hwmon: add driver for HTU31

Add base support for HTU31 temperature and humidity sensor.

Besides temperature and humidity values, the driver also exports a 24-bit
heater control to sysfs and serial number to debugfs.

Signed-off-by: Andrei Lalaev <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[groeck: Fixed continuation line alignment]
Signed-off-by: Guenter Roeck <[email protected]>

Author: AndreyLalaev

Documentation/hwmon/htu31.rst

@@ -0,0 +1,37 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver HTU31
+====================
+
+Supported chips:
+
+  * Measurement Specialties HTU31
+
+    Prefix: 'htu31'
+
+    Addresses scanned: -
+
+    Datasheet: Publicly available from https://www.te.com/en/product-CAT-HSC0007.html
+
+Author:
+
+  - Andrei Lalaev <[email protected]>
+
+Description
+-----------
+
+HTU31 is a humidity and temperature sensor.
+
+Supported temperature range is from -40 to 125 degrees Celsius.
+
+Communication with the device is performed via I2C protocol. Sensor's default address
+is 0x40.
+
+sysfs-Interface
+---------------
+
+=================== =================
+temp1_input:        temperature input
+humidity1_input:    humidity input
+heater_enable:      heater control
+=================== =================

Documentation/hwmon/index.rst

@@ -86,6 +86,7 @@ Hardware Monitoring Kernel Drivers
    hih6130
    hp-wmi-sensors
    hs3001
+   htu31
    ibmaem
    ibm-cffps
    ibmpowernv

MAINTAINERS

@@ -10690,6 +10690,12 @@ W:	http://www.st.com/
 F:	Documentation/devicetree/bindings/iio/humidity/st,hts221.yaml
 F:	drivers/iio/humidity/hts221*
 
+HTU31 Hardware Temperature and Humidity Sensor
+M:	Andrei Lalaev <[email protected]>
+L:	[email protected]
+S:	Maintained
+F:	drivers/hwmon/htu31.c
+
 HUAWEI ETHERNET DRIVER
 M:	Cai Huoqing <[email protected]>
 L:	[email protected]

drivers/hwmon/Kconfig

@@ -799,6 +799,17 @@ config SENSORS_HS3001
 	  This driver can also be built as a module. If so, the module
 	  will be called hs3001.
 
+config SENSORS_HTU31
+	tristate "Measurement Specialties HTU31 humidity and temperature sensor"
+	depends on I2C
+	select CRC8
+	help
+	  If you say yes here you get support for the HTU31 humidity
+	  and temperature sensors.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called htu31.
+
 config SENSORS_IBMAEM
 	tristate "IBM Active Energy Manager temperature/power sensors and control"
 	select IPMI_SI

drivers/hwmon/Makefile

@@ -92,6 +92,7 @@ obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
 obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
 obj-$(CONFIG_SENSORS_HS3001)	+= hs3001.o
+obj-$(CONFIG_SENSORS_HTU31)	+= htu31.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5500)	+= i5500_temp.o
 obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o