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