[S] Change in coreboot[master]: mb/google/herobrine: Mask out upper bits from sku_id()

[Shelley Chen (Code Review)]

Shelley Chen has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/70164 )

Change subject: mb/google/herobrine: Mask out upper bits from sku_id()
......................................................................

mb/google/herobrine: Mask out upper bits from sku_id()

When retrieving the SKU id bits through the sku_id() function in
mainboard_needs_pcie_init(), we only want the values in the lower 5
bits as we can only represent SKU id up to 27.  Everything in the
higher bits should be masked out because they are not needed.

BUG=b:254281839
BRANCH=None
TEST=Make sure that NVMe is not initialized
     Tested on a herobrine board with SKU id 0

Change-Id: I0e786ec392b5e1484cb2ff6d83a8d4fdd698950c
Signed-off-by: Shelley Chen 
---
M src/mainboard/google/herobrine/mainboard.c
1 file changed, 26 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/64/70164/1

diff --git a/src/mainboard/google/herobrine/mainboard.c b/src/mainboard/google/herobrine/mainboard.c
index 2648392..d2528b1 100644
--- a/src/mainboard/google/herobrine/mainboard.c
+++ b/src/mainboard/google/herobrine/mainboard.c
@@ -91,7 +91,12 @@
  */
 bool mainboard_needs_pcie_init(void)
 {
-	uint32_t sku = sku_id();
+	/*
+	 * Mask out everything above the actual SKU bits We have 3 sku bits,
+	 * each tristate, so we can represent numbers up to 27, or 5 bits
+	 */
+	uint32_t sku_bits_mask = 0x1F;
+	uint32_t sku = sku_id() & sku_bits_mask;

if (sku == CROS_SKU_UNKNOWN) {
    	printk(BIOS_WARNING, "Unknown SKU (%#x); assuming PCIe", sku);