SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
Host software sends and receives network frames via the CPDMA CPPI 3.0 compliant host interface. The host interface includes module registers and host memory data structures. The host memory data structures are buffer descriptors and data buffers. Buffer descriptors are data structures that contain information about a single data buffer. Buffer descriptors may be linked together to describe frames of queues of frames for transmission of data from the host to Ethernet and free buffer queues available for packet data from Ethernet to the host.
After reset, initialization, and configuration the host may initiate CPDMA host interface operations. Receive DMA operations are initiated by host writes to the appropriate receive channel head descriptor pointer. The receive DMA controller then fetches the first packet in the packet chain from memory in accordance with CPPI 3.0 protocol and proceeds with packet operations. The DMA controller fetches the packet data in 64-byte (maximum) bursts.
Host CPDMA transmit operation are initiated by host writes to the appropriate transmit channel head descriptor pointer after host initialization and configuration. The transmit DMA controller writes Ethernet received packet data to external host memory in accordance with CPPI 3.0 protocol.