[PATCH 1/1] acpi: consider XSDT in acpi_find_table()

[Heinrich Schuchardt]

The RSDT table is deprecated and does not exist on all systems.

By preference scan XSDT for the table to find. If no XSDT table exists, try
to use the RSDT table.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 lib/acpi/acpi.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/lib/acpi/acpi.c b/lib/acpi/acpi.c
index 14b15754f4..3938946fc6 100644
--- a/lib/acpi/acpi.c
+++ b/lib/acpi/acpi.c
@@ -16,18 +16,30 @@ struct acpi_table_header *acpi_find_table(const char *sig)
 {
 	struct acpi_rsdp *rsdp;
 	struct acpi_rsdt *rsdt;
+	struct acpi_xsdt *xsdt;
 	int len, i, count;
 
 	rsdp = map_sysmem(gd_acpi_start(), 0);
 	if (!rsdp)
 		return NULL;
-	rsdt = map_sysmem(rsdp->rsdt_address, 0);
-	len = rsdt->header.length - sizeof(rsdt->header);
-	count = len / sizeof(u32);
+	xsdt = map_sysmem(rsdp->xsdt_address, 0);
+	if (xsdt) {
+		len = xsdt->header.length - sizeof(xsdt->header);
+		count = len / sizeof(u64);
+	} else {
+		rsdt = map_sysmem(rsdp->rsdt_address, 0);
+		if (!rsdt)
+			return NULL;
+		len = rsdt->header.length - sizeof(rsdt->header);
+		count = len / sizeof(u32);
+	}
 	for (i = 0; i < count; i++) {
 		struct acpi_table_header *hdr;
 
-		hdr = map_sysmem(rsdt->entry[i], 0);
+		if (xsdt)
+			hdr = map_sysmem(xsdt->entry[i], 0);
+		else
+			hdr = map_sysmem(rsdt->entry[i], 0);
 		if (!memcmp(hdr->signature, sig, ACPI_NAME_LEN))
 			return hdr;
 		if (!memcmp(hdr->signature, "FACP", ACPI_NAME_LEN)) {
-- 
2.40.1