1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Sample application for SMBIOS communication over WMI interface
4 * Performs the following:
5 * - Simple cmd_class/cmd_select lookup for TPM information
6 * - Simple query of known tokens and their values
7 * - Simple activation of a token
8 *
9 * Copyright (C) 2017 Dell, Inc.
10 */
11
12#include <errno.h>
13#include <fcntl.h>
14#include <stdio.h>
15#include <stdlib.h>
16#include <sys/ioctl.h>
17#include <unistd.h>
18
19/* if uapi header isn't installed, this might not yet exist */
20#ifndef __packed
21#define __packed __attribute__((packed))
22#endif
23#include <linux/wmi.h>
24
25/* It would be better to discover these using udev, but for a simple
26 * application they're hardcoded
27 */
28static const char *ioctl_devfs = "/dev/wmi/dell-smbios";
29static const char *token_sysfs =
30 "/sys/bus/platform/devices/dell-smbios.0/tokens";
31
32static void show_buffer(struct dell_wmi_smbios_buffer *buffer)
33{
34 printf("Call: %x/%x [%x,%x,%x,%x]\nResults: [%8x,%8x,%8x,%8x]\n",
35 buffer->std.cmd_class, buffer->std.cmd_select,
36 buffer->std.input[0], buffer->std.input[1],
37 buffer->std.input[2], buffer->std.input[3],
38 buffer->std.output[0], buffer->std.output[1],
39 buffer->std.output[2], buffer->std.output[3]);
40}
41
42static int run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer *buffer)
43{
44 int fd;
45 int ret;
46
47 fd = open(ioctl_devfs, O_NONBLOCK);
48 ret = ioctl(fd, DELL_WMI_SMBIOS_CMD, buffer);
49 close(fd);
50 return ret;
51}
52
53static int find_token(__u16 token, __u16 *location, __u16 *value)
54{
55 char location_sysfs[60];
56 char value_sysfs[57];
57 char buf[4096];
58 FILE *f;
59 int ret;
60
61 ret = sprintf(buf: value_sysfs, fmt: "%s/%04x_value", token_sysfs, token);
62 if (ret < 0) {
63 printf("sprintf value failed\n");
64 return 2;
65 }
66 f = fopen(value_sysfs, "rb");
67 if (!f) {
68 printf("failed to open %s\n", value_sysfs);
69 return 2;
70 }
71 fread(buf, 1, 4096, f);
72 fclose(f);
73 *value = (__u16) strtol(buf, NULL, 16);
74
75 ret = sprintf(buf: location_sysfs, fmt: "%s/%04x_location", token_sysfs, token);
76 if (ret < 0) {
77 printf("sprintf location failed\n");
78 return 1;
79 }
80 f = fopen(location_sysfs, "rb");
81 if (!f) {
82 printf("failed to open %s\n", location_sysfs);
83 return 2;
84 }
85 fread(buf, 1, 4096, f);
86 fclose(f);
87 *location = (__u16) strtol(buf, NULL, 16);
88
89 if (*location)
90 return 0;
91 return 2;
92}
93
94static int token_is_active(__u16 *location, __u16 *cmpvalue,
95 struct dell_wmi_smbios_buffer *buffer)
96{
97 int ret;
98
99 buffer->std.cmd_class = CLASS_TOKEN_READ;
100 buffer->std.cmd_select = SELECT_TOKEN_STD;
101 buffer->std.input[0] = *location;
102 ret = run_wmi_smbios_cmd(buffer);
103 if (ret != 0 || buffer->std.output[0] != 0)
104 return ret;
105 ret = (buffer->std.output[1] == *cmpvalue);
106 return ret;
107}
108
109static int query_token(__u16 token, struct dell_wmi_smbios_buffer *buffer)
110{
111 __u16 location;
112 __u16 value;
113 int ret;
114
115 ret = find_token(token, location: &location, value: &value);
116 if (ret != 0) {
117 printf("unable to find token %04x\n", token);
118 return 1;
119 }
120 return token_is_active(location: &location, cmpvalue: &value, buffer);
121}
122
123static int activate_token(struct dell_wmi_smbios_buffer *buffer,
124 __u16 token)
125{
126 __u16 location;
127 __u16 value;
128 int ret;
129
130 ret = find_token(token, location: &location, value: &value);
131 if (ret != 0) {
132 printf("unable to find token %04x\n", token);
133 return 1;
134 }
135 buffer->std.cmd_class = CLASS_TOKEN_WRITE;
136 buffer->std.cmd_select = SELECT_TOKEN_STD;
137 buffer->std.input[0] = location;
138 buffer->std.input[1] = 1;
139 ret = run_wmi_smbios_cmd(buffer);
140 return ret;
141}
142
143static int query_buffer_size(__u64 *buffer_size)
144{
145 FILE *f;
146
147 f = fopen(ioctl_devfs, "rb");
148 if (!f)
149 return -EINVAL;
150 fread(buffer_size, sizeof(__u64), 1, f);
151 fclose(f);
152 return EXIT_SUCCESS;
153}
154
155int main(void)
156{
157 struct dell_wmi_smbios_buffer *buffer;
158 int ret;
159 __u64 value = 0;
160
161 ret = query_buffer_size(buffer_size: &value);
162 if (ret == EXIT_FAILURE || !value) {
163 printf("Unable to read buffer size\n");
164 goto out;
165 }
166 printf("Detected required buffer size %lld\n", value);
167
168 buffer = malloc(value);
169 if (buffer == NULL) {
170 printf("failed to alloc memory for ioctl\n");
171 ret = -ENOMEM;
172 goto out;
173 }
174 buffer->length = value;
175
176 /* simple SMBIOS call for looking up TPM info */
177 buffer->std.cmd_class = CLASS_FLASH_INTERFACE;
178 buffer->std.cmd_select = SELECT_FLASH_INTERFACE;
179 buffer->std.input[0] = 2;
180 ret = run_wmi_smbios_cmd(buffer);
181 if (ret) {
182 printf("smbios ioctl failed: %d\n", ret);
183 ret = EXIT_FAILURE;
184 goto out;
185 }
186 show_buffer(buffer);
187
188 /* query some tokens */
189 ret = query_token(CAPSULE_EN_TOKEN, buffer);
190 printf("UEFI Capsule enabled token is: %d\n", ret);
191 ret = query_token(CAPSULE_DIS_TOKEN, buffer);
192 printf("UEFI Capsule disabled token is: %d\n", ret);
193
194 /* activate UEFI capsule token if disabled */
195 if (ret) {
196 printf("Enabling UEFI capsule token");
197 if (activate_token(buffer, CAPSULE_EN_TOKEN)) {
198 printf("activate failed\n");
199 ret = -1;
200 goto out;
201 }
202 }
203 ret = EXIT_SUCCESS;
204out:
205 free(buffer);
206 return ret;
207}
208

source code of linux/tools/wmi/dell-smbios-example.c