[PATCH 1/1] ARM: dts: aspeed: msx4: enable BMC networking via MAC0

[Ender Hsieh <andhsieh@nvidia.com>]

Add &mac0, &mdio3, and the ethphy3 PHY node to enable BMC networking
on the AST2600-based NVIDIA MSX4 board. The PHY is attached to MDIO3
at address 2 and uses RGMII with PHY-internal delays.

These nodes were intentionally omitted in commit f28674fab34f ("ARM:
dts: aspeed: Add NVIDIA MSX4 HPM") at Andrew Lunn's request, pending
clarification of the RGMII delay handling. Following his guidance on
linux-aspeed, the bootloader has been modified to stop enabling MAC
clock delays on the SoC side, so phy-mode = "rgmii-id" correctly
results in the PHY adding the required ~2ns delay without any
double-delay from the MAC controller.

The corresponding U-Boot change has been submitted to openbmc/u-boot.

Link: https://patch.msgid.link/eac09481-0ba1-4ac2-ad8c-d859822ff0d5@lunn.ch
Link: https://patch.msgid.link/20260504044702.2613879-1-andhsieh@nvidia.com
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Marc Olberding <molberding@nvidia.com>
Signed-off-by: Ender Hsieh <andhsieh@nvidia.com>
---
 .../dts/aspeed/aspeed-bmc-nvidia-msx4-bmc.dts     | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed/aspeed-bmc-nvidia-msx4-bmc.dts b/arch/arm/boot/dts/aspeed/aspeed-bmc-nvidia-msx4-bmc.dts
index a12d4164de4a..29f56176e2ca 100644
--- a/arch/arm/boot/dts/aspeed/aspeed-bmc-nvidia-msx4-bmc.dts
+++ b/arch/arm/boot/dts/aspeed/aspeed-bmc-nvidia-msx4-bmc.dts
@@ -208,6 +208,21 @@ &lpc_reset {
 	status = "okay";
 };
 
+&mac0 {
+	phy-mode = "rgmii-id";
+	phy-handle = <&ethphy3>;
+	status = "okay";
+};
+
+&mdio3 {
+	status = "okay";
+
+	ethphy3: ethernet-phy@2 {
+		compatible = "ethernet-phy-ieee802.3-c22";
+		reg = <2>;
+	};
+};
+
 &rtc {
 	status = "okay";
 };
-- 
2.34.1