net: mediatek: add support for adjusting MDIO clock

User can assign a specific MDC speed to the eth node as follow:

&eth {
	...
	phy-mode = "usxgmii";
	phy-handle = <&phy8>;

	mdio {
		clock-frequency = <10500000>;
	};

	phy8: eth-phy@8 {
	      compatible = "ethernet-phy-id31c3.1c12";
	...
};

Signed-off-by: Bo-Cun Chen <bc-bocun.chen@mediatek.com>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
2 files changed