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 #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 /* Local prototypes */
52 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length);
53
54 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp);
55
56 /*******************************************************************************
57 *
58 * FUNCTION: acpi_tb_validate_rsdp
59 *
60 * PARAMETERS: Rsdp - Pointer to unvalidated RSDP
61 *
62 * RETURN: Status
63 *
64 * DESCRIPTION: Validate the RSDP (ptr)
65 *
66 ******************************************************************************/
67
acpi_tb_validate_rsdp(struct acpi_table_rsdp * rsdp)68 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
69 {
70 ACPI_FUNCTION_ENTRY();
71
72 /*
73 * The signature and checksum must both be correct
74 *
75 * Note: Sometimes there exists more than one RSDP in memory; the valid
76 * RSDP has a valid checksum, all others have an invalid checksum.
77 */
78 if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP,
79 sizeof(ACPI_SIG_RSDP) - 1) != 0) {
80
81 /* Nope, BAD Signature */
82
83 return (AE_BAD_SIGNATURE);
84 }
85
86 /* Check the standard checksum */
87
88 if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
89 return (AE_BAD_CHECKSUM);
90 }
91
92 /* Check extended checksum if table version >= 2 */
93
94 if ((rsdp->revision >= 2) &&
95 (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
96 return (AE_BAD_CHECKSUM);
97 }
98
99 return (AE_OK);
100 }
101
102 /*******************************************************************************
103 *
104 * FUNCTION: acpi_find_root_pointer
105 *
106 * PARAMETERS: table_address - Where the table pointer is returned
107 *
108 * RETURN: Status, RSDP physical address
109 *
110 * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor
111 * pointer structure. If it is found, set *RSDP to point to it.
112 *
113 * NOTE1: The RSDP must be either in the first 1_k of the Extended
114 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
115 * Only a 32-bit physical address is necessary.
116 *
117 * NOTE2: This function is always available, regardless of the
118 * initialization state of the rest of ACPI.
119 *
120 ******************************************************************************/
121
acpi_find_root_pointer(acpi_size * table_address)122 acpi_status acpi_find_root_pointer(acpi_size *table_address)
123 {
124 u8 *table_ptr;
125 u8 *mem_rover;
126 u32 physical_address;
127
128 ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
129
130 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
131
132 table_ptr = acpi_os_map_memory((acpi_physical_address)
133 ACPI_EBDA_PTR_LOCATION,
134 ACPI_EBDA_PTR_LENGTH);
135 if (!table_ptr) {
136 ACPI_ERROR((AE_INFO,
137 "Could not map memory at 0x%8.8X for length %u",
138 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
139
140 return_ACPI_STATUS(AE_NO_MEMORY);
141 }
142
143 ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
144
145 /* Convert segment part to physical address */
146
147 physical_address <<= 4;
148 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
149
150 /* EBDA present? */
151
152 if (physical_address > 0x400) {
153 /*
154 * 1b) Search EBDA paragraphs (EBDA is required to be a
155 * minimum of 1_k length)
156 */
157 table_ptr = acpi_os_map_memory((acpi_physical_address)
158 physical_address,
159 ACPI_EBDA_WINDOW_SIZE);
160 if (!table_ptr) {
161 ACPI_ERROR((AE_INFO,
162 "Could not map memory at 0x%8.8X for length %u",
163 physical_address, ACPI_EBDA_WINDOW_SIZE));
164
165 return_ACPI_STATUS(AE_NO_MEMORY);
166 }
167
168 mem_rover =
169 acpi_tb_scan_memory_for_rsdp(table_ptr,
170 ACPI_EBDA_WINDOW_SIZE);
171 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
172
173 if (mem_rover) {
174
175 /* Return the physical address */
176
177 physical_address +=
178 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
179
180 *table_address = physical_address;
181 return_ACPI_STATUS(AE_OK);
182 }
183 }
184
185 /*
186 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
187 */
188 table_ptr = acpi_os_map_memory((acpi_physical_address)
189 ACPI_HI_RSDP_WINDOW_BASE,
190 ACPI_HI_RSDP_WINDOW_SIZE);
191
192 if (!table_ptr) {
193 ACPI_ERROR((AE_INFO,
194 "Could not map memory at 0x%8.8X for length %u",
195 ACPI_HI_RSDP_WINDOW_BASE,
196 ACPI_HI_RSDP_WINDOW_SIZE));
197
198 return_ACPI_STATUS(AE_NO_MEMORY);
199 }
200
201 mem_rover =
202 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
203 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
204
205 if (mem_rover) {
206
207 /* Return the physical address */
208
209 physical_address = (u32)
210 (ACPI_HI_RSDP_WINDOW_BASE +
211 ACPI_PTR_DIFF(mem_rover, table_ptr));
212
213 *table_address = physical_address;
214 return_ACPI_STATUS(AE_OK);
215 }
216
217 /* A valid RSDP was not found */
218
219 ACPI_ERROR((AE_INFO, "A valid RSDP was not found"));
220 return_ACPI_STATUS(AE_NOT_FOUND);
221 }
222
223 /*******************************************************************************
224 *
225 * FUNCTION: acpi_tb_scan_memory_for_rsdp
226 *
227 * PARAMETERS: start_address - Starting pointer for search
228 * Length - Maximum length to search
229 *
230 * RETURN: Pointer to the RSDP if found, otherwise NULL.
231 *
232 * DESCRIPTION: Search a block of memory for the RSDP signature
233 *
234 ******************************************************************************/
acpi_tb_scan_memory_for_rsdp(u8 * start_address,u32 length)235 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length)
236 {
237 acpi_status status;
238 u8 *mem_rover;
239 u8 *end_address;
240
241 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
242
243 end_address = start_address + length;
244
245 /* Search from given start address for the requested length */
246
247 for (mem_rover = start_address; mem_rover < end_address;
248 mem_rover += ACPI_RSDP_SCAN_STEP) {
249
250 /* The RSDP signature and checksum must both be correct */
251
252 status =
253 acpi_tb_validate_rsdp(ACPI_CAST_PTR
254 (struct acpi_table_rsdp, mem_rover));
255 if (ACPI_SUCCESS(status)) {
256
257 /* Sig and checksum valid, we have found a real RSDP */
258
259 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
260 "RSDP located at physical address %p\n",
261 mem_rover));
262 return_PTR(mem_rover);
263 }
264
265 /* No sig match or bad checksum, keep searching */
266 }
267
268 /* Searched entire block, no RSDP was found */
269
270 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
271 "Searched entire block from %p, valid RSDP was not found\n",
272 start_address));
273 return_PTR(NULL);
274 }
275