drivers/acpi/acpica/tbxfroot.c

   1 /******************************************************************************
   2  *
   3  * Module Name: tbxfroot - Find the root ACPI table (RSDT)
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2013, Intel Corp.
   9  * All rights reserved.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions, and the following disclaimer,
  16  *    without modification.
  17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
  18  *    substantially similar to the "NO WARRANTY" disclaimer below
  19  *    ("Disclaimer") and any redistribution must be conditioned upon
  20  *    including a substantially similar Disclaimer requirement for further
  21  *    binary redistribution.
  22  * 3. Neither the names of the above-listed copyright holders nor the names
  23  *    of any contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * Alternatively, this software may be distributed under the terms of the
  27  * GNU General Public License ("GPL") version 2 as published by the Free
  28  * Software Foundation.
  29  *
  30  * NO WARRANTY
  31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
  34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  41  * POSSIBILITY OF SUCH DAMAGES.
  42  */
  43
  44 #include <acpi/acpi.h>
  45 #include "accommon.h"
  46 #include "actables.h"
  47
  48 #define _COMPONENT          ACPI_TABLES
  49 ACPI_MODULE_NAME("tbxfroot")
  50
  51 /*******************************************************************************
  52  *
  53  * FUNCTION:    acpi_tb_validate_rsdp
  54  *
  55  * PARAMETERS:  rsdp                - Pointer to unvalidated RSDP
  56  *
  57  * RETURN:      Status
  58  *
  59  * DESCRIPTION: Validate the RSDP (ptr)
  60  *
  61  ******************************************************************************/
  62 acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
  63 {
  64
  65         /*
  66          * The signature and checksum must both be correct
  67          *
  68          * Note: Sometimes there exists more than one RSDP in memory; the valid
  69          * RSDP has a valid checksum, all others have an invalid checksum.
  70          */
  71         if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
  72
  73                 /* Nope, BAD Signature */
  74
  75                 return (AE_BAD_SIGNATURE);
  76         }
  77
  78         /* Check the standard checksum */
  79
  80         if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
  81                 return (AE_BAD_CHECKSUM);
  82         }
  83
  84         /* Check extended checksum if table version >= 2 */
  85
  86         if ((rsdp->revision >= 2) &&
  87             (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
  88                 return (AE_BAD_CHECKSUM);
  89         }
  90
  91         return (AE_OK);
  92 }
  93
  94 /*******************************************************************************
  95  *
  96  * FUNCTION:    acpi_find_root_pointer
  97  *
  98  * PARAMETERS:  table_address           - Where the table pointer is returned
  99  *
 100  * RETURN:      Status, RSDP physical address
 101  *
 102  * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
 103  *              pointer structure. If it is found, set *RSDP to point to it.
 104  *
 105  * NOTE1:       The RSDP must be either in the first 1K of the Extended
 106  *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
 107  *              Only a 32-bit physical address is necessary.
 108  *
 109  * NOTE2:       This function is always available, regardless of the
 110  *              initialization state of the rest of ACPI.
 111  *
 112  ******************************************************************************/
 113
 114 acpi_status __init acpi_find_root_pointer(acpi_size *table_address)
 115 {
 116         u8 *table_ptr;
 117         u8 *mem_rover;
 118         u32 physical_address;
 119
 120         ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
 121
 122         /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
 123
 124         table_ptr = acpi_os_map_memory((acpi_physical_address)
 125                                        ACPI_EBDA_PTR_LOCATION,
 126                                        ACPI_EBDA_PTR_LENGTH);
 127         if (!table_ptr) {
 128                 ACPI_ERROR((AE_INFO,
 129                             "Could not map memory at 0x%8.8X for length %u",
 130                             ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
 131
 132                 return_ACPI_STATUS(AE_NO_MEMORY);
 133         }
 134
 135         ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
 136
 137         /* Convert segment part to physical address */
 138
 139         physical_address <<= 4;
 140         acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
 141
 142         /* EBDA present? */
 143
 144         if (physical_address > 0x400) {
 145                 /*
 146                  * 1b) Search EBDA paragraphs (EBDA is required to be a
 147                  *     minimum of 1K length)
 148                  */
 149                 table_ptr = acpi_os_map_memory((acpi_physical_address)
 150                                                physical_address,
 151                                                ACPI_EBDA_WINDOW_SIZE);
 152                 if (!table_ptr) {
 153                         ACPI_ERROR((AE_INFO,
 154                                     "Could not map memory at 0x%8.8X for length %u",
 155                                     physical_address, ACPI_EBDA_WINDOW_SIZE));
 156
 157                         return_ACPI_STATUS(AE_NO_MEMORY);
 158                 }
 159
 160                 mem_rover =
 161                     acpi_tb_scan_memory_for_rsdp(table_ptr,
 162                                                  ACPI_EBDA_WINDOW_SIZE);
 163                 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
 164
 165                 if (mem_rover) {
 166
 167                         /* Return the physical address */
 168
 169                         physical_address +=
 170                             (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
 171
 172                         *table_address = physical_address;
 173                         return_ACPI_STATUS(AE_OK);
 174                 }
 175         }
 176
 177         /*
 178          * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
 179          */
 180         table_ptr = acpi_os_map_memory((acpi_physical_address)
 181                                        ACPI_HI_RSDP_WINDOW_BASE,
 182                                        ACPI_HI_RSDP_WINDOW_SIZE);
 183
 184         if (!table_ptr) {
 185                 ACPI_ERROR((AE_INFO,
 186                             "Could not map memory at 0x%8.8X for length %u",
 187                             ACPI_HI_RSDP_WINDOW_BASE,
 188                             ACPI_HI_RSDP_WINDOW_SIZE));
 189
 190                 return_ACPI_STATUS(AE_NO_MEMORY);
 191         }
 192
 193         mem_rover =
 194             acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 195         acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 196
 197         if (mem_rover) {
 198
 199                 /* Return the physical address */
 200
 201                 physical_address = (u32)
 202                     (ACPI_HI_RSDP_WINDOW_BASE +
 203                      ACPI_PTR_DIFF(mem_rover, table_ptr));
 204
 205                 *table_address = physical_address;
 206                 return_ACPI_STATUS(AE_OK);
 207         }
 208
 209         /* A valid RSDP was not found */
 210
 211         ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found"));
 212         return_ACPI_STATUS(AE_NOT_FOUND);
 213 }
 214
 215 /*******************************************************************************
 216  *
 217  * FUNCTION:    acpi_tb_scan_memory_for_rsdp
 218  *
 219  * PARAMETERS:  start_address       - Starting pointer for search
 220  *              length              - Maximum length to search
 221  *
 222  * RETURN:      Pointer to the RSDP if found, otherwise NULL.
 223  *
 224  * DESCRIPTION: Search a block of memory for the RSDP signature
 225  *
 226  ******************************************************************************/
 227 u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length)
 228 {
 229         acpi_status status;
 230         u8 *mem_rover;
 231         u8 *end_address;
 232
 233         ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
 234
 235         end_address = start_address + length;
 236
 237         /* Search from given start address for the requested length */
 238
 239         for (mem_rover = start_address; mem_rover < end_address;
 240              mem_rover += ACPI_RSDP_SCAN_STEP) {
 241
 242                 /* The RSDP signature and checksum must both be correct */
 243
 244                 status =
 245                     acpi_tb_validate_rsdp(ACPI_CAST_PTR
 246                                           (struct acpi_table_rsdp, mem_rover));
 247                 if (ACPI_SUCCESS(status)) {
 248
 249                         /* Sig and checksum valid, we have found a real RSDP */
 250
 251                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 252                                           "RSDP located at physical address %p\n",
 253                                           mem_rover));
 254                         return_PTR(mem_rover);
 255                 }
 256
 257                 /* No sig match or bad checksum, keep searching */
 258         }
 259
 260         /* Searched entire block, no RSDP was found */
 261
 262         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 263                           "Searched entire block from %p, valid RSDP was not found\n",
 264                           start_address));
 265         return_PTR(NULL);
 266 }