realtek: wire up GPIO fan for Zyxel XS1930 switches

The switches from Zyxels XS1930 have one or two fans in the case. They
might be controlled in a limited fashion. There's a single GPIO which -
depending on the state - drives the fan in slow or fast mode. Wire that
up as a device tree node to be able to control that in userspace.

XS1930-10 and XS1930-12HP use the same GPIO while XS1930-12F moves that
to one of its GPIO expanders. Also add 'kmod-hwmon-gpiofan' for all
three devices to be selected by default.

Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23428
Signed-off-by: Robert Marko <robimarko@gmail.com>

target/linux/realtek/dts/rtl9313_zyxel_xs1930-12f.dts

@@ -122,6 +122,8 @@
 	};
 };
 
+&fan0 { gpios = <&gpio1 35 GPIO_ACTIVE_HIGH>; };
+
 &gpio0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinmux_disable_jtag>,

target/linux/realtek/dts/rtl9313_zyxel_xs1930.dtsi

@@ -78,6 +78,16 @@
 			gpios = <&gpio0 26 GPIO_ACTIVE_LOW>;
 		};
 	};
+
+	fan0: gpio-fan {
+		compatible = "gpio-fan";
+		gpios = <&gpio0 22 GPIO_ACTIVE_HIGH>;
+
+		gpio-fan,speed-map =
+			<3600 0>,
+			<9000 1>;
+		#cooling-cells = <2>;
+	};
 };
 
 &spi0 {

target/linux/realtek/image/rtl931x.mk

@@ -49,7 +49,7 @@ TARGET_DEVICES += xikestor_sks8300-12x-v1
 
 define Device/zyxel_xs1930
   SOC := rtl9313
-  DEVICE_PACKAGES := kmod-hwmon-lm85
+  DEVICE_PACKAGES := kmod-hwmon-lm85 kmod-hwmon-gpiofan
   FLASH_ADDR := 0xb4280000
   IMAGE_SIZE := 31808k
   ZYNFW_ALIGN := 0x10000