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