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1da177e4 LT |
1 | /****************************************************************************** |
2 | * | |
3 | * Module Name: tbxfroot - Find the root ACPI table (RSDT) | |
4 | * | |
5 | *****************************************************************************/ | |
6 | ||
7 | /* | |
75a44ce0 | 8 | * Copyright (C) 2000 - 2008, Intel Corp. |
1da177e4 LT |
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 | ||
1da177e4 LT |
44 | #include <acpi/acpi.h> |
45 | #include <acpi/actables.h> | |
46 | ||
1da177e4 | 47 | #define _COMPONENT ACPI_TABLES |
4be44fcd | 48 | ACPI_MODULE_NAME("tbxfroot") |
1da177e4 | 49 | |
44f6c012 | 50 | /* Local prototypes */ |
4be44fcd | 51 | static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length); |
1da177e4 | 52 | |
f3d2e786 BM |
53 | static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp); |
54 | ||
f9f4601f RM |
55 | /******************************************************************************* |
56 | * | |
57 | * FUNCTION: acpi_tb_validate_rsdp | |
58 | * | |
f3d2e786 | 59 | * PARAMETERS: Rsdp - Pointer to unvalidated RSDP |
f9f4601f RM |
60 | * |
61 | * RETURN: Status | |
62 | * | |
63 | * DESCRIPTION: Validate the RSDP (ptr) | |
64 | * | |
65 | ******************************************************************************/ | |
66 | ||
f3d2e786 | 67 | static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp) |
f9f4601f | 68 | { |
4be44fcd | 69 | ACPI_FUNCTION_ENTRY(); |
f9f4601f RM |
70 | |
71 | /* | |
f3d2e786 BM |
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. | |
f9f4601f | 76 | */ |
f3d2e786 BM |
77 | if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1) |
78 | != 0) { | |
52fc0b02 | 79 | |
f9f4601f RM |
80 | /* Nope, BAD Signature */ |
81 | ||
82 | return (AE_BAD_SIGNATURE); | |
83 | } | |
84 | ||
85 | /* Check the standard checksum */ | |
86 | ||
f3d2e786 | 87 | if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) { |
f9f4601f RM |
88 | return (AE_BAD_CHECKSUM); |
89 | } | |
90 | ||
91 | /* Check extended checksum if table version >= 2 */ | |
92 | ||
93 | if ((rsdp->revision >= 2) && | |
f3d2e786 | 94 | (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) { |
f9f4601f RM |
95 | return (AE_BAD_CHECKSUM); |
96 | } | |
97 | ||
98 | return (AE_OK); | |
99 | } | |
100 | ||
1da177e4 LT |
101 | /******************************************************************************* |
102 | * | |
239665a3 | 103 | * FUNCTION: acpi_find_root_pointer |
1da177e4 | 104 | * |
f3d2e786 | 105 | * PARAMETERS: table_address - Where the table pointer is returned |
1da177e4 | 106 | * |
f3d2e786 | 107 | * RETURN: Status, RSDP physical address |
1da177e4 | 108 | * |
f3d2e786 BM |
109 | * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor |
110 | * pointer structure. If it is found, set *RSDP to point to it. | |
1da177e4 | 111 | * |
f3d2e786 BM |
112 | * NOTE1: The RSDP must be either in the first 1_k of the Extended |
113 | * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) | |
114 | * Only a 32-bit physical address is necessary. | |
1da177e4 | 115 | * |
f3d2e786 BM |
116 | * NOTE2: This function is always available, regardless of the |
117 | * initialization state of the rest of ACPI. | |
1da177e4 LT |
118 | * |
119 | ******************************************************************************/ | |
120 | ||
67a119f9 | 121 | acpi_status acpi_find_root_pointer(acpi_size *table_address) |
1da177e4 | 122 | { |
f3d2e786 BM |
123 | u8 *table_ptr; |
124 | u8 *mem_rover; | |
125 | u32 physical_address; | |
1da177e4 | 126 | |
f3d2e786 | 127 | ACPI_FUNCTION_TRACE(acpi_find_root_pointer); |
1da177e4 | 128 | |
f3d2e786 | 129 | /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ |
1da177e4 | 130 | |
f3d2e786 BM |
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 %8.8X for length %X", | |
137 | ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); | |
1da177e4 | 138 | |
4be44fcd | 139 | return_ACPI_STATUS(AE_NO_MEMORY); |
1da177e4 LT |
140 | } |
141 | ||
f3d2e786 | 142 | ACPI_MOVE_16_TO_32(&physical_address, table_ptr); |
1da177e4 | 143 | |
f3d2e786 | 144 | /* Convert segment part to physical address */ |
1da177e4 | 145 | |
f3d2e786 BM |
146 | physical_address <<= 4; |
147 | acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH); | |
1da177e4 | 148 | |
f3d2e786 | 149 | /* EBDA present? */ |
1da177e4 | 150 | |
f3d2e786 | 151 | if (physical_address > 0x400) { |
73459f73 | 152 | /* |
f3d2e786 BM |
153 | * 1b) Search EBDA paragraphs (EBDA is required to be a |
154 | * minimum of 1_k length) | |
73459f73 | 155 | */ |
67a119f9 | 156 | table_ptr = acpi_os_map_memory((acpi_physical_address) |
f3d2e786 BM |
157 | physical_address, |
158 | ACPI_EBDA_WINDOW_SIZE); | |
159 | if (!table_ptr) { | |
160 | ACPI_ERROR((AE_INFO, | |
161 | "Could not map memory at %8.8X for length %X", | |
162 | physical_address, ACPI_EBDA_WINDOW_SIZE)); | |
1da177e4 | 163 | |
f3d2e786 | 164 | return_ACPI_STATUS(AE_NO_MEMORY); |
1da177e4 LT |
165 | } |
166 | ||
f3d2e786 BM |
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); | |
1da177e4 | 171 | |
f3d2e786 | 172 | if (mem_rover) { |
52fc0b02 | 173 | |
f3d2e786 | 174 | /* Return the physical address */ |
1da177e4 | 175 | |
f3d2e786 BM |
176 | physical_address += |
177 | (u32) ACPI_PTR_DIFF(mem_rover, table_ptr); | |
1da177e4 | 178 | |
f3d2e786 BM |
179 | *table_address = physical_address; |
180 | return_ACPI_STATUS(AE_OK); | |
1da177e4 LT |
181 | } |
182 | } | |
183 | ||
f3d2e786 BM |
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); | |
1da177e4 | 190 | |
f3d2e786 BM |
191 | if (!table_ptr) { |
192 | ACPI_ERROR((AE_INFO, | |
193 | "Could not map memory at %8.8X for length %X", | |
194 | ACPI_HI_RSDP_WINDOW_BASE, | |
195 | ACPI_HI_RSDP_WINDOW_SIZE)); | |
1da177e4 | 196 | |
f3d2e786 | 197 | return_ACPI_STATUS(AE_NO_MEMORY); |
88ac00f5 | 198 | } |
1da177e4 | 199 | |
f3d2e786 BM |
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); | |
1da177e4 | 203 | |
f3d2e786 | 204 | if (mem_rover) { |
1da177e4 | 205 | |
f3d2e786 | 206 | /* Return the physical address */ |
1da177e4 | 207 | |
f3d2e786 BM |
208 | physical_address = (u32) |
209 | (ACPI_HI_RSDP_WINDOW_BASE + | |
210 | ACPI_PTR_DIFF(mem_rover, table_ptr)); | |
1da177e4 | 211 | |
f3d2e786 BM |
212 | *table_address = physical_address; |
213 | return_ACPI_STATUS(AE_OK); | |
1da177e4 LT |
214 | } |
215 | ||
f3d2e786 BM |
216 | /* A valid RSDP was not found */ |
217 | ||
218 | ACPI_ERROR((AE_INFO, "A valid RSDP was not found")); | |
219 | return_ACPI_STATUS(AE_NOT_FOUND); | |
1da177e4 LT |
220 | } |
221 | ||
1da177e4 LT |
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 | ******************************************************************************/ | |
4be44fcd | 234 | static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length) |
1da177e4 | 235 | { |
4be44fcd LB |
236 | acpi_status status; |
237 | u8 *mem_rover; | |
238 | u8 *end_address; | |
1da177e4 | 239 | |
b229cf92 | 240 | ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp); |
1da177e4 LT |
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; | |
4be44fcd | 247 | mem_rover += ACPI_RSDP_SCAN_STEP) { |
52fc0b02 | 248 | |
f9f4601f | 249 | /* The RSDP signature and checksum must both be correct */ |
1da177e4 | 250 | |
4be44fcd LB |
251 | status = |
252 | acpi_tb_validate_rsdp(ACPI_CAST_PTR | |
f3d2e786 | 253 | (struct acpi_table_rsdp, mem_rover)); |
4be44fcd | 254 | if (ACPI_SUCCESS(status)) { |
52fc0b02 | 255 | |
f9f4601f | 256 | /* Sig and checksum valid, we have found a real RSDP */ |
1da177e4 | 257 | |
4be44fcd LB |
258 | ACPI_DEBUG_PRINT((ACPI_DB_INFO, |
259 | "RSDP located at physical address %p\n", | |
260 | mem_rover)); | |
261 | return_PTR(mem_rover); | |
1da177e4 LT |
262 | } |
263 | ||
f9f4601f | 264 | /* No sig match or bad checksum, keep searching */ |
1da177e4 LT |
265 | } |
266 | ||
267 | /* Searched entire block, no RSDP was found */ | |
268 | ||
4be44fcd LB |
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); | |
1da177e4 | 273 | } |