268 lines
7.0 KiB
C
268 lines
7.0 KiB
C
// 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 - 2022, 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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