mediatek: add stock layout for CMCC A10

This board is also as known as SuperElectron ZN-M5 and ZN-M8. However,
for ZN-M5 and ZN-M8, there's another version uses ZX279128 as CPU
chip, which is unsupported.
You can check it in "高级设置" > "系统日志" > "内核日志" page from webUI.

Stock layout flash instructions:
Login into webUI and upload sysupgrade firmware in "系统管理" > "升级固件" page.
Remember to unselect "保留配置" ("Keep configurations") first before doing that.

OpenWrt U-Boot layout flash instructions:
1. Flash stock layout firmware first.
2. Connect to the device via SSH, and backup everything,
   especially 'Factory' partition.
3. Unlock MTD partitions:
   opkg update && opkg install kmod-mtd-rw
   insmod mtd-rw i_want_a_brick=1
4. Write new BL2 and FIP:
   mtd write immortalwrt-mediatek-filogic-cmcc_a10-preloader.bin bl2
   mtd write immortalwrt-mediatek-filogic-cmcc_a10-bl31-uboot.fip fip
5. Set static IP on your PC:
   IP 192.168.1.254/24, GW 192.168.1.1
6. Serve ImmortalWrt initramfs image using TFTP server.
7. Cut off the power and re-engage, wait for TFTP recovery to complete.
8. After ImmortalWrt has booted, perform sysupgrade.

Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>
(cherry picked from commit 4e9240e7332f8a00713f284b0b0f4901d6b2b16c)

target/linux/mediatek/dts/mt7981b-cmcc-a10-stock.dts

@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
+
+/dts-v1/;
+#include "mt7981b-cmcc-a10.dts"
+
+
+/ {
+	model = "CMCC A10 (stock layout)";
+	compatible = "cmcc,a10-stock", "mediatek,mt7981";
+};
+
+&partitions {
+	partition@4580000 {
+		label = "firmware_backup";
+		reg = <0x4580000 0x2000000>;
+		read-only;
+	};
+
+	partition@6580000 {
+		label = "zrsave";
+		reg = <0x6580000 0x100000>;
+		read-only;
+	};
+
+	partition@6680000 {
+		label = "config2";
+		reg = <0x6680000 0x100000>;
+		read-only;
+	};
+};
+
+&spi0_flash_pins {
+	conf-pu {
+		/delete-property/ mediatek,pull-up-adv;
+		bias-pull-up = <MTK_PUPD_SET_R1R0_11>;
+	};
+
+	conf-pd {
+		/delete-property/ mediatek,pull-up-adv;
+		bias-pull-down = <MTK_PUPD_SET_R1R0_11>;
+	};
+};
+
+&spi_nand {
+	mediatek,nmbm;
+	mediatek,bmt-max-ratio = <1>;
+	mediatek,bmt-max-reserved-blocks = <64>;
+};
+
+&ubi {
+	reg = <0x580000 0x4000000>;
+};

target/linux/mediatek/dts/mt7981b-cmcc-a10.dts

@@ -135,7 +135,7 @@
 		spi-tx-bus-width = <4>;
 		spi-rx-bus-width = <4>;
 
-		partitions {
+		partitions: partitions {
 			compatible = "fixed-partitions";
 			#address-cells = <1>;
 			#size-cells = <1>;

target/linux/mediatek/filogic/base-files/etc/board.d/02_network

@@ -32,6 +32,7 @@ mediatek_setup_interfaces()
 	cetron,ct3003-stock|\
 	cetron,ct3003-ubootmod|\
 	cmcc,a10|\
+	cmcc,a10-stock|\
 	cmcc,a10-ubootmod|\
 	confiabits,mt7981|\
 	cudy,wr3000-v1|\

target/linux/mediatek/image/filogic.mk

@@ -394,6 +394,12 @@ define Device/cmcc_a10
   DEVICE_MODEL := A10
   DEVICE_DTS := mt7981b-cmcc-a10
   DEVICE_VARIANT := (OpenWrt U-Boot layout)
+  DEVICE_ALT0_VENDOR := SuperElectron
+  DEVICE_ALT0_MODEL := ZN-M5
+  DEVICE_ALT0_VARIANT := (OpenWrt U-Boot layout)
+  DEVICE_ALT1_VENDOR := SuperElectron
+  DEVICE_ALT1_MODEL := ZN-M8
+  DEVICE_ALT1_VARIANT := (OpenWrt U-Boot layout)
   DEVICE_DTS_DIR := ../dts
   DEVICE_PACKAGES := kmod-mt7981-firmware mt7981-wo-firmware
   UBINIZE_OPTS := -E 5
@@ -414,10 +420,45 @@ define Device/cmcc_a10
 endef
 TARGET_DEVICES += cmcc_a10
 
+define Device/cmcc_a10-stock
+  DEVICE_VENDOR := CMCC
+  DEVICE_MODEL := A10
+  DEVICE_VARIANT := (stock layout)
+  DEVICE_ALT0_VENDOR := SuperElectron
+  DEVICE_ALT0_MODEL := ZN-M5
+  DEVICE_ALT0_VARIANT := (stock layout)
+  DEVICE_ALT1_VENDOR := SuperElectron
+  DEVICE_ALT1_MODEL := ZN-M8
+  DEVICE_ALT1_VARIANT := (stock layout)
+  DEVICE_DTS := mt7981b-cmcc-a10-stock
+  DEVICE_DTS_DIR := ../dts
+  SUPPORTED_DEVICES += mediatek,mt7981-spim-snand-rfb
+  DEVICE_PACKAGES := kmod-mt7981-firmware mt7981-wo-firmware
+  UBINIZE_OPTS := -E 5
+  BLOCKSIZE := 128k
+  PAGESIZE := 2048
+  IMAGE_SIZE := 65536k
+  KERNEL_IN_UBI := 1
+  IMAGES += factory.bin
+  IMAGE/factory.bin := append-ubi | check-size $$$$(IMAGE_SIZE)
+  IMAGE/sysupgrade.bin := sysupgrade-tar | append-metadata
+  KERNEL = kernel-bin | lzma | \
+	fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb
+  KERNEL_INITRAMFS = kernel-bin | lzma | \
+	fit lzma $$(KDIR)/image-$$(firstword $$(DEVICE_DTS)).dtb with-initrd
+endef
+TARGET_DEVICES += cmcc_a10-stock
+
 define Device/cmcc_a10-ubootmod
   DEVICE_VENDOR := CMCC
   DEVICE_MODEL := A10
   DEVICE_VARIANT := (custom U-Boot layout)
+  DEVICE_ALT0_VENDOR := SuperElectron
+  DEVICE_ALT0_MODEL := ZN-M5
+  DEVICE_ALT0_VARIANT := (custom U-Boot layout)
+  DEVICE_ALT1_VENDOR := SuperElectron
+  DEVICE_ALT1_MODEL := ZN-M8
+  DEVICE_ALT1_VARIANT := (custom U-Boot layout)
   DEVICE_DTS := mt7981b-cmcc-a10-ubootmod
   DEVICE_DTS_DIR := ../dts
   DEVICE_PACKAGES := kmod-mt7981-firmware mt7981-wo-firmware