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267 lines
7.0 KiB
267 lines
7.0 KiB
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 |
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/****************************************************************************** |
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* |
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* Module Name: tbxfroot - Find the root ACPI table (RSDT) |
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* |
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* Copyright (C) 2000 - 2021, Intel Corp. |
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* |
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*****************************************************************************/ |
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#include <acpi/acpi.h> |
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#include "accommon.h" |
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#include "actables.h" |
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#define _COMPONENT ACPI_TABLES |
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ACPI_MODULE_NAME("tbxfroot") |
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/******************************************************************************* |
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* |
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* FUNCTION: acpi_tb_get_rsdp_length |
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* |
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* PARAMETERS: rsdp - Pointer to RSDP |
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* |
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* RETURN: Table length |
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* |
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* DESCRIPTION: Get the length of the RSDP |
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* |
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******************************************************************************/ |
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u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp) |
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{ |
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if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { |
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/* BAD Signature */ |
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return (0); |
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} |
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/* "Length" field is available if table version >= 2 */ |
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if (rsdp->revision >= 2) { |
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return (rsdp->length); |
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} else { |
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return (ACPI_RSDP_CHECKSUM_LENGTH); |
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} |
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} |
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/******************************************************************************* |
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* |
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* FUNCTION: acpi_tb_validate_rsdp |
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* |
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* PARAMETERS: rsdp - Pointer to unvalidated RSDP |
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* |
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* RETURN: Status |
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* |
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* DESCRIPTION: Validate the RSDP (ptr) |
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* |
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******************************************************************************/ |
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acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp) |
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{ |
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/* |
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* The signature and checksum must both be correct |
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* |
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* Note: Sometimes there exists more than one RSDP in memory; the valid |
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* RSDP has a valid checksum, all others have an invalid checksum. |
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*/ |
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if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { |
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/* Nope, BAD Signature */ |
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return (AE_BAD_SIGNATURE); |
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} |
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/* Check the standard checksum */ |
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if (acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) { |
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return (AE_BAD_CHECKSUM); |
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} |
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/* Check extended checksum if table version >= 2 */ |
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if ((rsdp->revision >= 2) && |
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(acpi_tb_checksum((u8 *) rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) { |
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return (AE_BAD_CHECKSUM); |
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} |
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return (AE_OK); |
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} |
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/******************************************************************************* |
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* |
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* FUNCTION: acpi_find_root_pointer |
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* |
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* PARAMETERS: table_address - Where the table pointer is returned |
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* |
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* RETURN: Status, RSDP physical address |
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* |
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* DESCRIPTION: Search lower 1Mbyte of memory for the root system descriptor |
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* pointer structure. If it is found, set *RSDP to point to it. |
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* |
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* NOTE1: The RSDP must be either in the first 1K of the Extended |
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* BIOS Data Area or between E0000 and FFFFF (From ACPI Spec.) |
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* Only a 32-bit physical address is necessary. |
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* |
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* NOTE2: This function is always available, regardless of the |
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* initialization state of the rest of ACPI. |
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* |
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******************************************************************************/ |
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acpi_status ACPI_INIT_FUNCTION |
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acpi_find_root_pointer(acpi_physical_address *table_address) |
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{ |
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u8 *table_ptr; |
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u8 *mem_rover; |
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u32 physical_address; |
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ACPI_FUNCTION_TRACE(acpi_find_root_pointer); |
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/* 1a) Get the location of the Extended BIOS Data Area (EBDA) */ |
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table_ptr = acpi_os_map_memory((acpi_physical_address) |
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ACPI_EBDA_PTR_LOCATION, |
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ACPI_EBDA_PTR_LENGTH); |
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if (!table_ptr) { |
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ACPI_ERROR((AE_INFO, |
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"Could not map memory at 0x%8.8X for length %u", |
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ACPI_EBDA_PTR_LOCATION, ACPI_EBDA_PTR_LENGTH)); |
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return_ACPI_STATUS(AE_NO_MEMORY); |
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} |
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ACPI_MOVE_16_TO_32(&physical_address, table_ptr); |
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/* Convert segment part to physical address */ |
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physical_address <<= 4; |
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acpi_os_unmap_memory(table_ptr, ACPI_EBDA_PTR_LENGTH); |
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/* EBDA present? */ |
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if (physical_address > 0x400) { |
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/* |
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* 1b) Search EBDA paragraphs (EBDA is required to be a |
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* minimum of 1K length) |
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*/ |
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table_ptr = acpi_os_map_memory((acpi_physical_address) |
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physical_address, |
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ACPI_EBDA_WINDOW_SIZE); |
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if (!table_ptr) { |
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ACPI_ERROR((AE_INFO, |
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"Could not map memory at 0x%8.8X for length %u", |
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physical_address, ACPI_EBDA_WINDOW_SIZE)); |
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return_ACPI_STATUS(AE_NO_MEMORY); |
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} |
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mem_rover = |
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acpi_tb_scan_memory_for_rsdp(table_ptr, |
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ACPI_EBDA_WINDOW_SIZE); |
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acpi_os_unmap_memory(table_ptr, ACPI_EBDA_WINDOW_SIZE); |
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if (mem_rover) { |
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/* Return the physical address */ |
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physical_address += |
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(u32) ACPI_PTR_DIFF(mem_rover, table_ptr); |
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*table_address = |
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(acpi_physical_address)physical_address; |
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return_ACPI_STATUS(AE_OK); |
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} |
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} |
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/* |
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* 2) Search upper memory: 16-byte boundaries in E0000h-FFFFFh |
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*/ |
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table_ptr = acpi_os_map_memory((acpi_physical_address) |
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ACPI_HI_RSDP_WINDOW_BASE, |
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ACPI_HI_RSDP_WINDOW_SIZE); |
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if (!table_ptr) { |
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ACPI_ERROR((AE_INFO, |
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"Could not map memory at 0x%8.8X for length %u", |
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ACPI_HI_RSDP_WINDOW_BASE, |
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ACPI_HI_RSDP_WINDOW_SIZE)); |
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return_ACPI_STATUS(AE_NO_MEMORY); |
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} |
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mem_rover = |
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acpi_tb_scan_memory_for_rsdp(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); |
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acpi_os_unmap_memory(table_ptr, ACPI_HI_RSDP_WINDOW_SIZE); |
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if (mem_rover) { |
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/* Return the physical address */ |
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physical_address = (u32) |
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(ACPI_HI_RSDP_WINDOW_BASE + |
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ACPI_PTR_DIFF(mem_rover, table_ptr)); |
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*table_address = (acpi_physical_address)physical_address; |
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return_ACPI_STATUS(AE_OK); |
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} |
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/* A valid RSDP was not found */ |
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ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found")); |
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return_ACPI_STATUS(AE_NOT_FOUND); |
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} |
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ACPI_EXPORT_SYMBOL_INIT(acpi_find_root_pointer) |
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/******************************************************************************* |
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* |
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* FUNCTION: acpi_tb_scan_memory_for_rsdp |
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* |
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* PARAMETERS: start_address - Starting pointer for search |
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* length - Maximum length to search |
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* |
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* RETURN: Pointer to the RSDP if found, otherwise NULL. |
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* |
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* DESCRIPTION: Search a block of memory for the RSDP signature |
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* |
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******************************************************************************/ |
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u8 *acpi_tb_scan_memory_for_rsdp(u8 *start_address, u32 length) |
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{ |
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acpi_status status; |
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u8 *mem_rover; |
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u8 *end_address; |
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ACPI_FUNCTION_TRACE(tb_scan_memory_for_rsdp); |
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end_address = start_address + length; |
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/* Search from given start address for the requested length */ |
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for (mem_rover = start_address; mem_rover < end_address; |
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mem_rover += ACPI_RSDP_SCAN_STEP) { |
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/* The RSDP signature and checksum must both be correct */ |
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status = |
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acpi_tb_validate_rsdp(ACPI_CAST_PTR |
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(struct acpi_table_rsdp, mem_rover)); |
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if (ACPI_SUCCESS(status)) { |
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/* Sig and checksum valid, we have found a real RSDP */ |
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ACPI_DEBUG_PRINT((ACPI_DB_INFO, |
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"RSDP located at physical address %p\n", |
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mem_rover)); |
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return_PTR(mem_rover); |
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} |
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/* No sig match or bad checksum, keep searching */ |
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} |
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/* Searched entire block, no RSDP was found */ |
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ACPI_DEBUG_PRINT((ACPI_DB_INFO, |
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"Searched entire block from %p, valid RSDP was not found\n", |
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start_address)); |
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return_PTR(NULL); |
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}
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