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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Sample application for SMBIOS communication over WMI interface4 * Performs the following:5 * - Simple cmd_class/cmd_select lookup for TPM information6 * - Simple query of known tokens and their values7 * - Simple activation of a token8 *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 __packed21#define __packed __attribute__((packed))22#endif23#include <linux/wmi.h>24 25/* It would be better to discover these using udev, but for a simple26 * application they're hardcoded27 */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