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IOAPIC Namespace Reference

Abstraction of the I/O APIC that is used for management of external interrupts. More...

Classes

union  Identification
 I/O APIC Identification. More...
 
union  RedirectionTableEntry
 Entry in the redirection table. More...
 

Structs

struct  Identification.__unnamed__
 

Typedefs

typedef uint32_t Index
 
typedef uint32_t Register
 

Enumerations

enum  DeliveryMode {
  FIXED = 0,
  LOWEST_PRIORITY = 1,
  SMI = 2,
  NMI = 4,
  INIT = 5,
  EXTERN_INT = 7
}
 Delivery mode specifies the type of interrupt sent to the CPU. More...
 
enum  DestinationMode {
  PHYSICAL = 0,
  LOGICAL = 1
}
 Way of interpreting the value written to the destination field. More...
 
enum  Polarity {
  HIGH = 0,
  LOW = 1
}
 Interrupt polarity for the redirection-table entry. More...
 
enum  TriggerMode {
  EDGE = 0,
  LEVEL = 1
}
 Trigger mode. More...
 
enum  DeliveryStatus {
  IDLE = 0,
  SEND_PENDING = 1
}
 Interrupt state. More...
 
enum  InterruptMask {
  UNMASKED = 0,
  MASKED = 1
}
 Interrupt masking. More...
 

Functions

void init ()
 Initializes the I/O APIC. More...
 
void config (uint8_t slot, Core::Interrupt::Vector vector, TriggerMode trigger_mode=TriggerMode::EDGE, Polarity polarity=Polarity::HIGH)
 Creates a mapping between an interrupt vector and an external interrupt. More...
 
void allow (uint8_t slot)
 Enables the redirection of particular external interrupts to the CPU(s). More...
 
void forbid (uint8_t slot)
 Selectively masks external interrupts by slot number. More...
 
bool status (uint8_t slot)
 Check whether an external interrupt source is masked. More...
 

Constants

volatile Index * IOREGSEL_REG = reinterpret_cast<volatile Index*>(0xfec00000)
 IOAPIC registers memory mapped into the CPU's virtual address space. More...
 
volatile Register * IOWIN_REG = reinterpret_cast<volatile Register*>(0xfec00010)
 IOAPIC registers memory mapped into the CPU's virtual address space. More...
 
const Index IOAPICID_IDX = 0x00
 
const Index IOREDTBL_IDX = 0x10
 
const uint8_t slot_max = 24
 

Detailed Description

Abstraction of the I/O APIC that is used for management of external interrupts.

The I/O APIC's Core component is the IO-redirection table. This table is used to configure a flexible mapping between the interrupt number and the external interruption. Entries within this table have a width of 64 bit. For convenience, the union IOAPIC::RedirectionTableEntry should be used for modifying these tables (see file ioapic_registers.h for details).

Enumeration Type Documentation

enum IOAPIC::DeliveryMode

Delivery mode specifies the type of interrupt sent to the CPU.

Enumerator
FIXED 

"ordinary" interrupt; send to ALL cores listed in the destination bit mask

LOWEST_PRIORITY 

"ordinary" interrupt; send to the lowest priority core from destination mask

SMI 

System Management Interrupt; vector number required to be 0.

NMI 

Non-Maskable Interrupt, vector number ignored, only edge triggered.

INIT 

Initialization interrupt (always treated as edge triggered)

EXTERN_INT 

external interrupt (only edge triggered)

enum IOAPIC::DestinationMode

Way of interpreting the value written to the destination field.

Enumerator
PHYSICAL 

Destination contains the physical destination APIC ID.

LOGICAL 

Destination contains a mask of logical APIC IDs.

enum IOAPIC::Polarity

Interrupt polarity for the redirection-table entry.

Enumerator
HIGH 

active high

LOW 

active low

enum IOAPIC::TriggerMode

Trigger mode.

Enumerator
EDGE 

edge triggered

LEVEL 

level triggered

enum IOAPIC::DeliveryStatus

Interrupt state.

Enumerator
IDLE 

No activity for this interrupt.

SEND_PENDING 

Interrupt will be sent as soon as the bus / LAPIC is ready.

enum IOAPIC::InterruptMask

Interrupt masking.

Enumerator
UNMASKED 

Redirection-table entry is active (non-masked)

MASKED 

Redirection-table entry is inactive (masked)

Function Documentation

void IOAPIC::init ( )

Initializes the I/O APIC.

This function will initialize the I/O APIC by initializing the IO-redirection table with sane default values. The default interrupt-vector number is chosen such that, in case the interrupt is issued, the panic handler is executed. In the beginning, all external interrupts are disabled within the I/O APIC. Apart from the redirection table, the APICID (read from the system description tables during boot) needs to be written to the IOAPICID register (see APIC::getIOAPICID() )

void IOAPIC::config ( uint8_t  slot,
Core::Interrupt::Vector  vector,
TriggerMode  trigger_mode = TriggerMode::EDGE,
Polarity  polarity = Polarity::HIGH 
)

Creates a mapping between an interrupt vector and an external interrupt.

Parameters
slotNumber of the slot (i.e., the external interrupt) to configure.
vectorNumber of the interrupt vector that will be issued for the external interrupt.
trigger_modeEdge or level triggered interrupt signaling (level-triggered interrupts required for the optional serial interface)
polarityPolarity of the interrupt signaling (active high or active low)
void IOAPIC::allow ( uint8_t  slot)

Enables the redirection of particular external interrupts to the CPU(s).

To fully enable interrupt handling, the interrupts must be enabled for every CPU (e.g., by calling Core::Interrupt::enable() in main)

Parameters
slotNumber of the external interrupt that should be enabled.
void IOAPIC::forbid ( uint8_t  slot)

Selectively masks external interrupts by slot number.

Parameters
slotSlot number of the interrupt to be disabled.
bool IOAPIC::status ( uint8_t  slot)

Check whether an external interrupt source is masked.

Parameters
slotSlot number of the interrupt to be checked.
Returns
Returns true iff the interrupt is unmasked, false otherwise

Constant Documentation

volatile Index * IOAPIC::IOREGSEL_REG = reinterpret_cast<volatile Index*>(0xfec00000)

IOAPIC registers memory mapped into the CPU's virtual address space.

Access to the actual IOAPIC registers can be obtained by performing the following steps:

  1. Write the number of the IOAPIC register to the address stored in IOREGSEL_REG
  2. Read the value from / write the value to the address referred to by IOWIN_REG.
See also
IO-APIC manual
volatile Register * IOAPIC::IOWIN_REG = reinterpret_cast<volatile Register*>(0xfec00010)

IOAPIC registers memory mapped into the CPU's virtual address space.

Access to the actual IOAPIC registers can be obtained by performing the following steps:

  1. Write the number of the IOAPIC register to the address stored in IOREGSEL_REG
  2. Read the value from / write the value to the address referred to by IOWIN_REG.
See also
IO-APIC manual