Hardware controlled PLL switching
First Claim
1. A method comprising:
- providing via a clock switching network a plurality of core clocks;
receiving a software-initiated request specifying a phase lock loop (PLL) configuration for a first core clock of the plurality of core clocks;
searching via a hardware control block for a given PLL of a plurality of PLLs which satisfies the request; and
controlling the clock switching network to switch connection of the first core clock from a current PLL to the given PLL.
1 Assignment
0 Petitions
Accused Products
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.
33 Citations
22 Claims
-
1. A method comprising:
-
providing via a clock switching network a plurality of core clocks; receiving a software-initiated request specifying a phase lock loop (PLL) configuration for a first core clock of the plurality of core clocks; searching via a hardware control block for a given PLL of a plurality of PLLs which satisfies the request; and controlling the clock switching network to switch connection of the first core clock from a current PLL to the given PLL. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A system-on-a-chip (SOC) comprising:
-
a plurality of phase lock loops (PLLs); a clock switching network; and a hardware PLL switching (HPS) control block coupled to the clock switching network, wherein the HPS control block is configured to; receive a software-initiated request specifying a phase lock loop (PLL) configuration for a first core clock of the plurality of core clocks; search for a given one of a plurality of PLLs as a target PLL, wherein the target PLL satisfies conditions specified in the PLL configuration; and configure the clock switching network to switch connection of the first core clock from a current PLL to the target PLL. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
-
-
17. An apparatus comprising:
-
a plurality of tables storing information corresponding to operating characteristics of a plurality of phase lock loops (PLLs); and control logic coupled to each of a first interface, a second interface and the plurality of tables, wherein the control logic is configured to; receive via the first interface a software-initiated request specifying a phase lock loop (PLL) configuration for a first core clock of the plurality of core clocks; search for a given one of a plurality of PLLs on the SOC as a target PLL, wherein the target PLL satisfies conditions specified in the PLL configuration; and in response to finding the target PLL, control the clock switching network to provide the first core clock via the target PLL. - View Dependent Claims (18, 19, 20)
-
-
21. A clock source switching system comprising:
-
a clock switching network (CSN) configured to provide a plurality of core clocks, each of said core clocks being provided from one of a plurality of phase locked loops (PLLs); a clock control circuit coupled to receive a software request that specifies a requested PLL configuration for one of a plurality of clock outputs, wherein the clock control circuit is configured to select one of the plurality of PLLs that matches the requested configuration and to control the CSN to connect the selected PLL to the one of the plurality of clock outputs; wherein the control circuit is configured to perform a search of the PLLs according to one of a plurality of methods indicated by the request. - View Dependent Claims (22)
-
Specification