ACPI

Advanced Configuration and Power Interface. More...

Collaboration diagram for ACPI:

Detailed Description

Advanced Configuration and Power Interface.

We use version 6.6 of the ACPI specification, but it contains minor mistakes or deprecated features that we use other versions to straighten out. If the "ACPI specification" is ever sourced, without mentioning its version, assume version 6.6.

Take a look at this osdev post if you want to understand how annoying the ACPI spec is.

Checklist for ACPI support from section 1.7.2 of the ACPI specification:

• [x] Use System Address Map Interfaces (this is done by the bootloader).
• [x] Find and consume the ACPI System Description Tables (this is done in acpi_tables_init())
• [x] Interpret ACPI machine language (AML). (this is done in aml_init())
• [X] Enumerate and configure motherboard devices described in the ACPI Namespace. (this is done in acpi_devices_init())
• [ ] Interface with the power management timer. <– We are here.
• [ ] Interface with the real-time clock wake alarm.
• [ ] Enter ACPI mode (on legacy hardware systems).
• [ ] Implement device power management policy.
• [ ] Implement power resource management.
• [ ] Implement processor power states in the scheduler idle handlers.
• [ ] Control processor and device performance states.
• [ ] Implement the ACPI thermal model.
• [ ] Support the ACPI Event programming model including handling SCI interrupts, managing fixed events, general- purpose events, embedded controller interrupts, and dynamic device support.
• [ ] Support acquisition and release of the Global Lock.
• [ ] Use the reset register to reset the system.
• [ ] Provide APIs to influence power management policy.
• [ ] Implement driver support for ACPI-defined devices.
• [ ] Implement APIs supporting the system indicators.
• [ ] Support all system states S1-S5.

Included below is a list of deviations from the ACPI specification that we have made. Each deviation is marked with the source of the deviation in parentheses:

• Copying an object to itself is a no-op. (Windows)
• Converting a zero-length String to a Buffer still copies the null-terminator. (ACPICA)

See also

Easier to read version of the ACPI Specification

ACPI Specification Version 6.6

ACPI Specification Version 6.3

ACPI Specification Version 4.0

ACPICA Reference Version 6.3

LAI Library

Modules
	AML
	ACPI AML.
	Devices
	Device and Power Management.
	Resources
	ACPI resource settings.
	Tables
	System Description Tables.

Data Structures
struct	sdt_header_t
	System Description Table Header. More...
struct	rsdp_t
	Root System Description Pointer. More...
struct	xsdt_t
	Extended System Description Table. More...

Macros
#define	RSDP_CURRENT_REVISION   2
	The expected value of the revision field in the RSDP structure.
#define	SDT_SIGNATURE_LENGTH   4
	The length of the signature field in the SDT header structure.
#define	SDT_OEM_ID_LENGTH   6
	The length of the OEM ID field in the SDT header structure.
#define	SDT_OEM_TABLE_ID_LENGTH   8
	The length of the OEM Table ID field in the SDT header structure.
#define	RSDP_SIGNATURE_LENGTH   8
	Length of the signature field in the RSDP structure.
#define	RSDP_V1_LENGTH   20
	Length of the RSDP structure for ACPI version 1.0.

Functions
bool	acpi_is_checksum_valid (void *table, uint64_t length)
	Check if the sum of all bytes in a table is 0.
dentry_t *	acpi_get_sysfs_root (void)
	Retrieve the sysfs root directory for ACPI.
void	acpi_reclaim_memory (const boot_memory_map_t *map)
	Reclaim ACPI memory regions.

Macro Definition Documentation

RSDP_CURRENT_REVISION

#define RSDP_CURRENT_REVISION   2

The expected value of the revision field in the RSDP structure.

See also

Section 5.2.5.3 of the ACPI specification for more details.

Definition at line 66 of file acpi.h.

SDT_SIGNATURE_LENGTH

#define SDT_SIGNATURE_LENGTH   4

The length of the signature field in the SDT header structure.

Definition at line 71 of file acpi.h.

SDT_OEM_ID_LENGTH

#define SDT_OEM_ID_LENGTH   6

The length of the OEM ID field in the SDT header structure.

Definition at line 76 of file acpi.h.

SDT_OEM_TABLE_ID_LENGTH

#define SDT_OEM_TABLE_ID_LENGTH   8

The length of the OEM Table ID field in the SDT header structure.

Definition at line 81 of file acpi.h.

RSDP_SIGNATURE_LENGTH

#define RSDP_SIGNATURE_LENGTH   8

Length of the signature field in the RSDP structure.

Definition at line 105 of file acpi.h.

RSDP_V1_LENGTH

#define RSDP_V1_LENGTH   20

Length of the RSDP structure for ACPI version 1.0.

Definition at line 129 of file acpi.h.

Function Documentation

acpi_is_checksum_valid()

bool acpi_is_checksum_valid	(	void *	table,
		uint64_t	length
	)

Check if the sum of all bytes in a table is 0.

Used to validate the checksum of ACPI tables.

Parameters

table

Pointer to the table structure.

Returns

true if the table is valid, false otherwise.

Definition at line 23 of file acpi.c.

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acpi_get_sysfs_root()

dentry_t * acpi_get_sysfs_root

(

void

)

Retrieve the sysfs root directory for ACPI.

The acpi group and by extension its directory is lazily initialized.

Returns

Pointer to the ACPI sysfs root directory.

Definition at line 34 of file acpi.c.

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acpi_reclaim_memory()

void acpi_reclaim_memory

(

const boot_memory_map_t *

map

)

Reclaim ACPI memory regions.

This function will free all memory regions marked as ACPI Reclaimable in the provided boot memory map.

Should be called after all ACPI initialization is complete.

Parameters

map	Pointer to the boot memory map.

Definition at line 51 of file acpi.c.

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