porting from 32 bit to 64 bit linux

Hello,

I want to port linux(redhat linux 8.0) driver from 32 bit to 64 bit
Intel architecture.
Can anyone tell me what change has to be done in driver code to support
64 bit architecture... or where can I find relevant information.
Will the same change work for 32 bit architecture also.

Any help will be highly appreciated.

Thanks in advance.
Regards,