ACPICA: hide private headers
[linux-2.6.git] / drivers / acpi / acpica / tbxfroot.c
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 <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
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, sizeof(ACPI_SIG_RSDP) - 1)
79             != 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
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 %8.8X for length %X",
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 %8.8X for length %X",
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 %8.8X for length %X",
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  ******************************************************************************/
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 }