intel/i945,gm45,pineview,x4x: Move stage cache support function

Let garbage-collection take care of stage_cache_external_region()
when it is not needed and move implementation to a suitable file
already building for needed stages.

Change-Id: Ic32adcc62c7ee21bf38e2e4e5ece00524871b091
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34670
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/northbridge/intel/gm45/Makefile.inc b/src/northbridge/intel/gm45/Makefile.inc
index e74f475..b59a7c3 100644
--- a/src/northbridge/intel/gm45/Makefile.inc
+++ b/src/northbridge/intel/gm45/Makefile.inc
@@ -39,8 +39,4 @@
 
 postcar-y += ram_calc.c
 
-romstage-$(CONFIG_CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM) += stage_cache.c
-ramstage-$(CONFIG_CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM) += stage_cache.c
-postcar-$(CONFIG_CACHE_RELOCATED_RAMSTAGE_OUTSIDE_CBMEM) += stage_cache.c
-
 endif
diff --git a/src/northbridge/intel/gm45/ram_calc.c b/src/northbridge/intel/gm45/ram_calc.c
index c614082..719c59f 100644
--- a/src/northbridge/intel/gm45/ram_calc.c
+++ b/src/northbridge/intel/gm45/ram_calc.c
@@ -26,6 +26,7 @@
 #include <cpu/x86/mtrr.h>
 #include <cbmem.h>
 #include <program_loading.h>
+#include <stage_cache.h>
 #include <cpu/intel/smm/gen1/smi.h>
 #include "gm45.h"
 
@@ -123,6 +124,17 @@
 	return (void *) top_of_ram;
 }
 
+void stage_cache_external_region(void **base, size_t *size)
+{
+	/*
+	 * The ramstage cache lives in the TSEG region at RESERVED_SMM_OFFSET.
+	 * The top of RAM is defined to be the TSEG base address.
+	 */
+	*size = CONFIG_SMM_RESERVED_SIZE;
+	*base = (void *)(northbridge_get_tseg_base()
+			 + CONFIG_SMM_RESERVED_SIZE);
+}
+
 /* platform_enter_postcar() determines the stack to use after
  * cache-as-ram is torn down as well as the MTRR settings to use,
  * and continues execution in postcar stage. */
diff --git a/src/northbridge/intel/gm45/stage_cache.c b/src/northbridge/intel/gm45/stage_cache.c
deleted file mode 100644
index 47f08c1..0000000
--- a/src/northbridge/intel/gm45/stage_cache.c
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- * This file is part of the coreboot project.
- *
- * Copyright 2015 Google, Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
-
-#include <stdint.h>
-#include <stage_cache.h>
-#include <cpu/intel/smm/gen1/smi.h>
-
-void stage_cache_external_region(void **base, size_t *size)
-{
-	/*
-	 * The ramstage cache lives in the TSEG region at RESERVED_SMM_OFFSET.
-	 * The top of RAM is defined to be the TSEG base address.
-	 */
-	*size = CONFIG_SMM_RESERVED_SIZE;
-	*base = (void *)(northbridge_get_tseg_base()
-			 + CONFIG_SMM_RESERVED_SIZE);
-}