nmigen-learning/fpga/spiflash_ideas.md

Ability to provide binary blobs to also be flashed to the FPGA's SPI flash

Whenever a SPI flash module is added to nmigen-stdio or wherever, there should be an option to define binary blobs to be programed/flashed along with the synthesized bitfile.

These binary blobs could either be added in if __main__ == ..., or possibly even during elaboration. Example:

with open("myfile.bin", "rv") as f:
    platform.add_spi_flash_data(start_addr=0x020000, label="riscv_program", data=f.read())
    # 'data' could be optional for RTL generation, but required for building/programming
    # perhaps an 'end_addr' or 'size' kwarg could be needed?

...

def elaborate(self, platform):
    start_addr, size = platform.get_spi_flash_data(label="riscv_rom") # throws if the label is not defined

Request for Comment:

Different FPGAs are programmed differently. The Ice40 usually write to the SPI flash when programmed, but the arty 7 is only programed in RAM, without neccesarily writing to the SPI flash.