Address
Offset
Register
Access
Description
0x010C
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.
0x0110
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.
0x0114
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
. To change the
RC Write Status and
Descriptor Base (Low)
base address, all
descriptors specified by the
WR_TABLE_
SIZE
must be exhausted.
0x0118
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.
UG-01145_avmm_dma
2015.11.02
DMA Descriptor Controller Registers
7-21
Registers
Altera Corporation
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