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PMLAR: Performance Monitors Lock Access Register

Purpose

Allows or disallows access to the Performance Monitors registers through a memory-mapped interface.

The optional Software Lock provides a lock to prevent memory-mapped writes to the Performance Monitors registers. Use of this lock mechanism reduces the risk of accidental damage to the contents of the Performance Monitors registers. It does not, and cannot, prevent all accidental or malicious damage.

Configuration

This register is present only when FEAT_PMUv3_EXT32 is implemented. Otherwise, direct accesses to PMLAR are RES0.

If FEAT_DoPD is implemented, Software Lock is not implemented by the architecturally-defined debug components of the PE in the Core power domain.

If FEAT_DoPD is not implemented, this register is in the Debug power domain.

Software uses PMLAR to set or clear the lock, and PMU.PMLSR to check the current status of the lock.

Attributes

PMLAR is a 32-bit register.

This register is part of the PMU block.

Field descriptions

When Software Lock is implemented:

313029282726252423222120191817161514131211109876543210
KEY

KEY, bits [31:0]

Lock Access control. Writing the key value 0xC5ACCE55 to this field unlocks the lock, enabling write accesses to this component's registers through a memory-mapped interface.

Writing any other value to this register locks the lock, disabling write accesses to this component's registers through a memory mapped interface.

Otherwise:

313029282726252423222120191817161514131211109876543210
RES0

Otherwise

Bits [31:0]

Reserved, RES0.

Accessing PMLAR

Accesses to this register use the following encodings:

Accessible at offset 0xFB0 from PMU