University of Michigan

Sudhir Kumar Satpathy

David Theodore Blaauw

Dennis Sylvester

Trevor N Mudge

Ronald George Dreslinski, Jr

Interconnect circuitryhas a plurality of data source circuitsconnected to respective input pathsand a plurality of data destination circuitsconnected to respective output paths. Connection cellsprovide selective connections between input pathsand output paths. Arbitration circuitryprovides adaptive priority arbitration between overlapping requests received at different input paths. Priority bitswithin a matrix of priority bitfor each output pathare used to represent the priority relationships between different input paths which compete for access to that output path. Update operations are applied on a per row or per column basis within the matrix to implement update schemes such as least recently granted, most recently granted, round robin, reversal, swap, selective least recently granted, selective most recently granted etc.

Crossbar circuitry for applying an adaptive priority scheme and method of operation of such crossbar circuitry

An apparatus including a first circuit and a second circuit connected in parallel to the bidirectional communication path, and one of the first and second circuits being an active circuit monitoring a value of the data signal on the bidirectional communication path while the other of the first and second circuits being a passive circuit that is not monitoring the value of the data signal. The active circuit initially starts in a low gain state, but on detection of a transition by transition detection circuitry, it enters a high gain state where the switch circuitry disconnects the transition detection circuitry from the bidirectional communication path, and the drive circuitry is activated in order to drive the data signal on the bidirectional communication path to the opposite value. Once the data signal has been driven to the opposite value, the active circuit and the passive circuits switch states.

Apparatus and method for transferring a data signal propagated along a bidirectional communication path within a data processing apparatus

Crossbar circuitry has an array of data input and output paths where the data output paths are transverse to the data input paths. At each intersection between a data input path and a data output path, a crossbar cell is provided which includes a configuration storage circuit programmable to store a routing value, a transmission circuit, and an arbitration circuit. In a transmission mode of operation, the transmission circuit is responsive to the routing value being a first value, indicating that the data input path should be coupled to the data output path, to detect the data input along the data input path, and to output an indication of that data on the data output path at the associated intersection. In an arbitration mode of operation, the arbitration circuitry is operable to selectively modify the voltage on said plurality of bit lines in order to apply an adaptive priority scheme.

Crossbar circuitry has data input and output paths, and at each intersection between a data input and output path, a crossbar cell is provided. A transmission circuit is responsive to a stored routing value to couple a data input path to a selected data output path. Pre-selection circuitry cooperates with the pre-selection circuits of other crossbar cells on the same data output path to use the bit lines of the data output path to compare quality-of-service values associated with multiple asserted transmission requests and to determine a subset thereof which have a highest value of the quality-of-service values. Arbitration circuitry implements a predetermined priority scheme to choose from that subset of requests and to cause the configuration storage circuit of only one crossbar cell associated with the same data output path to have its routing value programmed to the first value, thereby resolving conflict between multiple asserted transmission requests.

Crossbar circuitry for applying a pre-selection prior to arbitration between transmission requests and method of operation of such crossbar circuitry

Crossbar circuitry, and a method of operation of such crossbar circuitry, are provided. The crossbar circuitry has an array of data input paths and data output paths where the data output paths are transverse to the data input paths. At each intersection between a data input path and a data output path, a crossbar cell is provided that comprises a configuration storage circuit programmable to store a routing value, a transmission circuit, and an arbitration circuit. In a transmission mode of operation, the transmission circuit is responsive to the routing value being a first value, indicating that the data input path should be coupled to the data output path, to detect the data input along the data input path, and to output an indication of that data on the data output path at the associated intersection.

Crossbar circuitry and method of operation of such crossbar circuitry

Crossbar circuitry, and a method of operation of such crossbar circuitry, are provided. The crossbar circuitry has an array of data input paths and data output paths where the data output paths are transverse to the data input paths. At each intersection between a data input path and a data output path, a crossbar cell is provided that comprises a storage circuit programmable to store a routing value, and a transmission circuit. In a transmission mode of operation the transmission circuit is responsive to the routing value indicating that the data input path should be coupled to the data output path to detect the data input along the data input path, and to output an indication of that data on the data output path at the associated intersection. Control circuitry is used to issue control signals to the crossbar cells, and during a configuration mode of operation the control circuitry re-utilizes at least one of the data output paths to program the storage circuitry of one or more of the crossbar cells. Such a construction of crossbar circuitry provides a very regular design, with uniform delay across all paths, and which requires significantly less control lines than typical prior art crossbar designs. Such crossbar circuitry is readily scalable to form large crossbars.

Growing community of inventors

Ann Arbor, MI, United States of America

Sudhir Kumar Satpathy