Dma Overview - Motorola MPC8240 User Manual

Chapter 8
DMA Controller
This chapter describes the DMA controller of the MPC8240—the operation of the two
DMA channels, the function of the DMA transfer types, the DMA descriptors' format, and
the programming details for the DMA registers and their features.

8.1 DMA Overview

The MPC8240's DMA controller transfers blocks of data independent of the local
processor or PCI hosts. Data movement occurs on the PCI and/or memory bus. The
MPC8240 has two DMA channels, each with a 64-byte queue to facilitate the gathering and
sending of data. Both the local processor and PCI masters can initiate a DMA transfer.
Some of the features of the MPC8240 DMA unit are:
• Two DMA channels (0 and 1)
• Both channels accessible by processor core and remote PCI masters
• Misaligned transfer capability
• Chaining mode (including scatter gathering)
• Direct mode
• Interrupt on completed segment, chain, and error conditions
• Four DMA transfer types:
— Local memory to local memory
— PCI memory to PCI memory
— PCI memory to local memory
— Local memory to PCI memory
The DMA controller functions as a PCI agent relative to the other internal resources of the
MPC8240.
Chapter 8. DMA Controller 8-1