arch: Unify basic cache clearing API

Caching is a very architecture-specific thing, but most architectures
have a cache in general. Therefore it can be useful to have a generic
architecture-independent API to perform simple cache management tasks
from common code.

We have already standardized on the dcache_clean/invalidate naming
scheme that originally comes from ARM in libpayload, so let's just do
the same for coreboot. Unlike libpayload, there are other things than
just DMA coherency we may want to achieve with those functions, so
actually implement them for real even on architectures with
cache-snooping DMA like x86. (In the future, we may find applications
like this in libpayload as well and should probably rethink the API
there... maybe move the current functionality to a separate
dma_map/unmap API instead. But that's beyond scope of this patch.)

Change-Id: I2c1723a287f76cd4118ef38a445339840601aeea
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/19788
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/arch/mips/include/arch/cache.h b/src/arch/mips/include/arch/cache.h
index de1209a84c..d90a85f3f3 100644
--- a/src/arch/mips/include/arch/cache.h
+++ b/src/arch/mips/include/arch/cache.h
@@ -41,4 +41,11 @@ void perform_cache_operation(uintptr_t start, size_t size, uint8_t operation);
 /* Invalidate all caches: instruction, data, L2 data */
 void cache_invalidate_all(uintptr_t start, size_t size);
 
+/* TODO: Global cache API. Implement properly once we finally have a MIPS board
+   again where we can figure out what exactly these should be doing. */
+static inline void cache_sync_instructions(void) {}
+static inline void dcache_clean_all(void) {}
+static inline void dcache_invalidate_all(void) {}
+static inline void dcache_clean_invalidate_all(void) {}
+
 #endif /* __MIPS_ARCH_CACHE_H */