Dynamic clock and power gating with decentralized wake-ups

A method comprising:

• communicating over a first communications link of a plurality of communications links, said communicating being performed by a first functional unit of an integrated circuit (IC) and a second functional unit of the IC, the IC having a plurality of functional units including the first and second functional units, wherein each of the plurality of functional units is coupled to at least one other one of the plurality of functional units by a unique one of the plurality of communications links;
• entering, at internal circuitry of the second functional unit, a low power state, wherein entering the low power state is caused by a local power management circuit of the second functional unit based on communications with a power management unit coupled to each of the plurality of functional units;
• transmitting, from the first functional unit to the second functional unit, a request for communications over the first communication link;
• exiting the low power state at the second functional unit responsive to receiving the request from the first functional unit, wherein the request is conveyed directly from a local power management circuit of the first functional unit to the local power management circuit of the second functional unit and without receiving a signal from the power management unit;
• monitoring, by a link state machine in the power management unit, an availability of each of the plurality of communications links.

An integrated circuit comprising:

• a plurality of functional blocks, wherein at least a first subset of the plurality of functional blocks are each power manageable functional blocks configured to enter a low power state when idle, wherein each of the plurality of functional blocks includes a corresponding local power management circuit configured to perform power management functions on corresponding internal circuitry;
• a plurality of communications links, wherein each of the plurality of communications links is a two-way communications link uniquely coupled between corresponding logically adjacent pairs of the plurality of functional blocks;
• and
• a power management circuit coupled to each of the plurality of functional blocks, wherein the power management circuit includes a state machine configured to monitor availability of each of the plurality of communications links;
• wherein a first one of the plurality of functional blocks is configured to cause a second one of the plurality of functional blocks to exit the low power state responsive to a request conveyed from the first one of the functional blocks, wherein the request is conveyed directly to a local power management circuit of the second one of the plurality of functional blocks from a local power management circuit of the first one of the plurality of functional blocks.

A method comprising:

• conveying a first request from a first one of a plurality of functional blocks of an integrated circuit to a power management unit of the integrated circuit, wherein the first request is a request to enter a low power state, each of the plurality of functional blocks including a respective local power management circuit configured to perform power management functions on internal circuitry of its corresponding functional block;
• placing the first one of the plurality of functional blocks into the low power state responsive to the request, wherein said placing into the low power state is performed by the power management unit;
• conveying a second request from a second one of the plurality of functional blocks to the first one of the plurality of functional blocks over a first one of a plurality of communications links, wherein each of plurality of functional blocks is coupled to at least one other one of the plurality of functional blocks by a unique one of the plurality of communications links, wherein the second request is a request for the first one of the plurality of functional blocks to exit the low power state, wherein the first and seconds ones of the plurality of functional blocks are logically adjacent to one another, wherein the second request is conveyed directly from a local power management circuit of the second one of the plurality of functional circuit blocks to a local power management circuit of the first one of the plurality of functional circuit blocks;
• exiting the low power state at the first one of the plurality of functional blocks responsive to the second request;
• and
• monitoring, by a link state machine in the power management unit, an availability of each of the plurality of communications links.

An integrated circuit comprising:

• a plurality of functional units including first and second functional units, wherein the first and second functional units are logically adjacent to one another, and wherein each of the plurality of functional units includes a respective local power management circuit configured to perform power management of internal circuitry of its respective one of the plurality of functional units;
• a plurality of communications links including a first communications link coupled between the first and second functional units, wherein each of the plurality of functional units is coupled to at least one other one of the plurality of functional units by a unique one of the plurality of communications links;
• and
• a power management unit coupled to each of the plurality of functional units, wherein the power management unit is configured to cause the first functional unit, via its respective local power management circuit, to enter a low power state responsive to receiving a first request from the first functional unit, wherein the power management unit includes a state machine configured to monitor availability of each of the plurality of communications links;
• wherein a local power management circuit of the second functional unit is configured to directly convey a request to a local power management circuit of the first functional unit to cause the first functional unit to resume operation in an active state responsive to a second request conveyed from the second functional unit.