This switches stage2 to C and uses Jinja to change the C code based
on flash settings from https://github.com/adafruit/nvm.toml. It
produces the fastest settings for the given set of external flashes.
Flash size is no longer hard coded so switching flashes with similar
capabilities but different sizes should *just work*.
This PR also places "ITCM" code in RAM to save the XIP cache for
code execution. Further optimization is possible. A blink code.py
still requires a number of flash fetches every blink.
Fixes#4041
Instead of counting words in make, which is slightly awful, notice that
possible_devices is local to external_flash.c, so we can declare the array
with an automatic bound, and then get the count as the element-count
(MP_ARRAY_SIZE) of the array.
Since EXTERNAL_FLASH_DEVICE_COUNT is no longer a global macro, switch
a few sites to using EXTERNAL_FLASH_DEVICES in `#if` checks instead.
This started while adding USB MIDI support (and descriptor support is
in this change.) When seeing that I'd have to implement the MIDI class
logic twice, once for atmel-samd and once for nrf, I decided to refactor
the USB stack so its shared across ports. This has led to a number of
changes that remove items from the ports folder and move them into
supervisor.
Furthermore, we had external SPI flash support for nrf pending so I
factored out the connection between the usb stack and the flash API as
well. This PR also includes the QSPI support for nRF.
microDev
Scott Shawcroft
Jeff Epler
Diego Elio Pettenò