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# ICV_BPR0, Interrupt Controller Virtual Binary Point Register 0

The ICV_BPR0 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 0 interrupt preemption.

## Configuration

AArch32 System register ICV_BPR0 bits [31:0] are architecturally mapped to AArch64 System register ICV_BPR0_EL1[31:0] .

RW fields in this register reset to architecturally UNKNOWN values.

## Attributes

ICV_BPR0 is a 32-bit register.

## Field descriptions

The ICV_BPR0 bit assignments are:

31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
RES0 | BinaryPoint

#### Bits [31:3]

Reserved, RES0.

#### BinaryPoint, bits [2:0]

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 value | Group priority field | Subpriority field | Field with binary point
--- | --- | --- | ---
0 | [7:1] | [0] | ggggggg.s
1 | [7:2] | [1:0] | gggggg.ss
2 | [7:3] | [2:0] | ggggg.sss
3 | [7:4] | [3:0] | gggg.ssss
4 | [7:5] | [4:0] | ggg.sssss
5 | [7:6] | [5:0] | gg.ssssss
6 | [7] | [6:0] | g.sssssss
7 | No preemption | [7:0] | .ssssssss

This field resets to an architecturally UNKNOWN value.

## Accessing the ICV_BPR0

The minimum binary point value is derived from the number of implemented priority bits. The number of priority bits is IMPLEMENTATION DEFINED, and reported by ICV_CTLR.PRIbits.

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 set to the minimum supported value.

Accesses to this register use the following encodings:

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

coproc | opc1 | CRn | CRm | opc2
--- | --- | --- | --- | ---
0b1111 | 0b000 | 0b1100 | 0b1000 | 0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if 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.TALL0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TALL0 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.FMO == '1' then return ICV_BPR0; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR.FMO == '1' then return ICV_BPR0; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else return ICC_BPR0; elsif PSTATE.EL == EL2 then if ICC_HSRE.SRE == '0' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else return ICC_BPR0; elsif PSTATE.EL == EL3 then if ICC_MSRE.SRE == '0' then UNDEFINED; else return ICC_BPR0;

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

coproc | opc1 | CRn | CRm | opc2
--- | --- | --- | --- | ---
0b1111 | 0b000 | 0b1100 | 0b1000 | 0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if 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.TALL0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TALL0 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.FMO == '1' then ICV_BPR0 = R[t]; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR.FMO == '1' then ICV_BPR0 = R[t]; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else ICC_BPR0 = R[t]; elsif PSTATE.EL == EL2 then if ICC_HSRE.SRE == '0' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else ICC_BPR0 = R[t]; elsif PSTATE.EL == EL3 then if ICC_MSRE.SRE == '0' then UNDEFINED; else ICC_BPR0 = R[t];

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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