dt-bindings: Document EMAC Rockchip

* ARC EMAC 10/100 Ethernet platform driver for Rockchip Rk3066/RK3188 SoCs

Required properties:

- compatible: Should be "rockchip,rk3066-emac" or "rockchip,rk3188-emac"

  according to the target SoC.

- reg: Address and length of the register set for the device

- interrupts: Should contain the EMAC interrupts

- rockchip,grf: phandle to the syscon grf used to control speed and mode

  for emac.

- phy: see ethernet.txt file in the same directory.

- phy-mode: see ethernet.txt file in the same directory.

Optional properties:

- phy-supply: phandle to a regulator if the PHY needs one

Clock handling:

- clocks: Must contain an entry for each entry in clock-names.

- clock-names: Shall be "hclk" for the host clock needed to calculate and set

  polling period of EMAC and "macref" for the reference clock needed to transfer

  data to and from the phy.

Child nodes of the driver are the individual PHY devices connected to the

MDIO bus. They must have a "reg" property given the PHY address on the MDIO bus.

Examples:

ethernet@10204000 {

	compatible = "rockchip,rk3188-emac";

	reg = <0xc0fc2000 0x3c>;

	interrupts = <6>;

	mac-address = [ 00 11 22 33 44 55 ];

	clocks = <&cru HCLK_EMAC>, <&cru SCLK_MAC>;

	clock-names = "hclk", "macref";

	pinctrl-names = "default";

	pinctrl-0 = <&emac_xfer>, <&emac_mdio>, <&phy_int>;

	rockchip,grf = <&grf>;

	phy = <&phy0>;

	phy-mode = "rmii";

	phy-supply = <&vcc_rmii>;

	#address-cells = <1>;

	#size-cells = <0>;

	phy0: ethernet-phy@0 {

	      reg = <1>;

	};

};