| // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 |
| /****************************************************************************** |
| * |
| * Module Name: tbxfroot - Find the root ACPI table (RSDT) |
| * |
| * Copyright (C) 2000 - 2022, Intel Corp. |
| * |
| *****************************************************************************/ |
| |
| #include <acpi/acpi.h> |
| #include "accommon.h" |
| #include "actables.h" |
| |
| #define _COMPONENT ACPI_TABLES |
| ACPI_MODULE_NAME("tbxfroot") |
| |
| /******************************************************************************* |
| * |
| * FUNCTION: acpi_tb_get_rsdp_length |
| * |
| * PARAMETERS: rsdp - Pointer to RSDP |
| * |
| * RETURN: Table length |
| * |
| * DESCRIPTION: Get the length of the RSDP |
| * |
| ******************************************************************************/ |
| u32 acpi_tb_get_rsdp_length(struct acpi_table_rsdp *rsdp) |
| { |
| |
| if (!ACPI_VALIDATE_RSDP_SIG(rsdp->signature)) { |
| |
| /* BAD Signature */ |
| |
| return (0); |
| } |
| |
| /* "Length" field is available if table version >= 2 */ |
| |
| if (rsdp->revision >= 2) { |
| return (rsdp->length); |
| } else { |
| return (ACPI_RSDP_CHECKSUM_LENGTH); |
| } |
| } |
| |
| /******************************************************************************* |
| * |
| * FUNCTION: acpi_tb_validate_rsdp |
| * |
| * PARAMETERS: rsdp - Pointer to unvalidated RSDP |
| * |
| * RETURN: Status |
| * |
| * DESCRIPTION: Validate the RSDP (ptr) |
| * |
| ******************************************************************************/ |
| |
| acpi_status acpi_tb_validate_rsdp(struct acpi_table_rsdp *rsdp) |
| { |
| |
| /* |
| * 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_VALIDATE_RSDP_SIG(rsdp->signature)) { |
| |
| /* 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_find_root_pointer |
| * |
| * PARAMETERS: table_address - Where the table pointer is returned |
| * |
| * RETURN: Status, RSDP physical address |
| * |
| * DESCRIPTION: Search lower 1Mbyte 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 1K 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_INIT_FUNCTION |
| acpi_find_root_pointer(acpi_physical_address *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 0x%8.8X for length %u", |
| 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 1K length) |
| */ |
| table_ptr = acpi_os_map_memory((acpi_physical_address) |
| physical_address, |
| ACPI_EBDA_WINDOW_SIZE); |
| if (!table_ptr) { |
| ACPI_ERROR((AE_INFO, |
| "Could not map memory at 0x%8.8X for length %u", |
| 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 = |
| (acpi_physical_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 0x%8.8X for length %u", |
| 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 = (acpi_physical_address)physical_address; |
| return_ACPI_STATUS(AE_OK); |
| } |
| |
| /* A valid RSDP was not found */ |
| |
| ACPI_BIOS_ERROR((AE_INFO, "A valid RSDP was not found")); |
| return_ACPI_STATUS(AE_NOT_FOUND); |
| } |
| |
| ACPI_EXPORT_SYMBOL_INIT(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 |
| * |
| ******************************************************************************/ |
| 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); |
| } |