_LEN + SHT3X_CRC8_LEN);
512 return sysfs_emit(buf, "%d\n", !!(buffer[0] & 0x20));
515 static ssize_t heater_enable_store(struct device *dev,
516 struct device_attribute *attr,
520 struct sht3x_data *data = dev_get_drvdata(dev);
521 struct i2c_client *client = data->client;
525 ret = kstrtobool(buf, &status);
529 mutex_lock(&data->i2c_lock);
532 ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_on,
535 ret = i2c_master_send(client, (char *)&sht3x_cmd_heater_off,
538 mutex_unlock(&data->i2c_lock);
543 static int update_interval_read(struct device *dev)
545 struct sht3x_data *data = dev_get_drvdata(dev);
547 return mode_to_update_interval[data->mode];
550 static int update_interval_write(struct device *dev, int val)
555 struct sht3x_data *data = dev_get_drvdata(dev);
556 struct i2c_client *client = data->client;
558 mode = get_mode_from_update_interval(val);
560 mutex_lock(&data->data_lock);
561 /* mode did not change */
562 if (mode == data->mode) {
563 mutex_unlock(&data->data_lock);
567 mutex_lock(&data->i2c_lock);
569 * Abort periodic measure mode.
570 * To do any changes to the configuration while in periodic mode, we
571 * have to send a break command to the sensor, which then falls back
572 * to single shot (mode = 0).
574 if (data->mode > 0) {
575 ret = i2c_master_send(client, sht3x_cmd_break,
577 if (ret != SHT3X_CMD_LENGTH)
583 if (data->repeatability == high_repeatability)
584 command = periodic_measure_commands_hpm[mode - 1];
585 else if (data->repeatability == medium_repeatability)
586 command = periodic_measure_commands_mpm[mode - 1];
588 command = periodic_measure_commands_lpm[mode - 1];
591 ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
592 if (ret != SHT3X_CMD_LENGTH)
596 /* select mode and command */
598 sht3x_select_command(data);
601 mutex_unlock(&data->i2c_lock);
602 mutex_unlock(&data->data_lock);
603 if (ret != SHT3X_CMD_LENGTH)
604 return ret < 0 ? ret : -EIO;
609 static ssize_t repeatability_show(struct device *dev,
610 struct device_attribute *attr,
613 struct sht3x_data *data = dev_get_drvdata(dev);
615 return sysfs_emit(buf, "%d\n", data->repeatability);
618 static ssize_t repeatability_store(struct device *dev,
619 struct device_attribute *attr,
626 struct sht3x_data *data = dev_get_drvdata(dev);
628 ret = kstrtou8(buf, 0, &val);
635 data->repeatability = val;
640 static SENSOR_DEVICE_ATTR_RW(heater_enable, heater_enable, 0);
641 static SENSOR_DEVICE_ATTR_RW(repeatability, repeatability, 0);
643 static struct attribute *sht3x_attrs[] = {
644 &sensor_dev_attr_heater_enable.dev_attr.attr,
645 &sensor_dev_attr_repeatability.dev_attr.attr,
649 ATTRIBUTE_GROUPS(sht3x);
651 static umode_t sht3x_is_visible(const void *data, enum hwmon_sensor_types type,
652 u32 attr, int channel)
654 const struct sht3x_data *chip_data = data;
659 case hwmon_chip_update_interval:
667 case hwmon_temp_input:
668 case hwmon_temp_alarm:
671 case hwmon_temp_max_hyst:
673 case hwmon_temp_min_hyst:
680 if (chip_data->chip_id == sts3x)
683 case hwmon_humidity_input:
684 case hwmon_humidity_alarm:
686 case hwmon_humidity_max:
687 case hwmon_humidity_max_hyst:
688 case hwmon_humidity_min:
689 case hwmon_humidity_min_hyst:
702 static int sht3x_read(struct device *dev, enum hwmon_sensor_types type,
703 u32 attr, int channel, long *val)
705 enum sht3x_limits index;
710 case hwmon_chip_update_interval:
711 *val = update_interval_read(dev);
719 case hwmon_temp_input:
720 *val = temp1_input_read(dev);
722 case hwmon_temp_alarm:
723 *val = temp1_alarm_read(dev);
727 *val = temp1_limit_read(dev, index);
729 case hwmon_temp_max_hyst:
730 index = limit_max_hyst;
731 *val = temp1_limit_read(dev, index);
735 *val = temp1_limit_read(dev, index);
737 case hwmon_temp_min_hyst:
738 index = limit_min_hyst;
739 *val = temp1_limit_read(dev, index);
747 case hwmon_humidity_input:
748 *val = humidity1_input_read(dev);
750 case hwmon_humidity_alarm:
751 *val = humidity1_alarm_read(dev);
753 case hwmon_humidity_max:
755 *val = humidity1_limit_read(dev, index);
757 case hwmon_humidity_max_hyst:
758 index = limit_max_hyst;
759 *val = humidity1_limit_read(dev, index);
761 case hwmon_humidity_min:
763 *val = humidity1_limit_read(dev, index);
765 case hwmon_humidity_min_hyst:
766 index = limit_min_hyst;
767 *val = humidity1_limit_read(dev, index);
780 static int sht3x_write(struct device *dev, enum hwmon_sensor_types type,
781 u32 attr, int channel, long val)
783 enum sht3x_limits index;
788 case hwmon_chip_update_interval:
789 return update_interval_write(dev, val);
798 case hwmon_temp_max_hyst:
799 index = limit_max_hyst;
804 case hwmon_temp_min_hyst:
805 index = limit_min_hyst;
810 return temp1_limit_write(dev, index, val);
813 case hwmon_humidity_max:
816 case hwmon_humidity_max_hyst:
817 index = limit_max_hyst;
819 case hwmon_humidity_min:
822 case hwmon_humidity_min_hyst:
823 index = limit_min_hyst;
828 return humidity1_limit_write(dev, index, val);
834 static const struct hwmon_ops sht3x_ops = {
835 .is_visible = sht3x_is_visible,
837 .write = sht3x_write,
840 static const struct hwmon_chip_info sht3x_chip_info = {
842 .info = sht3x_channel_info,
845 /* device ID table */
846 static const struct i2c_device_id sht3x_ids[] = {
852 MODULE_DEVICE_TABLE(i2c, sht3x_ids);
854 static int sht3x_probe(struct i2c_client *client)
857 struct sht3x_data *data;
858 struct device *hwmon_dev;
859 struct i2c_adapter *adap = client->adapter;
860 struct device *dev = &client->dev;
863 * we require full i2c support since the sht3x uses multi-byte read and
864 * writes as well as multi-byte commands which are not supported by
867 if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
870 ret = i2c_master_send(client, sht3x_cmd_clear_status_reg,
872 if (ret != SHT3X_CMD_LENGTH)
873 return ret < 0 ? ret : -ENODEV;
875 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
879 data->repeatability = high_repeatability;
881 data->last_update = jiffies - msecs_to_jiffies(3000);
882 data->client = client;
883 data->chip_id = i2c_match_id(sht3x_ids, client)->driver_data;
884 crc8_populate_msb(sht3x_crc8_table, SHT3X_CRC8_POLYNOMIAL);
886 sht3x_select_command(data);
888 mutex_init(&data->i2c_lock);
889 mutex_init(&data->data_lock);
892 * An attempt to read limits register too early
893 * causes a NACK response from the chip.
894 * Waiting for an empirical delay of 500 us solves the issue.
896 usleep_range(500, 600);
898 ret = limits_update(data);
902 hwmon_dev = devm_hwmon_device_register_with_info(dev,
908 if (IS_ERR(hwmon_dev))
909 dev_dbg(dev, "unable to register hwmon device\n");
911 return PTR_ERR_OR_ZERO(hwmon_dev);
914 static const struct of_device_id sht3x_of_ids[] = {
915 { .compatible = "sensirion,sht3x" },
916 { .compatible = "sensirion,sts3x" },
919 MODULE_DEVICE_TABLE(of, sht3x_of_ids);
921 static struct i2c_driver sht3x_i2c_driver = {
924 .of_match_table = sht3x_of_ids,
926 .probe = sht3x_probe,
927 .id_table = sht3x_ids,
930 module_i2c_driver(sht3x_i2c_driver);
932 MODULE_AUTHOR("David Frey <david.frey@sensirion.com>");
933 MODULE_AUTHOR("Pascal Sachs <pascal.sachs@sensirion.com>");
934 MODULE_DESCRIPTION("Sensirion SHT3x humidity and temperature sensor driver");
935 MODULE_LICENSE("GPL");