baytrail: cache ROM space early in bootblock

Take advantage of the cache early in bootblock. The
intent is to speed up cbfs walking when trying to locate
romstage.

BUG=chrome-os-partner:22857
BRANCH=None
TEST=Built and booted.

Change-Id: If03210103c9782390230915db3b4a9759d172dce
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/170426
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/4849
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/src/soc/intel/baytrail/bootblock/bootblock.c b/src/soc/intel/baytrail/bootblock/bootblock.c
index 66120d9125..70ccc21f8b 100644
--- a/src/soc/intel/baytrail/bootblock/bootblock.c
+++ b/src/soc/intel/baytrail/bootblock/bootblock.c
@@ -18,12 +18,43 @@
  */
 
 #include <arch/io.h>
+#include <cpu/x86/cache.h>
+#include <cpu/x86/msr.h>
+#include <cpu/x86/mtrr.h>
 #include <baytrail/iosf.h>
 
+static void set_var_mtrr(int reg, uint32_t base, uint32_t size, int type)
+{
+	msr_t basem, maskm;
+	basem.lo = base | type;
+	basem.hi = 0;
+	wrmsr(MTRRphysBase_MSR(reg), basem);
+	maskm.lo = ~(size - 1) | MTRRphysMaskValid;
+	maskm.hi = (1 << (CONFIG_CPU_ADDR_BITS - 32)) - 1;
+	wrmsr(MTRRphysMask_MSR(reg), maskm);
+}
+
+static void enable_rom_caching(void)
+{
+	msr_t msr;
+
+	disable_cache();
+	/* Why only top 4MiB ? */
+	set_var_mtrr(1, 0xffc00000, 4*1024*1024, MTRR_TYPE_WRPROT);
+	enable_cache();
+
+	/* Enable Variable MTRRs */
+	msr.hi = 0x00000000;
+	msr.lo = 0x00000800;
+	wrmsr(MTRRdefType_MSR, msr);
+}
+
 static void bootblock_cpu_init(void)
 {
 	uint32_t reg;
 
+	enable_rom_caching();
+
 	/* Set up the MMCONF range. The register lives in the BUNIT. The
 	 * IO variant of the config access needs to be used initially to
 	 * properly configure as the IOSF access registers live in PCI