stm32: Implement vfs.rom_ioctl with support for internal/external flash.

This commit implements `vfs.rom_ioctl()` to query, erase and write both
internal and external flash, depending on how the board configures its
flash memory.

A board can configure ROM as follows.

To use internal flash memory:

    #define MICROPY_HW_ROMFS_ENABLE_INTERNAL_FLASH (1)

To use external flash memory (QSPI memory mapped):

    #define MICROPY_HW_ROMFS_ENABLE_EXTERNAL_QSPI (1)
    #define MICROPY_HW_ROMFS_QSPI_SPIFLASH_OBJ (&spi_obj)

Then the partition must be defined as symbols in the linker script:

    _micropy_hw_romfs_part1_start
    _micropy_hw_romfs_part1_size

And finally the partition needs to be enabled:

    #define MICROPY_HW_ROMFS_ENABLE_PART1 (1)

There's support for a second, optional partition via:

    _micropy_hw_romfs_part2_start
    _micropy_hw_romfs_part2_size

    #define MICROPY_HW_ROMFS_ENABLE_PART1 (1)

Signed-off-by: Damien George <damien@micropython.org>

0 files changed, 0 insertions, 0 deletions