[PATCH v2 1/2] arm64: dts: meson-gxbb-odroidc2: read the Ethernet MAC address from eFuse

[Fil Dunsky via B4 Relay]

From: Fil Dunsky <filipp.dunsky@xxxxxxxxx>

The vendor programs a unique factory MAC address into the SoC eFuse at
offset 0x34, where meson-gx.dtsi already describes the eth_mac nvmem
cell.  Reference the cell from the Ethernet controller so the kernel
picks up the factory address itself instead of depending on the
bootloader to populate local-mac-address, or falling back to a random
one when it does not.

The cell is 16 bytes long in meson-gx.dtsi, while
of_get_mac_address_nvmem() only accepts a cell of exactly ETH_ALEN
bytes, so narrow it to the 6 bytes of the address for this board.

Tested on an ODROID-C2 with the bootloader's MAC fixup out of the way
(ethernet0 alias removed from the DTB): with the 16-byte cell the
driver falls back to a random address, with the 6-byte cell eth0 comes
up with the factory address from the eFuse.

Signed-off-by: Fil Dunsky <filipp.dunsky@xxxxxxxxx>
---
 arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts b/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
index 5943bc810..3b74528ef 100644
--- a/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
+++ b/arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts
@@ -223,6 +223,10 @@ &cec_AO {
 	hdmi-phandle = <&hdmi_tx>;
 };
 
+&eth_mac {
+	reg = <0x34 0x6>;
+};
+
 &ethmac {
 	status = "okay";
 	pinctrl-0 = <&eth_rgmii_pins>;
@@ -230,6 +234,9 @@ &ethmac {
 	phy-handle = <&eth_phy0>;
 	phy-mode = "rgmii";
 
+	nvmem-cells = <&eth_mac>;
+	nvmem-cell-names = "mac-address";
+
 	amlogic,tx-delay-ns = <2>;
 
 	mdio {

-- 
2.53.0