soc/qualcomm/ipq40xx: Return NULL for cbmem_top if DRAM is not initialized

DRAM initialization on gale requires ipq blobs to be
loaded from cbfs. vboot_locator first checks cbmem_find to see if cbmem is
initialized and contains selected region info, else it falls back to
vboot work buffer.

Since cbmem_find calls into cbmem_top to identify the location of
cbmem area, board/chipset is expected to return NULL until the backing
store is ready, which in this case until DRAM is initialized in
romstage, return NULL for cbmem_top.

BUG=chrome-os-partner:49249
TEST=Able to compile and boot to depthcharge. Doesn't crash in
imd_handle_init_partial_recovery
BRANCH=none

Change-Id: Iaac24252ee4fb9f59d767730bf9dd68baa42a68f
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 4849c15dee2d3782ede4ee4157e432bd4d5602f0
Original-Change-Id: I3722b7ab5a6585a250138c828eb3d7919b0c1178
Original-Signed-off-by: Varadarajan Narayanan <varada@codeaurora.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/335425
Original-Commit-Ready: David Hendricks <dhendrix@chromium.org>
Original-Reviewed-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: https://review.coreboot.org/14660
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/src/soc/qualcomm/ipq40xx/cbmem.c b/src/soc/qualcomm/ipq40xx/cbmem.c
index 7aff231be7..05325cceb9 100644
--- a/src/soc/qualcomm/ipq40xx/cbmem.c
+++ b/src/soc/qualcomm/ipq40xx/cbmem.c
@@ -16,7 +16,23 @@
 #include <cbmem.h>
 #include <soc/soc_services.h>
 
+static int cbmem_backing_store_ready;
+
+void ipq_cbmem_backing_store_ready(void)
+{
+	cbmem_backing_store_ready = 1;
+}
+
 void *cbmem_top(void)
 {
+	/*
+	 * In romstage, make sure that cbmem backing store is ready before
+	 * returning pointer to cbmem top. Otherwise, it could lead to issues
+	 * with components that utilize cbmem in romstage (e.g. vboot_locator
+	 * for loading ipq blobs before DRAM is initialized).
+	 */
+	if (ENV_ROMSTAGE && (cbmem_backing_store_ready == 0))
+		return NULL;
+
 	return _memlayout_cbmem_top;
 }