Mikael Ågren 5535323b06
PoC: PicoRV32 interrupts
A proof-of-concept of enabling PicoRV32 interrupts. Two interrupt
sources, which can be triggered by writes to memory addresses, are
added.  The design has only been simulated, not run on hardware.

Synthesis:

Ice40 LC utilization is 93% (4934/5280) when built using tkey-builder:4

Simulation:

A `tb_application_fpga_irqpoc` target is added. Running `make
tb_application_fpga_irqpoc` creates `tb_application_fpga_sim.fst` which
can be inspected in GTKWave or Surfer.

Firmware:

A simple firmware is added in `fw/irqpoc`. It enables both interrupts
and triggers each interrupt once.

Custom PicoRV32 instructions are located in `custom_ops.S`. It is
imported from upstream PicoRV32 commit:
70f3c33ac8
2025-02-04 12:25:57 +01:00
..
2025-02-04 12:25:57 +01:00