Support for RTL838x based managed switches

[kitor]

@janh

The hardware profile appears to be selected at runtime using GPIOs 23, 19, 18. Maybe someone with a XGS1210-12 or XGS1250-12 can read the values to confirm:

• XGS1210-12 v1: 001
• XGS1210-12 v2: 101
• XGS1250-12 v1: 000
• XGS1250-12 v2: 100

On my XGS1010-12, all three GPIOs read 0.

I found a bit cryptic GPIO drawings on https://svanheule.net/switches/zyxel_xgs1210_series#board_details

So I opened my 1010 and under a microscope, cross referencing RTL8301 pinout, I found those three resistors to be the GPIOs we want. They are on the back side of the board. Their setting is indeed 0 0 0 (all three set to GND)

So i moved GPIO 18 resistor (all are 1K) from ground to 3v3:

I already had 1210 bootloader / flash layout / env vars installed on my unit. I found it on this comment on Reddit.

With that said, 1.0 firmware was rejecting to update from GUI. So I went UART upgrade method, and...

Everything seems to work, 1G, 2.5G, SPF+ ports

So thank you for this tip!