Intel® Stratix® 10 Hard Processor System Technical Reference Manual

ID 683222
Date 11/28/2022
Public

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16.4.2.5. Internal DMA Controller

Internal DMA controller (AHB Master) enables the core to act as a Master on the AHB to transfer data to and from the AHB.
  • Supports 32-bit data
  • Supports split, retry, and error AHB responses, but does not support wrap
  • Configurable for little-endian or big-endian mode
  • Allows the selection of AHB burst type through software

The internal DMA controller has a CSR and a single transmit or receive engine, which transfers data from system memory to the card and vice versa. The controller uses a descriptor mechanism to efficiently move data from source to destination with minimal host processor intervention. You can configure the controller to interrupt the host processor in situations such as transmit and receive data transfer completion from the card, as well as other normal or error conditions. The DMA controller and the host driver communicate through a single data structure.

The internal DMA controller transfers the data received from the card to the data buffer in the system memory, and transfers transmit data from the data buffer in the memory to the controller’s FIFO buffer. Descriptors that reside in the system memory act as pointers to these buffers.

A data buffer resides in the physical memory space of the system memory and consists of complete or partial data. The buffer status is maintained in the descriptor. Data chaining refers to data that spans multiple data buffers. However, a single descriptor cannot span multiple data buffers.

A single descriptor is used for both reception and transmission. The base address of the list is written into the descriptor list base address register (dbaddr). A descriptor list is forward linked. The last descriptor can point back to the first entry to create a ring structure. The descriptor list resides in the physical memory address space of the host. Each descriptor can point to a maximum of two data buffers.