Documentation: devicetree: add qca8k binding

Add device-tree binding for ar8xxx switch families.

Cc: devicetree@vger.kernel.org
Signed-off-by: John Crispin <john@phrozen.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/qca8k.txt

+* Qualcomm Atheros QCA8xxx switch family
+
+Required properties:
+
+- compatible: should be "qca,qca8337"
+- #size-cells: must be 0
+- #address-cells: must be 1
+
+Subnodes:
+
+The integrated switch subnode should be specified according to the binding
+described in dsa/dsa.txt. As the QCA8K switches do not have a N:N mapping of
+port and PHY id, each subnode describing a port needs to have a valid phandle
+referencing the internal PHY connected to it. The CPU port of this switch is
+always port 0.
+
+Example:
+
+
+	&mdio0 {
+		phy_port1: phy@0 {
+			reg = <0>;
+		};
+
+		phy_port2: phy@1 {
+			reg = <1>;
+		};
+
+		phy_port3: phy@2 {
+			reg = <2>;
+		};
+
+		phy_port4: phy@3 {
+			reg = <3>;
+		};
+
+		phy_port5: phy@4 {
+			reg = <4>;
+		};
+
+		switch0@0 {
+			compatible = "qca,qca8337";
+			#address-cells = <1>;
+			#size-cells = <0>;
+
+			reg = <0>;
+
+			ports {
+				#address-cells = <1>;
+				#size-cells = <0>;
+				port@0 {
+					reg = <0>;
+					label = "cpu";
+					ethernet = <&gmac1>;
+					phy-mode = "rgmii";
+				};
+
+				port@1 {
+					reg = <1>;
+					label = "lan1";
+					phy-handle = <&phy_port1>;
+				};
+
+				port@2 {
+					reg = <2>;
+					label = "lan2";
+					phy-handle = <&phy_port2>;
+				};
+
+				port@3 {
+					reg = <3>;
+					label = "lan3";
+					phy-handle = <&phy_port3>;
+				};
+
+				port@4 {
+					reg = <4>;
+					label = "lan4";
+					phy-handle = <&phy_port4>;
+				};
+
+				port@5 {
+					reg = <5>;
+					label = "wan";
+					phy-handle = <&phy_port5>;
+				};
+			};
+		};
+	};