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The CNTV_CTL characteristics are:
Control register for the virtual timer.
AArch32 System register CNTV_CTL bits [31:0] are architecturally mapped to AArch64 System register CNTV_CTL_EL0[31:0] .
This register is present only
when AArch32 is supported at any Exception level.
Otherwise, direct accesses to CNTV_CTL are UNDEFINEDUNKNOWN.
CNTV_CTL is a 32-bit register.
The CNTV_CTL 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 | ISTATUS | IMASK | ENABLE |
Reserved, RES0.
The status of the timer. This bit indicates whether the timer condition is met:
ISTATUS | Meaning |
---|---|
0b0 | Timer condition is not met. |
0b1 | Timer condition is met. |
When the value of the ENABLE bit is 1, ISTATUS indicates whether the timer condition is met. ISTATUS takes no account of the value of the IMASK bit. If the value of ISTATUS is 1 and the value of IMASK is 0 then the timer interrupt is asserted.
When the value of the ENABLE bit is 0, the ISTATUS field is UNKNOWN.
For more information see 'Operation of the CompareValue views of the timers' and 'Operation of the TimerValue views of the timers'.
This bit is read-only.
Timer interrupt mask bit. Permitted values are:
IMASK | Meaning |
---|---|
0b0 | Timer interrupt is not masked by the IMASK bit. |
0b1 | Timer interrupt is masked by the IMASK bit. |
For more information, see the description of the ISTATUS bit.
This field resets to an architecturally UNKNOWN value.
Enables the timer. Permitted values are:
ENABLE | Meaning |
---|---|
0b0 | Timer disabled. |
0b1 | Timer enabled. |
Setting this bit to 0 disables the timer output signal, but the timer value accessible from CNTV_TVAL continues to count down.
Disabling the output signal might be a power-saving option.
This field resets to 0.
Accesses to this register use the following encodings:
coproc | opc1 | CRn | CRm | opc2 |
---|---|---|---|---|
0b1111 | 0b000 | 0b1110 | 0b0011 | 0b001 |
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_SEL2ARMv8.4-SecEL2") then
return CNTHVS_CTL_EL2;
elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then
return CNTHV_CTL_EL2;
else
return CNTV_CTL;
elsif PSTATE.EL == EL1 then
if EL2Enabled() && !ELUsingAArch32(EL2) && CNTHCTL_EL2.EL1TVT == '1' then
AArch64.AArch32SystemAccessTrap(EL2, 0x03);
else
return CNTV_CTL;
elsif PSTATE.EL == EL2 then
return CNTV_CTL;
elsif PSTATE.EL == EL3 then
return CNTV_CTL;
coproc | opc1 | CRn | CRm | opc2 |
---|---|---|---|---|
0b1111 | 0b000 | 0b1110 | 0b0011 | 0b001 |
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_SEL2ARMv8.4-SecEL2") then
CNTHVS_CTL_EL2 = R[t];
elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCR_EL3.NS == '1' then
CNTHV_CTL_EL2 = R[t];
else
CNTV_CTL = R[t];
elsif PSTATE.EL == EL1 then
if EL2Enabled() && !ELUsingAArch32(EL2) && CNTHCTL_EL2.EL1TVT == '1' then
AArch64.AArch32SystemAccessTrap(EL2, 0x03);
else
CNTV_CTL = R[t];
elsif PSTATE.EL == EL2 then
CNTV_CTL = R[t];
elsif PSTATE.EL == EL3 then
CNTV_CTL = R[t];
0114/0704/2020 1520:5709; 80324f0b9997bede489cc15ad1565345720bcd2adff0d3e465311dd9ce541b6a1e1d6c05a0668645
Copyright © 2010-2020 Arm Limited or its affiliates. All rights reserved. This document is Non-Confidential.
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