1 /******************************************************************************
2 *
3 * Module Name: tbxfroot - Find the root ACPI table (RSDT)
4 *
5 *****************************************************************************/
6
7 /*
8 * Copyright (C) 2000 - 2008, 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 <xen/init.h>
45 #include <acpi/acpi.h>
46 #include <acpi/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 /*******************************************************************************
55 *
56 * FUNCTION: acpi_tb_validate_rsdp
57 *
58 * PARAMETERS: Rsdp - Pointer to unvalidated RSDP
59 *
60 * RETURN: Status
61 *
62 * DESCRIPTION: Validate the RSDP (ptr)
63 *
64 ******************************************************************************/
65
acpi_tb_validate_rsdp(struct acpi_table_rsdp * rsdp)66 static acpi_status __init acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
67 {
68 ACPI_FUNCTION_ENTRY();
69
70 /*
71 * The signature and checksum must both be correct
72 *
73 * Note: Sometimes there exists more than one RSDP in memory; the valid
74 * RSDP has a valid checksum, all others have an invalid checksum.
75 */
76 if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1)
77 != 0) {
78
79 /* Nope, BAD Signature */
80
81 return (AE_BAD_SIGNATURE);
82 }
83
84 /* Check the standard checksum */
85
86 if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
87 return (AE_BAD_CHECKSUM);
88 }
89
90 /* Check extended checksum if table version >= 2 */
91
92 if ((rsdp->revision >= 2) &&
93 (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
94 return (AE_BAD_CHECKSUM);
95 }
96
97 return (AE_OK);
98 }
99
100 /*******************************************************************************
101 *
102 * FUNCTION: acpi_find_root_pointer
103 *
104 * PARAMETERS: table_address - Where the table pointer is returned
105 *
106 * RETURN: Status, RSDP physical address
107 *
108 * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor
109 * pointer structure. If it is found, set *RSDP to point to it.
110 *
111 * NOTE1: The RSDP must be either in the first 1_k of the Extended
112 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
113 * Only a 32-bit physical address is necessary.
114 *
115 * NOTE2: This function is always available, regardless of the
116 * initialization state of the rest of ACPI.
117 *
118 ******************************************************************************/
119
acpi_find_root_pointer(acpi_native_uint * table_address)120 acpi_status __init acpi_find_root_pointer(acpi_native_uint * table_address)
121 {
122 u8 *table_ptr;
123 u8 *mem_rover;
124 u32 physical_address;
125
126 ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
127
128 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
129
130 table_ptr = acpi_os_map_memory((acpi_physical_address)
131 ACPI_EBDA_PTR_LOCATION,
132 ACPI_EBDA_PTR_LENGTH);
133 if (!table_ptr) {
134 ACPI_ERROR((AE_INFO,
135 "Could not map memory at %8.8X for length %X",
136 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
137
138 return_ACPI_STATUS(AE_NO_MEMORY);
139 }
140
141 ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
142
143 /* Convert segment part to physical address */
144
145 physical_address <<= 4;
146 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
147
148 /* EBDA present? */
149
150 if (physical_address > 0x400) {
151 /*
152 * 1b) Search EBDA paragraphs (EBDA is required to be a
153 * minimum of 1_k length)
154 */
155 table_ptr = acpi_os_map_memory((acpi_native_uint)
156 physical_address,
157 ACPI_EBDA_WINDOW_SIZE);
158 if (!table_ptr) {
159 ACPI_ERROR((AE_INFO,
160 "Could not map memory at %8.8X for length %X",
161 physical_address, ACPI_EBDA_WINDOW_SIZE));
162
163 return_ACPI_STATUS(AE_NO_MEMORY);
164 }
165
166 mem_rover =
167 acpi_tb_scan_memory_for_rsdp(table_ptr,
168 ACPI_EBDA_WINDOW_SIZE);
169 acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE);
170
171 if (mem_rover) {
172
173 /* Return the physical address */
174
175 physical_address +=
176 (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
177
178 *table_address = physical_address;
179 return_ACPI_STATUS(AE_OK);
180 }
181 }
182
183 /*
184 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
185 */
186 table_ptr = acpi_os_map_memory((acpi_physical_address)
187 ACPI_HI_RSDP_WINDOW_BASE,
188 ACPI_HI_RSDP_WINDOW_SIZE);
189
190 if (!table_ptr) {
191 ACPI_ERROR((AE_INFO,
192 "Could not map memory at %8.8X for length %X",
193 ACPI_HI_RSDP_WINDOW_BASE,
194 ACPI_HI_RSDP_WINDOW_SIZE));
195
196 return_ACPI_STATUS(AE_NO_MEMORY);
197 }
198
199 mem_rover =
200 acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
201 acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE);
202
203 if (mem_rover) {
204
205 /* Return the physical address */
206
207 physical_address = (u32)
208 (ACPI_HI_RSDP_WINDOW_BASE +
209 ACPI_PTR_DIFF(mem_rover, table_ptr));
210
211 *table_address = physical_address;
212 return_ACPI_STATUS(AE_OK);
213 }
214
215 /* A valid RSDP was not found */
216
217 ACPI_ERROR((AE_INFO, "A valid RSDP was not found"));
218 return_ACPI_STATUS(AE_NOT_FOUND);
219 }
220
221 /*******************************************************************************
222 *
223 * FUNCTION: acpi_tb_scan_memory_for_rsdp
224 *
225 * PARAMETERS: start_address - Starting pointer for search
226 * Length - Maximum length to search
227 *
228 * RETURN: Pointer to the RSDP if found, otherwise NULL.
229 *
230 * DESCRIPTION: Search a block of memory for the RSDP signature
231 *
232 ******************************************************************************/
acpi_tb_scan_memory_for_rsdp(u8 * start_address,u32 length)233 static u8 *__init acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length)
234 {
235 acpi_status status;
236 u8 *mem_rover;
237 u8 *end_address;
238
239 ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
240
241 end_address = start_address + length;
242
243 /* Search from given start address for the requested length */
244
245 for (mem_rover = start_address; mem_rover < end_address;
246 mem_rover += ACPI_RSDP_SCAN_STEP) {
247
248 /* The RSDP signature and checksum must both be correct */
249
250 status =
251 acpi_tb_validate_rsdp(ACPI_CAST_PTR
252 (struct acpi_table_rsdp, mem_rover));
253 if (ACPI_SUCCESS(status)) {
254
255 /* Sig and checksum valid, we have found a real RSDP */
256
257 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
258 "RSDP located at physical address %p\n",
259 mem_rover));
260 return_PTR(mem_rover);
261 }
262
263 /* No sig match or bad checksum, keep searching */
264 }
265
266 /* Searched entire block, no RSDP was found */
267
268 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
269 "Searched entire block from %p, valid RSDP was not found\n",
270 start_address));
271 return_PTR(NULL);
272 }
273