// 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");