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Niklas Gollenstede
2025-04-14 11:20:52 +02:00
commit 5a2e32aaeb
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/*! \file
* \brief Structs and methods related to the \ref ACPI "Advanced Configuration
* and Power Interface (ACPI)""
*/
#pragma once
#include "../types.h"
/*! \brief Abstracts the ACPI standard that provides interfaces for hardware
* detection, device configuration, and energy management.
* \ingroup io
*
* ACPI is the successor to APM (Advanced Power Management), aiming to give the
* operating system more control over the hardware. This extended control, for
* instance, enables the operating system to assign a particular amount of
* energy to every device (e.g., by disabling a device or changing to standby
* mode). For this purpose, BIOS and chipset provide a set of tables that
* describe the system and its components and provide routines the OS can call.
* These tables contain details about the system, such as the number of CPU
* cores and the LAPIC/IOAPIC, which are determined during system boot.
*/
namespace ACPI {
/*! \brief Root System Description Pointer (RSDP)
*
* The first step to using ACPI is finding the RSDP that is used to find the
* RSDT / XSDT, which themselves contain pointers to even more tables.
*
* On UEFI systems, the RSDP can be found in the EFI_SYSTEM_TABLE; for non-UEFI
* systems we have to search for the signature 'RSD PTR ' in the EBDA (Extended
* Bios Data Area) or in the memory area up to `FFFFFh`.
*
* \see [ACPI-Specification 5.2.5.3; Root System Description Pointer (RSDP)
* Structure](acpi.pdf#page=161)
*/
struct RSDP {
char signature[8]; /* must exactly be equal to 'RSD PTR ' */
uint8_t checksum;
char oemid[6];
uint8_t revision; /* specifies the ACPI version */
uint32_t rsdtaddress; /* physical address of the RSDT */
uint32_t length;
uint64_t xsdtaddress; /* physical address of the XSDT */
uint8_t extended_checksum;
uint8_t reserved[3];
} __attribute__((packed));
/*! \brief System Description Table Header (SDTH)
*
* All System Description Tables (e.g., the RSDT) contain the same entries at
* the very beginning of the structure, which are abstracted in the SDTH.
*
* \see [ACPI-Specification 5.2.6; System Description Table
* Header](acpi.pdf#page=162)
*/
struct SDTH {
uint32_t signature; /* table id */
uint32_t length;
uint8_t revision;
uint8_t checksum;
char oemid[6];
char oem_table_id[8];
uint32_t oem_revision;
uint32_t creator_id;
uint32_t creator_revision;
/* \brief Helper method
* \return Pointer to the end of the table
*/
void *end() { return reinterpret_cast<uint8_t *>(this) + length; }
} __attribute__((packed));
/*! \brief Root System Description Table (RSDT)
*
* The RSDT can be found in the RSDP. The RSDT contains physical addresses of
* all other System Description Tables, for example the MADT.
*
* \see [ACPI-Specification 5.2.7; Root System Description Table
* (RSDT)](acpi.pdf#page=167)
*/
struct RSDT : SDTH {
uint32_t entries[];
} __attribute__((packed));
/*! \brief Extended System Description Table (XSDT)
*
* Like RSDT, but contains 64-bit instead of 32-bit addresses.
*
* \see [ACPI-Specification 5.2.8; Extended System Description Table
* (XSDT)](acpi.pdf#page=168)
*/
struct XSDT : SDTH {
uint64_t entries[];
} __attribute__((packed));
/*! \brief Helper structure
*
* Is used for accessing the substructures present in SRAT / MADT.
*
*/
struct SubHeader {
uint8_t type;
uint8_t length;
/* Method to traverse multiple substructures */
SubHeader *next() {
return reinterpret_cast<SubHeader *>(reinterpret_cast<uint8_t *>(this) +
length);
}
} __attribute__((packed));
/*! \brief Multiple APIC Description Table (MADT)
*
* Describes all interrupt controllers present within the system. Is used to
* obtain the IDs of the APICs, along with the number of available processor
* cores.
*
* \see [ACPI-Specification 5.2.12; Multiple APIC Description Table
* (MADT)](acpi.pdf#page=193)
*/
struct MADT : SDTH {
uint32_t local_apic_address;
uint32_t flags_pcat_compat : 1, flags_reserved : 31;
/* method to access the first subheader */
SubHeader *first() {
return reinterpret_cast<SubHeader *>(reinterpret_cast<uint8_t *>(this) +
sizeof(MADT));
}
} __attribute__((packed));
enum class AddressSpace : uint8_t {
MEMORY = 0x0,
IO = 0x1,
};
/*! \brief ACPI address format
*
* The ACPI standard defines its own address format that is able to handle
* addresses both in memory address space, as well as IO-port address space.
*/
struct Address {
AddressSpace address_space;
uint8_t register_bit_width;
uint8_t register_bit_offset;
uint8_t reserved;
uint64_t address;
} __attribute__((packed));
// Multiple APIC Definition Structure
namespace MADS {
enum Type {
Type_LAPIC = 0,
Type_IOAPIC = 1,
Type_Interrupt_Source_Override = 2,
Type_LAPIC_Address_Override = 5,
};
/*! \brief Processor Local APIC (LAPIC) Structure
*
* Represents a physical processor along with its local interrupt controller.
* The MADT contains a LAPIC structure for every processor available in the
* system.
*
* \see [ACPI-Specification 5.2.12.2; Processor Local APIC
* Structure](acpi.pdf#page=195)
*/
struct LAPIC : SubHeader {
uint8_t acpi_processor_id;
uint8_t apic_id;
uint32_t flags_enabled : 1, flags_reserved : 31; /* must be 0 */
} __attribute__((packed));
/*! \brief I/O APIC Structure
*
* Represents an I/O-APIC.
* The MADT contains an IOAPIC structure for every I/O APIC present in the
* system.
*
* \see [ACPI-Specification 5.2.12.3; I/O APIC Structure](acpi.pdf#page=196)
*/
struct IOAPIC : SubHeader {
uint8_t ioapic_id;
uint8_t reserved;
uint32_t ioapic_address;
uint32_t global_system_interrupt_base;
} __attribute__((packed));
/*! \brief Interrupt Source Override Structure
*
* Is required to describe differences between the IA-PC standard interrupt
* definition and the actual hardware implementation.
*
* \see [ACPI-Specification 5.2.12.5; Interrupt Source Override
* Structure](acpi.pdf#page=197)
*/
struct Interrupt_Source_Override : SubHeader {
uint8_t bus;
uint8_t source;
uint32_t global_system_interrupt;
uint16_t flags_polarity : 2, flags_trigger_mode : 2,
flags_reserved : 12; /* must be 0 */
} __attribute__((packed));
/*! \brief Local APIC Address Override Structure
*
* Support for 64-bit systems is achieved by replacing the 32-bit physical LAPIC
* address stored in the MADT with the corresponding 64-bit address.
*
* \see [ACPI-Specification 5.2.12.8; Local APIC Address Override
* Structure](acpi.pdf#page=199)
*/
struct LAPIC_Address_Override : SubHeader {
uint16_t reserved;
union {
uint64_t lapic_address;
struct {
uint32_t lapic_address_low;
uint32_t lapic_address_high;
} __attribute__((packed));
};
} __attribute__((packed));
} // namespace MADS
/*! \brief Initialize the ACPI description table
*
* Searches physical memory ranges o 16-byte boundaries for a valid Root System
* Description Pointer (RSDP) structure signature and checksum. If present, the
* superseding Extended System Description Table (XSDT) is used.
*
* \see [ACPI-Specification 5.2.5 Root System Description Pointer
* (RSDP)](acpi.pdf#page=160)
* \see [ACPI-Specification 5.2.8 Extended System Description Table
* (XSDT)](acpi.pdf#page=168)
*/
bool init();
/*! \brief Number of entries in the description table
*/
unsigned count();
/*! \brief Get entry of description table by index
*
* \param num index in description table
* \return Pointer to corresponding entry or `nullptr` if not available
*/
SDTH *get(unsigned num);
/*! \brief Get entry of description table by four character identifier
*
* \param a first character of identifier
* \param b second character of identifier
* \param c third character of identifier
* \param d forth and last character of identifier
* \return Pointer to corresponding entry or `nullptr` if not available
*/
SDTH *get(char a, char b, char c, char d);
/*! \brief Retrieve the revision from the Root System Description Pointer (RSDP)
*/
int revision();
} // namespace ACPI