Arm Network-on Chip Interconnect PMU — The Linux Kernel documentation

# Arm Network-on Chip Interconnect PMU

NI-700 and friends implement a distinct PMU for each clock domain within the interconnect. Correspondingly, the driver exposes multiple PMU devices named arm_ni_<x>_cd_<y>, where <x> is an (arbitrary) instance identifier and <y> is the clock domain ID within that particular instance. If multiple NI instances exist within a system, the PMU devices can be correlated with the underlying hardware instance via sysfs parentage.

Each PMU exposes base event aliases for the interface types present in its clock domain. These require qualifying with the “eventid” and “nodeid” parameters to specify the event code to count and the interface at which to count it (per the configured hardware ID as reflected in the xxNI_NODE_INFO register). The exception is the “cycles” alias for the PMU cycle counter, which is encoded with the PMU node type and needs no further qualification.