hwmon: Add Congatec Board Controller monitoring driver

Add support for the Congatec Board Controller. This controller exposes
temperature, voltage, current and fan sensors.

The available sensors list cannot be predicted. Some sensors can be
present or not, depending the system.
The driver has an internal list of all possible sensors, for all Congatec
boards. The Board Controller gives to the driver its sensors list, and
their status (active or not).

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/20250203-congatec-board-controller-hwmon-v4-1-ff6c76a4662c@bootlin.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: thom24

Documentation/hwmon/cgbc-hwmon.rst

@@ -0,0 +1,63 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver cgbc-hwmon
+========================
+
+Supported chips:
+
+ * Congatec Board Controller.
+
+   Prefix: 'cgbc-hwmon'
+
+Author: Thomas Richard <thomas.richard@bootlin.com>
+
+Description
+-----------
+
+This driver enables monitoring support for the Congatec Board Controller.
+This controller is embedded on the x86 SoMs of Congatec.
+
+Sysfs entries
+-------------
+
+The following sysfs entries list contains all sensors defined in the Board
+Controller. The available sensors in sysfs depend on the SoM and the
+system.
+
+============= ======================
+Name          Description
+============= ======================
+temp1_input   CPU temperature
+temp2_input   Box temperature
+temp3_input   Ambient temperature
+temp4_input   Board temperature
+temp5_input   Carrier temperature
+temp6_input   Chipset temperature
+temp7_input   Video temperature
+temp8_input   Other temperature
+temp9_input   TOPDIM temperature
+temp10_input  BOTTOMDIM temperature
+in0_input     CPU voltage
+in1_input     DC Runtime voltage
+in2_input     DC Standby voltage
+in3_input     CMOS Battery voltage
+in4_input     Battery voltage
+in5_input     AC voltage
+in6_input     Other voltage
+in7_input     5V voltage
+in8_input     5V Standby voltage
+in9_input     3V3 voltage
+in10_input    3V3 Standby voltage
+in11_input    VCore A voltage
+in12_input    VCore B voltage
+in13_input    12V voltage
+curr1_input   DC current
+curr2_input   5V current
+curr3_input   12V current
+fan1_input    CPU fan
+fan2_input    Box fan
+fan3_input    Ambient fan
+fan4_input    Chiptset fan
+fan5_input    Video fan
+fan6_input    Other fan
+============= ======================

Documentation/hwmon/index.rst

@@ -53,6 +53,7 @@ Hardware Monitoring Kernel Drivers
    bel-pfe
    bpa-rs600
    bt1-pvt
+   cgbc-hwmon
    chipcap2
    coretemp
    corsair-cpro

MAINTAINERS

@@ -5874,6 +5874,7 @@ CONGATEC BOARD CONTROLLER MFD DRIVER
 M:	Thomas Richard <thomas.richard@bootlin.com>
 S:	Maintained
 F:	drivers/gpio/gpio-cgbc.c
+F:	drivers/hwmon/cgbc-hwmon.c
 F:	drivers/i2c/busses/i2c-cgbc.c
 F:	drivers/mfd/cgbc-core.c
 F:	drivers/watchdog/cgbc_wdt.c

drivers/hwmon/Kconfig

@@ -463,6 +463,16 @@ config SENSORS_BT1_PVT_ALARMS
 	  the data conversion will be periodically performed and the data will be
 	  saved in the internal driver cache.
 
+config SENSORS_CGBC
+	tristate "Congatec Board Controller Sensors"
+	depends on MFD_CGBC
+	help
+	  Enable sensors support for the Congatec Board Controller. It has
+	  temperature, voltage, current and fan sensors.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called cgbc-hwmon.
+
 config SENSORS_CHIPCAP2
 	tristate "Amphenol ChipCap 2 relative humidity and temperature sensor"
 	depends on I2C

drivers/hwmon/Makefile

@@ -59,6 +59,7 @@ obj-$(CONFIG_SENSORS_ASUS_ROG_RYUJIN)	+= asus_rog_ryujin.o
 obj-$(CONFIG_SENSORS_ATXP1)	+= atxp1.o
 obj-$(CONFIG_SENSORS_AXI_FAN_CONTROL) += axi-fan-control.o
 obj-$(CONFIG_SENSORS_BT1_PVT)	+= bt1-pvt.o
+obj-$(CONFIG_SENSORS_CGBC)	+= cgbc-hwmon.o
 obj-$(CONFIG_SENSORS_CHIPCAP2) += chipcap2.o
 obj-$(CONFIG_SENSORS_CORETEMP)	+= coretemp.o
 obj-$(CONFIG_SENSORS_CORSAIR_CPRO) += corsair-cpro.o