The code was dereferencing 0x800 and loading a value from there, trying to
use a literal value (not address) defined in the linker script
(_ram_fs_cache_block_size) which was 0x800.
Explicitly writing out the implementation of sys_tick_has_passed makes
these bdev files independent of systick.c and more reusable as a general
component. It also reduces the code size slightly.
The irq.h header is added to spibdev.c because it uses declarations in that
file (irq.h is usually included implicitly via mphalport.h but not always).
This config variable controls whether to support storage on the internal
flash of the MCU. It is enabled by default and should be explicitly
disabled by boards that don't want internal flash storage.
It makes it cleaner, and simpler to support multiple different block
devices. It also allows to easily extend a given block device with new
ioctl operations.
Prior to this patch, storage.c was a combination of code that handled
either internal flash or external SPI flash and exposed one of them as a
block device for the local storage. It was also exposed to the USB MSC.
This patch splits out the flash and SPI code to separate files, which each
provide a general block-device interface (at the C level). Then storage.c
just picks one of them to use as the local storage medium. The aim of this
factoring is to allow to add new block devices in the future and allow for
easier configurability.
