devicetree: bindings: dsa: qca8k: Document internal mdio definition

Document new way of declare mapping of internal PHY to port.
The new implementation directly declare the PHY connected to the port
by adding a node in the switch node. The driver detect this and register
an internal mdiobus using the mapping defined in the mdio node.
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -21,6 +21,10 @@ described in dsa/dsa.txt. If the QCA8K switch is connect to a SoC's external
 mdio-bus each subnode describing a port needs to have a valid phandle
 referencing the internal PHY it is connected to. This is because there's no
 N:N mapping of port and PHY id.
+To declare the internal mdio-bus configuration, declare a mdio node in the
+switch node and declare the phandle for the port referencing the internal
+PHY is connected to. In this config a internal mdio-bus is registered and
+the mdio MASTER is used as communication.
 
 Don't use mixed external and internal mdio-bus configurations, as this is
 not supported by the hardware.
@@ -150,26 +154,61 @@ for the internal master mdio-bus configuration:
 				port@1 {
 					reg = <1>;
 					label = "lan1";
+					phy-mode = "internal";
+					phy-handle = <&phy_port1>;
 				};
 
 				port@2 {
 					reg = <2>;
 					label = "lan2";
+					phy-mode = "internal";
+					phy-handle = <&phy_port2>;
 				};
 
 				port@3 {
 					reg = <3>;
 					label = "lan3";
+					phy-mode = "internal";
+					phy-handle = <&phy_port3>;
 				};
 
 				port@4 {
 					reg = <4>;
 					label = "lan4";
+					phy-mode = "internal";
+					phy-handle = <&phy_port4>;
 				};
 
 				port@5 {
 					reg = <5>;
 					label = "wan";
+					phy-mode = "internal";
+					phy-handle = <&phy_port5>;
+				};
+			};
+
+			mdio {
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				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>;
 				};
 			};
 		};