Add DT device node of mdio multiplexer device for cv18xx SoC.

Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
---
 arch/riscv/boot/dts/sophgo/cv180x.dtsi | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/riscv/boot/dts/sophgo/cv180x.dtsi b/arch/riscv/boot/dts/sophgo/cv180x.dtsi
index 7eecc67f896e..929864ba1b26 100644
--- a/arch/riscv/boot/dts/sophgo/cv180x.dtsi
+++ b/arch/riscv/boot/dts/sophgo/cv180x.dtsi
@@ -31,6 +31,32 @@ rst: reset-controller@3003000 {
 			#reset-cells = <1>;
 		};
 
+		mdio: mdio@3009000 {
+			compatible = "sophgo,cv1800b-mdio-mux";
+			reg = <0x3009000 0x1000>;
+			#address-cells = <1>;
+			#size-cells = <0>;
+			mdio-parent-bus = <&gmac0_mdio>;
+			status = "disabled";
+
+			external_mdio: mdio@0 {
+				#address-cells = <1>;
+				#size-cells = <0>;
+				reg = <0>;
+			};
+
+			internal_mdio: mdio@1 {
+				#address-cells = <1>;
+				#size-cells = <0>;
+				reg = <1>;
+
+				internal_ephy: phy@0 {
+					compatible = "ethernet-phy-ieee802.3-c22";
+					reg = <0>;
+				};
+			};
+		};
+
 		gpio0: gpio@3020000 {
 			compatible = "snps,dw-apb-gpio";
 			reg = <0x3020000 0x1000>;
-- 
2.49.0