CNTV_TVAL

AArch32 System register CNTV_TVAL bits [31:0] are architecturally mapped to AArch64 System register CNTV_TVAL_EL0[31:0].

This register is present only when AArch32 is supported. Otherwise, direct accesses to CNTV_TVAL are UNDEFINED.

Attributes

Field descriptions

TimerValue, bits [31:0]

The TimerValue view of the virtual timer.

On a read of this register:

If CNTV_CTL.ENABLE is 0, the value returned is UNKNOWN.
If CNTV_CTL.ENABLE is 1, the value returned is (CNTV_CVAL - CNTVCT).

On a write of this register, CNTV_CVAL is set to (CNTVCT + TimerValue), where TimerValue is treated as a signed 32-bit integer.

When CNTP_CTL.ENABLE is 1, the timer condition is met when (CNTVCT - CNTP_CVAL) is greater than or equal to zero. This means that TimerValue acts like a 32-bit downcounter timer. When the timer condition is met:

CNTV_CTL.ISTATUS is set to 1.
If CNTV_CTL.IMASK is 0, an interrupt is generated.

When CNTV_CTL.ENABLE is 0, the timer condition is not met, but CNTVCT continues to count, so the TimerValue view appears to continue to count down.

The reset behavior of this field is:

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

Accessing CNTV_TVAL

Accesses to this register use the following encodings in the System register encoding space:

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b000	0b1110	0b0011	0b000

if PSTATE.EL == EL0 then if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VTEN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); else AArch64.AArch32SystemAccessTrap(EL1, 0x03); elsif ELUsingAArch32(EL1) && CNTKCTL.PL0VTEN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then AArch32.TakeHypTrapException(0x00); else UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VTEN == '0' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && CNTHCTL_EL2.EL1TVT == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '0' && IsFeatureImplemented(FEAT_SEL2) then if CNTHVS_CTL_EL2.ENABLE == '0' then R[t] = bits(32) UNKNOWN; else R[t] = (CNTHVS_CVAL_EL2 - PhysicalCountInt())<31:0>; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then if CNTHV_CTL_EL2.ENABLE == '0' then R[t] = bits(32) UNKNOWN; else R[t] = (CNTHV_CVAL_EL2 - PhysicalCountInt())<31:0>; else if CNTV_CTL.ENABLE == '0' then R[t] = bits(32) UNKNOWN; elsif HaveEL(EL2) && !ELUsingAArch32(EL2) then R[t] = (CNTV_CVAL - (PhysicalCountInt() - CNTVOFF_EL2))<31:0>; elsif HaveEL(EL2) && ELUsingAArch32(EL2) then R[t] = (CNTV_CVAL - (PhysicalCountInt() - CNTVOFF))<31:0>; else R[t] = (CNTV_CVAL - PhysicalCountInt())<31:0>; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && CNTHCTL_EL2.EL1TVT == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); else if CNTV_CTL.ENABLE == '0' then R[t] = bits(32) UNKNOWN; elsif HaveEL(EL2) && !ELUsingAArch32(EL2) then R[t] = (CNTV_CVAL - (PhysicalCountInt() - CNTVOFF_EL2))<31:0>; elsif HaveEL(EL2) && ELUsingAArch32(EL2) then R[t] = (CNTV_CVAL - (PhysicalCountInt() - CNTVOFF))<31:0>; else R[t] = (CNTV_CVAL - PhysicalCountInt())<31:0>; elsif PSTATE.EL == EL2 then if CNTV_CTL.ENABLE == '0' then R[t] = bits(32) UNKNOWN; else R[t] = (CNTV_CVAL - (PhysicalCountInt() - CNTVOFF))<31:0>; elsif PSTATE.EL == EL3 then if CNTV_CTL.ENABLE == '0' then R[t] = bits(32) UNKNOWN; elsif HaveEL(EL2) then R[t] = (CNTV_CVAL - (PhysicalCountInt() - CNTVOFF))<31:0>; else R[t] = (CNTV_CVAL - PhysicalCountInt())<31:0>;

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b000	0b1110	0b0011	0b000

if PSTATE.EL == EL0 then if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VTEN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); else AArch64.AArch32SystemAccessTrap(EL1, 0x03); elsif ELUsingAArch32(EL1) && CNTKCTL.PL0VTEN == '0' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then AArch32.TakeHypTrapException(0x00); else UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VTEN == '0' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && CNTHCTL_EL2.EL1TVT == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '0' && IsFeatureImplemented(FEAT_SEL2) then CNTHVS_CVAL_EL2 = SignExtend(R[t], 64) + PhysicalCountInt(); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then CNTHV_CVAL_EL2 = SignExtend(R[t], 64) + PhysicalCountInt(); else if HaveEL(EL2) && !ELUsingAArch32(EL2) then CNTV_CVAL = (SignExtend(R[t], 64) + PhysicalCountInt()) - CNTVOFF_EL2; elsif HaveEL(EL2) && ELUsingAArch32(EL2) then CNTV_CVAL = (SignExtend(R[t], 64) + PhysicalCountInt()) - CNTVOFF; else CNTV_CVAL = SignExtend(R[t], 64) + PhysicalCountInt(); elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && CNTHCTL_EL2.EL1TVT == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); else if HaveEL(EL2) && !ELUsingAArch32(EL2) then CNTV_CVAL = (SignExtend(R[t], 64) + PhysicalCountInt()) - CNTVOFF_EL2; elsif HaveEL(EL2) && ELUsingAArch32(EL2) then CNTV_CVAL = (SignExtend(R[t], 64) + PhysicalCountInt()) - CNTVOFF; else CNTV_CVAL = SignExtend(R[t], 64) + PhysicalCountInt(); elsif PSTATE.EL == EL2 then CNTV_CVAL = (SignExtend(R[t], 64) + PhysicalCountInt()) - CNTVOFF; elsif PSTATE.EL == EL3 then if HaveEL(EL2) then CNTV_CVAL = (SignExtend(R[t], 64) + PhysicalCountInt()) - CNTVOFF; else CNTV_CVAL = SignExtend(R[t], 64) + PhysicalCountInt();

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TimerValue

CNTV_TVAL, Counter-timer Virtual Timer TimerValue register