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ICC_PMR, Interrupt Controller Interrupt Priority Mask Register

The ICC_PMR characteristics are:

Purpose

Provides an interrupt priority filter. Only interrupts with a higher priority than the value in this register are signaled to the PE.

Configuration

AArch32 System register ICC_PMR bits [31:0] are architecturally mapped to AArch64 System register ICC_PMR_EL1[31:0] .

This register is present only when AArch32 is supported at any Exception level. Otherwise, direct accesses to ICC_PMR are UNDEFINED.

To allow software to ensure appropriate observability of actions initiated by GIC register accesses, the PE and CPU interface logic must ensure that writes to this register are self-synchronising. This ensures that no interrupts below the written PMR value will be taken after a write to this register is architecturally executed. For more information, see 'Observability of the effects of accesses to the GIC registers' in ARM® Generic Interrupt Controller Architecture Specification, GIC architecture version 3.0 and version 4.0 (ARM IHI 0069).

Attributes

ICC_PMR is a 32-bit register.

Field descriptions

The ICC_PMR bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0Priority

Bits [31:8]

Reserved, RES0.

Priority, bits [7:0]

The priority mask level for the CPU interface. If the priority of an interrupt is higher than the value indicated by this field, the interface signals the interrupt to the PE.

The possible priority field values are as follows:

Implemented priority bitsPossible priority field valuesNumber of priority levels
[7:0]0x00-0xFF (0-255), all values256
[7:1]0x00-0xFE (0-254), even values only128
[7:2]0x00-0xFC (0-252), in steps of 464
[7:3]0x00-0xF8 (0-248), in steps of 832
[7:4]0x00-0xF0 (0-240), in steps of 1616

Unimplemented priority bits are RAZ/WI.

This field resets to 0.

Accessing the ICC_PMR

Accesses to this register use the following encodings:

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b01000b01100b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && ICH_HCR_EL2.TC == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TC == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.FMO == '1' then
        return ICV_PMR;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.IMO == '1' then
        return ICV_PMR;
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.FMO == '1' then
        return ICV_PMR;
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.IMO == '1' then
        return ICV_PMR;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    else
        return ICC_PMR;
elsif PSTATE.EL == EL2 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && ELUsingAArch32(EL3) && SCR.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif ICC_HSRE.SRE == '0' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    else
        return ICC_PMR;
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        return ICC_PMR;
              

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b01000b01100b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && ICH_HCR_EL2.TC == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TC == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.FMO == '1' then
        ICV_PMR = R[t];
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.IMO == '1' then
        ICV_PMR = R[t];
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.FMO == '1' then
        ICV_PMR = R[t];
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.IMO == '1' then
        ICV_PMR = R[t];
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    else
        ICC_PMR = R[t];
elsif PSTATE.EL == EL2 then
    if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && ELUsingAArch32(EL3) && SCR.<IRQ,FIQ> == '11' then
        UNDEFINED;
    elsif ICC_HSRE.SRE == '0' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.<IRQ,FIQ> == '11' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    else
        ICC_PMR = R[t];
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        ICC_PMR = R[t];