The SoC has a Synopsys gigabit MAC, glue registers for the interface
type and clock timing, and a multiplexer that points the management bus
at the on-chip 100M PHY or the external pins. None of it was described.

The controller reaches memory through a pipeline stage with a gate
nothing else claims, so it is switched off as unused. The
glue registers share a clock with the multiplexer, which probes after
the controller has programmed them: unless the controller holds that
clock, the writes are lost and the port keeps the
bootloader's delays.

The multiplexer and the on-chip PHY bus start disabled: a board enables
the multiplexer with the controller, and the on-chip bus only when it
uses that PHY.

Assisted-by: LLM
Signed-off-by: Lucas Tanure <tanure@linux.com>
---
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi | 60 +++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
index 7bd53ec16607..f15fd8f6cdd2 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
@@ -250,6 +250,33 @@ gic: interrupt-controller@fff01000 {
 			interrupts = <GIC_PPI 9 (GIC_CPU_MASK_SIMPLE(8) | IRQ_TYPE_LEVEL_HIGH)>;
 		};
 
+		ethmac: ethernet@fdc00000 {
+			compatible = "amlogic,t7-dwmac",
+				     "snps,dwmac-5.10a",
+				     "snps,dwmac";
+			reg = <0x0 0xfdc00000 0x0 0x10000>,
+			      <0x0 0xfe024000 0x0 0x8>;
+			interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>;
+			interrupt-names = "macirq";
+			clocks = <&clkc_periphs CLKID_SYS_ETH>,
+				 <&scmi_clk CLKID_FCLK_DIV2>,
+				 <&mpll CLKID_MPLL2>,
+				 <&clkc_periphs CLKID_SYS_AMPIPE_ETH>,
+				 <&clkc_periphs CLKID_SYS_ETHPHY>;
+			clock-names = "stmmaceth", "clkin0", "clkin1", "pipeline",
+				      "pclk";
+			power-domains = <&pwrc PWRC_T7_ETH_ID>;
+			rx-fifo-depth = <4096>;
+			tx-fifo-depth = <2048>;
+			status = "disabled";
+
+			mdio0: mdio {
+				compatible = "snps,dwmac-mdio";
+				#address-cells = <1>;
+				#size-cells = <0>;
+			};
+		};
+
 		apb4: bus@fe000000 {
 			compatible = "simple-bus";
 			reg = <0x0 0xfe000000 0x0 0x480000>;
@@ -645,6 +672,39 @@ gpio_intc: interrupt-controller@4080 {
 					<10 11 12 13 14 15 16 17 18 19 20 21>;
 			};
 
+			eth_phy: mdio-multiplexer@28000 {
+				compatible = "amlogic,g12a-mdio-mux";
+				reg = <0x0 0x28000 0x0 0xa4>;
+				clocks = <&clkc_periphs CLKID_SYS_ETHPHY>,
+					 <&xtal>,
+					 <&scmi_clk CLKID_FCLK_50M>;
+				clock-names = "pclk", "clkin0", "clkin1";
+				mdio-parent-bus = <&mdio0>;
+				#address-cells = <1>;
+				#size-cells = <0>;
+				status = "disabled";
+
+				ext_mdio: mdio@0 {
+					reg = <0>;
+					#address-cells = <1>;
+					#size-cells = <0>;
+				};
+
+				int_mdio: mdio@1 {
+					reg = <1>;
+					#address-cells = <1>;
+					#size-cells = <0>;
+					status = "disabled";
+
+					internal_ephy: ethernet-phy@8 {
+						compatible = "ethernet-phy-id0180.3301",
+							     "ethernet-phy-ieee802.3-c22";
+						interrupts = <GIC_SPI 340 IRQ_TYPE_LEVEL_HIGH>;
+						reg = <8>;
+					};
+				};
+			};
+
 			uart_a: serial@78000 {
 				compatible = "amlogic,t7-uart", "amlogic,meson-s4-uart";
 				reg = <0x0 0x78000 0x0 0x18>;
-- 
2.56.0