On 5/21/21 11:09 PM, Navin Sankar Velliangiri wrote:
This patch adds a hwmon driver for the SHT4x Temperature and Humidity sensor. Signed-off-by: Navin Sankar Velliangiri <navin@xxxxxxxxxxx> Changes in v2: * Removed unused macro SHT4X_MIN_POLL_INTERVAL * Replaced time_after instead of ktime_after * Used goto statements for error handling * Hardcoded the interval_time instead of clamp_val(). Changes in v3: * Accept the poll interval if it is greater than SHT4X_MIN_POLL_INTERVAL and return -EINVAL for negative values & less than SHT4X_MIN_POLL_INTERVAL * Changed the data type of update_interval and last_updated to long. Changes in v4: * "update_interval" is long but msecs_to_jiffies() accepts only unsigned int. clamp_val() api is used to assign the update_interval stays within UINT_MAX. Changes in v5: * Added error handling when master unable to send the data. Changes in v6: * clamp_val() alone is used to set the update interval. since the update interval is a continuous setting. --- Documentation/hwmon/index.rst | 1 + Documentation/hwmon/sht4x.rst | 45 +++++ drivers/hwmon/Kconfig | 11 ++ drivers/hwmon/Makefile | 1 + drivers/hwmon/sht4x.c | 305 ++++++++++++++++++++++++++++++++++ 5 files changed, 363 insertions(+) create mode 100644 Documentation/hwmon/sht4x.rst create mode 100644 drivers/hwmon/sht4x.c diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst index 9ed60fa84cbe..b6fcae40258c 100644 --- a/Documentation/hwmon/index.rst +++ b/Documentation/hwmon/index.rst @@ -164,6 +164,7 @@ Hardware Monitoring Kernel Drivers sht15 sht21 sht3x + sht4x shtc1 sis5595 sl28cpld diff --git a/Documentation/hwmon/sht4x.rst b/Documentation/hwmon/sht4x.rst new file mode 100644 index 000000000000..3b37abcd4a46 --- /dev/null +++ b/Documentation/hwmon/sht4x.rst @@ -0,0 +1,45 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Kernel driver sht4x +=================== + +Supported Chips: + + * Sensirion SHT4X + + Prefix: 'sht4x' + + Addresses scanned: None + + Datasheet: + + English: https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/2_Humidity_Sensors/Datasheets/Sensirion_Humidity_Sensors_SHT4x_Datasheet.pdf + +Author: Navin Sankar Velliangiri <navin@xxxxxxxxxxx> + + +Description +----------- + +This driver implements support for the Sensirion SHT4x chip, a humidity +and temperature sensor. Temperature is measured in degree celsius, relative +humidity is expressed as a percentage. In sysfs interface, all values are +scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500. + +Usage Notes +----------- + +The device communicates with the I2C protocol. Sensors can have the I2C +address 0x44. See Documentation/i2c/instantiating-devices.rst for methods +to instantiate the device. + +Sysfs entries +------------- + +=============== ============================================ +temp1_input Measured temperature in millidegrees Celcius +humidity1_input Measured humidity in %H +update_interval The minimum interval for polling the sensor, + in milliseconds. Writable. Must be at least + 2000. +============== ============================================= diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index 87624902ea80..e3675377bc5d 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -1583,6 +1583,17 @@ config SENSORS_SHT3x This driver can also be built as a module. If so, the module will be called sht3x.+config SENSORS_SHT4x+ tristate "Sensiron humidity and temperature sensors. SHT4x and compat." + depends on I2C + select CRC8 + help + If you say yes here you get support for the Sensiron SHT40, SHT41 and + SHT45 humidity and temperature sensors. + + This driver can also be built as a module. If so, the module + will be called sht4x. + config SENSORS_SHTC1 tristate "Sensiron humidity and temperature sensors. SHTC1 and compat." depends on I2C diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 59e78bc212cf..d712c61c1f5e 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -171,6 +171,7 @@ obj-$(CONFIG_SENSORS_SL28CPLD) += sl28cpld-hwmon.o obj-$(CONFIG_SENSORS_SHT15) += sht15.o obj-$(CONFIG_SENSORS_SHT21) += sht21.o obj-$(CONFIG_SENSORS_SHT3x) += sht3x.o +obj-$(CONFIG_SENSORS_SHT4x) += sht4x.o obj-$(CONFIG_SENSORS_SHTC1) += shtc1.o obj-$(CONFIG_SENSORS_SIS5595) += sis5595.o obj-$(CONFIG_SENSORS_SMM665) += smm665.o diff --git a/drivers/hwmon/sht4x.c b/drivers/hwmon/sht4x.c new file mode 100644 index 000000000000..39e1b4a123fa --- /dev/null +++ b/drivers/hwmon/sht4x.c @@ -0,0 +1,305 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Copyright (c) Linumiz 2021 + * + * sht4x.c - Linux hwmon driver for SHT4x Temperature and Humidity sensor + * + * Author: Navin Sankar Velliangiri <navin@xxxxxxxxxxx> + */ + +#include <linux/crc8.h> +#include <linux/delay.h> +#include <linux/hwmon.h> +#include <linux/i2c.h> +#include <linux/jiffies.h> +#include <linux/module.h> + +/* + * Poll intervals (in milliseconds) + */ +#define SHT4X_MIN_POLL_INTERVAL 2000 + +/* + * I2C command delays (in microseconds) + */ +#define SHT4X_MEAS_DELAY 1000 +#define SHT4X_DELAY_EXTRA 10000 + +/* + * Command Bytes + */ +#define SHT4X_CMD_MEASURE_HPM 0b11111101 +#define SHT4X_CMD_RESET 0b10010100 + +#define SHT4X_CMD_LEN 1 +#define SHT4X_CRC8_LEN 1 +#define SHT4X_WORD_LEN 2 +#define SHT4X_RESPONSE_LENGTH 6 +#define SHT4X_CRC8_POLYNOMIAL 0x31 +#define SHT4X_CRC8_INIT 0xff +#define SHT4X_MIN_TEMPERATURE -45000 +#define SHT4X_MAX_TEMPERATURE 125000 +#define SHT4X_MIN_HUMIDITY 0 +#define SHT4X_MAX_HUMIDITY 100000 + +DECLARE_CRC8_TABLE(sht4x_crc8_table); + +/** + * struct sht4x_data - All the data required to operate an SHT4X chip + * @client: the i2c client associated with the SHT4X + * @lock: a mutex that is used to prevent parallel access to the i2c client + * @update_interval: the minimum poll interval + * @last_updated: the previous time that the SHT4X was polled + * @temperature: the latest temperature value received from the SHT4X + * @humidity: the latest humidity value received from the SHT4X + */ +struct sht4x_data { + struct i2c_client *client; + struct mutex lock; /* atomic read data updates */ + bool valid; /* validity of fields below */ + long update_interval; /* in milli-seconds */ + long last_updated; /* in jiffies */ + s32 temperature; + s32 humidity; +}; + +/** + * sht4x_read_values() - read and parse the raw data from the SHT4X + * @sht4x_data: the struct sht4x_data to use for the lock + * Return: 0 if succesfull, 1 if not + */ +static int sht4x_read_values(struct sht4x_data *data) +{ + int ret;
Ah yes, the value of ret will be uninitialized, and the function will return a random value if data->valid is false or if two measurements follow each other. Please fix and resubmit. The driver looks good otherwise. Guenter
