From 51518e585d2dc0d71a4782fe1bd68af6cffa9e59 Mon Sep 17 00:00:00 2001
From: Patrick Rudolph <patrick.rudolph@9elements.com>
Date: Sun, 29 Oct 2023 19:44:52 +0100
Subject: nb/intel/sandybridge: Use SA devid to identify PC type

Instead of using MSR IA32_PLATFORM_ID read the SystemAgent device id
to figure out the PC type. This follows the BWG which suggest to not
use MSR IA32_PLATFORM_ID for system identification.

Tested: Lenovo X220 still boots.

Change-Id: Ibddf6c75d15ca7a99758c377ed956d483abe7ec1
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78826
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
---
 src/northbridge/intel/sandybridge/common.c     | 17 +++++++++++------
 src/northbridge/intel/sandybridge/early_init.c |  6 ++++--
 2 files changed, 15 insertions(+), 8 deletions(-)

(limited to 'src/northbridge/intel')

diff --git a/src/northbridge/intel/sandybridge/common.c b/src/northbridge/intel/sandybridge/common.c
index a8f718c184..a6704914ac 100644
--- a/src/northbridge/intel/sandybridge/common.c
+++ b/src/northbridge/intel/sandybridge/common.c
@@ -2,14 +2,19 @@
 
 #include <console/console.h>
 #include <device/device.h>
-#include <cpu/intel/model_206ax/model_206ax.h>
+#include <device/pci_def.h>
+#include <device/pci_ops.h>
 #include "sandybridge.h"
 
 enum platform_type get_platform_type(void)
 {
-	const int id = get_platform_id();
-	if (id != 1 && id != 4)
-		printk(BIOS_WARNING, "Unknown platform id 0x%x\n", id);
-
-	return (id == 4) ? PLATFORM_MOBILE : PLATFORM_DESKTOP_SERVER;
+	switch (pci_s_read_config16(HOST_BRIDGE, PCI_DEVICE_ID) & 0xc) {
+	case 0x0: /* Desktop */
+		return PLATFORM_DESKTOP_SERVER;
+	case 0x4: /* Mobile */
+		return PLATFORM_MOBILE;
+	case 0x8: /* Server */
+	default:
+		return PLATFORM_DESKTOP_SERVER;
+	}
 }
diff --git a/src/northbridge/intel/sandybridge/early_init.c b/src/northbridge/intel/sandybridge/early_init.c
index e35251359a..a5ebf9d3a7 100644
--- a/src/northbridge/intel/sandybridge/early_init.c
+++ b/src/northbridge/intel/sandybridge/early_init.c
@@ -150,14 +150,13 @@ static void start_peg_link_training(void)
 
 void systemagent_early_init(void)
 {
+	const size_t is_mobile = get_platform_type() == PLATFORM_MOBILE;
 	u32 capid0_a;
 	u8 reg8;
 
 	/* Device ID Override Enable should be done very early */
 	capid0_a = pci_read_config32(HOST_BRIDGE, CAPID0_A);
 	if (capid0_a & (1 << 10)) {
-		const size_t is_mobile = get_platform_type() == PLATFORM_MOBILE;
-
 		reg8 = pci_read_config8(HOST_BRIDGE, DIDOR);
 		reg8 &= ~7; /* Clear 2:0 */
 
@@ -167,6 +166,9 @@ void systemagent_early_init(void)
 		pci_write_config8(HOST_BRIDGE, DIDOR, reg8);
 	}
 
+	/* Print platform type */
+	printk(BIOS_INFO, "Detected system type: %s\n", is_mobile ? "mobile" : "desktop");
+
 	/* Setup all BARs required for early PCIe and raminit */
 	sandybridge_setup_bars();
 
-- 
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