Hardware-based automatic clock gating

Abstract

A system and method for automatically updating with hardware clock tree settings on a system-on-a-chip (SOC). A SOC includes a hardware clock control unit (HCCU) coupled to a software interface and a clock tree. The SOC also includes multiple integrated circuit (IC) devices, wherein each IC device receives one or more associated core clocks provided by one or more phase lock loops (PLLs) via the clock tree. The HCCU receives a software-initiated request specifying a given IC device is to be enabled. The HCCU identifies one or more core clocks used by the given IC device. For each one of the identified core clocks, the HCCU configures associated circuitry within the clock tree to generate an identified core clock. The HCCU may also traverse the clock tree and disable clock generating gates found not to drive any other enabled gates or IC devices.