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(value_sysfs, "%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(location_sysfs, "%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, &value);
116	if (ret != 0) {
117		printf("unable to find token %04x\n", token);
118		return 1;
119	}
120	return token_is_active(&location, &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, &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(&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