ramips: add support for ELECOM WMC-C2533GST

ELECOM WMC-C2533GST is a 2.4/5 GHz band 11ac (Wi-Fi 5) mesh
router, based on MT7621A.

It shares the same basic hardware and 32 MiB flash layout as
WRC-2533GST2, but the factory image uses the WMC-2HC hardware name.

Specification:

- SoC           : MediaTek MT7621A
- RAM           : DDR3 256 MiB
- Flash         : SPI-NOR 32 MiB (Macronix MX25L25635E)
- WLAN          : 2.4/5 GHz 4T4R (2x MediaTek MT7615)
- Ethernet      : 10/100/1000 Mbps x5
  - Switch      : MediaTek MT7530 (SoC)
- LED/keys      : 4x/6x (2x buttons, 1x slide-switch)
- UART          : through-hole on PCB
  - J4: 3.3V, GND, TX, RX from ethernet port side
  - 57600n8
- Power         : 12VDC, 1.5A

Flash instruction using factory image:

1. Boot WMC-C2533GST normally with "Router" mode
2. Access to "http://192.168.2.1/" and open firmware update page
   ("ファームウェア更新")
3. Select the OpenWrt factory image and click apply ("適用") button
4. Wait ~150 seconds to complete flashing

MAC addresses:

LAN     : 04:AB:18:xx:xx:BF (Factory, 0xFFF4 (hex))
WAN     : 04:AB:18:xx:xx:C0 (Factory, 0xFFFA (hex))
2.4GHz  : 04:AB:18:xx:xx:C1 (Factory, 0x4    (hex))
5GHz    : 04:AB:18:xx:xx:C2 (Factory, 0x8004 (hex))

Signed-off-by: Taiga Ogawa <zectaiga@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/23568
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>

target/linux/ramips/dts/mt7621_elecom_wmc-c2533gst.dts

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+#include "mt7621_elecom_wrc-gs-2pci.dtsi"
+
+/ {
+	compatible = "elecom,wmc-c2533gst", "mediatek,mt7621-soc";
+	model = "ELECOM WMC-C2533GST";
+};
+
+&partitions {
+	partition@50000 {
+		compatible = "denx,uimage";
+		label = "firmware";
+		reg = <0x50000 0x1800000>;
+	};
+
+	partition@1850000 {
+		label = "tm_pattern";
+		reg = <0x1850000 0x400000>;
+		read-only;
+	};
+
+	partition@1c50000 {
+		label = "tm_key";
+		reg = <0x1c50000 0x100000>;
+		read-only;
+	};
+
+	partition@1d50000 {
+		label = "nvram";
+		reg = <0x1d50000 0xb0000>;
+		read-only;
+	};
+
+	partition@1e00000 {
+		label = "user_data";
+		reg = <0x1e00000 0x200000>;
+		read-only;
+	};
+};
+
+&gmac0 {
+	nvmem-cells = <&macaddr_factory_fff4>;
+	nvmem-cell-names = "mac-address";
+};
+
+&gmac1 {
+	nvmem-cells = <&macaddr_factory_fffa>;
+	nvmem-cell-names = "mac-address";
+};
+
+&factory {
+	nvmem-layout {
+		compatible = "fixed-layout";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		macaddr_factory_fff4: macaddr@fff4 {
+			reg = <0xfff4 0x6>;
+		};
+
+		macaddr_factory_fffa: macaddr@fffa {
+			reg = <0xfffa 0x6>;
+		};
+	};
+};

target/linux/ramips/image/mt7621.mk

@@ -1279,6 +1279,14 @@ define Device/elecom_wrc-gs
   DEVICE_PACKAGES := kmod-mt7615-firmware -uboot-envtools
 endef
 
+define Device/elecom_wmc-c2533gst
+  $(Device/elecom_wrc-gs)
+  IMAGE_SIZE := 24576k
+  DEVICE_MODEL := WMC-C2533GST
+  ELECOM_HWNAME := WMC-2HC
+endef
+TARGET_DEVICES += elecom_wmc-c2533gst
+
 define Device/elecom_wmc-m1267gst2
   $(Device/elecom_wrc-gs)
   IMAGE_SIZE := 24576k