sunxi: R40: add gigabit ethernet devicetree node

Add a device tree node for the Allwinner R40/V40 GMAC gigabit
ethernet interface.
The R40 SoC does not use the syscon register for GMAC settings.
The gigabit ethernet interface can only be routed to a fixed set of
pins.
Updated to match the Linux kernel's device tree.

Signed-off-by: Lothar Felten <lothar.felten@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Tested-by: Jagan Teki <jagan@openedev.com>

arch/arm/dts/sun8i-r40.dtsi

@@ -161,6 +161,19 @@
 			#interrupt-cells = <3>;
 			#gpio-cells = <3>;
 
+			gmac_rgmii_pins: gmac-rgmii-pins {
+				pins = "PA0", "PA1", "PA2", "PA3",
+				       "PA4", "PA5", "PA6", "PA7",
+				       "PA8", "PA10", "PA11", "PA12",
+				       "PA13", "PA15", "PA16";
+				function = "gmac";
+				/*
+				 * data lines in RGMII mode use DDR mode
+				 * and need a higher signal drive strength
+				 */
+				drive-strength = <40>;
+			};
+
 			i2c0_pins: i2c0_pins {
 				pins = "PB0", "PB1";
 				function = "i2c0";
@@ -202,6 +215,27 @@
 			#size-cells = <0>;
 		};
 
+		gmac: ethernet@1c50000 {
+			compatible = "allwinner,sun8i-r40-gmac";
+			syscon = <&ccu>;
+			reg = <0x01c50000 0x10000>;
+			interrupts = <GIC_SPI 85 IRQ_TYPE_LEVEL_HIGH>;
+			interrupt-names = "macirq";
+			resets = <&ccu RST_BUS_GMAC>;
+			reset-names = "stmmaceth";
+			clocks = <&ccu CLK_BUS_GMAC>;
+			clock-names = "stmmaceth";
+			#address-cells = <1>;
+			#size-cells = <0>;
+			status = "disabled";
+
+			gmac_mdio: mdio {
+				compatible = "snps,dwmac-mdio";
+				#address-cells = <1>;
+				#size-cells = <0>;
+			};
+		};
+
 		gic: interrupt-controller@1c81000 {
 			compatible = "arm,cortex-a7-gic", "arm,cortex-a15-gic";
 			reg = <0x01c81000 0x1000>,