git.oblomov.eu Git - linux-2.6/blob - drivers/acpi/tables/tbxfroot.c

   1 /******************************************************************************
   2  *
   3  * Module Name: tbxfroot - Find the root ACPI table (RSDT)
   4  *
   5  *****************************************************************************/
   6
   7 /*
   8  * Copyright (C) 2000 - 2006, R. Byron Moore
   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 <acpi/actables.h>
  46
  47 #define _COMPONENT          ACPI_TABLES
  48 ACPI_MODULE_NAME("tbxfroot")
  49
  50 /* Local prototypes */
  51 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length);
  52
  53 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp);
  54
  55 /*******************************************************************************
  56  *
  57  * FUNCTION:    acpi_tb_validate_rsdp
  58  *
  59  * PARAMETERS:  Rsdp                - Pointer to unvalidated RSDP
  60  *
  61  * RETURN:      Status
  62  *
  63  * DESCRIPTION: Validate the RSDP (ptr)
  64  *
  65  ******************************************************************************/
  66
  67 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
  68 {
  69         ACPI_FUNCTION_ENTRY();
  70
  71         /*
  72          * The signature and checksum must both be correct
  73          *
  74          * Note: Sometimes there exists more than one RSDP in memory; the valid
  75          * RSDP has a valid checksum, all others have an invalid checksum.
  76          */
  77         if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1)
  78             != 0) {
  79
  80                 /* Nope, BAD Signature */
  81
  82                 return (AE_BAD_SIGNATURE);
  83         }
  84
  85         /* Check the standard checksum */
  86
  87         if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
  88                 return (AE_BAD_CHECKSUM);
  89         }
  90
  91         /* Check extended checksum if table version >= 2 */
  92
  93         if ((rsdp->revision >= 2) &&
  94             (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
  95                 return (AE_BAD_CHECKSUM);
  96         }
  97
  98         return (AE_OK);
  99 }
 100
 101 #if ACPI_MACHINE_WIDTH != 16
 102
 103 /*******************************************************************************
 104  *
 105  * FUNCTION:    acpi_tb_find_rsdp
 106  *
 107  * PARAMETERS:  table_address           - Where the table pointer is returned
 108  *
 109  * RETURN:      Status, RSDP physical address
 110  *
 111  * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor
 112  *              pointer structure.  If it is found, set *RSDP to point to it.
 113  *
 114  * NOTE1:       The RSDP must be either in the first 1_k of the Extended
 115  *              BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
 116  *              Only a 32-bit physical address is necessary.
 117  *
 118  * NOTE2:       This function is always available, regardless of the
 119  *              initialization state of the rest of ACPI.
 120  *
 121  ******************************************************************************/
 122
 123 acpi_status acpi_find_root_pointer(acpi_native_uint * table_address)
 124 {
 125         u8 *table_ptr;
 126         u8 *mem_rover;
 127         u32 physical_address;
 128
 129         ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
 130
 131         /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
 132
 133         table_ptr = acpi_os_map_memory((acpi_physical_address)
 134                                        ACPI_EBDA_PTR_LOCATION,
 135                                        ACPI_EBDA_PTR_LENGTH);
 136         if (!table_ptr) {
 137                 ACPI_ERROR((AE_INFO,
 138                             "Could not map memory at %8.8X for length %X",
 139                             ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
 140
 141                 return_ACPI_STATUS(AE_NO_MEMORY);
 142         }
 143
 144         ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
 145
 146         /* Convert segment part to physical address */
 147
 148         physical_address <<= 4;
 149         acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
 150
 151         /* EBDA present? */
 152
 153         if (physical_address > 0x400) {
 154                 /*
 155                  * 1b) Search EBDA paragraphs (EBDA is required to be a
 156                  *     minimum of 1_k length)
 157                  */
 158                 table_ptr = acpi_os_map_memory((acpi_native_uint)
 159                                                physical_address,
 160                                                ACPI_EBDA_WINDOW_SIZE);
 161                 if (!table_ptr) {
 162                         ACPI_ERROR((AE_INFO,
 163                                     "Could not map memory at %8.8X for length %X",
 164                                     physical_address, ACPI_EBDA_WINDOW_SIZE));
 165
 166                         return_ACPI_STATUS(AE_NO_MEMORY);
 167                 }
 168
 169                 mem_rover =
 170                     acpi_tb_scan_memory_for_rsdp(table_ptr,
 171                                                  ACPI_EBDA_WINDOW_SIZE);
 172                 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
 173
 174                 if (mem_rover) {
 175
 176                         /* Return the physical address */
 177
 178                         physical_address +=
 179                             (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
 180
 181                         *table_address = physical_address;
 182                         return_ACPI_STATUS(AE_OK);
 183                 }
 184         }
 185
 186         /*
 187          * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
 188          */
 189         table_ptr = acpi_os_map_memory((acpi_physical_address)
 190                                        ACPI_HI_RSDP_WINDOW_BASE,
 191                                        ACPI_HI_RSDP_WINDOW_SIZE);
 192
 193         if (!table_ptr) {
 194                 ACPI_ERROR((AE_INFO,
 195                             "Could not map memory at %8.8X for length %X",
 196                             ACPI_HI_RSDP_WINDOW_BASE,
 197                             ACPI_HI_RSDP_WINDOW_SIZE));
 198
 199                 return_ACPI_STATUS(AE_NO_MEMORY);
 200         }
 201
 202         mem_rover =
 203             acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 204         acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
 205
 206         if (mem_rover) {
 207
 208                 /* Return the physical address */
 209
 210                 physical_address = (u32)
 211                     (ACPI_HI_RSDP_WINDOW_BASE +
 212                      ACPI_PTR_DIFF(mem_rover, table_ptr));
 213
 214                 *table_address = physical_address;
 215                 return_ACPI_STATUS(AE_OK);
 216         }
 217
 218         /* A valid RSDP was not found */
 219
 220         ACPI_ERROR((AE_INFO, "A valid RSDP was not found"));
 221         return_ACPI_STATUS(AE_NOT_FOUND);
 222 }
 223
 224 ACPI_EXPORT_SYMBOL(acpi_find_root_pointer)
 225
 226 /*******************************************************************************
 227  *
 228  * FUNCTION:    acpi_tb_scan_memory_for_rsdp
 229  *
 230  * PARAMETERS:  start_address       - Starting pointer for search
 231  *              Length              - Maximum length to search
 232  *
 233  * RETURN:      Pointer to the RSDP if found, otherwise NULL.
 234  *
 235  * DESCRIPTION: Search a block of memory for the RSDP signature
 236  *
 237  ******************************************************************************/
 238 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length)
 239 {
 240         acpi_status status;
 241         u8 *mem_rover;
 242         u8 *end_address;
 243
 244         ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
 245
 246         end_address = start_address + length;
 247
 248         /* Search from given start address for the requested length */
 249
 250         for (mem_rover = start_address; mem_rover < end_address;
 251              mem_rover += ACPI_RSDP_SCAN_STEP) {
 252
 253                 /* The RSDP signature and checksum must both be correct */
 254
 255                 status =
 256                     acpi_tb_validate_rsdp(ACPI_CAST_PTR
 257                                           (struct acpi_table_rsdp, mem_rover));
 258                 if (ACPI_SUCCESS(status)) {
 259
 260                         /* Sig and checksum valid, we have found a real RSDP */
 261
 262                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 263                                           "RSDP located at physical address %p\n",
 264                                           mem_rover));
 265                         return_PTR(mem_rover);
 266                 }
 267
 268                 /* No sig match or bad checksum, keep searching */
 269         }
 270
 271         /* Searched entire block, no RSDP was found */
 272
 273         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 274                           "Searched entire block from %p, valid RSDP was not found\n",
 275                           start_address));
 276         return_PTR(NULL);
 277 }
 278
 279 #endif