CNTPS_CVAL_EL1, Counter-timer Physical Secure Timer CompareValue register

The CNTPS_CVAL_EL1 characteristics are:

Purpose

Holds the compare value for the secure physical timer, usually accessible at EL3 but configurably accessible at EL1 in Secure state.

Configuration

There are no configuration notes.

Attributes

CNTPS_CVAL_EL1 is a 64-bit register.

Field descriptions

The CNTPS_CVAL_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
CompareValue
CompareValue
313029282726252423222120191817161514131211109876543210

CompareValue, bits [63:0]

Holds the secure physical timer CompareValue.

When CNTPS_CTL_EL1.ENABLE is 1, the timer condition is met when (CNTPCT_EL0 - CompareValue) is greater than or equal to zero. This means that CompareValue acts like a 64-bit upcounter timer. When the timer condition is met:

When CNTPS_CTL_EL1.ENABLE is 0, the timer condition is not met, but CNTPCT_EL0 continues to count.

If the Generic counter is implemented at a size less than 64 bits, then this field is permitted to be implemented at the same width as the counter, and the upper bits are RES0.

The value of this field is treated as zero-extended in all counter calculations.

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

Accessing the CNTPS_CVAL_EL1

Accesses to this register use the following encodings:

MRS <Xt>, CNTPS_CVAL_EL1

op0op1CRnCRmop2
0b110b1110b11100b00100b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && SCR_EL3.NS == '0' then if SCR_EL3.EEL2 == '1' then UNDEFINED; elsif SCR_EL3.ST == '0' then AArch64.SystemAccessTrap(EL3, 0x18); else return CNTPS_CVAL_EL1; else UNDEFINED; elsif PSTATE.EL == EL2 then UNDEFINED; elsif PSTATE.EL == EL3 then return CNTPS_CVAL_EL1;

MSR CNTPS_CVAL_EL1, <Xt>

op0op1CRnCRmop2
0b110b1110b11100b00100b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && SCR_EL3.NS == '0' then if SCR_EL3.EEL2 == '1' then UNDEFINED; elsif SCR_EL3.ST == '0' then AArch64.SystemAccessTrap(EL3, 0x18); else CNTPS_CVAL_EL1 = X[t]; else UNDEFINED; elsif PSTATE.EL == EL2 then UNDEFINED; elsif PSTATE.EL == EL3 then CNTPS_CVAL_EL1 = X[t];




30/09/2020 15:07; ccead0cb9f089f9ceec50268e82aec9e71047211

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