1 /******************************************************************************
3 * Module Name: tbxfroot - Find the root ACPI table (RSDT)
5 *****************************************************************************/
8 * Copyright (C) 2000 - 2015, Intel Corp.
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44 #include <contrib/dev/acpica/include/acpi.h>
45 #include <contrib/dev/acpica/include/accommon.h>
46 #include <contrib/dev/acpica/include/actables.h>
49 #define _COMPONENT ACPI_TABLES
50 ACPI_MODULE_NAME ("tbxfroot")
53 /*******************************************************************************
55 * FUNCTION: AcpiTbGetRsdpLength
57 * PARAMETERS: Rsdp - Pointer to RSDP
59 * RETURN: Table length
61 * DESCRIPTION: Get the length of the RSDP
63 ******************************************************************************/
67 ACPI_TABLE_RSDP *Rsdp)
70 if (!ACPI_VALIDATE_RSDP_SIG (Rsdp->Signature))
77 /* "Length" field is available if table version >= 2 */
79 if (Rsdp->Revision >= 2)
81 return (Rsdp->Length);
85 return (ACPI_RSDP_CHECKSUM_LENGTH);
90 /*******************************************************************************
92 * FUNCTION: AcpiTbValidateRsdp
94 * PARAMETERS: Rsdp - Pointer to unvalidated RSDP
98 * DESCRIPTION: Validate the RSDP (ptr)
100 ******************************************************************************/
104 ACPI_TABLE_RSDP *Rsdp)
108 * The signature and checksum must both be correct
110 * Note: Sometimes there exists more than one RSDP in memory; the valid
111 * RSDP has a valid checksum, all others have an invalid checksum.
113 if (!ACPI_VALIDATE_RSDP_SIG (Rsdp->Signature))
115 /* Nope, BAD Signature */
117 return (AE_BAD_SIGNATURE);
120 /* Check the standard checksum */
122 if (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0)
124 return (AE_BAD_CHECKSUM);
127 /* Check extended checksum if table version >= 2 */
129 if ((Rsdp->Revision >= 2) &&
130 (AcpiTbChecksum ((UINT8 *) Rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0))
132 return (AE_BAD_CHECKSUM);
139 /*******************************************************************************
141 * FUNCTION: AcpiFindRootPointer
143 * PARAMETERS: TableAddress - Where the table pointer is returned
145 * RETURN: Status, RSDP physical address
147 * DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor
148 * pointer structure. If it is found, set *RSDP to point to it.
150 * NOTE1: The RSDP must be either in the first 1K of the Extended
151 * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.)
152 * Only a 32-bit physical address is necessary.
154 * NOTE2: This function is always available, regardless of the
155 * initialization state of the rest of ACPI.
157 ******************************************************************************/
160 AcpiFindRootPointer (
161 ACPI_PHYSICAL_ADDRESS *TableAddress)
165 UINT32 PhysicalAddress;
168 ACPI_FUNCTION_TRACE (AcpiFindRootPointer);
171 /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */
173 TablePtr = AcpiOsMapMemory (
174 (ACPI_PHYSICAL_ADDRESS) ACPI_EBDA_PTR_LOCATION,
175 ACPI_EBDA_PTR_LENGTH);
178 ACPI_ERROR ((AE_INFO,
179 "Could not map memory at 0x%8.8X for length %u",
180 ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH));
182 return_ACPI_STATUS (AE_NO_MEMORY);
185 ACPI_MOVE_16_TO_32 (&PhysicalAddress, TablePtr);
187 /* Convert segment part to physical address */
189 PhysicalAddress <<= 4;
190 AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_PTR_LENGTH);
194 if (PhysicalAddress > 0x400)
197 * 1b) Search EBDA paragraphs (EBDA is required to be a
198 * minimum of 1K length)
200 TablePtr = AcpiOsMapMemory (
201 (ACPI_PHYSICAL_ADDRESS) PhysicalAddress,
202 ACPI_EBDA_WINDOW_SIZE);
205 ACPI_ERROR ((AE_INFO,
206 "Could not map memory at 0x%8.8X for length %u",
207 PhysicalAddress, ACPI_EBDA_WINDOW_SIZE));
209 return_ACPI_STATUS (AE_NO_MEMORY);
212 MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_EBDA_WINDOW_SIZE);
213 AcpiOsUnmapMemory (TablePtr, ACPI_EBDA_WINDOW_SIZE);
217 /* Return the physical address */
219 PhysicalAddress += (UINT32) ACPI_PTR_DIFF (MemRover, TablePtr);
221 *TableAddress = (ACPI_PHYSICAL_ADDRESS) PhysicalAddress;
222 return_ACPI_STATUS (AE_OK);
227 * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh
229 TablePtr = AcpiOsMapMemory (
230 (ACPI_PHYSICAL_ADDRESS) ACPI_HI_RSDP_WINDOW_BASE,
231 ACPI_HI_RSDP_WINDOW_SIZE);
235 ACPI_ERROR ((AE_INFO,
236 "Could not map memory at 0x%8.8X for length %u",
237 ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE));
239 return_ACPI_STATUS (AE_NO_MEMORY);
242 MemRover = AcpiTbScanMemoryForRsdp (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE);
243 AcpiOsUnmapMemory (TablePtr, ACPI_HI_RSDP_WINDOW_SIZE);
247 /* Return the physical address */
249 PhysicalAddress = (UINT32)
250 (ACPI_HI_RSDP_WINDOW_BASE + ACPI_PTR_DIFF (MemRover, TablePtr));
252 *TableAddress = (ACPI_PHYSICAL_ADDRESS) PhysicalAddress;
253 return_ACPI_STATUS (AE_OK);
256 /* A valid RSDP was not found */
258 ACPI_BIOS_ERROR ((AE_INFO, "A valid RSDP was not found"));
259 return_ACPI_STATUS (AE_NOT_FOUND);
262 ACPI_EXPORT_SYMBOL (AcpiFindRootPointer)
265 /*******************************************************************************
267 * FUNCTION: AcpiTbScanMemoryForRsdp
269 * PARAMETERS: StartAddress - Starting pointer for search
270 * Length - Maximum length to search
272 * RETURN: Pointer to the RSDP if found, otherwise NULL.
274 * DESCRIPTION: Search a block of memory for the RSDP signature
276 ******************************************************************************/
279 AcpiTbScanMemoryForRsdp (
288 ACPI_FUNCTION_TRACE (TbScanMemoryForRsdp);
291 EndAddress = StartAddress + Length;
293 /* Search from given start address for the requested length */
295 for (MemRover = StartAddress; MemRover < EndAddress;
296 MemRover += ACPI_RSDP_SCAN_STEP)
298 /* The RSDP signature and checksum must both be correct */
300 Status = AcpiTbValidateRsdp (ACPI_CAST_PTR (ACPI_TABLE_RSDP, MemRover));
301 if (ACPI_SUCCESS (Status))
303 /* Sig and checksum valid, we have found a real RSDP */
305 ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
306 "RSDP located at physical address %p\n", MemRover));
307 return_PTR (MemRover);
310 /* No sig match or bad checksum, keep searching */
313 /* Searched entire block, no RSDP was found */
315 ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
316 "Searched entire block from %p, valid RSDP was not found\n",