Kconfig: introduce writable boot device notion

Indicate to the build system that a platform provides support
for a writable boot device. The following will provide the
necessary support:

COMMON_CBFS_SPI_WRAPPER users
soc/intel/apollolake
soc/intel/baytrail
soc/intel/braswell
soc/intel/broadwell
soc/intel/skylake

The SPI_FLASH option is auto-selected if the platform provides
write supoprt for the boot device and SPI flash is the boot
device.

Other platforms may provide similar support, but they do that
in a device specific manner such as selecting SPI_FLASH
explicitly. This provides clearance against build failures
where chipsets don't provide SPI API implementations even
though the platform may use a SPI flash to boot.

BUG=chrome-os-partner:56151

Change-Id: If78160f231c8312a313f9b9753607d044345d274
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/16211
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Martin Roth <martinroth@google.com>

0 files changed, 0 insertions, 0 deletions