Add rpi-poe-fan driver

Signed-off-by: Serge Schneider <[email protected]>

PoE HAT driver cleanup

* Fix undeclared variable in rpi_poe_fan_suspend
* Add SPDX-License-Identifier
* Expand PoE acronym in Kconfig help
* Give clearer error message on of_property_count_u32_elems fail
* Add documentation
* Add vendor to of_device_id compatible string.
* Rename m_data_s struct to fw_data_s
* Fix typos

Fixes: #2665

Signed-off-by: Serge Schneider <[email protected]>

rpi-poe-fan: fix def_pwm1 writes

Signed-off-by: Serge Schneider <[email protected]>

Author: XECDesign

Documentation/devicetree/bindings/hwmon/rpi-poe-fan.txt

@@ -0,0 +1,55 @@
+Bindings for the Raspberry Pi PoE HAT fan
+
+Required properties:
+- compatible	: "raspberrypi,rpi-poe-fan"
+- firmware	: Reference to the RPi firmware device node
+- pwms		: the PWM that is used to control the PWM fan
+- cooling-levels      : PWM duty cycle values in a range from 0 to 255
+			which correspond to thermal cooling states
+
+Example:
+	fan0: rpi-poe-fan@0 {
+		compatible = "raspberrypi,rpi-poe-fan";
+		firmware = <&firmware>;
+		cooling-min-state = <0>;
+		cooling-max-state = <3>;
+		#cooling-cells = <2>;
+		cooling-levels = <0 50 150 255>;
+		status = "okay";
+	};
+
+	thermal-zones {
+		cpu_thermal: cpu-thermal {
+			trips {
+				threshold: trip-point@0 {
+					temperature = <45000>;
+					hysteresis = <5000>;
+					type = "active";
+				};
+				target: trip-point@1 {
+					temperature = <50000>;
+					hysteresis = <2000>;
+					type = "active";
+				};
+				cpu_hot: cpu_hot@0 {
+					temperature = <55000>;
+					hysteresis = <2000>;
+					type = "active";
+				};
+			};
+			cooling-maps {
+				map0 {
+					trip = <&threshold>;
+					cooling-device = <&fan0 0 1>;
+				};
+				map1 {
+					trip = <&target>;
+					cooling-device = <&fan0 1 2>;
+				};
+				map2 {
+					trip = <&cpu_hot>;
+					cooling-device = <&fan0 2 3>;
+				};
+			};
+		};
+	};

Documentation/hwmon/rpi-poe-fan

@@ -0,0 +1,15 @@
+Kernel driver rpi-poe-fan
+=====================
+
+This driver enables the use of the Raspberry Pi PoE HAT fan.
+
+Author: Serge Schneider <[email protected]>
+
+Description
+-----------
+
+The driver implements a simple interface for driving the Raspberry Pi PoE
+(Power over Ethernet) HAT fan. The driver passes commands to the Raspberry Pi
+firmware through the mailbox property interface. The firmware then forwards
+the commands to the board over I2C on the ID_EEPROM pins. The driver exposes
+the fan to the user space through the hwmon sysfs interface.

drivers/hwmon/Kconfig

@@ -1531,6 +1531,17 @@ config SENSORS_RASPBERRYPI_HWMON
 	  This driver can also be built as a module. If so, the module
 	  will be called raspberrypi-hwmon.
 
+config SENSORS_RPI_POE_FAN
+	tristate "Raspberry Pi PoE HAT fan"
+	depends on RASPBERRYPI_FIRMWARE
+	depends on THERMAL || THERMAL=n
+	help
+	  If you say yes here you get support for Raspberry Pi PoE (Power over
+	  Ethernet) HAT fan.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called rpi-poe-fan.
+
 config SENSORS_SL28CPLD
 	tristate "Kontron sl28cpld hardware monitoring driver"
 	depends on MFD_SL28CPLD || COMPILE_TEST

drivers/hwmon/Makefile

@@ -161,6 +161,7 @@ obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
 obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)	+= pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)	+= raspberrypi-hwmon.o
+obj-$(CONFIG_SENSORS_RPI_POE_FAN)	+= rpi-poe-fan.o
 obj-$(CONFIG_SENSORS_S3C)	+= s3c-hwmon.o
 obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi_temp.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o