econet: add ChinaMobile GS3101

econet: add ChinaMobile GS3101

The ChinaMobile GS3101 has:
256MB RAM
256MB flash (TC58CVG1S3H)
1x MT7603 802.11 b/g/n - DISABLED
1x optical port
On-die MT7530 switch with:
- 1x gigabit ethernet port
- 3x 100Mb ethernet ports
1x USB 2.0 port
1x telephone VoIP port
3 controllable LEDs
1 GPIO button (reset), 1 WPS button (not detected in GPIOs)
UART header inside (solder required) 115200 baud
12v power (5.5mm x 2.1mm barrel connector)

Installation instructions: You will need a USB stick
1. Reformat the USB stick as VFAT with MBR partition table. This is important,
if it is GPT then it will silently fail to load.
2. Download openwrt-econet-en751221-chinamobile_gs3101-squashfs-tclinux.trx and
store it in the USB stick.
3. Start the device with the vendor OS
4. Connect a cable and request an IP address - it will issue in 192.168.1.0/24
5. Use telnet to connect to the modem on 192.168.1.1
6. Login as root@2024 / system
7. Plugin the USB stick
8. cp /mnt/usb1_1/openwrt-econet-en751221-chinamobile_gs3101-squashfs-tclinux.trx /tmp/openwrt.trx
9. mtd -r -f write /tmp/openwrt.trx tclinux
10. You will lose your shell, look at the power light on the device, it should
begin blinking and then go back to solid. You should NOT see any red light.
11. re-request an IP address
12. ssh root@192.168.1.1
13. You should be on OpenWrt now

MAC address matches that of vendor OS but it is not the address on the label
of the device. It is in a compressed xml file in the 'romfile' partition.
WAN is this mac, LAN is mac+1 and 2.4Ghz WLAN is mac+2, there is no 5Ghz WLAN.

Wifi Note: Of the devices tested, there were numerous upon which starting the
wlan chip caused the CPU to hang. In the interest of avoiding bricked boards,
the wlan is disabled in the DT.

Signed-off-by: Caleb James DeLisle <cjd@cjdns.fr>
Link: https://github.com/openwrt/openwrt/pull/23533
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>