/****************************************************************************** * * Module Name: tbxfroot - Find the root ACPI table (RSDT) * *****************************************************************************/ /* * Copyright (C) 2000 - 2007, R. Byron Moore * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions, and the following disclaimer, * without modification. * 2. Redistributions in binary form must reproduce at minimum a disclaimer * substantially similar to the "NO WARRANTY" disclaimer below * ("Disclaimer") and any redistribution must be conditioned upon * including a substantially similar Disclaimer requirement for further * binary redistribution. * 3. Neither the names of the above-listed copyright holders nor the names * of any contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * Alternatively, this software may be distributed under the terms of the * GNU General Public License ("GPL") version 2 as published by the Free * Software Foundation. * * NO WARRANTY * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGES. */ #include <acpi/acpi.h> #include <acpi/actables.h> #define _COMPONENT ACPI_TABLES ACPI_MODULE_NAME("tbxfroot") /* Local prototypes */ static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length); static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp); /******************************************************************************* * * FUNCTION: acpi_tb_validate_rsdp * * PARAMETERS: Rsdp - Pointer to unvalidated RSDP * * RETURN: Status * * DESCRIPTION: Validate the RSDP (ptr) * ******************************************************************************/ static acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp) { ACPI_FUNCTION_ENTRY(); /* * The signature and checksum must both be correct * * Note: Sometimes there exists more than one RSDP in memory; the valid * RSDP has a valid checksum, all others have an invalid checksum. */ if (ACPI_STRNCMP((char *)rsdp, ACPI_SIG_RSDP, sizeof(ACPI_SIG_RSDP) - 1) != 0) { /* Nope, BAD Signature */ return (AE_BAD_SIGNATURE); } /* Check the standard checksum */ if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) { return (AE_BAD_CHECKSUM); } /* Check extended checksum if table version >= 2 */ if ((rsdp->revision >= 2) && (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) { return (AE_BAD_CHECKSUM); } return (AE_OK); } /******************************************************************************* * * FUNCTION: acpi_tb_find_rsdp * * PARAMETERS: table_address - Where the table pointer is returned * * RETURN: Status, RSDP physical address * * DESCRIPTION: Search lower 1_mbyte of memory for the root system descriptor * pointer structure. If it is found, set *RSDP to point to it. * * NOTE1: The RSDP must be either in the first 1_k of the Extended * BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) * Only a 32-bit physical address is necessary. * * NOTE2: This function is always available, regardless of the * initialization state of the rest of ACPI. * ******************************************************************************/ acpi_status acpi_find_root_pointer(acpi_native_uint * table_address) { u8 *table_ptr; u8 *mem_rover; u32 physical_address; ACPI_FUNCTION_TRACE(acpi_find_root_pointer); /* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ table_ptr = acpi_os_map_memory((acpi_physical_address) ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH); if (!table_ptr) { ACPI_ERROR((AE_INFO, "Could not map memory at %8.8X for length %X", ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); return_ACPI_STATUS(AE_NO_MEMORY); } ACPI_MOVE_16_TO_32(&physical_address, table_ptr); /* Convert segment part to physical address */ physical_address <<= 4; acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH); /* EBDA present? */ if (physical_address > 0x400) { /* * 1b) Search EBDA paragraphs (EBDA is required to be a * minimum of 1_k length) */ table_ptr = acpi_os_map_memory((acpi_native_uint) physical_address, ACPI_EBDA_WINDOW_SIZE); if (!table_ptr) { ACPI_ERROR((AE_INFO, "Could not map memory at %8.8X for length %X", physical_address, ACPI_EBDA_WINDOW_SIZE)); return_ACPI_STATUS(AE_NO_MEMORY); } mem_rover = acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_EBDA_WINDOW_SIZE); acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE); if (mem_rover) { /* Return the physical address */ physical_address += (u32) ACPI_PTR_DIFF(mem_rover, table_ptr); *table_address = physical_address; return_ACPI_STATUS(AE_OK); } } /* * 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh */ table_ptr = acpi_os_map_memory((acpi_physical_address) ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE); if (!table_ptr) { ACPI_ERROR((AE_INFO, "Could not map memory at %8.8X for length %X", ACPI_HI_RSDP_WINDOW_BASE, ACPI_HI_RSDP_WINDOW_SIZE)); return_ACPI_STATUS(AE_NO_MEMORY); } mem_rover = acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); if (mem_rover) { /* Return the physical address */ physical_address = (u32) (ACPI_HI_RSDP_WINDOW_BASE + ACPI_PTR_DIFF(mem_rover, table_ptr)); *table_address = physical_address; return_ACPI_STATUS(AE_OK); } /* A valid RSDP was not found */ ACPI_ERROR((AE_INFO, "A valid RSDP was not found")); return_ACPI_STATUS(AE_NOT_FOUND); } ACPI_EXPORT_SYMBOL(acpi_find_root_pointer) /******************************************************************************* * * FUNCTION: acpi_tb_scan_memory_for_rsdp * * PARAMETERS: start_address - Starting pointer for search * Length - Maximum length to search * * RETURN: Pointer to the RSDP if found, otherwise NULL. * * DESCRIPTION: Search a block of memory for the RSDP signature * ******************************************************************************/ static u8 *acpi_tb_scan_memory_for_rsdp(u8 * start_address, u32 length) { acpi_status status; u8 *mem_rover; u8 *end_address; ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp); end_address = start_address + length; /* Search from given start address for the requested length */ for (mem_rover = start_address; mem_rover < end_address; mem_rover += ACPI_RSDP_SCAN_STEP) { /* The RSDP signature and checksum must both be correct */ status = acpi_tb_validate_rsdp(ACPI_CAST_PTR (struct acpi_table_rsdp, mem_rover)); if (ACPI_SUCCESS(status)) { /* Sig and checksum valid, we have found a real RSDP */ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "RSDP located at physical address %p\n", mem_rover)); return_PTR(mem_rover); } /* No sig match or bad checksum, keep searching */ } /* Searched entire block, no RSDP was found */ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Searched entire block from %p, valid RSDP was not found\n", start_address)); return_PTR(NULL); }