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] .
Some or all RW fields of this register have defined reset values. These apply only if the PE resets into an Exception level that is using AArch32. If the PE resets into EL3 using AArch32 they apply only to the Secure instance of the register. Otherwise, RW fields in this register reset to architecturally UNKNOWN values.
Attributes
ICV_BPR1 is a 32-bit register.
Field descriptions
The ICV_BPR1 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]
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 value | Group priority field | Subpriority field | Field 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.
This field resets to an IMPLEMENTATION DEFINED non-zero value.
Accessing the ICV_BPR1
The reset value is IMPLEMENTATION DEFINED, but 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 reset value sets the field to the reset 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 | 0b1100 | 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.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
AArch64.AArch32SystemAccessTrap(EL3, 0x03);
elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.IRQ == '1' then
AArch32.TakeMonitorTrapException();
elsif HaveEL(EL3) then
if SCR.NS == '0' then
return ICC_BPR1_S;
else
return ICC_BPR1_NS;
else
return ICC_BPR1;
elsif PSTATE.EL == EL2 then
if ICC_HSRE.SRE == '0' then
UNDEFINED;
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.IRQ == '1' then
AArch64.AArch32SystemAccessTrap(EL3, 0x03);
elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.IRQ == '1' then
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>}
| coproc | opc1 | CRn | CRm | opc2 |
|---|---|---|---|---|
| 0b1111 | 0b000 | 0b1100 | 0b1100 | 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.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
AArch64.AArch32SystemAccessTrap(EL3, 0x03);
elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.IRQ == '1' then
AArch32.TakeMonitorTrapException();
elsif HaveEL(EL3) then
if SCR.NS == '0' then
ICC_BPR1_S = R[t];
else
ICC_BPR1_NS = R[t];
else
ICC_BPR1 = R[t];
elsif PSTATE.EL == EL2 then
if ICC_HSRE.SRE == '0' then
UNDEFINED;
elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.IRQ == '1' then
AArch64.AArch32SystemAccessTrap(EL3, 0x03);
elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.IRQ == '1' then
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];