intel i945 gm45 x4x post-car: Use postcar_frame for MTRR setup

Adapt implementation from skylake to prepare for removal of
HIGH_MEMORY_SAVE and moving on to RELOCATABLE_RAMSTAGE.
With this change, CBMEM region is set early-on as WRBACK
with MTRRs and romstage ram stack is moved to CBMEM.

Change-Id: Idee5072fd499aa3815b0d78f54308c273e756fd1
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/15791
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 33 insertions, 1 deletions

diff --git a/src/northbridge/intel/gm45/ram_calc.c b/src/northbridge/intel/gm45/ram_calc.c
index c22b491c66..780bed48b1 100644
--- a/src/northbridge/intel/gm45/ram_calc.c
+++ b/src/northbridge/intel/gm45/ram_calc.c
@@ -18,11 +18,14 @@
 #define __SIMPLE_DEVICE__
 
 #include <stdint.h>
+#include <arch/cpu.h>
 #include <arch/io.h>
 #include <device/pci_def.h>
 #include <console/console.h>
 #include <cpu/intel/romstage.h>
+#include <cpu/x86/mtrr.h>
 #include <cbmem.h>
+#include <program_loading.h>
 #include "gm45.h"
 
 /*
@@ -92,7 +95,36 @@ void *cbmem_top(void)
 	return (void *) top_of_ram;
 }
 
+#define ROMSTAGE_RAM_STACK_SIZE 0x5000
+
+/* setup_stack_and_mtrrs() determines the stack to use after
+ * cache-as-ram is torn down as well as the MTRR settings to use. */
 void *setup_stack_and_mtrrs(void)
 {
-	return (void*)CONFIG_RAMTOP;
+	struct postcar_frame pcf;
+	uintptr_t top_of_ram;
+
+	if (postcar_frame_init(&pcf, ROMSTAGE_RAM_STACK_SIZE))
+		die("Unable to initialize postcar frame.\n");
+
+	/* Cache the ROM as WP just below 4GiB. */
+	postcar_frame_add_mtrr(&pcf, -CACHE_ROM_SIZE, CACHE_ROM_SIZE,
+		MTRR_TYPE_WRPROT);
+
+	/* Cache RAM as WB from 0 -> CACHE_TMP_RAMTOP. */
+	postcar_frame_add_mtrr(&pcf, 0, CACHE_TMP_RAMTOP, MTRR_TYPE_WRBACK);
+
+	/* Cache two separate 4 MiB regions below the top of ram, this
+	 * satisfies MTRR alignment requirements. If you modify this to
+	 * cover TSEG, make sure UMA region is not set with WRBACK as it
+	 * causes hard-to-recover boot failures.
+	 */
+	top_of_ram = (uintptr_t)cbmem_top();
+	postcar_frame_add_mtrr(&pcf, top_of_ram - 4*MiB, 4*MiB, MTRR_TYPE_WRBACK);
+	postcar_frame_add_mtrr(&pcf, top_of_ram - 8*MiB, 4*MiB, MTRR_TYPE_WRBACK);
+
+	/* Save the number of MTRRs to setup. Return the stack location
+	 * pointing to the number of MTRRs.
+	 */
+	return postcar_commit_mtrrs(&pcf);
 }