ramips: mt7621: add support for Arcadyan WE410443

ramips: mt7621: add support for Arcadyan WE410443

The Arcadyan WE410443 is a WiFi AC access point distributed by various ISPs
under various names, including KPN SuperWifi and BT Whole Home Wi-Fi. It
features one ethernet port, dual MT7615N radios and four internal antennas.

Hardware:
- SoC: Mediatek MT7621AT
- Flash: 32 MB
- RAM: 128 MB
- Ethernet: 1x 10/100/1000 Mbps, built into the SoC
- WLAN: 2x MediaTek MT7615N
- Buttons: 1 Reset button, 1 WPS button
- LEDs: 1x Green, 1x Blue, 1x Red, all unmarked
- Power: 12 VDC, 1.5A barrel plug

Installation:
The bootloader is locked with a password, so the image needs to be written
directly to the SPI flash chip. To do this, you need to open up the case,
remove the heatsink and connect the flash chip to a Raspberry Pi. Use the
following connections:

Flash chip --> Raspberry Pi

VCC --> 3v3
RESET --> 3v3
/CS --> GPIO 8
DO --> GPIO 9
CLK --> GPIO 11
DI --> GPIO 10
GND --> Ground

You can solder wires to the flash chip, or use a SOIC16 clip. More details on
the Raspberry Pi and SPI chip pinouts are available on the wiki [1]
When you have the Raspberry Pi connected to the flash chip, boot your Pi and
follow the instructions:

1) Make sure your Pi has SPI enabled with sudo raspi-config

2) Install necessary tools: sudo apt install xxd libubootenv-tool mtd-utils

3) Upload overlay and execute:
sudo dtc -@ -I dts -O dtb -o
/boot/overlays/we410443.dtbo we410443-overlay.dts

4) Enable in /boot/firmware/config.txt by adding a new line containing
dtoverlay=we410443

5) Reboot your Pi and verify the mtd partitions with
cat /proc/mtd, you should see:

dev:    size   erasesize  name
mtd0: 02000000 00001000 "all"
mtd1: 00030000 00001000 "u-boot"
mtd2: 00010000 00001000 "u-boot-env"
mtd3: 00010000 00001000 "factory"
mtd4: 01f60000 00001000 "firmware"
mtd5: 00010000 00001000 "glbcfg"
mtd6: 00010000 00001000 "config"
mtd7: 00010000 00001000 "glbcfg2"
mtd8: 00010000 00001000 "config2"

6) Optionally (but recommended), make a backup:
sudo dd if=/dev/mtd0 of=backup.bin
It can be restored with: sudo flashcp backup.bin /dev/mtd0

7) Set the variables for the bootloader:
echo '/dev/mtd2 0x0 0x1000 0x1000' > fw_env.config
sudo fw_setenv -c fw_env.config bootpartition 0

8) Finally, flash the image:
sudo flashcp openwrt-ramips-mt7621-arcadyan_we410443-
squashfs-sysupgrade.bin /dev/mtd4

MAC addresses
The label address is stored in ASCII in the config partition

Use --> Address

Device --> label
Ethernet --> label
WLAN 2g --> + 1
WLAN 5g --> + 2

References:
[1] https://openwrt.org/toh/arcadyan/astoria/we410443

Signed-off-by: Sander van Deijck <sander@vandeijck.com>
Link: https://github.com/openwrt/openwrt/pull/17981
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>