Many simple kconfig configurations are added to boards and brought in with the board name.
This makes a common import of these configs so one only requires adding a BOARD.config without having to alter the makefile.
This introduces KCONFIG_BOARD_CONFIG and KCONFIG_CPU_CONFIG variable for
boards and CPUs (including common directories) to add default
configuration files to be merged. The current approach, as it uses
Makefile.features, would include boards first, not allowing them to
override CPU configurations.
There is no difference between 4k erase and sector erase.
But sector erase would previously do `.block_erase` which would not
erase a sector (4k) but a whole block (64k).
Fortunately all boards declare `SPI_NOR_F_SECT_4K` and all file systems
don't try to erase anything smaller, so this was never triggered.
Add an `assert(0)` to crash instead of corrupting data.
cpu/$(CPU)/Makefile.features and cpu/$(CPU)/Makefile.dep are
automatically included
The multiple boards handling has been changed to use 'CPU_MODEL ?='.
Part of moving CPU/CPU_MODEL definition to Makefile.features to have it
available before Makefile.include.
Keep the compiled '.bin' file to remove the need to compile it when
flashing. This remove the need to have the toolchain when flashing so
allow compiling and flashing with `BUILD_IN_DOCKER=1` without a local
toolchain.
Even if it ends up storing a binary, the file is only 34 bytes.
With the canned recipe for flashing, flash dependencies should be
added to FLASHDEPS, instead of writing `flash: dependencies`. This
ensures that both flash and flash-only depend on the same prerequisites.
This allows a board configuration to select which kind of averaging
should be applied to the pin instead of always using 32 sample average.
Very high impedance sources may need to disable hardware averaging in
order to give correct values, the on-chip temperature sensor is one such
signal source.
