2 files changed, 67 insertions, 0 deletions
diff --git a/arch/x86/include/asm/amd/fch.h b/arch/x86/include/asm/amd/fch.h
new file mode 100644
index 000000000000..2cf5153edbc2
--- /dev/null
+++ b/arch/x86/include/asm/amd/fch.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_AMD_FCH_H_
+#define _ASM_X86_AMD_FCH_H_
+
+#define FCH_PM_BASE			0xFED80300
+
+/* Register offsets from PM base: */
+#define FCH_PM_DECODEEN			0x00
+#define FCH_PM_DECODEEN_SMBUS0SEL	GENMASK(20, 19)
+#define FCH_PM_SCRATCH			0x80
+#define FCH_PM_S5_RESET_STATUS		0xC0
+
+#endif /* _ASM_X86_AMD_FCH_H_ */
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index d8365c4d9057..fb4da9a7f910 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -9,6 +9,7 @@
 #include <linux/sched/clock.h>
 #include <linux/random.h>
 #include <linux/topology.h>
+#include <asm/amd/fch.h>
 #include <asm/processor.h>
 #include <asm/apic.h>
 #include <asm/cacheinfo.h>
@@ -1238,3 +1239,56 @@ void amd_check_microcode(void)
 	if (cpu_feature_enabled(X86_FEATURE_ZEN2))
 		on_each_cpu(zenbleed_check_cpu, NULL, 1);
 }
+
+static const char * const s5_reset_reason_txt[] = {
+	[0]  = "thermal pin BP_THERMTRIP_L was tripped",
+	[1]  = "power button was pressed for 4 seconds",
+	[2]  = "shutdown pin was tripped",
+	[4]  = "remote ASF power off command was received",
+	[9]  = "internal CPU thermal limit was tripped",
+	[16] = "system reset pin BP_SYS_RST_L was tripped",
+	[17] = "software issued PCI reset",
+	[18] = "software wrote 0x4 to reset control register 0xCF9",
+	[19] = "software wrote 0x6 to reset control register 0xCF9",
+	[20] = "software wrote 0xE to reset control register 0xCF9",
+	[21] = "ACPI power state transition occurred",
+	[22] = "keyboard reset pin KB_RST_L was tripped",
+	[23] = "internal CPU shutdown event occurred",
+	[24] = "system failed to boot before failed boot timer expired",
+	[25] = "hardware watchdog timer expired",
+	[26] = "remote ASF reset command was received",
+	[27] = "an uncorrected error caused a data fabric sync flood event",
+	[29] = "FCH and MP1 failed warm reset handshake",
+	[30] = "a parity error occurred",
+	[31] = "a software sync flood event occurred",
+};
+
+static __init int print_s5_reset_status_mmio(void)
+{
+	unsigned long value;
+	void __iomem *addr;
+	int i;
+
+	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
+		return 0;
+
+	addr = ioremap(FCH_PM_BASE + FCH_PM_S5_RESET_STATUS, sizeof(value));
+	if (!addr)
+		return 0;
+
+	value = ioread32(addr);
+	iounmap(addr);
+
+	for (i = 0; i < ARRAY_SIZE(s5_reset_reason_txt); i++) {
+		if (!(value & BIT(i)))
+			continue;
+
+		if (s5_reset_reason_txt[i]) {
+			pr_info("x86/amd: Previous system reset reason [0x%08lx]: %s\n",
+				value, s5_reset_reason_txt[i]);
+		}
+	}
+
+	return 0;
+}
+late_initcall(print_s5_reset_status_mmio);