Writing a Packet-Based Bus Master DMA Driver

In packet-based bus master DMA, the device transfers data to or from the locked down pages of the caller's buffer, using DMA hardware that is part of the device itself. Depending on the capabilities of the device, it might be providing its own scatter/gather support as well.

The architecture of a packet-based bus master driver is almost identical to that of a driver for a slave device. The only difference is the way the driver sets up the bus master hardware. The following sections describe these differences.