Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 925 insertions, 0 deletions

diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
new file mode 100644
index 0000000000..79657910b7
--- /dev/null
+++ b/drivers/hwmon/sht3x.c
@@ -0,0 +1,925 @@
+// 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/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 };
+
+/* 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 */
+
+	u8 mode;
+	const unsigned char *command;
+	u32 wait_time;			/* in us*/
+	unsigned long last_update;	/* last update in periodic mode*/
+	enum sht3x_repeatability repeatability;
+
+	/*
+	 * 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 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;
+
+	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,
+};
+
+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");