Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
521
Application DMA Unit—Intel
®
81341 and 81342
5.16.1
ADMA Channel Control Register x — ACCRx
The ADMA Control Register (ACCR) specifies parameters that dictate the overall
operating environment. The ACCR should be initialized prior to all other ADMA registers
following a system reset.
shows the register format. This register can be
read or written while the ADMA is active.
Table 316. ADMA Channel Control Register x — ACCRx
Bit
Default
Description
31
0
2
Preserved
30
0
2
Preserved
29
INTERFACE_S
EL_PCIX#
I/O Interface Select:
This bit is read/write and used to select which ATU interface PCI-to-Memory
operations use.
0 = When cleared, the ADMA uses the PCI-X interface for PCI-to-Local Memory transfers.
1 = When set, the ADMA uses the PCI Express interface for PCI-to-Local Memory transfers.
Note:
This bit automatically defaults to the interface selected by the INTERFACE_SEL_PCIX# strap.
For single interface products, this means that the bit always remains in its’ default state while
for dual interface products, the user may choose to set this bit differently across the three
ADMA channels.
28
0
2
Preserved
27:24
0H
Upper CRC Address
-- This field represents bits[35:32] of the local memory address used by the
ADMA for the CRC address defined for the CRC-32C operation.
Note:
This restricts the CRC-32C values referenced by the ADMA descriptors through the CRC Address
to be located within the single 4 Gbyte address range defined by this register.
23:20
0H
Upper Next Descriptor Address
-- This field represents bits[35:32] of the local memory address used
to fetch the next descriptor.
Note:
This restricts the entire descriptor chain to be located within a single 4 Gbyte address range
defined by this register.
19
0
2
Endian Mode Selector
- This bit selects the Host vs. Local Memory Endian mode. This is used by the
ADMA when the Endian Swap Enable in the ADCR is set.
0 = Host Memory is Little Endian, Local Memory is Big Endian
1 = Host Memory is Big Endian, Local Memory is Little Endian
18:02
00000H
Reserved
01
0
2
Chain Resume
- when set, causes the ADMA to resume chaining by re-reading the current descriptor
located at the address in the ADMA Descriptor Address Register when the ADMA is idle (ADMA Active bit
in the ACSR is clear) or when the ADMA completes a transfer. This bit is cleared by hardware when
either:
• The ADMA completes a transfer and the ADMA Next Descriptor Address Register is non-zero. In this
case, the ADMA proceeds to the next descriptor in the chain.
• The ADMA re-reads the chain descriptor located at the address in the ADMA Descriptor Address
Register and loads the Next Descriptor Address of that descriptor into the ADMA Next Descriptor
Address Register
00
0
2
ADMA Enable
- When set, the ADMA enables transfers. When clear, the ADMA disables any transfer.
Clearing this bit when the ADMA is active suspends the current transfer at the earliest opportunity by
halting all internal bus transactions. The ADMA does not initiate any new transfers when this bit is
cleared. Data held in queues remains valid. Setting the bit after the ADMA is suspended causes the
ADMA to resume the previously ongoing transfer.
Host
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
pr
na
pr
na
rw
na
pr
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rw
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rw
na
rw
na
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Channel #
0
1
2
Internal bus address offset
0000H
0200H
0400H