Altera V-Series Avalon-MM DMA User Manual
Page 89
Address
Offset
Register
Access
Description
0x010
C
EP Write Status and Descriptor
FIFO Base (High)
RW
Specifies the upper 32 bits of the base
address of the write descriptor table in
Endpoint memory. The read DMA fetches
the table from Root Complex memory and
writes the table to this location. Software
must program this register before
programming the lower 32-bit register at
offset 0x108.
0x011
0
WR_DMA_LAST_PTR
RW
When read, returns the ID of the last
descriptor requested. If no DMA request
is outstanding or the DMA is in reset,
returns a value 0xFF.
When written, specifies the ID of the last
descriptor requested. The difference
between the value read and the value
written is the number of descriptors to be
processed.
For example, if the value reads 4, the last
descriptor requested is 4. To specify 5
more descriptors, software should write a
9 into the
RD_DMA_LAST_PTR
register. The
DMA executes 5 more descriptors.
The
Descriptor ID
loops back to 0 after
reaching
WR_TABLE_SIZE
.
For example, if the
WR_TABLE_SIZE
value
read is 126 and you want to execute three
more descriptors, software must write 127,
and then 1 into the
WR_DMA_LAST_PTR
register.
0x011
4
WR_TABLE_SIZE
RW
Specifies the size of the Read descriptor
table. Set to the number of descriptors - 1.
By default,
WR_TABLE_SIZE
is set to 127.
This value specifies the last
Descriptor
ID
.
0x011
8
WR_CONTROL
RW
[31:1] Reserved.
[0]
Done
. When set, the Descriptor
Controller writes the
Done
bit for each
descriptor in the status table. The
Descriptor Controller sends a single MSI
interrupt after the final descriptor
completes.
5-20
DMA Descriptor Controller Registers
UG-01154
2014.12.18
Altera Corporation
Registers