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cpu/x86/mtrr: Prepare for ROM_SIZE > 16MiB 

Most, if not all, chipsets have MMIO between 0xfe000000 and 0xff000000.
So don't try to cache more than 16MiB of the ROM. It's also common that
at most 16MiB are memory mapped.

Change-Id: I5dfa2744190a34c56c86e108a8c50dca9d428268
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/26567
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Nico Huber 2018-05-26 20:34:21 +02:00
parent b4953a93aa
commit 6197b76988
1 changed files with 14 additions and 4 deletions
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18
src/include/cpu/x86/mtrr.h
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@ -1,6 +1,8 @@
#ifndef CPU_X86_MTRR_H
#define CPU_X86_MTRR_H
#include <commonlib/helpers.h>
/* These are the region types */
#define MTRR_TYPE_UNCACHEABLE 0
#define MTRR_TYPE_WRCOMB 1
@ -152,12 +154,20 @@ static inline unsigned int fls(unsigned int x)
to get a power of 2 again, for a single MTRR. */
#define CAR_END (CONFIG_DCACHE_RAM_BASE + CONFIG_DCACHE_RAM_SIZE)
#if CAR_END > OPTIMAL_CACHE_ROM_BASE
# define CACHE_ROM_SIZE _ALIGN_DOWN_POW2(_FROM_4G_TOP(CAR_END))
# define CAR_CACHE_ROM_SIZE _ALIGN_DOWN_POW2(_FROM_4G_TOP(CAR_END))
#else
# define CACHE_ROM_SIZE OPTIMAL_CACHE_ROM_SIZE
# define CAR_CACHE_ROM_SIZE OPTIMAL_CACHE_ROM_SIZE
#endif
#if ((CACHE_ROM_SIZE & (CACHE_ROM_SIZE - 1)) != 0)
# error "CACHE_ROM_SIZE is not a power of 2, _POW2_MASK needs refinement."
#if ((CAR_CACHE_ROM_SIZE & (CAR_CACHE_ROM_SIZE - 1)) != 0)
# error "CAR CACHE_ROM_SIZE is not a power of 2, _POW2_MASK needs refinement."
#endif
/* Last but not least, most (if not all) chipsets have MMIO
between 0xfe000000 and 0xff000000, so limit to 16MiB. */
#if CAR_CACHE_ROM_SIZE >= 16 * MiB
# define CACHE_ROM_SIZE (16 * MiB)
#else
# define CACHE_ROM_SIZE CAR_CACHE_ROM_SIZE
#endif
#define CACHE_ROM_BASE _FROM_4G_TOP(CACHE_ROM_SIZE)