The SHTC3 is a digital humidity and temperature sensor. It covers humidity measurement range from 0 to 100% relative humidity and temperature measurement range from -45 to 125 deg C. Datasheet: https://www.sensirion.com/file/datasheet_shtc3 Signed-off-by: Gilles Talis <gilles.talis@xxxxxxxxx> --- drivers/iio/humidity/Kconfig | 11 ++ drivers/iio/humidity/Makefile | 1 + drivers/iio/humidity/shtc3.c | 286 ++++++++++++++++++++++++++++++++++ 3 files changed, 298 insertions(+) create mode 100644 drivers/iio/humidity/shtc3.c diff --git a/drivers/iio/humidity/Kconfig b/drivers/iio/humidity/Kconfig index 2de5494e7c22..7aab6141c64b 100644 --- a/drivers/iio/humidity/Kconfig +++ b/drivers/iio/humidity/Kconfig @@ -98,6 +98,17 @@ config HTU21 This driver can also be built as a module. If so, the module will be called htu21. +config SHTC3 + tristate "Sensirion SHTC3 humidity and temperature sensor" + depends on I2C + select CRC8 + help + Say yes here to build support for the Sensirion SHTC3 + humidity and temperature sensor. + + To compile this driver as a module, choose M here: the module + will be called shtc3. + config SI7005 tristate "SI7005 relative humidity and temperature sensor" depends on I2C diff --git a/drivers/iio/humidity/Makefile b/drivers/iio/humidity/Makefile index f19ff3de97c5..13020dfad1b3 100644 --- a/drivers/iio/humidity/Makefile +++ b/drivers/iio/humidity/Makefile @@ -16,6 +16,7 @@ obj-$(CONFIG_HTS221_I2C) += hts221_i2c.o obj-$(CONFIG_HTS221_SPI) += hts221_spi.o obj-$(CONFIG_HTU21) += htu21.o +obj-$(CONFIG_SHTC3) += shtc3.o obj-$(CONFIG_SI7005) += si7005.o obj-$(CONFIG_SI7020) += si7020.o diff --git a/drivers/iio/humidity/shtc3.c b/drivers/iio/humidity/shtc3.c new file mode 100644 index 000000000000..ec3d7215e378 --- /dev/null +++ b/drivers/iio/humidity/shtc3.c @@ -0,0 +1,286 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Sensirion SHTC3 Humidity and Temperature Sensor + * + * Copyright (c) 2021 Gilles Talis <gilles.talis@xxxxxxxxx> + * + * Datasheet: https://www.sensirion.com/file/datasheet_shtc3 + * + * I2C slave address: 0x70 + */ + +#include <linux/crc8.h> +#include <linux/delay.h> +#include <linux/i2c.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> + +#include <linux/iio/iio.h> + +#define SHTC3_CMD(cmd_word) cpu_to_be16(cmd_word) +#define SHTC3_CMD_LEN 2 + +#define SHTC3_ID_MASK 0x083F +#define SHTC3_ID 0x0807 + +#define SHTC3_CRC8_POLYNOMIAL 0x31 + +enum shtc3_cmd { + SHTC3_CMD_GET_ID = SHTC3_CMD(0xEFC8), + SHTC3_CMD_SOFT_RESET = SHTC3_CMD(0x805D), + SHTC3_CMD_SLEEP = SHTC3_CMD(0xB098), + SHTC3_CMD_WAKEUP = SHTC3_CMD(0x3517), + /* + * Run measurement, low-power mode, clock stretching + * temperature first + */ + SHTC3_CMD_TEMP_MEAS_LP_CS = SHTC3_CMD(0x6458), + /* + * Run measurement, low-power mode, clock stretching + * relative humidity first + */ + SHTC3_CMD_RH_MEAS_LP_CS = SHTC3_CMD(0x44DE), +}; + +DECLARE_CRC8_TABLE(shtc3_crc8_tbl); + +struct shtc3_rx_data { + __be16 data; + u8 crc; +} __packed; + +static int shtc3_send_cmd(struct i2c_client *client, u16 cmd, u16 *data) +{ + int ret; + struct shtc3_rx_data rx_data; + u8 crc; + + ret = i2c_master_send(client, (const char *)&cmd, SHTC3_CMD_LEN); + if (ret != SHTC3_CMD_LEN) + return -EIO; + + /* + * This is used to read temperature and humidity measurements + * as well as the sensor ID. + * Sensor sends 2 bytes of data followed by one byte of CRC + */ + if (data) { + ret = i2c_master_recv(client, (u8 *) &rx_data, + sizeof(struct shtc3_rx_data)); + if (ret < 0) + return ret; + if (ret != sizeof(struct shtc3_rx_data)) + return -EIO; + + crc = crc8(shtc3_crc8_tbl, (u8 *)&rx_data.data, + 2, CRC8_INIT_VALUE); + if (crc != rx_data.crc) + return -EIO; + + *data = be16_to_cpu(rx_data.data); + } + + return 0; +} + +static int shtc3_sleep(struct i2c_client *client) +{ + return shtc3_send_cmd(client, SHTC3_CMD_SLEEP, 0); +} + +static int shtc3_wakeup(struct i2c_client *client) +{ + if (shtc3_send_cmd(client, SHTC3_CMD_WAKEUP, 0) < 0) + return -EIO; + + /* Wait for device to wake up */ + usleep_range(180, 240); + + return 0; +} + +static int shtc3_read_channel(struct i2c_client *client, bool temp) +{ + int ret; + u16 cmd; + u16 meas; + + ret = shtc3_wakeup(client); + if (ret < 0) + return ret; + + /* + * Sensor sends back measurement results after measurement command + * has been issued by the host. + * Sensor sends 3 bytes (2 bytes of data + 1 byte of CRC) for each + * channel sequentially + * The command issued by the host determines the channel for which + * the sensor will first send the data. + * We select the channel for which we need the results + * then only read back the 2 bytes corresponding to this channel. + */ + cmd = temp ? SHTC3_CMD_TEMP_MEAS_LP_CS : SHTC3_CMD_RH_MEAS_LP_CS; + ret = shtc3_send_cmd(client, cmd, &meas); + if (ret < 0) + return ret; + + /* Go back to sleep */ + shtc3_sleep(client); + + return meas; +} + +static int shtc3_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) +{ + struct i2c_client **client = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + ret = shtc3_read_channel(*client, (chan->type == IIO_TEMP)); + if (ret < 0) + return ret; + *val = ret; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + if (chan->type == IIO_TEMP) { + *val = 2; + *val2 = 670000; + } else { + *val = 0; + *val2 = 1525; + } + return IIO_VAL_INT_PLUS_MICRO; + case IIO_CHAN_INFO_OFFSET: + *val = -16852; + return IIO_VAL_INT; + default: + break; + } + + return -EINVAL; +} + +static const struct iio_chan_spec shtc3_channels[] = { + { + .type = IIO_HUMIDITYRELATIVE, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, + { + .type = IIO_TEMP, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET), + } +}; + +static const struct iio_info shtc3_info = { + .read_raw = shtc3_read_raw, +}; + +static int shtc3_verify_id(struct i2c_client *client) +{ + int ret; + u16 device_id; + u16 reg_val; + + ret = shtc3_send_cmd(client, SHTC3_CMD_GET_ID, ®_val); + if (ret < 0) + return ret; + + device_id = reg_val & SHTC3_ID_MASK; + if (device_id != SHTC3_ID) + return -ENODEV; + + return 0; +} + +static int shtc3_reset(struct i2c_client *client) +{ + int ret; + + ret = shtc3_send_cmd(client, SHTC3_CMD_SOFT_RESET, 0); + if (ret < 0) + return ret; + + /* Wait for device to enter idle state */ + usleep_range(180, 240); + + return 0; +} + +static int shtc3_setup(struct i2c_client *client) +{ + int ret; + + ret = shtc3_verify_id(client); + if (ret < 0) { + dev_err(&client->dev, "SHTC3 not found\n"); + return -ENODEV; + } + + ret = shtc3_reset(client); + if (ret < 0) + return ret; + + return shtc3_sleep(client); +} + +static int shtc3_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct iio_dev *indio_dev; + struct i2c_client **data; + int ret; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + *data = client; + + indio_dev->name = dev_name(&client->dev); + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->info = &shtc3_info; + indio_dev->channels = shtc3_channels; + indio_dev->num_channels = ARRAY_SIZE(shtc3_channels); + + crc8_populate_msb(shtc3_crc8_tbl, SHTC3_CRC8_POLYNOMIAL); + + ret = shtc3_setup(client); + if (ret < 0) { + dev_err(&client->dev, "SHTC3 setup failed\n"); + return ret; + } + + return devm_iio_device_register(&client->dev, indio_dev); +} + +static const struct i2c_device_id shtc3_id[] = { + { "shtc3", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, shtc3_id); + +static const struct of_device_id shtc3_dt_ids[] = { + { .compatible = "sensirion,shtc3" }, + { } +}; +MODULE_DEVICE_TABLE(of, shtc3_dt_ids); + +static struct i2c_driver shtc3_driver = { + .driver = { + .name = "shtc3", + .of_match_table = shtc3_dt_ids, + }, + .probe = shtc3_probe, + .id_table = shtc3_id, +}; + +module_i2c_driver(shtc3_driver); +MODULE_DESCRIPTION("Sensirion SHTC3 Humidity and Temperature Sensor"); +MODULE_AUTHOR("Gilles Talis <gilles.talis@xxxxxxxxx>"); +MODULE_LICENSE("GPL"); -- 2.27.0
