From 9c1b53dca1ffb018e6277afd35fc0badb065af70 Mon Sep 17 00:00:00 2001
From: Lee Leahy <leroy.p.leahy@intel.com>
Date: Thu, 5 Jan 2017 10:23:36 -0800
Subject: [PATCH] UPSTREAM: soc/intel/quark: Return NULL for top_of_memory

Return NULL for top_of_memory when the register has not been set.

TEST=Build and run on Galileo Gen2

Change-Id: I86684044fc282eaa8deda2b5dbd8ab6cae095d72
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 6edb3140501ad6ad4224e9c79e7d63b8af970466
Original-Change-Id: If79cac68c2a64aa9bf3be72d3cfc4c73fceef12b
Original-Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Original-Reviewed-on: https://review.coreboot.org/18802
Original-Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Original-Tested-by: Martin Roth <martinroth@google.com>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/455822
---
 src/soc/intel/quark/memmap.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/soc/intel/quark/memmap.c b/src/soc/intel/quark/memmap.c
index 53a1b24094..d67856cc74 100644
--- a/src/soc/intel/quark/memmap.c
+++ b/src/soc/intel/quark/memmap.c
@@ -26,7 +26,8 @@ void *cbmem_top(void)
 	top_of_memory <<= 16;
 
 	/* Reserve 64 KiB for RMU firmware */
-	top_of_memory -= 0x10000;
+	if (top_of_memory)
+		top_of_memory -= 0x10000;
 
 	/* Return the top of memory */
 	return (void *)top_of_memory;