1 /****************************************************************************** 2 * 3 * Module Name: tbxfroot - Find the root ACPI table (RSDT) 4 * 5 *****************************************************************************/ 6 7 /* 8 * Copyright (C) 2000 - 2012, 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 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, 78 sizeof(ACPI_SIG_RSDP) - 1) != 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 /******************************************************************************* 102 * 103 * FUNCTION: acpi_find_root_pointer 104 * 105 * PARAMETERS: table_address - Where the table pointer is returned 106 * 107 * RETURN: Status, RSDP physical address 108 * 109 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor 110 * pointer structure. If it is found, set *RSDP to point to it. 111 * 112 * NOTE1: The RSDP must be either in the first 1K of the Extended 113 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) 114 * Only a 32-bit physical address is necessary. 115 * 116 * NOTE2: This function is always available, regardless of the 117 * initialization state of the rest of ACPI. 118 * 119 ******************************************************************************/ 120 121 acpi_status acpi_find_root_pointer(acpi_size *table_address) 122 { 123 u8 *table_ptr; 124 u8 *mem_rover; 125 u32 physical_address; 126 127 ACPI_FUNCTION_TRACE(acpi_find_root_pointer); 128 129 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ 130 131 table_ptr = acpi_os_map_memory((acpi_physical_address) 132 ACPI_EBDA_PTR_LOCATION, 133 ACPI_EBDA_PTR_LENGTH); 134 if (!table_ptr) { 135 ACPI_ERROR((AE_INFO, 136 "Could not map memory at 0x%8.8X for length %u", 137 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); 138 139 return_ACPI_STATUS(AE_NO_MEMORY); 140 } 141 142 ACPI_MOVE_16_TO_32(&physical_address, table_ptr); 143 144 /* Convert segment part to physical address */ 145 146 physical_address <<= 4; 147 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH); 148 149 /* EBDA present? */ 150 151 if (physical_address > 0x400) { 152 /* 153 * 1b) Search EBDA paragraphs (EBDA is required to be a 154 * minimum of 1K length) 155 */ 156 table_ptr = acpi_os_map_memory((acpi_physical_address) 157 physical_address, 158 ACPI_EBDA_WINDOW_SIZE); 159 if (!table_ptr) { 160 ACPI_ERROR((AE_INFO, 161 "Could not map memory at 0x%8.8X for length %u", 162 physical_address, ACPI_EBDA_WINDOW_SIZE)); 163 164 return_ACPI_STATUS(AE_NO_MEMORY); 165 } 166 167 mem_rover = 168 acpi_tb_scan_memory_for_rsdp(table_ptr, 169 ACPI_EBDA_WINDOW_SIZE); 170 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE); 171 172 if (mem_rover) { 173 174 /* Return the physical address */ 175 176 physical_address += 177 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr); 178 179 *table_address = physical_address; 180 return_ACPI_STATUS(AE_OK); 181 } 182 } 183 184 /* 185 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh 186 */ 187 table_ptr = acpi_os_map_memory((acpi_physical_address) 188 ACPI_HI_RSDP_WINDOW_BASE, 189 ACPI_HI_RSDP_WINDOW_SIZE); 190 191 if (!table_ptr) { 192 ACPI_ERROR((AE_INFO, 193 "Could not map memory at 0x%8.8X for length %u", 194 ACPI_HI_RSDP_WINDOW_BASE, 195 ACPI_HI_RSDP_WINDOW_SIZE)); 196 197 return_ACPI_STATUS(AE_NO_MEMORY); 198 } 199 200 mem_rover = 201 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); 202 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); 203 204 if (mem_rover) { 205 206 /* Return the physical address */ 207 208 physical_address = (u32) 209 (ACPI_HI_RSDP_WINDOW_BASE + 210 ACPI_PTR_DIFF(mem_rover, table_ptr)); 211 212 *table_address = physical_address; 213 return_ACPI_STATUS(AE_OK); 214 } 215 216 /* A valid RSDP was not found */ 217 218 ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found")); 219 return_ACPI_STATUS(AE_NOT_FOUND); 220 } 221 222 /******************************************************************************* 223 * 224 * FUNCTION: acpi_tb_scan_memory_for_rsdp 225 * 226 * PARAMETERS: start_address - Starting pointer for search 227 * length - Maximum length to search 228 * 229 * RETURN: Pointer to the RSDP if found, otherwise NULL. 230 * 231 * DESCRIPTION: Search a block of memory for the RSDP signature 232 * 233 ******************************************************************************/ 234 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length) 235 { 236 acpi_status status; 237 u8 *mem_rover; 238 u8 *end_address; 239 240 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp); 241 242 end_address = start_address + length; 243 244 /* Search from given start address for the requested length */ 245 246 for (mem_rover = start_address; mem_rover < end_address; 247 mem_rover += ACPI_RSDP_SCAN_STEP) { 248 249 /* The RSDP signature and checksum must both be correct */ 250 251 status = 252 acpi_tb_validate_rsdp(ACPI_CAST_PTR 253 (struct acpi_table_rsdp, mem_rover)); 254 if (ACPI_SUCCESS(status)) { 255 256 /* Sig and checksum valid, we have found a real RSDP */ 257 258 ACPI_DEBUG_PRINT((ACPI_DB_INFO, 259 "RSDP located at physical address %p\n", 260 mem_rover)); 261 return_PTR(mem_rover); 262 } 263 264 /* No sig match or bad checksum, keep searching */ 265 } 266 267 /* Searched entire block, no RSDP was found */ 268 269 ACPI_DEBUG_PRINT((ACPI_DB_INFO, 270 "Searched entire block from %p, valid RSDP was not found\n", 271 start_address)); 272 return_PTR(NULL); 273 } 274