1 /******************************************************************************
3 * Module Name: tbxfroot - Find the root ACPI table (RSDT)
5 *****************************************************************************/
8 * Copyright (C) 2000 - 2011, Intel Corp.
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44 #define __TBXFROOT_C__
46 #include <contrib/dev/acpica/include/acpi.h>
47 #include <contrib/dev/acpica/include/accommon.h>
48 #include <contrib/dev/acpica/include/actables.h>
51 #define _COMPONENT ACPI_TABLES
52 ACPI_MODULE_NAME ("tbxfroot")
54 /* Local prototypes */
57 AcpiTbScanMemoryForRsdp (
63 ACPI_TABLE_RSDP *Rsdp);
66 /*******************************************************************************
68 * FUNCTION: AcpiTbValidateRsdp
70 * PARAMETERS: Rsdp - Pointer to unvalidated RSDP
74 * DESCRIPTION: Validate the RSDP (ptr)
76 ******************************************************************************/
80 ACPI_TABLE_RSDP *Rsdp)
82 ACPI_FUNCTION_ENTRY ();
86 * The signature and checksum must both be correct
88 * Note: Sometimes there exists more than one RSDP in memory; the valid
89 * RSDP has a valid checksum, all others have an invalid checksum.
91 if (ACPI_STRNCMP ((char *) Rsdp, ACPI_SIG_RSDP,
92 sizeof (ACPI_SIG_RSDP)-1) != 0)
94 /* Nope, BAD Signature */
96 return (AE_BAD_SIGNATURE);
99 /* Check the standard checksum */
101 if (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0)
103 return (AE_BAD_CHECKSUM);
106 /* Check extended checksum if table version >= 2 */
108 if ((Rsdp->Revision >= 2) &&
109 (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0))
111 return (AE_BAD_CHECKSUM);
118 /*******************************************************************************
120 * FUNCTION: AcpiFindRootPointer
122 * PARAMETERS: TableAddress - Where the table pointer is returned
124 * RETURN: Status, RSDP physical address
126 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
127 * pointer structure. If it is found, set *RSDP to point to it.
129 * NOTE1: The RSDP must be either in the first 1K of the Extended
130 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
131 * Only a 32-bit physical address is necessary.
133 * NOTE2: This function is always available, regardless of the
134 * initialization state of the rest of ACPI.
136 ******************************************************************************/
139 AcpiFindRootPointer (
140 ACPI_SIZE *TableAddress)
144 UINT32 PhysicalAddress;
147 ACPI_FUNCTION_TRACE (AcpiFindRootPointer);
150 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
152 TablePtr = AcpiOsMapMemory (
153 (ACPI_PHYSICAL_ADDRESS) ACPI_EBDA_PTR_LOCATION,
154 ACPI_EBDA_PTR_LENGTH);
157 ACPI_ERROR ((AE_INFO,
158 "Could not map memory at 0x%8.8X for length %u",
159 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
161 return_ACPI_STATUS (AE_NO_MEMORY);
164 ACPI_MOVE_16_TO_32 (&PhysicalAddress, TablePtr);
166 /* Convert segment part to physical address */
168 PhysicalAddress <<= 4;
169 AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_PTR_LENGTH);
173 if (PhysicalAddress > 0x400)
176 * 1b) Search EBDA paragraphs (EBDA is required to be a
177 * minimum of 1K length)
179 TablePtr = AcpiOsMapMemory (
180 (ACPI_PHYSICAL_ADDRESS) PhysicalAddress,
181 ACPI_EBDA_WINDOW_SIZE);
184 ACPI_ERROR ((AE_INFO,
185 "Could not map memory at 0x%8.8X for length %u",
186 PhysicalAddress, ACPI_EBDA_WINDOW_SIZE));
188 return_ACPI_STATUS (AE_NO_MEMORY);
191 MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_EBDA_WINDOW_SIZE);
192 AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_WINDOW_SIZE);
196 /* Return the physical address */
198 PhysicalAddress += (UINT32) ACPI_PTR_DIFF (MemRover, TablePtr);
200 *TableAddress = PhysicalAddress;
201 return_ACPI_STATUS (AE_OK);
206 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
208 TablePtr = AcpiOsMapMemory (
209 (ACPI_PHYSICAL_ADDRESS) ACPI_HI_RSDP_WINDOW_BASE,
210 ACPI_HI_RSDP_WINDOW_SIZE);
214 ACPI_ERROR ((AE_INFO,
215 "Could not map memory at 0x%8.8X for length %u",
216 ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE));
218 return_ACPI_STATUS (AE_NO_MEMORY);
221 MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE);
222 AcpiOsUnmapMemory (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE);
226 /* Return the physical address */
228 PhysicalAddress = (UINT32)
229 (ACPI_HI_RSDP_WINDOW_BASE + ACPI_PTR_DIFF (MemRover, TablePtr));
231 *TableAddress = PhysicalAddress;
232 return_ACPI_STATUS (AE_OK);
235 /* A valid RSDP was not found */
237 ACPI_ERROR ((AE_INFO, "A valid RSDP was not found"));
238 return_ACPI_STATUS (AE_NOT_FOUND);
241 ACPI_EXPORT_SYMBOL (AcpiFindRootPointer)
244 /*******************************************************************************
246 * FUNCTION: AcpiTbScanMemoryForRsdp
248 * PARAMETERS: StartAddress - Starting pointer for search
249 * Length - Maximum length to search
251 * RETURN: Pointer to the RSDP if found, otherwise NULL.
253 * DESCRIPTION: Search a block of memory for the RSDP signature
255 ******************************************************************************/
258 AcpiTbScanMemoryForRsdp (
267 ACPI_FUNCTION_TRACE (TbScanMemoryForRsdp);
270 EndAddress = StartAddress + Length;
272 /* Search from given start address for the requested length */
274 for (MemRover = StartAddress; MemRover < EndAddress;
275 MemRover += ACPI_RSDP_SCAN_STEP)
277 /* The RSDP signature and checksum must both be correct */
279 Status = AcpiTbValidateRsdp (ACPI_CAST_PTR (ACPI_TABLE_RSDP, MemRover));
280 if (ACPI_SUCCESS (Status))
282 /* Sig and checksum valid, we have found a real RSDP */
284 ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
285 "RSDP located at physical address %p\n", MemRover));
286 return_PTR (MemRover);
289 /* No sig match or bad checksum, keep searching */
292 /* Searched entire block, no RSDP was found */
294 ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
295 "Searched entire block from %p, valid RSDP was not found\n",