armv7/exynos/snow: new cache maintenance API

This adds a new API for cache maintenance operations. The idea is
to be more explicit about operations that are going on so it's easier
to manage branch predictor, cache, and TLB cleans and invalidations.

Also, this adds some operations that were missing but required early
on, such as branch predictor invalidation. Instruction and sync
barriers were wrong earlier as well since the imported API assumed
we compield with -march=armv5 (which we don't) and was missing
wrappers for the native ARMv7 ISB/DSB/DMB instructions.

For now, this is a start and it gives us something we can easily use
in libpayload for doing things like cleaning and invalidating dcache
when doing DMA transfers.

TODO:
- Set cache policy explicitly before re-enabling. Right now it's left
  at default.
- Finish deprecating old cache maintenance API.
- We do an extra icache/dcache flush when going from bootblock to
  romstage.

Change-Id: I7390981190e3213f4e1431f8e56746545c5cc7c9
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2729
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/cpu/samsung/exynos5250/Makefile.inc

@@ -30,7 +30,6 @@ ramstage-y += power.c
 ramstage-y += soc.c
 ramstage-$(CONFIG_CONSOLE_SERIAL_UART) += uart.c
 ramstage-y += cpu.c
-ramstage-y += exynos_cache.c
 
 #ramstage-$(CONFIG_SATA_AHCI) += sata.c
 

src/cpu/samsung/exynos5250/exynos_cache.c

@@ -33,17 +33,6 @@ enum l2_cache_params {
 	CACHE_DATA_RAM_LATENCY = (2<<0)
 };
 
-
-/* FIXME(dhendrix): maybe move this to a romstage-specific file? */
-#ifdef __PRE_RAM__
-void enable_caches(void)
-{
-	/* Enable D-cache. I-cache is already enabled in start.S */
-	/* can't use it anyway -- it has dependencies we have to fix. */
-	//dcache_enable();
-}
-#endif
-
 /*
  * Set L2 cache parameters
  */