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GICR_IPRIORITYR<n>, Interrupt Priority Registers, n = 0 - 7

The GICR_IPRIORITYR<n> characteristics are:

Purpose

Holds the priority of the corresponding interrupt for each SGI and PPI supported by the GIC.

Configuration

RW fields in this register reset to architecturally UNKNOWN values.

A copy of these registers is provided for each Redistributor.

These registers are configured as follows:

  • GICR_IPRIORITYR0-GICR_IPRIORITYR3 store the priority of SGIs.
  • GICR_IPRIORITYR4-GICR_IPRIORITYR7 store the priority of PPIs.

Attributes

GICR_IPRIORITYR<n> is a 32-bit register.

Field descriptions

The GICR_IPRIORITYR<n> bit assignments are:

313029282726252423222120191817161514131211109876543210
Priority_offset_3BPriority_offset_2BPriority_offset_1BPriority_offset_0B

Priority_offset_3B, bits [31:24]

Interrupt priority value from an IMPLEMENTATION DEFINED range, at byte offset 3. Lower priority values correspond to greater priority of the interrupt.

This field resets to an architecturally UNKNOWN value.

Priority_offset_2B, bits [23:16]

Interrupt priority value from an IMPLEMENTATION DEFINED range, at byte offset 2. Lower priority values correspond to greater priority of the interrupt.

This field resets to an architecturally UNKNOWN value.

Priority_offset_1B, bits [15:8]

Interrupt priority value from an IMPLEMENTATION DEFINED range, at byte offset 1. Lower priority values correspond to greater priority of the interrupt.

This field resets to an architecturally UNKNOWN value.

Priority_offset_0B, bits [7:0]

Interrupt priority value from an IMPLEMENTATION DEFINED range, at byte offset 0. Lower priority values correspond to greater priority of the interrupt.

This field resets to an architecturally UNKNOWN value.

Accessing the GICR_IPRIORITYR<n>

These registers are used when affinity routing is enabled for the Security state of the interrupt. When affinity routing is not enabled the bits corresponding to the interrupt are RAZ/WI and GICD_IPRIORITYR<n> provides equivalent functionality.

These registers are used for SGIs and PPIs only. Equivalent functionality for SPIs is provided by GICD_IPRIORITYR<n>.

These registers are byte-accessible.

When GICD_CTLR.DS == 0:

  • A field that corresponds to a Group 0 or Secure Group 1 interrupt is RAZ/WI to Non-secure accesses.
  • A Non-secure access to a field that corresponds to a Non-secure Group 1 interrupt behaves as described in Software accesses of interrupt priority.
Note

Implementations must ensure that an interrupt that is pending at the time of the write uses either the old value or the new value and must ensure that the interrupt is neither lost nor handled more than one time. The effect of the change must be visible in finite time.

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

ComponentFrameOffsetInstance
GIC RedistributorSGI_base0x0400 + 4nGICR_IPRIORITYR<n>

This interface is accessible as follows:

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


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