Flash programming on Blackice Mx

[lawrie]

After a bit of difficulty, I now have SB_WARMBOOT working.

So on power-on, my writeflash SoC runs. I can then send it a bistream to write to slot 1 (0x28000) and warm boot to it.

I don't need that STM32 processor and usb programming port any more

The latest version of the SoC is in the repository.

[lawrie]

And I now have a SoC that support execute-in-place (XIP), i.e it executes Risc-V code directly from the flash memory, I am using address 0x50000 for this, and using my writeflash SoC to write the XIP SoC image to address 0x28000, as XIP only works if the image is booted from flash memory (as the SaxonSoc XIP code does not wake up flash memory).