1 /****************************************************************************** 2 * 3 * Module Name: tbxfroot - Find the root ACPI table (RSDT) 4 * 5 *****************************************************************************/ 6 7 /* 8 * Copyright (C) 2000 - 2011, 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 #define __TBXFROOT_C__ 45 46 #include "acpi.h" 47 #include "accommon.h" 48 #include "actables.h" 49 50 51 #define _COMPONENT ACPI_TABLES 52 ACPI_MODULE_NAME ("tbxfroot") 53 54 /* Local prototypes */ 55 56 static UINT8 * 57 AcpiTbScanMemoryForRsdp ( 58 UINT8 *StartAddress, 59 UINT32 Length); 60 61 static ACPI_STATUS 62 AcpiTbValidateRsdp ( 63 ACPI_TABLE_RSDP *Rsdp); 64 65 66 /******************************************************************************* 67 * 68 * FUNCTION: AcpiTbValidateRsdp 69 * 70 * PARAMETERS: Rsdp - Pointer to unvalidated RSDP 71 * 72 * RETURN: Status 73 * 74 * DESCRIPTION: Validate the RSDP (ptr) 75 * 76 ******************************************************************************/ 77 78 static ACPI_STATUS 79 AcpiTbValidateRsdp ( 80 ACPI_TABLE_RSDP *Rsdp) 81 { 82 ACPI_FUNCTION_ENTRY (); 83 84 85 /* 86 * The signature and checksum must both be correct 87 * 88 * Note: Sometimes there exists more than one RSDP in memory; the valid 89 * RSDP has a valid checksum, all others have an invalid checksum. 90 */ 91 if (ACPI_STRNCMP ((char *) Rsdp, ACPI_SIG_RSDP, 92 sizeof (ACPI_SIG_RSDP)-1) != 0) 93 { 94 /* Nope, BAD Signature */ 95 96 return (AE_BAD_SIGNATURE); 97 } 98 99 /* Check the standard checksum */ 100 101 if (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) 102 { 103 return (AE_BAD_CHECKSUM); 104 } 105 106 /* Check extended checksum if table version >= 2 */ 107 108 if ((Rsdp->Revision >= 2) && 109 (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) 110 { 111 return (AE_BAD_CHECKSUM); 112 } 113 114 return (AE_OK); 115 } 116 117 118 /******************************************************************************* 119 * 120 * FUNCTION: AcpiFindRootPointer 121 * 122 * PARAMETERS: TableAddress - Where the table pointer is returned 123 * 124 * RETURN: Status, RSDP physical address 125 * 126 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor 127 * pointer structure. If it is found, set *RSDP to point to it. 128 * 129 * NOTE1: The RSDP must be either in the first 1K of the Extended 130 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) 131 * Only a 32-bit physical address is necessary. 132 * 133 * NOTE2: This function is always available, regardless of the 134 * initialization state of the rest of ACPI. 135 * 136 ******************************************************************************/ 137 138 ACPI_STATUS 139 AcpiFindRootPointer ( 140 ACPI_SIZE *TableAddress) 141 { 142 UINT8 *TablePtr; 143 UINT8 *MemRover; 144 UINT32 PhysicalAddress; 145 146 147 ACPI_FUNCTION_TRACE (AcpiFindRootPointer); 148 149 150 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ 151 152 TablePtr = AcpiOsMapMemory ( 153 (ACPI_PHYSICAL_ADDRESS) ACPI_EBDA_PTR_LOCATION, 154 ACPI_EBDA_PTR_LENGTH); 155 if (!TablePtr) 156 { 157 ACPI_ERROR ((AE_INFO, 158 "Could not map memory at 0x%8.8X for length %u", 159 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); 160 161 return_ACPI_STATUS (AE_NO_MEMORY); 162 } 163 164 ACPI_MOVE_16_TO_32 (&PhysicalAddress, TablePtr); 165 166 /* Convert segment part to physical address */ 167 168 PhysicalAddress <<= 4; 169 AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_PTR_LENGTH); 170 171 /* EBDA present? */ 172 173 if (PhysicalAddress > 0x400) 174 { 175 /* 176 * 1b) Search EBDA paragraphs (EBDA is required to be a 177 * minimum of 1K length) 178 */ 179 TablePtr = AcpiOsMapMemory ( 180 (ACPI_PHYSICAL_ADDRESS) PhysicalAddress, 181 ACPI_EBDA_WINDOW_SIZE); 182 if (!TablePtr) 183 { 184 ACPI_ERROR ((AE_INFO, 185 "Could not map memory at 0x%8.8X for length %u", 186 PhysicalAddress, ACPI_EBDA_WINDOW_SIZE)); 187 188 return_ACPI_STATUS (AE_NO_MEMORY); 189 } 190 191 MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_EBDA_WINDOW_SIZE); 192 AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_WINDOW_SIZE); 193 194 if (MemRover) 195 { 196 /* Return the physical address */ 197 198 PhysicalAddress += (UINT32) ACPI_PTR_DIFF (MemRover, TablePtr); 199 200 *TableAddress = PhysicalAddress; 201 return_ACPI_STATUS (AE_OK); 202 } 203 } 204 205 /* 206 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh 207 */ 208 TablePtr = AcpiOsMapMemory ( 209 (ACPI_PHYSICAL_ADDRESS) ACPI_HI_RSDP_WINDOW_BASE, 210 ACPI_HI_RSDP_WINDOW_SIZE); 211 212 if (!TablePtr) 213 { 214 ACPI_ERROR ((AE_INFO, 215 "Could not map memory at 0x%8.8X for length %u", 216 ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE)); 217 218 return_ACPI_STATUS (AE_NO_MEMORY); 219 } 220 221 MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE); 222 AcpiOsUnmapMemory (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE); 223 224 if (MemRover) 225 { 226 /* Return the physical address */ 227 228 PhysicalAddress = (UINT32) 229 (ACPI_HI_RSDP_WINDOW_BASE + ACPI_PTR_DIFF (MemRover, TablePtr)); 230 231 *TableAddress = PhysicalAddress; 232 return_ACPI_STATUS (AE_OK); 233 } 234 235 /* A valid RSDP was not found */ 236 237 ACPI_ERROR ((AE_INFO, "A valid RSDP was not found")); 238 return_ACPI_STATUS (AE_NOT_FOUND); 239 } 240 241 ACPI_EXPORT_SYMBOL (AcpiFindRootPointer) 242 243 244 /******************************************************************************* 245 * 246 * FUNCTION: AcpiTbScanMemoryForRsdp 247 * 248 * PARAMETERS: StartAddress - Starting pointer for search 249 * Length - Maximum length to search 250 * 251 * RETURN: Pointer to the RSDP if found, otherwise NULL. 252 * 253 * DESCRIPTION: Search a block of memory for the RSDP signature 254 * 255 ******************************************************************************/ 256 257 static UINT8 * 258 AcpiTbScanMemoryForRsdp ( 259 UINT8 *StartAddress, 260 UINT32 Length) 261 { 262 ACPI_STATUS Status; 263 UINT8 *MemRover; 264 UINT8 *EndAddress; 265 266 267 ACPI_FUNCTION_TRACE (TbScanMemoryForRsdp); 268 269 270 EndAddress = StartAddress + Length; 271 272 /* Search from given start address for the requested length */ 273 274 for (MemRover = StartAddress; MemRover < EndAddress; 275 MemRover += ACPI_RSDP_SCAN_STEP) 276 { 277 /* The RSDP signature and checksum must both be correct */ 278 279 Status = AcpiTbValidateRsdp (ACPI_CAST_PTR (ACPI_TABLE_RSDP, MemRover)); 280 if (ACPI_SUCCESS (Status)) 281 { 282 /* Sig and checksum valid, we have found a real RSDP */ 283 284 ACPI_DEBUG_PRINT ((ACPI_DB_INFO, 285 "RSDP located at physical address %p\n", MemRover)); 286 return_PTR (MemRover); 287 } 288 289 /* No sig match or bad checksum, keep searching */ 290 } 291 292 /* Searched entire block, no RSDP was found */ 293 294 ACPI_DEBUG_PRINT ((ACPI_DB_INFO, 295 "Searched entire block from %p, valid RSDP was not found\n", 296 StartAddress)); 297 return_PTR (NULL); 298 } 299 300