Dynamic bus locking in a cross bar switch

Abstract

A cross-bar switch which includes a plurality of master bus ports, the master bus ports adapted to receive a plurality of master buses; a plurality of slave bus ports, the slave bus ports adapted to receive a plurality of slave buses; a switching mechanism for selectively coupling the plurality of master bus ports to the plurality of slave bus ports; and a configuration mechanism for locking at least one of the plurality of slave buses in response to a transfer request initiated by a master device attached to one of the plurality of master buses. The cross-bar switch has the capability of selectively locking slave buses during a bus lock transfer. In the preferred embodiment, the configuration mechanism is a Bus Lock Bit on Configuration Registers on the cross-bar switch. The Bus Lock Bit is programmable through the Device Control Register bus, which allows the cross-bar switch to be dynamically programmable and changed by a processor in a larger system. The cross-bar switch minimizes the cycle latency between data transfers. This improves the bandwidth and throughput on the on-chip bus.