1 /****************************************************************************** 2 * 3 * Module Name: tbxfroot - Find the root ACPI table (RSDT) 4 * 5 *****************************************************************************/ 6 7 /* 8 * Copyright (C) 2000 - 2015, 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_get_rsdp_length 54 * 55 * PARAMETERS: rsdp - Pointer to RSDP 56 * 57 * RETURN: Table length 58 * 59 * DESCRIPTION: Get the length of the RSDP 60 * 61 ******************************************************************************/ 62 u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp) 63 { 64 65 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { 66 67 /* BAD Signature */ 68 69 return (0); 70 } 71 72 /* "Length" field is available if table version >= 2 */ 73 74 if (rsdp->revision >= 2) { 75 return (rsdp->length); 76 } else { 77 return (ACPI_RSDP_CHECKSUM_LENGTH); 78 } 79 } 80 81 /******************************************************************************* 82 * 83 * FUNCTION: acpi_tb_validate_rsdp 84 * 85 * PARAMETERS: rsdp - Pointer to unvalidated RSDP 86 * 87 * RETURN: Status 88 * 89 * DESCRIPTION: Validate the RSDP (ptr) 90 * 91 ******************************************************************************/ 92 93 acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp * rsdp) 94 { 95 96 /* 97 * The signature and checksum must both be correct 98 * 99 * Note: Sometimes there exists more than one RSDP in memory; the valid 100 * RSDP has a valid checksum, all others have an invalid checksum. 101 */ 102 if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { 103 104 /* Nope, BAD Signature */ 105 106 return (AE_BAD_SIGNATURE); 107 } 108 109 /* Check the standard checksum */ 110 111 if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) { 112 return (AE_BAD_CHECKSUM); 113 } 114 115 /* Check extended checksum if table version >= 2 */ 116 117 if ((rsdp->revision >= 2) && 118 (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) { 119 return (AE_BAD_CHECKSUM); 120 } 121 122 return (AE_OK); 123 } 124 125 /******************************************************************************* 126 * 127 * FUNCTION: acpi_find_root_pointer 128 * 129 * PARAMETERS: table_address - Where the table pointer is returned 130 * 131 * RETURN: Status, RSDP physical address 132 * 133 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor 134 * pointer structure. If it is found, set *RSDP to point to it. 135 * 136 * NOTE1: The RSDP must be either in the first 1K of the Extended 137 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) 138 * Only a 32-bit physical address is necessary. 139 * 140 * NOTE2: This function is always available, regardless of the 141 * initialization state of the rest of ACPI. 142 * 143 ******************************************************************************/ 144 145 acpi_status __init acpi_find_root_pointer(acpi_physical_address * table_address) 146 { 147 u8 *table_ptr; 148 u8 *mem_rover; 149 u32 physical_address; 150 151 ACPI_FUNCTION_TRACE(acpi_find_root_pointer); 152 153 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ 154 155 table_ptr = acpi_os_map_memory((acpi_physical_address) 156 ACPI_EBDA_PTR_LOCATION, 157 ACPI_EBDA_PTR_LENGTH); 158 if (!table_ptr) { 159 ACPI_ERROR((AE_INFO, 160 "Could not map memory at 0x%8.8X for length %u", 161 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); 162 163 return_ACPI_STATUS(AE_NO_MEMORY); 164 } 165 166 ACPI_MOVE_16_TO_32(&physical_address, table_ptr); 167 168 /* Convert segment part to physical address */ 169 170 physical_address <<= 4; 171 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH); 172 173 /* EBDA present? */ 174 175 if (physical_address > 0x400) { 176 /* 177 * 1b) Search EBDA paragraphs (EBDA is required to be a 178 * minimum of 1K length) 179 */ 180 table_ptr = acpi_os_map_memory((acpi_physical_address) 181 physical_address, 182 ACPI_EBDA_WINDOW_SIZE); 183 if (!table_ptr) { 184 ACPI_ERROR((AE_INFO, 185 "Could not map memory at 0x%8.8X for length %u", 186 physical_address, ACPI_EBDA_WINDOW_SIZE)); 187 188 return_ACPI_STATUS(AE_NO_MEMORY); 189 } 190 191 mem_rover = 192 acpi_tb_scan_memory_for_rsdp(table_ptr, 193 ACPI_EBDA_WINDOW_SIZE); 194 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE); 195 196 if (mem_rover) { 197 198 /* Return the physical address */ 199 200 physical_address += 201 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr); 202 203 *table_address = 204 (acpi_physical_address) physical_address; 205 return_ACPI_STATUS(AE_OK); 206 } 207 } 208 209 /* 210 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh 211 */ 212 table_ptr = acpi_os_map_memory((acpi_physical_address) 213 ACPI_HI_RSDP_WINDOW_BASE, 214 ACPI_HI_RSDP_WINDOW_SIZE); 215 216 if (!table_ptr) { 217 ACPI_ERROR((AE_INFO, 218 "Could not map memory at 0x%8.8X for length %u", 219 ACPI_HI_RSDP_WINDOW_BASE, 220 ACPI_HI_RSDP_WINDOW_SIZE)); 221 222 return_ACPI_STATUS(AE_NO_MEMORY); 223 } 224 225 mem_rover = 226 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); 227 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); 228 229 if (mem_rover) { 230 231 /* Return the physical address */ 232 233 physical_address = (u32) 234 (ACPI_HI_RSDP_WINDOW_BASE + 235 ACPI_PTR_DIFF(mem_rover, table_ptr)); 236 237 *table_address = (acpi_physical_address) physical_address; 238 return_ACPI_STATUS(AE_OK); 239 } 240 241 /* A valid RSDP was not found */ 242 243 ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found")); 244 return_ACPI_STATUS(AE_NOT_FOUND); 245 } 246 247 /******************************************************************************* 248 * 249 * FUNCTION: acpi_tb_scan_memory_for_rsdp 250 * 251 * PARAMETERS: start_address - Starting pointer for search 252 * length - Maximum length to search 253 * 254 * RETURN: Pointer to the RSDP if found, otherwise NULL. 255 * 256 * DESCRIPTION: Search a block of memory for the RSDP signature 257 * 258 ******************************************************************************/ 259 u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length) 260 { 261 acpi_status status; 262 u8 *mem_rover; 263 u8 *end_address; 264 265 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp); 266 267 end_address = start_address + length; 268 269 /* Search from given start address for the requested length */ 270 271 for (mem_rover = start_address; mem_rover < end_address; 272 mem_rover += ACPI_RSDP_SCAN_STEP) { 273 274 /* The RSDP signature and checksum must both be correct */ 275 276 status = 277 acpi_tb_validate_rsdp(ACPI_CAST_PTR 278 (struct acpi_table_rsdp, mem_rover)); 279 if (ACPI_SUCCESS(status)) { 280 281 /* Sig and checksum valid, we have found a real RSDP */ 282 283 ACPI_DEBUG_PRINT((ACPI_DB_INFO, 284 "RSDP located at physical address %p\n", 285 mem_rover)); 286 return_PTR(mem_rover); 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 start_address)); 297 return_PTR(NULL); 298 } 299