mediatek: filogic: Add support for cudy wr3000h

mediatek: filogic: Add support for cudy wr3000h

The manufacturer Cudy usually releases signed openwrt firmware, to
facilitate the migration from the proprietary version to the official
versions of openwrt. In contact with the manufacturer tells me that only
releases the firmware of the WR3000H if and only if
there is an official version. With this proposal I pretend to have an
initial operative version so that they do their part, and facilitate to
the users the possibility of using openwrt. In the present state, it is
only possible to use this firmware by uploading and installing it with
UART connection.

AX3000 2.5G Dual Band Wi-Fi 6 Mesh Router (WR3000H)

Hardware
--------
MediaTek MT7981 WiSoC
256MB DDR3 RAM
128MB SPI-NAND (XMC XM25QH128C)
MediaTek MT7981 2x2 DBDC 802.11ax 2T2R (2.4 / 5)
4 LAN MediaTek MT7531 PHY
1 WAN RTL8221B-VB-CG 2.5Gbps PHY (C22)
2 Radios MT7976CN
UART: 115200 8N1 3.3V

MAC:
LAN MAC: label mac
WAN MAC: label mac + 1
2.4G MAC: label mac
5G MAC: label mac + 1 with LA bit set

Installation
------------

1. Connect to the serial port as described in the "Hardware" section.

2. Power on the device + press reset pin. Keep pressing reset pin to
   enter the U-Boot shell (The recovery.bin image load process must fail).

3. Download the OpenWrt initramfs image. Place it on an TFTP server
   connected to the Cudy LAN ports. Make sure the server is reachable at
   192.168.1.88. Rename the image to "cudy3000h.bin"

4. Download and boot the OpenWrt initramfs image.

   $ tftpboot 0x46000000 cudy3000h.bin; bootm 0x46000000

5. IMPORTANT: Make backup from original firmware. System -> Backup
   /Flash Firmware -> Save mtdblock contents. All mtdblock one by one,
keep unaltered (BL2, u-boot-env, Factory, bdinfo, FIP, and ubi).

6. Transfer the OpenWrt sysupgrade image to the device using scp.
   Install with sysupgrade.

Warning for BL2 and U-BOOT developers
-------------------------------------
The nand partition layout from vendor is slightly diferent from "standard".
The FIP partition starts at 0x3c0000 be carefull with BL2 to BL31.
The UBI partition start at 0x5c0000 be carefull.
DO NOT OVERWRITE bdinfo partition it contains hardware MAC definition
Layout is start-end (not start size)
  - 0x000000000000-0x000007800000 : "nmbm0"
          - 0x000000000000-0x000000100000 : "bl2"
          - 0x000000100000-0x000000180000 : "u-boot-env"
          - 0x000000180000-0x000000380000 : "factory"
          - 0x000000380000-0x0000003c0000 : "bdinfo"
          - 0x0000003c0000-0x0000005c0000 : "fip"
          - 0x0000005c0000-0x0000045c0000 : "ubi"
ALLWAYS for U-BOOT operations check this
setenv mtdids nmbm0=nmbm0
setenv mtdparts nmbm0:1024k(bl2),512k(u-boot-env),2048k(factory),256k(bdinfo),2048k(fip),65536k(ubi)

Signed-off-by: Juan Pedro Paredes Caballero <juanpedro.paredes@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/17458
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>