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ICV_BPR1, Interrupt Controller Virtual Binary Point Register 1

The ICV_BPR1 characteristics are:

Purpose

Defines the point at which the priority value fields split into two parts, the group priority field and the subpriority field. The group priority field determines virtual Group 1 interrupt preemption.

Configuration

AArch32 System register ICV_BPR1 bits [31:0] are architecturally mapped to AArch64 System register ICV_BPR1_EL1[31:0] .

This register is present only when AArch32 is supported at any Exception level. Otherwise, direct accesses to ICV_BPR1 are UNDEFINED.

Attributes

ICV_BPR1 is a 32-bit register.

Field descriptions

The ICV_BPR1 bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0BinaryPoint

Bits [31:3]

Reserved, RES0.

BinaryPoint, bits [2:0]

If the GIC is configured to use separate binary point fields for virtual Group 0 and virtual Group 1 interrupts, the value of this field controls how the 8-bit interrupt priority field is split into a group priority field, that determines interrupt preemption, and a subpriority field. This is done as follows:

Binary point valueGroup priority fieldSubpriority fieldField with binary point
0---
1[7:1][0]ggggggg.s
2[7:2][1:0]gggggg.ss
3[7:3][2:0]ggggg.sss
4[7:4][3:0]gggg.ssss
5[7:5][4:0]ggg.sssss
6[7:6][5:0]gg.ssssss
7[7][6:0]g.sssssss

Writing 0 to this field will set this field to its reset value.

If ICV_CTLR.CBPR is set to 1, Non-secure EL1 reads return ICV_BPR0 + 1 saturated to 0b111. Non-secure EL1 writes are ignored.

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing the ICV_BPR1

The minimum valuse of this register is equal to the minimum value of ICV_BPR0 plus one.

An attempt to program the binary point field to a value less than the minimum value sets the field to the minimum value. On a reset, the binary point field is UNKNOWN.

Accesses to this register use the following encodings:

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

coprocopc1CRnCRmopc2
0b11110b0000b11000b11000b011
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 == '1' 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 == '1' 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 ICC_SRE.SRE == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && ICH_HCR_EL2.TALL1 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TALL1 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.IMO == '1' then
        return ICV_BPR1;
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.IMO == '1' then
        return ICV_BPR1;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    elsif HaveEL(EL3) then
        return ICC_BPR1_NS;
    else
        return ICC_BPR1;
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 == '1' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && ELUsingAArch32(EL3) && SCR.IRQ == '1' then
        UNDEFINED;
    elsif ICC_HSRE.SRE == '0' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    elsif HaveEL(EL3) then
        return ICC_BPR1_NS;
    else
        return ICC_BPR1;
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        if SCR.NS == '0' then
            return ICC_BPR1_S;
        else
            return ICC_BPR1_NS;
              

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

coprocopc1CRnCRmopc2
0b11110b0000b11000b11000b011
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 == '1' 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 == '1' 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 ICC_SRE.SRE == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && ICH_HCR_EL2.TALL1 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TALL1 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.IMO == '1' then
        ICV_BPR1 = R[t];
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.IMO == '1' then
        ICV_BPR1 = R[t];
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    elsif HaveEL(EL3) then
        ICC_BPR1_NS = R[t];
    else
        ICC_BPR1 = 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 == '1' then
        UNDEFINED;
    elsif Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && ELUsingAArch32(EL3) && SCR.IRQ == '1' then
        UNDEFINED;
    elsif ICC_HSRE.SRE == '0' then
        UNDEFINED;
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch64.AArch32SystemAccessTrap(EL3, 0x03);
    elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.IRQ == '1' then
        if Halted() && EDSCR.SDD == '1' then
            UNDEFINED;
        else
            AArch32.TakeMonitorTrapException();
    elsif HaveEL(EL3) then
        ICC_BPR1_NS = R[t];
    else
        ICC_BPR1 = R[t];
elsif PSTATE.EL == EL3 then
    if ICC_MSRE.SRE == '0' then
        UNDEFINED;
    else
        if SCR.NS == '0' then
            ICC_BPR1_S = R[t];
        else
            ICC_BPR1_NS = R[t];