Flash encryption support
Flash encryption support in build system, tooling
To come in future MR:
* On-device key generation on first boot (for production devices), need to finalise testing of bootloader entropy seeding.
* spi_flash_encrypted_write to support non-32-byte block writes (at least optionally.)
* I think a lot of the bootloader_support component can possibly be rolled into "spiflash" and other components, to use a common API.
See merge request !240
* App access functions are all flash encryption-aware
* Documentation for flash encryption
* Partition read/write is flash aware
* New encrypted write function
SPI flash hardware sends 52h command, which is a 32KB erase.
There is a matching bug in the ROM SPIEraseArea code, unless
flashchip->block_size is modified first.
ROM SPIWrite routine can work with unaligned sources, so this check is unnecessary.
Furthermore, it breaks nvs_set_str and nvs_get_blob when data pointer is unaligned.
Also fix stray backslash in COUNTER_STOP macro
spi_flash_read and spi_flash_write currently have a limitation that source and destination must be word-aligned.
This can be fixed by adding code paths for various unaligned scenarios, but function signatures also need to be adjusted.
As a first step (since we are pre-1.0 and can still change function signatures) alignment checks are added, and pointer types are relaxed to uint8_t.
Later we will add handling of unaligned operations.
This change also introduces spi_flash_erase_range and spi_flash_get_chip_size functions.
We probably need something like spi_flash_chip_size_detect which will detect actual chip size.
This is to allow single application binary to be used on a variety of boards and modules.
