1 files changed, 33 insertions, 0 deletions
diff --git a/src/soc/amd/stoneyridge/ramtop.c b/src/soc/amd/stoneyridge/ramtop.c
new file mode 100644
index 0000000000..8fa81c715a
--- /dev/null
+++ b/src/soc/amd/stoneyridge/ramtop.c
@@ -0,0 +1,33 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * 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.
+ */
+
+#define __SIMPLE_DEVICE__
+
+#include <stdint.h>
+#include <arch/io.h>
+#include <cbmem.h>
+
+#define CBMEM_TOP_SCRATCHPAD 0x78
+
+void backup_top_of_low_cacheable(uintptr_t ramtop)
+{
+	uint16_t top_cache = ramtop >> 16;
+	pci_write_config16(PCI_DEV(0,0,0), CBMEM_TOP_SCRATCHPAD, top_cache);
+}
+
+uintptr_t restore_top_of_low_cacheable(void)
+{
+	uint16_t top_cache;
+	top_cache = pci_read_config16(PCI_DEV(0,0,0), CBMEM_TOP_SCRATCHPAD);
+	return (top_cache << 16);
+}