How to use a serial keyboard on UART0

I have a serial keyboard connected to uart0 in my rock-S0 board. How can I make it work? In my laptop (running debian) it is recognized in the ttyUSB0, and running

inputattach --baud 115200 --newtonkbd /dev/ttyUSB0

makes the connection to the keyboard with the serio driver (loading also the newtonkbd module)
In my radxa rock-s0, I have the keyboard connected to the UART0 (pins 8 and 10), and enabled the UART0 overlay. Which device would I use to connect to the UART0? there is no ttyUSB0 of course, but neither ttyACM0. Trying with ttyS0 doesnt work neither.

Is it something related to the serial console? should I disable (somehow) the serial console prior to use UART0?
Any advise would be appreciated.