SysReg_v83A_xml-00bet4 (old)htmldiff from-SysReg_v83A_xml-00bet4(new) SysReg_v83A_xml-00bet5

CNTV_CVAL, Counter-timer Virtual Timer CompareValue

The CNTV_CVAL characteristics are:

Purpose

Holds the 64-bit compare value for the virtual timer.

This register is part of the Generic Timer registers functional group.

Usage constraints

This register is accessible as follows:

Default
RW

CNTV_CVAL can be implemented in any implemented CNTBaseN frame that has virtual timer capability, and in the corresponding CNTEL0BaseN frame.

'CNTCTLBase status and control fields for the CNTBaseN and CNTEL0BaseN frames' in Chapter I1 of the ARMv8 ARM describes the status fields that identify whether a CNTBaseN frame is implemented, and for an implemented frame:

For an implemented CNTBaseN frame that has virtual timer capability:

For an implemented CNTEL0BaseN frame:

If the implementation supports 64-bit atomic accesses, then the CNTV_CVAL register must be accessible as an atomic 64-bit value.

Configuration

The power domain of CNTV_CVAL is IMPLEMENTATION DEFINED.

On a reset of the reset domain in which an RW instance of this register is implemented, RW fields in the register reset to UNKNOWN values. The register is not affected by a reset of any other reset domain. For more information see 'Power and reset domains for the system level implementation of the Generic Timer' in Chapter I1 of the ARMv8 ARM.

Attributes

CNTV_CVAL is a 64-bit register.

Field descriptions

The CNTV_CVAL bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
CompareValue
CompareValue
313029282726252423222120191817161514131211109876543210

CompareValue, bits [63:0]

Holds the virtual timer CompareValue.

When CNTV_CTL.ENABLE is 1, the timer condition is met when (CNTVCT - 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 CNTV_CTL.ENABLE is 0, the timer condition is not met, but CNTVCT continues to count.

Accessing the CNTV_CVAL

CNTV_CVAL[31:0] can be accessed through its memory-mapped interface:

ComponentFrameOffset
TimerCNTBaseN0x030
TimerCNTEL0BaseN0x030

CNTV_CVAL[63:32] can be accessed through its memory-mapped interface:

ComponentFrameOffset
TimerCNTBaseN0x034
TimerCNTEL0BaseN0x034



28/0907/2017 0816:2440

Copyright © 2010-2017 ARM Limited or its affiliates. All rights reserved. This document is Non-Confidential.

SysReg_v83A_xml-00bet4 (old)htmldiff from-SysReg_v83A_xml-00bet4(new) SysReg_v83A_xml-00bet5