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coreboot_tables.c: Expose the ACPI RSDP

The ACPI RSDP can only be found in:
- legacy BIOS region
- via UEFI service

On some systems like ARM that legacy BIOS region is not an option, so
to avoid needing UEFI it makes sense to expose the RSDP via a coreboot
table entry.

Change-Id: I591312a2c48f0cbbb03b2787e4b365e9c932afff
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
---
M src/acpi/acpi.c
M src/commonlib/include/commonlib/coreboot_tables.h
M src/include/acpi/acpi.h
M src/lib/coreboot_table.c
4 files changed, 34 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/73/62573/1

diff --git a/src/acpi/acpi.c b/src/acpi/acpi.c
index 3bf57c6..390c727 100644
--- a/src/acpi/acpi.c
+++ b/src/acpi/acpi.c
@@ -1588,6 +1588,13 @@
 	cbfs_preload(file);
 }
 
+uintptr_t coreboot_rsdp;
+
+uintptr_t get_coreboot_rsdp(void)
+{
+	return coreboot_rsdp;
+}
+
 unsigned long write_acpi_tables(unsigned long start)
 {
 	unsigned long current;
@@ -1695,6 +1702,7 @@
 
 	/* We need at least an RSDP and an RSDT Table */
 	rsdp = (acpi_rsdp_t *) current;
+	coreboot_rsdp = (uintptr_t)rsdp;
 	current += sizeof(acpi_rsdp_t);
 	current = acpi_align_current(current);
 	rsdt = (acpi_rsdt_t *) current;
diff --git a/src/commonlib/include/commonlib/coreboot_tables.h b/src/commonlib/include/commonlib/coreboot_tables.h
index 91da8e0..3b215bf 100644
--- a/src/commonlib/include/commonlib/coreboot_tables.h
+++ b/src/commonlib/include/commonlib/coreboot_tables.h
@@ -85,6 +85,7 @@
 	LB_TAG_BOARD_CONFIG		= 0x0040,
 	LB_TAG_ACPI_CNVS		= 0x0041,
 	LB_TAG_TYPE_C_INFO		= 0x0042,
+	LB_TAG_ACPI_RSDP                = 0x0043,
 	/* The following options are CMOS-related */
 	LB_TAG_CMOS_OPTION_TABLE	= 0x00c8,
 	LB_TAG_OPTION			= 0x00c9,
@@ -574,4 +575,15 @@
 	uint8_t tpm_version;	/* 1: TPM1.2, 2: TPM2.0 */
 	uint8_t ppi_version;	/* BCD encoded */
 } __packed;
+
+
+/*
+ * Handoff the ACPI RSDP
+ */
+struct lb_acpi_rsdp {
+	uint32_t tag;
+	uint32_t size;
+	uint64_t rsdp_pointer; /* Address of the ACPI RSDP */
+} __packed;
+
 #endif
diff --git a/src/include/acpi/acpi.h b/src/include/acpi/acpi.h
index dade92d..0ba8767 100644
--- a/src/include/acpi/acpi.h
+++ b/src/include/acpi/acpi.h
@@ -54,6 +54,7 @@
 };
 
 #define RSDP_SIG		"RSD PTR "  /* RSDT pointer signature */
+uintptr_t get_coreboot_rsdp(void);
 #define ASLC			"CORE"      /* Must be exactly 4 bytes long! */
 
 #define ACPI_NAME_BUFFER_SIZE	5 /* 4 chars + 1 NUL */
diff --git a/src/lib/coreboot_table.c b/src/lib/coreboot_table.c
index d0cba80..ec10ff2 100644
--- a/src/lib/coreboot_table.c
+++ b/src/lib/coreboot_table.c
@@ -1,5 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <acpi/acpi.h>
 #include <arch/cbconfig.h>
 #include <console/console.h>
 #include <console/uart.h>
@@ -420,6 +421,16 @@
 	return (unsigned long)rec + rec->size;
 }
 
+static void lb_add_acpi_rsdp(struct lb_header *head)
+{
+	struct lb_acpi_rsdp *acpi_rsdp;
+	struct lb_record *rec = lb_new_record(head);
+	acpi_rsdp = (struct lb_acpi_rsdp *)rec;
+	acpi_rsdp->tag = LB_TAG_ACPI_RSDP;
+	acpi_rsdp->size = sizeof(*acpi_rsdp);
+	acpi_rsdp->rsdp_pointer = get_coreboot_rsdp();
+}
+
 size_t write_coreboot_forwarding_table(uintptr_t entry, uintptr_t target)
 {
 	struct lb_header *head;
@@ -523,6 +534,8 @@
 	/* Add all cbmem entries into the coreboot tables. */
 	cbmem_add_records_to_cbtable(head);
 
+	lb_add_acpi_rsdp(head);
+
 	/* Remember where my valid memory ranges are */
 	return lb_table_fini(head);
 }

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