Replicate etpu on radiona ULX3S

VexriscV using Litex to test skywater 130 etpu from https://github.com/tucanae47/etpu

Setup

pyenv virtualenv litex_env
pyenv activate litex_env
wget https://raw.githubusercontent.com/enjoy-digital/litex/master/litex_setup.py
chmod +x litex_setup.py
./litex_setup.py --init --install
pip3 install meson ninja
./litex_setup.py --gcc=riscv

Serial access to the softcore

litex_term --speed 9600 /dev/ttyUSB0

Important links:

Most of the work is based on projects listed here https://github.com/betrusted-io https://github.com/semify-eda/waveform-generator https://github.com/BrunoLevy/learn-fpga https://github.com/efabless/caravel_mgmt_soc_litex