arm64: dts: rockchip: Add NanoPC-T4 IR receiver

In common with most Rockchip reference designs, NanoPC-T4 has a passive
IR receiver connected to PWM3. In lieu of a specialised driver for
PWM-based IR pulse measurement, running the pin as a GPIO with the basic
driver works perfectly well.
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-nanopc-t4.dts

@@ -45,6 +45,22 @@ recovery {
 			press-threshold-microvolt = <18000>;
 		};
 	};
+
+	ir-receiver {
+		compatible = "gpio-ir-receiver";
+		gpios = <&gpio0 RK_PA6 GPIO_ACTIVE_LOW>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&ir_rx>;
+	};
+};
+
+&pinctrl {
+	ir {
+		ir_rx: ir-rx {
+			/* external pullup to VCC3V3_SYS, despite being 1.8V :/ */
+			rockchip,pins = <0 RK_PA6 RK_FUNC_1 &pcfg_pull_none>;
+		};
+	};
 };
 
 &sdhci {