hwmon: (sfctemp) Add StarFive JH71x0 temperature sensor

Add driver for the StarFive JH71x0 temperature sensor. You
can enable/disable it and read temperature in milli Celcius
through sysfs.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Co-developed-by: Samin Guo <samin.guo@starfivetech.com>
Signed-off-by: Samin Guo <samin.guo@starfivetech.com>
Signed-off-by: Hal Feng <hal.feng@starfivetech.com>
Link: https://lore.kernel.org/r/20230321022644.107027-3-hal.feng@starfivetech.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: esmil

Documentation/hwmon/index.rst

@@ -184,6 +184,7 @@ Hardware Monitoring Kernel Drivers
    sch5627
    sch5636
    scpi-hwmon
+   sfctemp
    sht15
    sht21
    sht3x

Documentation/hwmon/sfctemp.rst

@@ -0,0 +1,33 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver sfctemp
+=====================
+
+Supported chips:
+ - StarFive JH7100
+ - StarFive JH7110
+
+Authors:
+ - Emil Renner Berthing <kernel@esmil.dk>
+
+Description
+-----------
+
+This driver adds support for reading the built-in temperature sensor on the
+JH7100 and JH7110 RISC-V SoCs by StarFive Technology Co. Ltd.
+
+``sysfs`` interface
+-------------------
+
+The temperature sensor can be enabled, disabled and queried via the standard
+hwmon interface in sysfs under ``/sys/class/hwmon/hwmonX`` for some value of
+``X``:
+
+================ ==== =============================================
+Name             Perm Description
+================ ==== =============================================
+temp1_enable     RW   Enable or disable temperature sensor.
+                      Automatically enabled by the driver,
+                      but may be disabled to save power.
+temp1_input      RO   Temperature reading in milli-degrees Celsius.
+================ ==== =============================================

MAINTAINERS

@@ -18908,6 +18908,14 @@ S:	Supported
 F:	Documentation/networking/devlink/sfc.rst
 F:	drivers/net/ethernet/sfc/
 
+SFCTEMP HWMON DRIVER
+M:	Emil Renner Berthing <kernel@esmil.dk>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/hwmon/starfive,jh71x0-temp.yaml
+F:	Documentation/hwmon/sfctemp.rst
+F:	drivers/hwmon/sfctemp.c
+
 SFF/SFP/SFP+ MODULE SUPPORT
 M:	Russell King <linux@armlinux.org.uk>
 L:	netdev@vger.kernel.org

drivers/hwmon/Kconfig

@@ -1929,6 +1929,16 @@ config SENSORS_STTS751
 	  This driver can also be built as a module. If so, the module
 	  will be called stts751.
 
+config SENSORS_SFCTEMP
+	tristate "Starfive JH71x0 temperature sensor"
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	help
+	  If you say yes here you get support for temperature sensor
+	  on the Starfive JH71x0 SoCs.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called sfctemp.
+
 config SENSORS_SMM665
 	tristate "Summit Microelectronics SMM665"
 	depends on I2C

drivers/hwmon/Makefile

@@ -181,6 +181,7 @@ obj-$(CONFIG_SENSORS_SBRMI)	+= sbrmi.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636)	+= sch5636.o
+obj-$(CONFIG_SENSORS_SFCTEMP)	+= sfctemp.o
 obj-$(CONFIG_SENSORS_SL28CPLD)	+= sl28cpld-hwmon.o
 obj-$(CONFIG_SENSORS_SHT15)	+= sht15.o
 obj-$(CONFIG_SENSORS_SHT21)	+= sht21.o