GICC_HPPIR, CPU Interface Highest Priority Pending Interrupt Register

The GICC_HPPIR characteristics are:

Purpose

Provides the INTID of the highest priority pending interrupt on the CPU interface.

Configuration

If GICD_CTLR.DS==0:

• This register is Common.
• GICC_AHPPIR is an alias of the Non-secure view of this register.

Attributes

GICC_HPPIR is a 32-bit register.

Field descriptions

The GICC_HPPIR bit assignments are:

Bits [31:24]

Reserved, RES0.

INTID, bits [23:0]

The INTID of the signaled interrupt.

When affinity routing is not enabled:

• Bits [23:13] are RES0.
• For SGIs, bits [12:10] identify the CPU interface corresponding to the source PE. For all other interrupts these bits are RES0.

Accessing the GICC_HPPIR

This register is used only when System register access is not enabled. When System register access is enabled:

• For AArch32 implementations, ICC_HPPIR0 and ICC_HPPIR1 provide equivalent functionality.
• For AArch64 implementations, ICC_HPPIR0_EL1 and ICC_HPPIR1_EL1 provide equivalent functionality.

If the highest priority pending interrupt is in Group 0, a Non-secure read of this register returns the special INTID 1023.

For Secure reads when GICD_CTLR.DS==0, or for Secure and Non-secure reads when GICD_CTLR.DS==1, returns the special INTID 1022 if the highest priority pending interrupt is in Group 1.

If no interrupts are in the pending state, a read of this register returns the special INTID 1023.

Interrupt identifiers corresponding to an interrupt group that is not enabled are ignored.

If the highest priority pending interrupt is a direct interrupt that is both individually enabled in the Distributor and part of an interrupt group that is enabled in the Distributor, and the interrupt group is disabled in the CPU interface for this PE, this register returns the special INTID 1023.

For more information about pending interrupts that are not considered when determining the highest priority pending interrupt, see 'Preemption' in ARM® Generic Interrupt Controller Architecture Specification, GIC architecture version 3.0 and version 4.0 (ARM IHI 0069).

When affinity routing is enabled for a Security state, it is a programming error to use memory-mapped registers to access the GIC.

GICC_HPPIR can be accessed through the memory-mapped interfaces:

This interface is accessible as follows:

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