To run these you need icarus verilog, and a ppc64le toolchain. On Fedora these are available as packages:
sudo dnf install iverilog gcc-powerpc64le-linux-gnu
And on Ubuntu:
sudo apt install iverilog gcc-powerpc64le-linux-gnu
The test cases need a path to the PDK, eg:
make PDK_PATH=/home/anton/pdk/sky130A
This is probably where you should start. This is a minimal test that verifies that Microwatt is running. The SPI flash controller is lightly tested because Microwatt uses it to fetch instructions for the test case. The GPIO macro is also lightly tested because Microwatt uses that to signal back to the management engine that it is alive.
This reads the IDCODE register out of the Microwatt JTAG TAP interface.
A simple UART test where we send a character to Microwatt and it echoes it back.
Before starting flash is initialized with a hash of the offset. The test case then does reads at various offsets and checks if the values returned are correct.
A simple memory tester. Writes hashes of the offset of memory into memory, then reads them back.