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 - 2008, 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 /* Local prototypes */
  52 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length);
  53
  54 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp);
  55
  56 /*******************************************************************************
  57  *
  58  * FUNCTION:    acpi_tb_validate_rsdp
  59  *
  60  * PARAMETERS:  Rsdp                - Pointer to unvalidated RSDP
  61  *
  62  * RETURN:      Status
  63  *
  64  * DESCRIPTION: Validate the RSDP (ptr)
  65  *
  66  ******************************************************************************/
  67
  68 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
  69 {
  70         ACPI_FUNCTION_ENTRY();
  71
  72         /*
  73          * The signature and checksum must both be correct
  74          *
  75          * Note: Sometimes there exists more than one RSDP in memory; the valid
  76          * RSDP has a valid checksum, all others have an invalid checksum.
  77          */
  78         if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP,
  79                          sizeof(ACPI_SIG_RSDP) - 1) != 0) {
  80
  81                 /* Nope, BAD Signature */
  82
  83                 return (AE_BAD_SIGNATURE);
  84         }
  85
  86         /* Check the standard checksum */
  87
  88         if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
  89                 return (AE_BAD_CHECKSUM);
  90         }
  91
  92         /* Check extended checksum if table version >= 2 */
  93
  94         if ((rsdp->revision >= 2) &&
  95             (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
  96                 return (AE_BAD_CHECKSUM);
  97         }
  98
  99         return (AE_OK);
 100 }
 101
 102 /*******************************************************************************
 103  *
 104  * FUNCTION:    acpi_find_root_pointer
 105  *
 106  * PARAMETERS:  table_address           - Where the table pointer is returned
 107  *
 108  * RETURN:      Status, RSDP physical address
 109  *
 110  * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor
 111  *              pointer structure.  If it is found, set *RSDP to point to it.
 112  *
 113  * NOTE1:       The RSDP must be either in the first 1_k of the Extended
 114  *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
 115  *              Only a 32-bit physical address is necessary.
 116  *
 117  * NOTE2:       This function is always available, regardless of the
 118  *              initialization state of the rest of ACPI.
 119  *
 120  ******************************************************************************/
 121
 122 acpi_status acpi_find_root_pointer(acpi_size *table_address)
 123 {
 124         u8 *table_ptr;
 125         u8 *mem_rover;
 126         u32 physical_address;
 127
 128         ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
 129
 130         /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
 131
 132         table_ptr = acpi_os_map_memory((acpi_physical_address)
 133                                        ACPI_EBDA_PTR_LOCATION,
 134                                        ACPI_EBDA_PTR_LENGTH);
 135         if (!table_ptr) {
 136                 ACPI_ERROR((AE_INFO,
 137                             "Could not map memory at %8.8X for length %X",
 138                             ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
 139
 140                 return_ACPI_STATUS(AE_NO_MEMORY);
 141         }
 142
 143         ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
 144
 145         /* Convert segment part to physical address */
 146
 147         physical_address <<= 4;
 148         acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
 149
 150         /* EBDA present? */
 151
 152         if (physical_address > 0x400) {
 153                 /*
 154                  * 1b) Search EBDA paragraphs (EBDA is required to be a
 155                  *     minimum of 1_k length)
 156                  */
 157                 table_ptr = acpi_os_map_memory((acpi_physical_address)
 158                                                physical_address,
 159                                                ACPI_EBDA_WINDOW_SIZE);
 160                 if (!table_ptr) {
 161                         ACPI_ERROR((AE_INFO,
 162                                     "Could not map memory at %8.8X for length %X",
 163                                     physical_address, ACPI_EBDA_WINDOW_SIZE));
 164
 165                         return_ACPI_STATUS(AE_NO_MEMORY);
 166                 }
 167
 168                 mem_rover =
 169                     acpi_tb_scan_memory_for_rsdp(table_ptr,
 170                                                  ACPI_EBDA_WINDOW_SIZE);
 171                 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
 172
 173                 if (mem_rover) {
 174
 175                         /* Return the physical address */
 176
 177                         physical_address +=
 178                             (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
 179
 180                         *table_address = physical_address;
 181                         return_ACPI_STATUS(AE_OK);
 182                 }
 183         }
 184
 185         /*
 186          * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
 187          */
 188         table_ptr = acpi_os_map_memory((acpi_physical_address)
 189                                        ACPI_HI_RSDP_WINDOW_BASE,
 190                                        ACPI_HI_RSDP_WINDOW_SIZE);
 191
 192         if (!table_ptr) {
 193                 ACPI_ERROR((AE_INFO,
 194                             "Could not map memory at %8.8X for length %X",
 195                             ACPI_HI_RSDP_WINDOW_BASE,
 196                             ACPI_HI_RSDP_WINDOW_SIZE));
 197
 198                 return_ACPI_STATUS(AE_NO_MEMORY);
 199         }
 200
 201         mem_rover =
 202             acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 203         acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 204
 205         if (mem_rover) {
 206
 207                 /* Return the physical address */
 208
 209                 physical_address = (u32)
 210                     (ACPI_HI_RSDP_WINDOW_BASE +
 211                      ACPI_PTR_DIFF(mem_rover, table_ptr));
 212
 213                 *table_address = physical_address;
 214                 return_ACPI_STATUS(AE_OK);
 215         }
 216
 217         /* A valid RSDP was not found */
 218
 219         ACPI_ERROR((AE_INFO, "A valid RSDP was not found"));
 220         return_ACPI_STATUS(AE_NOT_FOUND);
 221 }
 222
 223 /*******************************************************************************
 224  *
 225  * FUNCTION:    acpi_tb_scan_memory_for_rsdp
 226  *
 227  * PARAMETERS:  start_address       - Starting pointer for search
 228  *              Length              - Maximum length to search
 229  *
 230  * RETURN:      Pointer to the RSDP if found, otherwise NULL.
 231  *
 232  * DESCRIPTION: Search a block of memory for the RSDP signature
 233  *
 234  ******************************************************************************/
 235 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length)
 236 {
 237         acpi_status status;
 238         u8 *mem_rover;
 239         u8 *end_address;
 240
 241         ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
 242
 243         end_address = start_address + length;
 244
 245         /* Search from given start address for the requested length */
 246
 247         for (mem_rover = start_address; mem_rover < end_address;
 248              mem_rover += ACPI_RSDP_SCAN_STEP) {
 249
 250                 /* The RSDP signature and checksum must both be correct */
 251
 252                 status =
 253                     acpi_tb_validate_rsdp(ACPI_CAST_PTR
 254                                           (struct acpi_table_rsdp, mem_rover));
 255                 if (ACPI_SUCCESS(status)) {
 256
 257                         /* Sig and checksum valid, we have found a real RSDP */
 258
 259                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 260                                           "RSDP located at physical address %p\n",
 261                                           mem_rover));
 262                         return_PTR(mem_rover);
 263                 }
 264
 265                 /* No sig match or bad checksum, keep searching */
 266         }
 267
 268         /* Searched entire block, no RSDP was found */
 269
 270         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 271                           "Searched entire block from %p, valid RSDP was not found\n",
 272                           start_address));
 273         return_PTR(NULL);
 274 }