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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—USB 2.0 Host Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
360
Order Number: 306262-004US
9.6.3.3
DMA Engine
The DMA Engine Block presents a bus initiator (master) interface to the system
memory bus. It is responsible for moving all of the data to be transferred over the USB
between the UHS Host core and buffers in system memory. Like the microprocessor
interface block the DMA block uses the AHB protocol.
The DMA controller must access both control information and packet data from system
memory. The control information is contained in link list based queue structures. The
DMA controller has state machines that are able to parse all of the data structures
defined in this controller specification. In host mode, the data structures are from the
EHCI specification and represent queues of transfers to be performed by the host
controller, including the split transaction requests that allow an EHCI controller to direct
packets to Low and Full speed devices.
Figure 42.
DMA Engine Block Diagram
B4201-01
Context Storage
Update Logic
Byte Count ALU
Address Incrementing
Device Master
State Machine
Prime/Un-prime Control
Endpoint Manager
Device Only
Host Master
State
Machine
EHCI
Scheduler
Host Only
DMA Microprocessor Registers
To Microprocessor Interface
Burst
movement
Bus state
machine
FIFO
arbitration
Traffic
Context
Registers
Packet
movement
Host HS
Device HS
& FS
BVCI/
AMBA
Initiator
RX FIFO
TX FIFO
Vusb_hs_dma_
mem_arb_[
bvci|amba]
Vusb_hs_dma_traf
Vusb_hs_dma_up_int
Vusb_hs_dma_dev
Vusb_hs_dma_hst
Vusb_hs_dma_context