155 lines
3.6 KiB
C
155 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* SMI methods for use with dell-smbios
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*
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* Copyright (c) Red Hat <mjg@redhat.com>
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* Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
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* Copyright (c) 2014 Pali Rohár <pali@kernel.org>
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* Copyright (c) 2017 Dell Inc.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/dmi.h>
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#include <linux/gfp.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/platform_device.h>
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#include "dcdbas.h"
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#include "dell-smbios.h"
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static int da_command_address;
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static int da_command_code;
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static struct smi_buffer smi_buf;
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static struct calling_interface_buffer *buffer;
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static struct platform_device *platform_device;
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static DEFINE_MUTEX(smm_mutex);
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static void parse_da_table(const struct dmi_header *dm)
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{
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struct calling_interface_structure *table =
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container_of(dm, struct calling_interface_structure, header);
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/* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
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* 6 bytes of entry
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*/
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if (dm->length < 17)
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return;
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da_command_address = table->cmdIOAddress;
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da_command_code = table->cmdIOCode;
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}
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static void find_cmd_address(const struct dmi_header *dm, void *dummy)
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{
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switch (dm->type) {
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case 0xda: /* Calling interface */
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parse_da_table(dm);
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break;
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}
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}
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static int dell_smbios_smm_call(struct calling_interface_buffer *input)
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{
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struct smi_cmd command;
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size_t size;
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size = sizeof(struct calling_interface_buffer);
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command.magic = SMI_CMD_MAGIC;
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command.command_address = da_command_address;
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command.command_code = da_command_code;
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command.ebx = smi_buf.dma;
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command.ecx = 0x42534931;
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mutex_lock(&smm_mutex);
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memcpy(buffer, input, size);
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dcdbas_smi_request(&command);
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memcpy(input, buffer, size);
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mutex_unlock(&smm_mutex);
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return 0;
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}
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/* When enabled this indicates that SMM won't work */
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static bool test_wsmt_enabled(void)
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{
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struct calling_interface_token *wsmt;
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/* if token doesn't exist, SMM will work */
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wsmt = dell_smbios_find_token(WSMT_EN_TOKEN);
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if (!wsmt)
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return false;
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/* If token exists, try to access over SMM but set a dummy return.
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* - If WSMT disabled it will be overwritten by SMM
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* - If WSMT enabled then dummy value will remain
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*/
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buffer->cmd_class = CLASS_TOKEN_READ;
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buffer->cmd_select = SELECT_TOKEN_STD;
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memset(buffer, 0, sizeof(struct calling_interface_buffer));
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buffer->input[0] = wsmt->location;
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buffer->output[0] = 99;
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dell_smbios_smm_call(buffer);
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if (buffer->output[0] == 99)
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return true;
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return false;
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}
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int init_dell_smbios_smm(void)
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{
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int ret;
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/*
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* Allocate buffer below 4GB for SMI data--only 32-bit physical addr
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* is passed to SMI handler.
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*/
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ret = dcdbas_smi_alloc(&smi_buf, PAGE_SIZE);
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if (ret)
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return ret;
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buffer = (void *)smi_buf.virt;
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dmi_walk(find_cmd_address, NULL);
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if (test_wsmt_enabled()) {
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pr_debug("Disabling due to WSMT enabled\n");
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ret = -ENODEV;
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goto fail_wsmt;
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}
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platform_device = platform_device_alloc("dell-smbios", 1);
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if (!platform_device) {
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ret = -ENOMEM;
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goto fail_platform_device_alloc;
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}
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ret = platform_device_add(platform_device);
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if (ret)
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goto fail_platform_device_add;
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ret = dell_smbios_register_device(&platform_device->dev,
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&dell_smbios_smm_call);
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if (ret)
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goto fail_register;
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return 0;
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fail_register:
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platform_device_del(platform_device);
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fail_platform_device_add:
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platform_device_put(platform_device);
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fail_wsmt:
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fail_platform_device_alloc:
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dcdbas_smi_free(&smi_buf);
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return ret;
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}
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void exit_dell_smbios_smm(void)
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{
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if (platform_device) {
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dell_smbios_unregister_device(&platform_device->dev);
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platform_device_unregister(platform_device);
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dcdbas_smi_free(&smi_buf);
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}
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}
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