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 } 268