@User Sadly, most of what is on OpenCores is badly outdated and nothing really happens there so unfortunately it has become more of an hindrance nowadays since most people think that's still the state of open source silicon. We did a copy of OpenCores a couple of years ago here
https://github.com/freecores since the OpenCores servers kept going down all the time during a period. Out of those cores I have taken special care and try to maintain some of the most common ones like the uart16550, simple_spi and i2c cores. These are also all available in the FuseSoC base library
https://github.com/fusesoc/fusesoc-cores