1// SPDX-License-Identifier: GPL-2.0-only
2// Copyright 2022 Google LLC
3// Author: Ard Biesheuvel <ardb@google.com>
4
5#include <linux/efi.h>
6
7#include "efistub.h"
8
9typedef struct efi_smbios_protocol efi_smbios_protocol_t;
10
11struct efi_smbios_protocol {
12	efi_status_t (__efiapi *add)(efi_smbios_protocol_t *, efi_handle_t,
13				     u16 *, struct efi_smbios_record *);
14	efi_status_t (__efiapi *update_string)(efi_smbios_protocol_t *, u16 *,
15					       unsigned long *, u8 *);
16	efi_status_t (__efiapi *remove)(efi_smbios_protocol_t *, u16);
17	efi_status_t (__efiapi *get_next)(efi_smbios_protocol_t *, u16 *, u8 *,
18					  struct efi_smbios_record **,
19					  efi_handle_t *);
20
21	u8 major_version;
22	u8 minor_version;
23};
24
25const struct efi_smbios_record *efi_get_smbios_record(u8 type)
26{
27	struct efi_smbios_record *record;
28	efi_smbios_protocol_t *smbios;
29	efi_status_t status;
30	u16 handle = 0xfffe;
31
32	status = efi_bs_call(locate_protocol, &EFI_SMBIOS_PROTOCOL_GUID, NULL,
33			     (void **)&smbios) ?:
34		 efi_call_proto(smbios, get_next, &handle, &type, &record, NULL);
35	if (status != EFI_SUCCESS)
36		return NULL;
37	return record;
38}
39
40const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,
41				  u8 type, int offset)
42{
43	const u8 *strtable;
44
45	if (!record)
46		return NULL;
47
48	strtable = (u8 *)record + record->length;
49	for (int i = 1; i < ((u8 *)record)[offset]; i++) {
50		int len = strlen(strtable);
51
52		if (!len)
53			return NULL;
54		strtable += len + 1;
55	}
56	return strtable;
57}
58