Lsi Logic Corporation

Russell Andrew Johnson

Andrew Carl Brown

Stephen B Johnson

An intelligent host adapter for coupling a host PC to peripheral I/O devices through I/O channels wherein the host adapter has a master/slave architecture. A master I/O processor includes circuits for coupling the host adapter to a slot in an I/O interface bus of the host PC such as a PCI bus. The master I/O processor also includes circuits for a relatively small fixed number of I/O channels for connection to associated I/O peripheral busses such as SCSI, Fiber Channel and networks (i.e., Ethernet, token ring, etc.). A slave I/O processor is coupled to the master I/O processor via a dedicated master/slave interface bus. The slave I/O processor provides for addition of I/O channels to the host adapter without requiring use of additional slots of the I/O interface bus of the host PC and without using associated I/O computing resources within the host PC.

Methods and systems for intelligent I/O controller with channel expandability via master/slave configuration

A set of registers are provided for a protocol engine driving I/O transactions requested by a host. A fixed set of defined data elements are determined for the protocol under which the I/O transaction is to be performed. Each register maps to a data structure base address or to a different data element offset or byte count. During initialization, the registers are programmed by an operating system device driver with offsets from a base address and byte counts for each data element within the defined set as those data elements are found within an operating system specific data structure for the I/O transaction, although data elements having a fixed size for each operating system may not require the byte count to be specified. For each I/O transaction requested, the base address in the host memory of the operating system specific data structure is programmed by the device driver into a register. The I/O protocol engine utilizes the base address together with the offset and byte count information to commence the requested I/O transaction. The base address is programmed by the device driver into the appropriate register on an each I/O basis, without requiring translation of the entire data structure. By permitting the hardware to be configured to effectively utilize the operating system data structure, the need for data structure translation is eliminated, CPU utilization is reduced, and increased I/O throughput is achieved.

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Monument, CO, United States of America

Russell Andrew Johnson