hwmon: (gxp-fan-ctrl) Add GXP fan controller

The GXP SoC can support up to 16 fans through the interface provided by
the CPLD. The fans speeds are controlled via a pwm value 0-255. The fans
are also capable of reporting if they have failed to the CPLD which in
turn reports the status to the GXP SoC. There are no tachometers so fan
speeds are reported as a percent of the pwm value.

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>

Documentation/hwmon/gxp-fan-ctrl.rst

@@ -0,0 +1,36 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver gxp-fan-ctrl
+==========================
+
+Supported chips:
+
+  * HPE GXP SOC
+
+Author: Nick Hawkins <nick.hawkins@hpe.com>
+
+
+Description
+-----------
+
+gxp-fan-ctrl is a driver which provides fan control for the hpe gxp soc.
+The driver allows the gathering of fan status and the use of fan
+pwm control.
+
+
+Usage Notes
+-----------
+
+Traditionally fanY_input returns an RPM value, on HPE GXP systems it is
+the pwm value [0-255] due to the fan speeds being reported as
+percentages.
+
+
+Sysfs attributes
+----------------
+
+======================= =================================================
+pwm[0-15]		Fan 0 to 15 respective pwm value
+fan[0-15]_input		Fan 0 to 15 respective input value: pwm value
+fan[0-15]_fault		Fan 0 to 15 respective fault status: 1 fail, 0 ok
+======================= =================================================

drivers/hwmon/Kconfig

@@ -2339,6 +2339,14 @@ config SENSORS_INTEL_M10_BMC_HWMON
 	  sensors monitor various telemetry data of different components on the
 	  card, e.g. board temperature, FPGA core temperature/voltage/current.
 
+config SENSORS_GXP_FAN_CTRL
+	tristate "GXP Fan Control driver"
+	depends on ARCH_HPE_GXP || COMPILE_TEST
+	help
+	  If you say yes here you get support for GXP fan control functionality.
+	  The GXP controls fan function via the CPLD through the use of PWM
+	  registers. This driver reports status and pwm setting of the fans.
+
 if ACPI
 
 comment "ACPI drivers"

drivers/hwmon/Makefile

@@ -83,6 +83,7 @@ obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
 obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
+obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5500)	+= i5500_temp.o