realtek: HPE 1920-48G-PoE: allow fan speed control

The JG928A has an RTL8231 on the aux mdio bus. Add it to dts to expose
the GPIO pins used to control and monitor the fan speed. To enable speed
control, add the appropriate kernel driver module to DEVICE_PACKAGES.

Of note, this does not control all fans for the unit. The power supply
fans are not controlled.

Signed-off-by: Evan Jobling <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/17699
Signed-off-by: Sander Vanheule <[email protected]>

target/linux/realtek/dts/rtl8393_hpe_1920-48g-poe.dts

@@ -5,8 +5,37 @@
 / {
 	compatible = "hpe,1920-48g-poe", "realtek,rtl8393-soc";
 	model = "HPE 1920-48G-PoE (JG928A)";
+
+	gpio_fan_array {
+		compatible = "gpio-fan";
+
+		gpios = <&gpio1 5 GPIO_ACTIVE_HIGH>;
+		gpio-fan,speed-map =    <5000 0>,
+					<8200 1>;
+
+		alarm-gpios = <&gpio1 6 GPIO_ACTIVE_LOW>;
+		#cooling-cells = <2>;
+	};
 };
 
 &uart1 {
 	status = "okay";
 };
+
+&mdio_aux {
+	status = "okay";
+
+	gpio1: expander@0 {
+		compatible = "realtek,rtl8231";
+		reg = <0>;
+
+		gpio-controller;
+		#gpio-cells = <2>;
+		gpio-ranges = <&gpio1 0 0 37>;
+
+		led-controller {
+			compatible = "realtek,rtl8231-leds";
+			status = "disabled";
+		};
+	};
+};

target/linux/realtek/image/rtl839x.mk

@@ -21,7 +21,7 @@ define Device/hpe_1920-48g-poe
   $(Device/hpe_1920)
   SOC := rtl8393
   DEVICE_MODEL := 1920-48G-PoE (JG928A)
-  DEVICE_PACKAGES += realtek-poe
+  DEVICE_PACKAGES += realtek-poe kmod-hwmon-gpiofan
   H3C_DEVICE_ID := 0x0001002b
 endef
 TARGET_DEVICES += hpe_1920-48g-poe