Merge master.kernel.org:/pub/scm/linux/kernel/git/wim/linux-2.6-watchdog
[linux-2.6] / drivers / acpi / tables / tbxfroot.c
1 /******************************************************************************
2  *
3  * Module Name: tbxfroot - Find the root ACPI table (RSDT)
4  *
5  *****************************************************************************/
6
7 /*
8  * Copyright (C) 2000 - 2007, R. Byron Moore
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 <acpi/actables.h>
46
47 #define _COMPONENT          ACPI_TABLES
48 ACPI_MODULE_NAME("tbxfroot")
49
50 /* Local prototypes */
51 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length);
52
53 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp);
54
55 /*******************************************************************************
56  *
57  * FUNCTION:    acpi_tb_validate_rsdp
58  *
59  * PARAMETERS:  Rsdp                - Pointer to unvalidated RSDP
60  *
61  * RETURN:      Status
62  *
63  * DESCRIPTION: Validate the RSDP (ptr)
64  *
65  ******************************************************************************/
66
67 static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp)
68 {
69         ACPI_FUNCTION_ENTRY();
70
71         /*
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.
76          */
77         if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1)
78             != 0) {
79
80                 /* Nope, BAD Signature */
81
82                 return (AE_BAD_SIGNATURE);
83         }
84
85         /* Check the standard checksum */
86
87         if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
88                 return (AE_BAD_CHECKSUM);
89         }
90
91         /* Check extended checksum if table version >= 2 */
92
93         if ((rsdp->revision >= 2) &&
94             (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
95                 return (AE_BAD_CHECKSUM);
96         }
97
98         return (AE_OK);
99 }
100
101 /*******************************************************************************
102  *
103  * FUNCTION:    acpi_tb_find_rsdp
104  *
105  * PARAMETERS:  table_address           - Where the table pointer is returned
106  *
107  * RETURN:      Status, RSDP physical address
108  *
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.
111  *
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.
115  *
116  * NOTE2:       This function is always available, regardless of the
117  *              initialization state of the rest of ACPI.
118  *
119  ******************************************************************************/
120
121 acpi_status acpi_find_root_pointer(acpi_native_uint * table_address)
122 {
123         u8 *table_ptr;
124         u8 *mem_rover;
125         u32 physical_address;
126
127         ACPI_FUNCTION_TRACE(acpi_find_root_pointer);
128
129         /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
130
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));
138
139                 return_ACPI_STATUS(AE_NO_MEMORY);
140         }
141
142         ACPI_MOVE_16_TO_32(&physical_address, table_ptr);
143
144         /* Convert segment part to physical address */
145
146         physical_address <<= 4;
147         acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH);
148
149         /* EBDA present? */
150
151         if (physical_address > 0x400) {
152                 /*
153                  * 1b) Search EBDA paragraphs (EBDA is required to be a
154                  *     minimum of 1_k length)
155                  */
156                 table_ptr = acpi_os_map_memory((acpi_native_uint)
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));
163
164                         return_ACPI_STATUS(AE_NO_MEMORY);
165                 }
166
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);
171
172                 if (mem_rover) {
173
174                         /* Return the physical address */
175
176                         physical_address +=
177                             (u32) ACPI_PTR_DIFF(mem_rover, table_ptr);
178
179                         *table_address = physical_address;
180                         return_ACPI_STATUS(AE_OK);
181                 }
182         }
183
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);
190
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));
196
197                 return_ACPI_STATUS(AE_NO_MEMORY);
198         }
199
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);
203
204         if (mem_rover) {
205
206                 /* Return the physical address */
207
208                 physical_address = (u32)
209                     (ACPI_HI_RSDP_WINDOW_BASE +
210                      ACPI_PTR_DIFF(mem_rover, table_ptr));
211
212                 *table_address = physical_address;
213                 return_ACPI_STATUS(AE_OK);
214         }
215
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);
220 }
221
222 ACPI_EXPORT_SYMBOL(acpi_find_root_pointer)
223
224 /*******************************************************************************
225  *
226  * FUNCTION:    acpi_tb_scan_memory_for_rsdp
227  *
228  * PARAMETERS:  start_address       - Starting pointer for search
229  *              Length              - Maximum length to search
230  *
231  * RETURN:      Pointer to the RSDP if found, otherwise NULL.
232  *
233  * DESCRIPTION: Search a block of memory for the RSDP signature
234  *
235  ******************************************************************************/
236 static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length)
237 {
238         acpi_status status;
239         u8 *mem_rover;
240         u8 *end_address;
241
242         ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp);
243
244         end_address = start_address + length;
245
246         /* Search from given start address for the requested length */
247
248         for (mem_rover = start_address; mem_rover < end_address;
249              mem_rover += ACPI_RSDP_SCAN_STEP) {
250
251                 /* The RSDP signature and checksum must both be correct */
252
253                 status =
254                     acpi_tb_validate_rsdp(ACPI_CAST_PTR
255                                           (struct acpi_table_rsdp, mem_rover));
256                 if (ACPI_SUCCESS(status)) {
257
258                         /* Sig and checksum valid, we have found a real RSDP */
259
260                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
261                                           "RSDP located at physical address %p\n",
262                                           mem_rover));
263                         return_PTR(mem_rover);
264                 }
265
266                 /* No sig match or bad checksum, keep searching */
267         }
268
269         /* Searched entire block, no RSDP was found */
270
271         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
272                           "Searched entire block from %p, valid RSDP was not found\n",
273                           start_address));
274         return_PTR(NULL);
275 }