Chapter 8. DMA Controller
8-3
DMA Operation
8.3 DMA Operation
The DMA controller operates in two modes—direct and chaining. In direct mode, the
software is responsible for initializing the source address register (SAR), destination
address register (DAR), and byte count register (BCR). In chaining mode, the software
must first build descriptors segments in local or remote memory. Then the current
descriptor address register (CDAR) is initialized to point to the first descriptor in memory.
In both modes, setting the channel start bit in the DMA mode register (DMR) starts the
DMA transfer.
The DMA controller supports misaligned transfers for both the source and destination
addresses. It gathers data beginning at the source address and aligns it accordingly before
sending it to the destination address. The DMA controller assumes that the source and
Table 8-1. DMA Register Summary
PCI Memory
Offset
Local
Memory
Offset
Register Name
Description
0x100
0x0_1100
DMA 0 mode register
(DMR)
Allows software to setup up different DMA modes
and interrupt enables
0x104
0x0_1104
DMA 0 status register
(DSR)
Tracks DMA processes and errors
0x108
0x0_1108
DMA 0 current descriptor
address register (CDAR)
Contains the location of the current descriptor to
be loaded
0x110
0x0_1110
DMA 0 source address
register (SAR)
Contains the source address from which data will
be read
0x118
0x0_1118
DMA 0 destination address
register (DAR)
Contains the destination address to which data
will be written
0x120
0x0_1120
DMA 0 byte count register
(BCR)
Contains the number of bytes to transfer
0x124
0x0_1124
DMA 0 next descriptor
address register (NDAR)
Contains the next descriptor address
0x200
0x0_1200
DMA 1 mode register
(DMR)
Allows software to setup up different DMA modes
and interrupt enables
0x204
0x0_1204
DMA 1 status register
(DSR)
Tracks DMA processes and errors
0x208
0x0_1208
DMA 1 current descriptor
address register (CDAR)
Contains the location of the current descriptor to
be loaded
0x210
0x0_1210
DMA 1 source address
register (SAR)
Contains the source address from which data will
be read
0x218
0x0_1218
DMA 1 destination address
register (DAR)
Contains the destination address to which data
will be written
0x220
0x0_1220
DMA 1 byte count register
(BCR)
Contains the number of bytes to transfer
0x224
0x0_1224
DMA 1 next descriptor
address register (NDAR)
Contains the next descriptor address
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...