Can we change the input/output mode of io pin after fabrication, using firmware? I need to use that pin as both input and output

Pin direction is determined by two factors. One is the

GPIO_MODE_*

set up in

user_defines.v

that you can also change from firmware. For

USER

mode pins, the other is

io_oeb

in your

user_project_wrapper

, and you can't change that after fabrication. If you intend to access the pins using

io_in

&

io_out

, you should set your pin mode to

GPIO_MODE_USER_STD_BIDIRECTIONAL

and use

io_oeb

to set the pin direction.