Split filtering in multilayer systems
AssigneeAltera Corporation
InventorsFabio P Sousa, Andrew Draper
Life of this patent
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Abstract
Circuitry and methods enable masters without split capability to communicate with split capable slaves in a multilayer system. The output stage associated with each split capable slave, which usually comprises an arbiter, is augmented with a split filter. This split filter designates a channel on behalf of the master without split capability, filters the split and unsplit responses from the slave, and issues a second read request on behalf of the same master. Consequently, both the master without split capability and the split capable slave do not perceive any difference between this transaction and a normal one. The split filter implementation requires, at most, little change to the master and slave devices of the system.
Claims22
A method of communication between a master device and a slave device with the aid of output stage circuitry that conveys signals between the master device and the slave device, comprising:
- issuing a first request from the master device to the slave device;
- receiving with the output stage circuitry a split response from the slave device in response to the first request;
- receiving with the output stage circuitry an unsplit response from the slave device;
- issuing a second request to the slave device from the output stage circuitry in response to receiving the unsplit response from the slave device;
- and
- fulfilling the first request from the slave device in response to the second request, wherein:
- the master device is not capable of performing split transactions;
- and
- the slave device is capable of performing split transactions.
A split filter circuit associated with a slave device, comprising:
- means for communicating a first request from a master device to the slave device;
- means for receiving a split response from the slave device;
- means for receiving an unsplit response from the slave device;
- means for communicating a second request to the slave device in response to receiving the unsplit response from the slave device;
- and
- means for communicating a fulfillment of the first request from the slave device to the master device in response to the second request, wherein:
- the master device is not capable of performing split transactions;
- and
- the slave device is capable of performing split transactions.
A method of facilitating communication between split capable slave circuitry and master circuitry that is not split capable, the communication taking place at least in part via output stage circuitry, the method comprising:
- receiving with the output stage circuitry a request for communication from the master circuitry;
- storing the request in the output stage circuitry;
- applying the request from the output stage circuitry to the slave circuitry;
- communicating a not ready signal from the output stage circuitry to the master circuitry;
- receiving with the output stage circuitry a split signal from the slave circuitry;
- receiving with the output stage circuitry an unsplit signal from the slave circuitry;
- using results of the storing to re-apply the request by the output stage circuitry to the slave circuitry in response to the output stage circuitry receiving the unsplit signal from the slave circuitry;
- and
- applying a ready signal from the output stage circuitry to the master circuitry.
Apparatus for facilitating communication between split capable slave circuitry and master circuitry that does not have split capability, comprising:
- first circuitry that (1) receives from the master circuitry a request for communication between the master and slave circuitries, (2) stores the request, (3) forwards the request to the slave circuitry, and (4) communicates a not ready signal to the master circuitry;
- second circuitry that receives a split signal from the slave circuitry;
- third circuitry that receives an unsplit signal from the slave circuitry and again communicates the request stored by the first circuitry to the slave circuitry in response to receiving the unsplit signal from the slave circuitry;
- and
- fourth circuitry that communicates a ready signal to the master circuitry.
Dependencies are inferred from the claim text.