coreboot: kgpe-d16: print DIMM voltages to console

This commit adds a patch which causes coreboot to print a message to
the serial console when adjusting any of the DIMM slot voltages.

src/coreboot/default.nix

@@ -107,6 +107,7 @@ stdenv.mkDerivation {
     ./patches/0002-mc146818rtc_boot.c-always-report-cmos_chksum_valid-i.patch
     ./patches/0003-kgpe-d16-bootblock.c-use-RTC_BOOT_BYTE-even-when-CON.patch
     ./patches/0004-superio-winbond-w83667hg-a-superio.c-do-not-use-get_.patch
+    ./patches/0001-romstage-print-out-dimm-voltages.patch
 
     # am1i patches
     ./patches/0021-am1i-omit-amdfw.rom-completely-it-has-broken-address.patch

src/coreboot/patches/0001-romstage-print-out-dimm-voltages.patch

@@ -0,0 +1,30 @@
+From bc685f6dfa802fa8861e72c323b2655217584a51 Mon Sep 17 00:00:00 2001
+From: Your Name <you@example.com>
+Date: Sat, 10 Jun 2023 21:23:12 -0700
+Subject: [PATCH 1/4] romstage: print out dimm voltages
+
+---
+ src/mainboard/asus/kgpe-d16/romstage.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/src/mainboard/asus/kgpe-d16/romstage.c b/src/mainboard/asus/kgpe-d16/romstage.c
+index 01e7afc0416..81a5bf5d67d 100644
+--- a/src/mainboard/asus/kgpe-d16/romstage.c
++++ b/src/mainboard/asus/kgpe-d16/romstage.c
+@@ -238,7 +238,12 @@ static void set_ddr3_voltage(uint8_t node, uint8_t index) {
+ 	byte &= 0x0f;
+ 	pci_write_config8(PCI_DEV(0, 0x14, 3), 0xd0, byte);
+ 
+-	printk(BIOS_DEBUG, "Node %02d DIMM voltage set to index %02x\n", node, index);
++        switch (index) {
++          case 0: printk(BIOS_ERR, "Socket %02d DIMM voltage set to 1.50V\n", node); break;
++          case 1: printk(BIOS_ERR, "Socket %02d DIMM voltage set to 1.35V\n", node); break;
++          case 2: printk(BIOS_ERR, "Socket %02d DIMM voltage set to 1.25V\n", node); break;
++          case 3: printk(BIOS_ERR, "Socket %02d DIMM voltage set to 1.15V\n", node); break;
++        }
+ }
+ 
+ void DIMMSetVoltages(struct MCTStatStruc *pMCTstat,
+-- 
+2.39.1
+