From a89a4ea8ea04aaf369cd99f487f3537fe9e46702 Mon Sep 17 00:00:00 2001
From: Raul E Rangel <rrangel@chromium.org>
Date: Mon, 19 Apr 2021 17:09:30 -0600
Subject: [PATCH] soc/amd/{cezanne,common}/acpi: Add _OSC method

The linux kernel requires a valid _OSC method. Otherwise the _LPI table
is ignored.
See https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/third_party/kernel/v5.10/drivers/acpi/bus.c;l=324

Before this patch:
acpi_processor_get_lpi_info: LPI is not supported

After this patch:
acpi_processor_evaluate_lpi: ACPI: \_SB_.CP00: ACPI: Found 4 power states

BUG=b:178728116
TEST=Boot OS and verify _LPI table is parsed

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I44e554b9db6f70fdd1559105cdaee53aeb2bfbf5
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52528
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
---
 src/soc/amd/cezanne/acpi/soc.asl |  2 ++
 src/soc/amd/common/acpi/osc.asl  | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 src/soc/amd/common/acpi/osc.asl

diff --git a/src/soc/amd/cezanne/acpi/soc.asl b/src/soc/amd/cezanne/acpi/soc.asl
index be511042e499..f7781dab2e3c 100644
--- a/src/soc/amd/cezanne/acpi/soc.asl
+++ b/src/soc/amd/cezanne/acpi/soc.asl
@@ -8,6 +8,8 @@ Scope(\_SB) {
 
 	#include <soc/amd/common/acpi/gpio_bank_lib.asl>
 
+	#include <soc/amd/common/acpi/osc.asl>
+
 	#include "pci_int_defs.asl"
 
 	#include "mmio.asl"
diff --git a/src/soc/amd/common/acpi/osc.asl b/src/soc/amd/common/acpi/osc.asl
new file mode 100644
index 000000000000..22175caa456a
--- /dev/null
+++ b/src/soc/amd/common/acpi/osc.asl
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <acpi/acpi_osc.h>
+
+/*
+ * Platform-Wide _OSC Operating System Capabilities
+ *
+ * Arg0: A Buffer containing a UUID
+ * Arg1: An Integer containing a Revision ID of the buffer format
+ * Arg2: An Integer containing a count of entries in Arg3
+ * Arg3: A Buffer containing a list of DWORD capabilities
+ */
+Method (_OSC, 4, NotSerialized) {
+	CreateDWordField (Arg3, 0, CDW1)
+	If (Arg0 == ToUUID (OSC_SB_UUID)) {
+		/* Don't mask any capability bits off. */
+		Return (Arg3)
+	} Else {
+		CDW1 |= OSC_CDW1_UNRECOGNIZED_UUID
+		Return (Arg3)
+	}
+}