1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Utility functions for ACPI
4  *
5  * Copyright 2023 Google LLC
6  */
7 
8 #include <common.h>
9 #include <mapmem.h>
10 #include <acpi/acpi_table.h>
11 #include <asm/global_data.h>
12 
13 DECLARE_GLOBAL_DATA_PTR;
14 
acpi_find_table(const char * sig)15 struct acpi_table_header *acpi_find_table(const char *sig)
16 {
17 	struct acpi_rsdp *rsdp;
18 	struct acpi_rsdt *rsdt;
19 	int len, i, count;
20 
21 	rsdp = map_sysmem(gd_acpi_start(), 0);
22 	if (!rsdp)
23 		return NULL;
24 	rsdt = map_sysmem(rsdp->rsdt_address, 0);
25 	len = rsdt->header.length - sizeof(rsdt->header);
26 	count = len / sizeof(u32);
27 	for (i = 0; i < count; i++) {
28 		struct acpi_table_header *hdr;
29 
30 		hdr = map_sysmem(rsdt->entry[i], 0);
31 		if (!memcmp(hdr->signature, sig, ACPI_NAME_LEN))
32 			return hdr;
33 		if (!memcmp(hdr->signature, "FACP", ACPI_NAME_LEN)) {
34 			struct acpi_fadt *fadt = (struct acpi_fadt *)hdr;
35 
36 			if (!memcmp(sig, "DSDT", ACPI_NAME_LEN) && fadt->dsdt)
37 				return map_sysmem(fadt->dsdt, 0);
38 			if (!memcmp(sig, "FACS", ACPI_NAME_LEN) &&
39 			    fadt->firmware_ctrl)
40 				return map_sysmem(fadt->firmware_ctrl, 0);
41 		}
42 	}
43 
44 	return NULL;
45 }
46