The CNTFRQ_EL0 characteristics are:
This register is provided so that software can discover the frequency of the system counter. It must be programmed with this value as part of system initialization. The value of the register is not interpreted by hardware.
AArch64 System register CNTFRQ_EL0 bits [31:0] are architecturally mapped to AArch32 System register CNTFRQ[31:0] .
RW fields in this register reset to architecturally UNKNOWN values.
CNTFRQ_EL0 is a 64-bit register.
The CNTFRQ_EL0 bit assignments are:
63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 |
RES0 | |||||||||||||||||||||||||||||||
Clock frequency | |||||||||||||||||||||||||||||||
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 |
Reserved, RES0.
Clock frequency. Indicates the system counter clock frequency, in Hz.
This field resets to an architecturally UNKNOWN value.
Accesses to this register use the following encodings:
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b011 | 0b1110 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); elsif !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.<EL0PCTEN,EL0VCTEN> == '00' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.<EL0PCTEN,EL0VCTEN> == '00' then AArch64.SystemAccessTrap(EL2, 0x18); else return CNTFRQ_EL0; elsif PSTATE.EL == EL1 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else return CNTFRQ_EL0; elsif PSTATE.EL == EL2 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else return CNTFRQ_EL0; elsif PSTATE.EL == EL3 then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then AArch64.SystemAccessTrap(EL3, 0x18); else return CNTFRQ_EL0;
op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|
0b11 | 0b011 | 0b1110 | 0b0000 | 0b000 |
if IsHighestEL(PSTATE.EL) then if IsFeatureImplemented("Morello") && !CapIsSystemAccessEnabled() && !Halted() then if TargetELForCapabilityExceptions() == EL1 then AArch64.SystemAccessTrap(EL1, 0x18); elsif TargetELForCapabilityExceptions() == EL2 then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL3, 0x18); else CNTFRQ_EL0 = X[t]; else UNDEFINED;
12/01/2022 09:56; 05a4944b4b04e7ab50def8c126b479d22136f35b
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