Hardware controlled pll switching

Abstract

A system and method for efficiently managing multiple PLLs on a system on a chip (SOC). A SOC includes a hardware phase lock loop (PLL) switching control block coupled to a software interface. The hardware PLL switching (HPS) control block receives PLL switch requests from software. The request identifies a given core clock received by a given processing core of multiple processor cores on the SOC and indicates the identified core clock is not to be provided anymore by a current PLL. The request indicates a given search method including search conditions. The HPS control block searches for a target PLL that satisfies these search conditions. In response to finding the target PLL, the HPS control block changes clock network connections and parameters across the die of the SOC. These changes across the die disconnect the identified core clock from the current PLL and connects the identified core clock to the target PLL.