dt-bindings: net: Add fixed-link support

Update device-tree binding with fixed-link support.

With fixed-link support the formerly required property 'phy-handle'
is now optional if 'fixed-link' child is present.

Signed-off-by: Moritz Fischer <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/devicetree/bindings/net/nixge.txt

···
 - interrupts: Should contain tx and rx interrupt
 - interrupt-names: Should be "rx" and "tx"
 - phy-mode: See ethernet.txt file in the same directory.
-- phy-handle: See ethernet.txt file in the same directory.
 - nvmem-cells: Phandle of nvmem cell containing the MAC address
 - nvmem-cell-names: Should be "address"
 
 Optional properties:
 - mdio subnode to indicate presence of MDIO controller
+- fixed-link : Assume a fixed link. See fixed-link.txt in the same directory.
+  Use instead of phy-handle.
+- phy-handle: See ethernet.txt file in the same directory.
 
 Examples (10G generic PHY):
 	nixge0: ethernet@40000000 {
···
 
 		phy-mode = "xgmii";
 		phy-handle = <&ethernet_phy1>;
+	};
+
+Examples (1G generic fixed-link + MDIO):
+	nixge0: ethernet@40000000 {
+		compatible = "ni,xge-enet-2.00";
+		reg = <0x40000000 0x6000>;
+
+		nvmem-cells = <&eth1_addr>;
+		nvmem-cell-names = "address";
+
+		interrupts = <0 29 IRQ_TYPE_LEVEL_HIGH>, <0 30 IRQ_TYPE_LEVEL_HIGH>;
+		interrupt-names = "rx", "tx";
+		interrupt-parent = <&intc>;
+
+		phy-mode = "xgmii";
+
+		fixed-link {
+			speed = <1000>;
+			pause;
+			link-gpios = <&gpio0 63 GPIO_ACTIVE_HIGH>;
+		};
+
+		mdio {
+			ethernet_phy1: ethernet-phy@4 {
+				compatible = "ethernet-phy-ieee802.3-c22";
+				reg = <4>;
+			};
+		};
+
 	};