On-chip bus

1. An on-chip bus, comprising:

an independent bus topology portion of an on-chip bus that includes a collector node and at least one device node, each device node being positioned on a chip and being coupled to an on-chip device, the collector node is capable of conducting multiple outstanding transactions with a plurality of on-chip devices over the on-chip bus wherein each on-chip device transmits respective data signals across the on-chip bus in the form of split transactions that use packets that include a header having an address, the on-chip bus includes at least one bus register, and each of the plurality of on-chip devices include at least one device register; and

wherein the on-chip bus can provide top level register to register communications between the device register and the bus register within the independent bus topology.

2. The on-chip bus of claim 1 , wherein data packets can be transferred over the top level register to register communication.

3. The on-chip bus of claim 1 , wherein a request signal and a grant signal can each be transferred over the top level register to register communication.

4. The on-chip bus of claim 1 , wherein the on-chip bus is a distributed packet on-chip (DPO) bus.

5. The on-chip bus of claim 1 , wherein the on-chip devices are arranged in a point-to-point topology.

6. The on-chip bus of claim 1 , wherein the on-chip devices are arranged in a ring topology.

7. The on-chip bus of claim 1 , wherein the topology of the on-chip devices within the on-chip bus can be selected based on software.

8. The on-chip bus of claim 1 , wherein the topology of the on-chip devices within the on-chip bus can be selected based on firmware.

9. The on-chip bus of claim 1 , wherein the topology of the on-chip devices within the on-chip bus can be selected based on hardware.

10. The on-chip bus of claim 1 , wherein for request signals and grant signals, the device register and the bus register communicate directly with each other not through a logic portion in the on-chip bus.

11. The on-chip bus of claim 1 , further comprising a mechanism that allows alteration of the physical layers to support insertion of the on-chip bus into different topologies.

12. The on-chip bus architecture of claim 1 , wherein the further comprising a bridge device which includes one of the device nodes within the independent bus topology, the bridge device further including a second collector node that is in a top-level register-to-register communication with a second device register with one or more second on-chip devices contained within a second independent bus topology.

13. The on-chip bus of claim 1 , wherein the collector node and an interrupt collector device are included in a root collector device.

14. The on-chip bus of claim 1 , wherein there is one collector node associated with each on-chip bus.

15. The on-chip bus of claim 1 , wherein the collector node is included in a root collector device, and wherein there is one root collector device associated with each on-chip bus.

16. The on-chip bus of claim 1 , in which one of multiple on-chip devices is provided with use of the on-chip bus based on an arbitration device.

17. The on-chip bus of claim 1 , wherein the on-chip bus is configured so an on-chip device can be configured as a master device that generates transactions to memory or is a target of a transaction to memory, or a slave device that is a target of a transaction to memory but does not generate transactions to memory.

18. An integrated circuit chip comprising:

an on-chip bus to provide one or more independent bus topologies, the on-chip bus comprising a root collector device and at least partially including at least one terminal device; and

a plurality of terminal devices, each terminal device including an on-chip device and such on-chip device is not included in the on-chip bus, but such on-chip device communicates via the on-chip bus;

wherein the root collector device is configured to facilitate data communications using split transactions of packets having an addressable header to and from the on-chip device of each of the plurality of terminal devices.

19. A method comprising:

topographically arranging terminal devices relative to an on-chip bus by:

establishing a first independent bus topology by connecting a first plurality of terminal devices to a root collector device, wherein the first independent bus topology is facilitated by data communications using split transactions of packets, each having a header that includes an address, between the root collector device and the first plurality of terminal devices;

establishing a second independent bus topology by connecting a first bridge device to the root collector device and connecting a second plurality of terminal devices to the first bridge device, wherein the second independent bus topology is facilitated by data communications using split transactions of packets, each having a header that includes an address, between the first bridge device and the second plurality of terminal devices; and

establishing a third independent bus topology by connecting a second bridge device to the root collector device and connecting a third plurality of terminal devices to the second bridge device, wherein the third independent bus topology is facilitated by data communications using split transactions of packets, each having a header that includes an address, between the second bridge device and the third plurality of terminal devices.