You copied the Doc URL to your clipboard.

TRCCNTCTLR<n>, Counter Control Register <n>, n = 0 - 3

The TRCCNTCTLR<n> characteristics are:

Purpose

Controls the operation of Counter <n>.

Configuration

External register TRCCNTCTLR<n> bits [31:0] are architecturally mapped to AArch64 System register TRCCNTCTLR<n>[31:0] .

This register is present only when FEAT_ETE is implemented and TRCIDR5.NUMCNTR > n. Otherwise, direct accesses to TRCCNTCTLR<n> are RES0.

Attributes

TRCCNTCTLR<n> is a 32-bit register.

Field descriptions

The TRCCNTCTLR<n> bit assignments are:

313029282726252423222120191817161514131211109876543210
RES0CNTCHAINRLDSELFRLDEVENT_TYPERES0RLDEVENT_SELCNTEVENT_TYPERES0CNTEVENT_SEL

Bits [31:18]

Reserved, RES0.

CNTCHAIN, bit [17]

For TRCCNTCTLR3 and TRCCNTCTLR1, this bit controls whether the Counter decrements when a reload event occurs for Counter <n-1>.

CNTCHAINMeaning
0b0

The Counter does not decrement when a reload event for Counter <n-1> occurs.

0b1

Counter <n> decrements when a reload event for Counter <n-1> occurs. This concatenates Counter <n> and Counter <n-1>, to provide a larger count value.

CNTCHAIN is not implemented for TRCCNTCTLR0 and TRCCNTCTLR2.

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

RLDSELF, bit [16]

Controls whether a reload event occurs for the Counter, when the Counter reaches zero.

RLDSELFMeaning
0b0

Normal mode.

The Counter is in Normal mode.

0b1

Self-reload mode.

The Counter is in Self-reload mode.

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

RLDEVENT_TYPE, bit [15]

Chooses the type of Resource Selector.

Selects an event, that when it occurs causes a reload event for Counter <n>.

RLDEVENT_TYPEMeaning
0b0

A single Resource Selector.

TRCCNTCTLR<n>.RLDEVENT.SEL[4:0] selects the single Resource Selector, from 0-31, used to activate the resource event.

0b1

A Boolean-combined pair of Resource Selectors.

TRCCNTCTLR<n>.RLDEVENT.SEL[3:0] selects the Resource Selector pair, from 0-15, that has a Boolean function that is applied to it whose output is used to activate the resource event. TRCCNTCTLR<n>.RLDEVENT.SEL[4] is RES0.

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

Bits [14:13]

Reserved, RES0.

RLDEVENT_SEL, bits [12:8]

Defines the selected Resource Selector or pair of Resource Selectors. TRCCNTCTLR<n>.RLDEVENT.TYPE controls whether TRCCNTCTLR<n>.RLDEVENT.SEL is the index of a single Resource Selector, or the index of a pair of Resource Selectors.

Selects an event, that when it occurs causes a reload event for Counter <n>.

If an unimplemented Resource Selector is selected using this field, the behavior of the resource event is UNPREDICTABLE, and the resource event might fire or might not fire when the resources are not in the Paused state.

Selecting Resource Selector pair 0 using this field is UNPREDICTABLE, and the resource event might fire or might not fire when the resources are not in the Paused state.

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

CNTEVENT_TYPE, bit [7]

Chooses the type of Resource Selector.

Selects an event, that when it occurs causes Counter <n> to decrement.

CNTEVENT_TYPEMeaning
0b0

A single Resource Selector.

TRCCNTCTLR<n>.CNTEVENT.SEL[4:0] selects the single Resource Selector, from 0-31, used to activate the resource event.

0b1

A Boolean-combined pair of Resource Selectors.

TRCCNTCTLR<n>.CNTEVENT.SEL[3:0] selects the Resource Selector pair, from 0-15, that has a Boolean function that is applied to it whose output is used to activate the resource event. TRCCNTCTLR<n>.CNTEVENT.SEL[4] is RES0.

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

Bits [6:5]

Reserved, RES0.

CNTEVENT_SEL, bits [4:0]

Defines the selected Resource Selector or pair of Resource Selectors. TRCCNTCTLR<n>.CNTEVENT.TYPE controls whether TRCCNTCTLR<n>.CNTEVENT.SEL is the index of a single Resource Selector, or the index of a pair of Resource Selectors.

Selects an event, that when it occurs causes Counter <n> to decrement.

If an unimplemented Resource Selector is selected using this field, the behavior of the resource event is UNPREDICTABLE, and the resource event might fire or might not fire when the resources are not in the Paused state.

Selecting Resource Selector pair 0 using this field is UNPREDICTABLE, and the resource event might fire or might not fire when the resources are not in the Paused state.

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

Accessing the TRCCNTCTLR<n>

Must be programmed if TRCRSCTLR<a>.GROUP == 0b0010 and TRCRSCTLR<a>.COUNTERS[n] == 0b1.

Writes are CONSTRAINED UNPREDICTABLE if the trace unit is not in the Idle state.

TRCCNTCTLR<n> can be accessed through the external debug interface:

ComponentOffsetInstance
ETE0x150 + (4 * n)TRCCNTCTLR<n>

This interface is accessible as follows:

  • When OSLockStatus(), or !AllowExternalTraceAccess() or !IsTraceCorePowered() accesses to this register generate an error response.
  • Otherwise accesses to this register are RW.