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DBGPRCR, Debug Power Control Register

The DBGPRCR characteristics are:

Purpose

Controls behavior of the PE on powerdown request.

Configuration

AArch32 System register DBGPRCR bits [31:0] are architecturally mapped to AArch64 System register DBGPRCR_EL1[31:0] .

Bit [0] of this register is mapped to EDPRCR.CORENPDRQ, bit [0] of the external view of this register.

The other bits in these registers are not mapped to each other.

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. Otherwise, RW fields in this register reset to architecturally UNKNOWN values.

Attributes

DBGPRCR is a 32-bit register.

Field descriptions

The DBGPRCR bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0CORENPDRQ

Bits [31:1]

Reserved, RES0.

CORENPDRQ, bit [0]

When ARMv8.3-DoPD is implemented:

Core no powerdown request. Requests emulation of powerdown.

This request is typically passed to an external power controller. This means that whether a request causes power up is dependent on the IMPLEMENTATION DEFINED nature of the system. The power controller must not allow the Core power domain to switch off while this bit is 1.

CORENPDRQMeaning
0b0

If the system responds to a powerdown request, it powers down Core power domain.

0b1

If the system responds to a powerdown request, it does not powerdown the Core power domain, but instead emulates a powerdown of that domain.

In an implementation that includes the recommended external debug interface, this bit drives the DBGNOPWRDWN signal.

It is IMPLEMENTATION DEFINED whether this bit is reset to the Cold reset value on exit from an IMPLEMENTATION DEFINED software-visible retention state. For more information about retention states see Core power domain power states.

Note

Writes to this bit are not prohibited by the IMPLEMENTATION DEFINED authentication interface. This means that a debugger can request emulation of powerdown regardless of whether invasive debug is permitted.

The following resets apply:

  • On a Cold reset, this field is set to 1 if the powerup request is implemented and the powerup request has been asserted, and is set to 0 otherwise.

  • On a Warm reset, the value of this field is unchanged.


Otherwise:

Core no powerdown request. Requests emulation of powerdown.

This request is typically passed to an external power controller. This means that whether a request causes power up is dependent on the IMPLEMENTATION DEFINED nature of the system. The power controller must not allow the Core power domain to switch off while this bit is 1.

CORENPDRQMeaning
0b0

If the system responds to a powerdown request, it powers down Core power domain.

0b1

If the system responds to a powerdown request, it does not powerdown the Core power domain, but instead emulates a powerdown of that domain.

In an implementation that includes the recommended external debug interface, this bit drives the DBGNOPWRDWN signal.

It is IMPLEMENTATION DEFINED whether this bit is reset to the value of EDPRCR.COREPURQ on exit from an IMPLEMENTATION DEFINED software-visible retention state. For more information about retention states see Core power domain power states.

Note

Writes to this bit are not prohibited by the IMPLEMENTATION DEFINED authentication interface. This means that a debugger can request emulation of powerdown regardless of whether invasive debug is permitted.

The following resets apply:

  • On a Cold reset, this field resets to the value in EDPRCR.COREPURQ.

  • On a Warm reset, the value of this field is unchanged.

Accessing the DBGPRCR

Accesses to this register use the following encodings:

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

coprocopc1CRnCRmopc2
0b11100b0000b00010b01000b100
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDOSA> != '00' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x05);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.<TDE,TDOSA> != '00' then
        AArch32.TakeHypTrapException(0x05);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x05);
    else
        return DBGPRCR;
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x05);
    else
        return DBGPRCR;
elsif PSTATE.EL == EL3 then
    return DBGPRCR;
              

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

coprocopc1CRnCRmopc2
0b11100b0000b00010b01000b100
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDOSA> != '00' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x05);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.<TDE,TDOSA> != '00' then
        AArch32.TakeHypTrapException(0x05);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x05);
    else
        DBGPRCR = R[t];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDOSA == '1' then
        AArch64.AArch32SystemAccessTrap(EL3, 0x05);
    else
        DBGPRCR = R[t];
elsif PSTATE.EL == EL3 then
    DBGPRCR = R[t];
              


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