1 files changed, 49 insertions, 0 deletions
diff --git a/lib/acpi/ssdt.c b/lib/acpi/ssdt.c
new file mode 100644
index 00000000000..659c1aad406
--- /dev/null
+++ b/lib/acpi/ssdt.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Write an ACPI Secondary System Descriptor Table (SSDT) table
+ *
+ * Copyright 2021 Google LLC
+ */
+
+#define LOG_CATEGORY LOGC_ACPI
+
+#include <common.h>
+#include <acpi/acpi_table.h>
+#include <dm/acpi.h>
+#include <tables_csum.h>
+
+int acpi_write_ssdt(struct acpi_ctx *ctx, const struct acpi_writer *entry)
+{
+	struct acpi_table_header *ssdt;
+	int ret;
+
+	ssdt = ctx->current;
+	memset((void *)ssdt, '\0', sizeof(struct acpi_table_header));
+
+	acpi_fill_header(ssdt, "SSDT");
+	memcpy(ssdt->oem_table_id, OEM_TABLE_ID, sizeof(ssdt->oem_table_id));
+	ssdt->revision = acpi_get_table_revision(ACPITAB_SSDT);
+	ssdt->aslc_revision = 1;
+	ssdt->length = sizeof(struct acpi_table_header);
+
+	acpi_inc(ctx, sizeof(struct acpi_table_header));
+
+	ret = acpi_fill_ssdt(ctx);
+	if (ret) {
+		ctx->current = ssdt;
+		return log_msg_ret("fill", ret);
+	}
+
+	/* (Re)calculate length and checksum */
+	ssdt->length = ctx->current - (void *)ssdt;
+	ssdt->checksum = table_compute_checksum((void *)ssdt, ssdt->length);
+	log_debug("SSDT at %p, length %x\n", ssdt, ssdt->length);
+
+	/* Drop the table if it is empty */
+	if (ssdt->length == sizeof(struct acpi_table_header))
+		return log_msg_ret("fill", -ENOENT);
+	acpi_add_table(ctx, ssdt);
+
+	return 0;
+}
+ACPI_WRITER(6ssdt, "SSDT", acpi_write_ssdt, 0);