x86/cache.c: Implement dcache_*

A new ChromeOS automated test will be introduced to check the cbmem log
of diagnostic boot mode. Because the diagnostic boot does not allow
booting into kernel, the test must perform AP reset and then check the
cbmem log afterwards. However, the memory content might not be written
back to memory (from CPU cache) during AP reset because of the cache
snooping mechanism on x86. Hence, some API to flush cache is needed.

Implement dcache_* to allow flushing cache proactively in x86. To avoid
unnecessary flush, check dma_coherent before calling dcache_* functions,
which will be always true in x86. Therefore, this change won't affect
the original functionality.

BUG=b:190026346
TEST=FW_NAME=primus emerge-brya libpayload

Cq-Depend: chromium:3841252
Signed-off-by: Hsin-Te Yuan <yuanhsinte@google.com>
Change-Id: I622d8b1cc652cbe477954a900885d12e6494d94d
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66578
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>

0 files changed, 0 insertions, 0 deletions