CLINT and CLINTx extension

Created by: davideschiavone

CLINT

• RI5CY is now compatible with the RISC-V Clint.

• Code heavily based on the Ibex Core from lowRISC

• See documentation at https://ibex-core.readthedocs.io/en/latest/exception_interrupts.html

CLINTx

• Added 32 interrupt lines more (namely FAST 32 to 63)

• Added MTVECx and MIEx to control where the core jumps on these 32 requests and to control the interrupt enables

• ACK signal from the core now active only on these 32 interrupt requests

TestBench

• Adapted firmwares and linker scripts to have 32 lines more in the IVT

• Added interrupt test

TODO

• Update documentation

• Adapt DM testbench