1/****************************************************************************** 2 * 3 * Module Name: tbxfroot - Find the root ACPI table (RSDT) 4 * 5 *****************************************************************************/ 6 7/* 8 * Copyright (C) 2000 - 2010, 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 49ACPI_MODULE_NAME("tbxfroot") 50 51/* Local prototypes */ 52static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length); 53 54static 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 68static 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 122acpi_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 0x%8.8X for length %u", 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 0x%8.8X for length %u", 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 0x%8.8X for length %u", 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 ******************************************************************************/ 235static 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} 275