Encoding assertion and de-assertion of interrupt requests and DMA requests in a serial bus I/O system

摘要

A computing system encodes and emulates requests signals, such as DMA requests or interrupt requests. A first peripheral device is connected to a first request pin of a first input/output (I/O) device. When the first peripheral device asserts a first request signal on the first request pin, a serializer within the first I/O device generates a first packet. The serializer forwards the first packet to a serial out port of the first I/O device. The first packet identifies the type of request and the direction of the edge transition. The serial out port forwards the first packet to a serial in port of a controller device. Upon the serial in port receiving the first packet, an unserializer within the controller device asserts an emulated first request signal, the emulated first request signal being coupled to a first request controller within the controller device. When the first peripheral device de-asserts the first request signal on the first request pin of the first I/O device, the serializer generates a second packet. The second packet identifies the type of request and the direction of the edge transition. The serializer forwards the second packet to the serial out port of the first I/O device. The serial out port of the first I/O device forwards the second packet to the serial in port of the controller device. Upon the serial in port receiving the second packet, the unserializer within the request controller de-asserts the emulated first request signal. When the first peripheral device pulses the first request signal by quickly de-asserting and asserting the first request signal in quick succession, the second packet is sent, but not the first packet.