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// SPDX-License-Identifier: GPL-2.0-only
/*
* Sample application for SMBIOS communication over WMI interface
* Performs the following:
* - Simple cmd_class/cmd_select lookup for TPM information
* - Simple query of known tokens and their values
* - Simple activation of a token
*
* Copyright (C) 2017 Dell, Inc.
*/
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <unistd.h>
/* if uapi header isn't installed, this might not yet exist */
#ifndef __packed
#define __packed __attribute__((packed))
#endif
#include <linux/wmi.h>
/* It would be better to discover these using udev, but for a simple
* application they're hardcoded
*/
static const char *ioctl_devfs = "/dev/wmi/dell-smbios";
static const char *token_sysfs =
"/sys/bus/platform/devices/dell-smbios.0/tokens";
static void show_buffer(struct dell_wmi_smbios_buffer *buffer)
{
printf("Call: %x/%x [%x,%x,%x,%x]\nResults: [%8x,%8x,%8x,%8x]\n",
buffer->std.cmd_class, buffer->std.cmd_select,
buffer->std.input[0], buffer->std.input[1],
buffer->std.input[2], buffer->std.input[3],
buffer->std.output[0], buffer->std.output[1],
buffer->std.output[2], buffer->std.output[3]);
}
static int run_wmi_smbios_cmd(struct dell_wmi_smbios_buffer *buffer)
{
int fd;
int ret;
fd = open(ioctl_devfs, O_NONBLOCK);
ret = ioctl(fd, DELL_WMI_SMBIOS_CMD, buffer);
close(fd);
return ret;
}
static int find_token(__u16 token, __u16 *location, __u16 *value)
{
char location_sysfs[60];
char value_sysfs[57];
char buf[4096];
FILE *f;
int ret;
ret = sprintf(value_sysfs, "%s/%04x_value", token_sysfs, token);
if (ret < 0) {
printf("sprintf value failed\n");
return 2;
}
f = fopen(value_sysfs, "rb");
if (!f) {
printf("failed to open %s\n", value_sysfs);
return 2;
}
fread(buf, 1, 4096, f);
fclose(f);
*value = (__u16) strtol(buf, NULL, 16);
ret = sprintf(location_sysfs, "%s/%04x_location", token_sysfs, token);
if (ret < 0) {
printf("sprintf location failed\n");
return 1;
}
f = fopen(location_sysfs, "rb");
if (!f) {
printf("failed to open %s\n", location_sysfs);
return 2;
}
fread(buf, 1, 4096, f);
fclose(f);
*location = (__u16) strtol(buf, NULL, 16);
if (*location)
return 0;
return 2;
}
static int token_is_active(__u16 *location, __u16 *cmpvalue,
struct dell_wmi_smbios_buffer *buffer)
{
int ret;
buffer->std.cmd_class = CLASS_TOKEN_READ;
buffer->std.cmd_select = SELECT_TOKEN_STD;
buffer->std.input[0] = *location;
ret = run_wmi_smbios_cmd(buffer);
if (ret != 0 || buffer->std.output[0] != 0)
return ret;
ret = (buffer->std.output[1] == *cmpvalue);
return ret;
}
static int query_token(__u16 token, struct dell_wmi_smbios_buffer *buffer)
{
__u16 location;
__u16 value;
int ret;
ret = find_token(token, &location, &value);
if (ret != 0) {
printf("unable to find token %04x\n", token);
return 1;
}
return token_is_active(&location, &value, buffer);
}
static int activate_token(struct dell_wmi_smbios_buffer *buffer,
__u16 token)
{
__u16 location;
__u16 value;
int ret;
ret = find_token(token, &location, &value);
if (ret != 0) {
printf("unable to find token %04x\n", token);
return 1;
}
buffer->std.cmd_class = CLASS_TOKEN_WRITE;
buffer->std.cmd_select = SELECT_TOKEN_STD;
buffer->std.input[0] = location;
buffer->std.input[1] = 1;
ret = run_wmi_smbios_cmd(buffer);
return ret;
}
static int query_buffer_size(__u64 *buffer_size)
{
FILE *f;
f = fopen(ioctl_devfs, "rb");
if (!f)
return -EINVAL;
fread(buffer_size, sizeof(__u64), 1, f);
fclose(f);
return EXIT_SUCCESS;
}
int main(void)
{
struct dell_wmi_smbios_buffer *buffer;
int ret;
__u64 value = 0;
ret = query_buffer_size(&value);
if (ret == EXIT_FAILURE || !value) {
printf("Unable to read buffer size\n");
goto out;
}
printf("Detected required buffer size %lld\n", value);
buffer = malloc(value);
if (buffer == NULL) {
printf("failed to alloc memory for ioctl\n");
ret = -ENOMEM;
goto out;
}
buffer->length = value;
/* simple SMBIOS call for looking up TPM info */
buffer->std.cmd_class = CLASS_FLASH_INTERFACE;
buffer->std.cmd_select = SELECT_FLASH_INTERFACE;
buffer->std.input[0] = 2;
ret = run_wmi_smbios_cmd(buffer);
if (ret) {
printf("smbios ioctl failed: %d\n", ret);
ret = EXIT_FAILURE;
goto out;
}
show_buffer(buffer);
/* query some tokens */
ret = query_token(CAPSULE_EN_TOKEN, buffer);
printf("UEFI Capsule enabled token is: %d\n", ret);
ret = query_token(CAPSULE_DIS_TOKEN, buffer);
printf("UEFI Capsule disabled token is: %d\n", ret);
/* activate UEFI capsule token if disabled */
if (ret) {
printf("Enabling UEFI capsule token");
if (activate_token(buffer, CAPSULE_EN_TOKEN)) {
printf("activate failed\n");
ret = -1;
goto out;
}
}
ret = EXIT_SUCCESS;
out:
free(buffer);
return ret;
}
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