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}