I think LiteX's SoCIORegions are reserved regions. Non-cached regions
are then placed inside these reserved regions. Each module also has
a "do_finalize" method that runs at code generation.
The previous code did not properly assign all values on all cases,
and did not properly assign values (master interfaces, which are
poorly named because they are the interfaces to the master, connect
to the slave lines directly in the interconnect)
Peter McGoron
Adam Mooers