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 - 2015, 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_get_rsdp_length
  54  *
  55  * PARAMETERS:  rsdp                - Pointer to RSDP
  56  *
  57  * RETURN:      Table length
  58  *
  59  * DESCRIPTION: Get the length of the RSDP
  60  *
  61  ******************************************************************************/
  62 u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp)
  63 {
  64
  65         if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
  66
  67                 /* BAD Signature */
  68
  69                 return (0);
  70         }
  71
  72         /* "Length" field is available if table version >= 2 */
  73
  74         if (rsdp->revision >= 2) {
  75                 return (rsdp->length);
  76         } else {
  77                 return (ACPI_RSDP_CHECKSUM_LENGTH);
  78         }
  79 }
  80
  81 /*******************************************************************************
  82  *
  83  * FUNCTION:    acpi_tb_validate_rsdp
  84  *
  85  * PARAMETERS:  rsdp                - Pointer to unvalidated RSDP
  86  *
  87  * RETURN:      Status
  88  *
  89  * DESCRIPTION: Validate the RSDP (ptr)
  90  *
  91  ******************************************************************************/
  92
  93 acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp * rsdp)
  94 {
  95
  96         /*
  97          * The signature and checksum must both be correct
  98          *
  99          * Note: Sometimes there exists more than one RSDP in memory; the valid
 100          * RSDP has a valid checksum, all others have an invalid checksum.
 101          */
 102         if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) {
 103
 104                 /* Nope, BAD Signature */
 105
 106                 return (AE_BAD_SIGNATURE);
 107         }
 108
 109         /* Check the standard checksum */
 110
 111         if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
 112                 return (AE_BAD_CHECKSUM);
 113         }
 114
 115         /* Check extended checksum if table version >= 2 */
 116
 117         if ((rsdp->revision >= 2) &&
 118             (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
 119                 return (AE_BAD_CHECKSUM);
 120         }
 121
 122         return (AE_OK);
 123 }
 124
 125 /*******************************************************************************
 126  *
 127  * FUNCTION:    acpi_find_root_pointer
 128  *
 129  * PARAMETERS:  table_address           - Where the table pointer is returned
 130  *
 131  * RETURN:      Status, RSDP physical address
 132  *
 133  * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
 134  *              pointer structure. If it is found, set *RSDP to point to it.
 135  *
 136  * NOTE1:       The RSDP must be either in the first 1K of the Extended
 137  *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
 138  *              Only a 32-bit physical address is necessary.
 139  *
 140  * NOTE2:       This function is always available, regardless of the
 141  *              initialization state of the rest of ACPI.
 142  *
 143  ******************************************************************************/
 144
 145 acpi_status __init acpi_find_root_pointer(acpi_physical_address * table_address)
 146 {
 147         u8 *table_ptr;
 148         u8 *mem_rover;
 149         u32 physical_address;
 150
 151         ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
 152
 153         /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
 154
 155         table_ptr = acpi_os_map_memory((acpi_physical_address)
 156                                        ACPI_EBDA_PTR_LOCATION,
 157                                        ACPI_EBDA_PTR_LENGTH);
 158         if (!table_ptr) {
 159                 ACPI_ERROR((AE_INFO,
 160                             "Could not map memory at 0x%8.8X for length %u",
 161                             ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
 162
 163                 return_ACPI_STATUS(AE_NO_MEMORY);
 164         }
 165
 166         ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
 167
 168         /* Convert segment part to physical address */
 169
 170         physical_address <<= 4;
 171         acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
 172
 173         /* EBDA present? */
 174
 175         if (physical_address > 0x400) {
 176                 /*
 177                  * 1b) Search EBDA paragraphs (EBDA is required to be a
 178                  *     minimum of 1K length)
 179                  */
 180                 table_ptr = acpi_os_map_memory((acpi_physical_address)
 181                                                physical_address,
 182                                                ACPI_EBDA_WINDOW_SIZE);
 183                 if (!table_ptr) {
 184                         ACPI_ERROR((AE_INFO,
 185                                     "Could not map memory at 0x%8.8X for length %u",
 186                                     physical_address, ACPI_EBDA_WINDOW_SIZE));
 187
 188                         return_ACPI_STATUS(AE_NO_MEMORY);
 189                 }
 190
 191                 mem_rover =
 192                     acpi_tb_scan_memory_for_rsdp(table_ptr,
 193                                                  ACPI_EBDA_WINDOW_SIZE);
 194                 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
 195
 196                 if (mem_rover) {
 197
 198                         /* Return the physical address */
 199
 200                         physical_address +=
 201                             (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
 202
 203                         *table_address =
 204                             (acpi_physical_address) physical_address;
 205                         return_ACPI_STATUS(AE_OK);
 206                 }
 207         }
 208
 209         /*
 210          * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
 211          */
 212         table_ptr = acpi_os_map_memory((acpi_physical_address)
 213                                        ACPI_HI_RSDP_WINDOW_BASE,
 214                                        ACPI_HI_RSDP_WINDOW_SIZE);
 215
 216         if (!table_ptr) {
 217                 ACPI_ERROR((AE_INFO,
 218                             "Could not map memory at 0x%8.8X for length %u",
 219                             ACPI_HI_RSDP_WINDOW_BASE,
 220                             ACPI_HI_RSDP_WINDOW_SIZE));
 221
 222                 return_ACPI_STATUS(AE_NO_MEMORY);
 223         }
 224
 225         mem_rover =
 226             acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 227         acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 228
 229         if (mem_rover) {
 230
 231                 /* Return the physical address */
 232
 233                 physical_address = (u32)
 234                     (ACPI_HI_RSDP_WINDOW_BASE +
 235                      ACPI_PTR_DIFF(mem_rover, table_ptr));
 236
 237                 *table_address = (acpi_physical_address) physical_address;
 238                 return_ACPI_STATUS(AE_OK);
 239         }
 240
 241         /* A valid RSDP was not found */
 242
 243         ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found"));
 244         return_ACPI_STATUS(AE_NOT_FOUND);
 245 }
 246
 247 /*******************************************************************************
 248  *
 249  * FUNCTION:    acpi_tb_scan_memory_for_rsdp
 250  *
 251  * PARAMETERS:  start_address       - Starting pointer for search
 252  *              length              - Maximum length to search
 253  *
 254  * RETURN:      Pointer to the RSDP if found, otherwise NULL.
 255  *
 256  * DESCRIPTION: Search a block of memory for the RSDP signature
 257  *
 258  ******************************************************************************/
 259 u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length)
 260 {
 261         acpi_status status;
 262         u8 *mem_rover;
 263         u8 *end_address;
 264
 265         ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
 266
 267         end_address = start_address + length;
 268
 269         /* Search from given start address for the requested length */
 270
 271         for (mem_rover = start_address; mem_rover < end_address;
 272              mem_rover += ACPI_RSDP_SCAN_STEP) {
 273
 274                 /* The RSDP signature and checksum must both be correct */
 275
 276                 status =
 277                     acpi_tb_validate_rsdp(ACPI_CAST_PTR
 278                                           (struct acpi_table_rsdp, mem_rover));
 279                 if (ACPI_SUCCESS(status)) {
 280
 281                         /* Sig and checksum valid, we have found a real RSDP */
 282
 283                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 284                                           "RSDP located at physical address %p\n",
 285                                           mem_rover));
 286                         return_PTR(mem_rover);
 287                 }
 288
 289                 /* No sig match or bad checksum, keep searching */
 290         }
 291
 292         /* Searched entire block, no RSDP was found */
 293
 294         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 295                           "Searched entire block from %p, valid RSDP was not found\n",
 296                           start_address));
 297         return_PTR(NULL);
 298 }