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