x86: Add a simple header file for ACPI

We don't use many features yet, so this only has a few declarations.
It will be expanded as needed.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/include/asm/acpi.h

@@ -0,0 +1,24 @@
+/*
+ * From coreboot
+ *
+ * Copyright (C) 2004 SUSE LINUX AG
+ * Copyright (C) 2004 Nick Barker
+ * Copyright (C) 2008-2009 coresystems GmbH
+ * (Written by Stefan Reinauer <stepan@coresystems.de>)
+ *
+ * SPDX-License-Identifier:	GPL-2.0
+ */
+
+#ifndef __ASM_ACPI_H
+#define __ASM_ACPI_H
+
+#define RSDP_SIG		"RSD PTR "  /* RSDT pointer signature */
+#define ACPI_TABLE_CREATOR	"U-BootAC"  /* Must be exactly 8 bytes long! */
+#define OEM_ID			"U-Boot"    /* Must be exactly 6 bytes long! */
+#define ASLC			"U-Bo"      /* Must be exactly 4 bytes long! */
+
+/* 0 = S0, 1 = S1 ...*/
+int acpi_get_slp_type(void);
+void apci_set_slp_type(int type);
+
+#endif