royalty free embedded processor
Besides the likes of RiscV, there is OpenRISC ( https://openrisc.io/ ) 


  a free and open RISC instruction set architecture with DSP features
  
  a set of free, open source implementations of the architecture
  
  a complete set of free, open source software development tools,
  libraries, operating systems and applications
  
  a variety of system-on-chip and system simulators


The or1200 implementation is done is verilog and is released under the LGPL license

https://github.com/openrisc/or1200

mor1kx is written in verilog and released under the OHLD license 

https://github.com/openrisc/mor1kx