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

[Shelley Chen (Code Review)]

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

(

4 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )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 value 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 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70164
Reviewed-by: Julius Werner 
Tested-by: build bot (Jenkins) 
---
M src/mainboard/google/herobrine/mainboard.c
1 file changed, 29 insertions(+), 1 deletion(-)

Approvals:
  build bot (Jenkins): Verified
  Julius Werner: Looks good to me, approved

diff --git a/src/mainboard/google/herobrine/mainboard.c b/src/mainboard/google/herobrine/mainboard.c
index 2648392..c9bca73 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 pins,
+	 * each tristate, so we can represent numbers up to 27, or 5 bits
+	 */
+	uint32_t sku_bits_mask = 0xff;
+	uint32_t sku = sku_id() & sku_bits_mask;

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