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CNTCV, Counter Count Value register

The CNTCV characteristics are:

Purpose

Indicates the current count value.

Configuration

The power domain of CNTCV is IMPLEMENTATION DEFINED.

For more information see 'Power and reset domains for the system level implementation of the Generic Timer' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

Attributes

CNTCV is a 64-bit register.

Field descriptions

The CNTCV bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
CountValue
CountValue
313029282726252423222120191817161514131211109876543210

CountValue, bits [63:0]

Indicates the counter value.

This field resets to an architecturally UNKNOWN value.

Accessing the CNTCV

FrameAccessibility
CNTControlBaseRW
CNTReadBaseRO

A write to CNTCV must be visible in the CNTPCT register of each running processor in a finite time.

For the instance of the register in the CNTControlBase frame:

  • In a system that supports Secure and Non-secure memory maps the CNTControlBase frame, and therefore this register instance, is implemented only in the Secure memory map.
  • If the counter is enabled, the effect of writing to the register is UNKNOWN.

In an implementation that supports 64-bit atomic memory accesses, this register must be accessible using a 64-bit atomic access.

CNTCV can be accessed through the memory-mapped interfaces:

ComponentFrameOffsetInstanceRange
TimerCNTControlBase0x008CNTCV63:0

Accesses on this interface are RW.

ComponentFrameOffsetInstanceRange
TimerCNTReadBase0x000CNTCV63:0

Accesses on this interface are RO.