drivers/platform/x86/dell-smbios.c

   1 /*
   2  *  Common functions for kernel modules using Dell SMBIOS
   3  *
   4  *  Copyright (c) Red Hat <mjg@redhat.com>
   5  *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@gmail.com>
   6  *  Copyright (c) 2014 Pali Rohár <pali.rohar@gmail.com>
   7  *
   8  *  Based on documentation in the libsmbios package:
   9  *  Copyright (C) 2005-2014 Dell Inc.
  10  *
  11  *  This program is free software; you can redistribute it and/or modify
  12  *  it under the terms of the GNU General Public License version 2 as
  13  *  published by the Free Software Foundation.
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/dmi.h>
  19 #include <linux/err.h>
  20 #include <linux/gfp.h>
  21 #include <linux/mutex.h>
  22 #include <linux/slab.h>
  23 #include <linux/io.h>
  24 #include "../../firmware/dcdbas.h"
  25 #include "dell-smbios.h"
  26
  27 struct calling_interface_structure {
  28         struct dmi_header header;
  29         u16 cmdIOAddress;
  30         u8 cmdIOCode;
  31         u32 supportedCmds;
  32         struct calling_interface_token tokens[];
  33 } __packed;
  34
  35 static struct calling_interface_buffer *buffer;
  36 static DEFINE_MUTEX(buffer_mutex);
  37
  38 static int da_command_address;
  39 static int da_command_code;
  40 static int da_num_tokens;
  41 static struct calling_interface_token *da_tokens;
  42
  43 int dell_smbios_error(int value)
  44 {
  45         switch (value) {
  46         case 0: /* Completed successfully */
  47                 return 0;
  48         case -1: /* Completed with error */
  49                 return -EIO;
  50         case -2: /* Function not supported */
  51                 return -ENXIO;
  52         default: /* Unknown error */
  53                 return -EINVAL;
  54         }
  55 }
  56 EXPORT_SYMBOL_GPL(dell_smbios_error);
  57
  58 struct calling_interface_buffer *dell_smbios_get_buffer(void)
  59 {
  60         mutex_lock(&buffer_mutex);
  61         dell_smbios_clear_buffer();
  62         return buffer;
  63 }
  64 EXPORT_SYMBOL_GPL(dell_smbios_get_buffer);
  65
  66 void dell_smbios_clear_buffer(void)
  67 {
  68         memset(buffer, 0, sizeof(struct calling_interface_buffer));
  69 }
  70 EXPORT_SYMBOL_GPL(dell_smbios_clear_buffer);
  71
  72 void dell_smbios_release_buffer(void)
  73 {
  74         mutex_unlock(&buffer_mutex);
  75 }
  76 EXPORT_SYMBOL_GPL(dell_smbios_release_buffer);
  77
  78 void dell_smbios_send_request(int class, int select)
  79 {
  80         struct smi_cmd command;
  81
  82         command.magic = SMI_CMD_MAGIC;
  83         command.command_address = da_command_address;
  84         command.command_code = da_command_code;
  85         command.ebx = virt_to_phys(buffer);
  86         command.ecx = 0x42534931;
  87
  88         buffer->class = class;
  89         buffer->select = select;
  90
  91         dcdbas_smi_request(&command);
  92 }
  93 EXPORT_SYMBOL_GPL(dell_smbios_send_request);
  94
  95 struct calling_interface_token *dell_smbios_find_token(int tokenid)
  96 {
  97         int i;
  98
  99         for (i = 0; i < da_num_tokens; i++) {
 100                 if (da_tokens[i].tokenID == tokenid)
 101                         return &da_tokens[i];
 102         }
 103
 104         return NULL;
 105 }
 106 EXPORT_SYMBOL_GPL(dell_smbios_find_token);
 107
 108 static void __init parse_da_table(const struct dmi_header *dm)
 109 {
 110         /* Final token is a terminator, so we don't want to copy it */
 111         int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
 112         struct calling_interface_token *new_da_tokens;
 113         struct calling_interface_structure *table =
 114                 container_of(dm, struct calling_interface_structure, header);
 115
 116         /* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
 117            6 bytes of entry */
 118
 119         if (dm->length < 17)
 120                 return;
 121
 122         da_command_address = table->cmdIOAddress;
 123         da_command_code = table->cmdIOCode;
 124
 125         new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
 126                                  sizeof(struct calling_interface_token),
 127                                  GFP_KERNEL);
 128
 129         if (!new_da_tokens)
 130                 return;
 131         da_tokens = new_da_tokens;
 132
 133         memcpy(da_tokens+da_num_tokens, table->tokens,
 134                sizeof(struct calling_interface_token) * tokens);
 135
 136         da_num_tokens += tokens;
 137 }
 138
 139 static void __init find_tokens(const struct dmi_header *dm, void *dummy)
 140 {
 141         switch (dm->type) {
 142         case 0xd4: /* Indexed IO */
 143         case 0xd5: /* Protected Area Type 1 */
 144         case 0xd6: /* Protected Area Type 2 */
 145                 break;
 146         case 0xda: /* Calling interface */
 147                 parse_da_table(dm);
 148                 break;
 149         }
 150 }
 151
 152 static int __init dell_smbios_init(void)
 153 {
 154         int ret;
 155
 156         dmi_walk(find_tokens, NULL);
 157
 158         if (!da_tokens)  {
 159                 pr_info("Unable to find dmi tokens\n");
 160                 return -ENODEV;
 161         }
 162
 163         /*
 164          * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
 165          * is passed to SMI handler.
 166          */
 167         buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
 168         if (!buffer) {
 169                 ret = -ENOMEM;
 170                 goto fail_buffer;
 171         }
 172
 173         return 0;
 174
 175 fail_buffer:
 176         kfree(da_tokens);
 177         return ret;
 178 }
 179
 180 static void __exit dell_smbios_exit(void)
 181 {
 182         kfree(da_tokens);
 183         free_page((unsigned long)buffer);
 184 }
 185
 186 subsys_initcall(dell_smbios_init);
 187 module_exit(dell_smbios_exit);
 188
 189 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
 190 MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@gmail.com>");
 191 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
 192 MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
 193 MODULE_LICENSE("GPL");