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GICD_ISACTIVER<n>, Interrupt Set-Active Registers, n = 0 - 31

The GICD_ISACTIVER<n> characteristics are:

Purpose

Activates the corresponding interrupt. These registers are used when saving and restoring GIC state.

Configuration

Some or all RW fields of this register have defined reset values.

These registers are available in all GIC configurations. If GICD_CTLR.DS==0, these registers are Common.

The number of implemented GICD_ISACTIVER<n> registers is (GICD_TYPER.ITLinesNumber+1). Registers are numbered from 0.

GICD_ISACTIVER0 is Banked for each connected PE with GICR_TYPER.Processor_Number < 8.

Accessing GICD_ISACTIVER0 from a PE with GICR_TYPER.Processor_Number > 7 is CONSTRAINED UNPREDICTABLE:

  • Register is RAZ/WI.
  • An UNKNOWN banked copy of the register is accessed.

Attributes

GICD_ISACTIVER<n> is a 32-bit register.

Field descriptions

The GICD_ISACTIVER<n> bit assignments are:

313029282726252423222120191817161514131211109876543210
Set_active_bit<x>, bit [x], for x = 0 to 31

Set_active_bit<x>, bit [x], for x = 0 to 31

Adds the active state to interrupt number 32n + x. Reads and writes have the following behavior:

Set_active_bit<x>Meaning
0b0

If read, indicates that the corresponding interrupt is not active, and is not active and pending.

If written, has no effect.

0b1

If read, indicates that the corresponding interrupt is active, or is active and pending.

If written, activates the corresponding interrupt, if the interrupt is not already active. If the interrupt is already active, the write has no effect.

After a write of 1 to this bit, a subsequent read of this bit returns 1.

This field resets to 0.

For INTID m, when DIV and MOD are the integer division and modulo operations:

  • The corresponding GICD_ISACTIVER<n> number, n, is given by n = m DIV 32.
  • The offset of the required GICD_ISACTIVER is (0x300 + (4*n)).
  • The bit number of the required group modifier bit in this register is m MOD 32.

Accessing the GICD_ISACTIVER<n>

When affinity routing is enabled for the Security state of an interrupt, bits corresponding to SGIs and PPIs are RAZ/WI, and equivalent functionality for SGIs and PPIs is provided by GICR_ISACTIVER0.

Bits corresponding to unimplemented interrupts are RAZ/WI.

If GICD_CTLR.DS==0, unless the GICD_NSACR<n> registers permit Non-secure software to control Group 0 and Secure Group 1 interrupts, any bits that correspond to Group 0 or Secure Group 1 interrupts are accessible only by Secure accesses and are RAZ/WI to Non-secure accesses.

The bit reads as one if the status of the interrupt is active or active and pending. GICD_ISPENDR<n> and GICD_ICPENDR<n> provide the pending status of the interrupt.

GICD_ISACTIVER<n> can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
GIC Distributor0x0300 + 4nGICD_ISACTIVER<n>

This interface is accessible as follows:

  • When GICD_CTLR.DS == 0b0 accesses to this register are RW.
  • When IsAccessSecure() accesses to this register are RW.
  • When !IsAccessSecure() accesses to this register are RW.


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