Product specifications

VT8235 V-Link South Bridge
Revision 1.22 October 24, 2002 -115- Device 17 Function 6 Modem Controller Registers
I/O Base 0 Regs – Modem Scatter / Gather DMA
Modem SGD Read Channel Registers
I/O Offset 40 – Modem SGD Read Channel Status.....RWC
7 SGD Active ......................................................... RO
0 SGD has completed or been terminated default
1 SGD Active
6 SGD Paused ......................................................... RO
0 SGD not paused..................................... default
1 SGD Paused
5-4 Reserved ........................................ always reads 0
3 SGD Trigger Queued.......................................... RO
This bit reports whether the trigger used to restart the
SGD operation is queued (I/O Offset 41[1] = 1 while
the SGD engine is running).
0 SGD trigger not queued......................... default
1 SGD trigger queued (when SGD reaches EOL,
it will restart).
2 SGD Stop Interrupt Status..............................RWC
1 SGD finished the index equal to the stop index
set in 4B-48[31-24].
1 SGD EOL (End Of Link).................................RWC
1 Block is the last of the link. May be used by
software as a signal to generate an interrupt
request if I/O Offset 41[1] = 1.
0 SGD Flag ......................................................RWC
1 Block complete. May be used by software as a
signal to generate an interrupt request if I/O
Offset 41[0] = 1.
I/O Offset 41 – Modem SGD Read Channel Control.....RW
7 SGD Start ............................WO (always reads 0)
0 No effect
1 Start SGD read channel operation
6 SGD Terminate ......................WO (always reads 0)
0 No effect
1 Terminate SGD read channel operation
5-4 Test (Do Not Program) .......................always write 0
3 SGD Pause .........................................................RW
0 Release SGD read channel pause and resume
the transfer from the paused line
1 Pause SGD read channel operation (SGD read
channel pointer stays at the current address)
2-0 Reserved ........................................ always reads 0
I/O Offset 42 – Modem SGD Read Channel Type ......... RW
7 Auto-Start SGD at EOL
0 Stop at EOL ...........................................default
1 Auto restart at EOL
6-4 Reserved ........................................always reads 0
3-2 Interrupt Select
This bit determines the timing of interrupt generation
when bit-1 or bit-0 of this register are equal to 1.
00 Interrupt at PCI Read of Last Line.........default
01 Interrupt at Last Sample Sent
10 Interrupt at Less Than One Line to Send
11 -reserved-
1 Interrupt on EOL @ End of Block
0 Disable...................................................default
1 Enable
0 Interrupt on FLAG @ End-of-Blk
0 Disable...................................................default
1 Enable
I/O Offset 47-44 – Modem SGD R Ch Table Ptr Base... RW
31-0 SGD Table Pointer Base Address (even addr)....W
Current Pointer Address .......................................R
I/O Offset 4F-4C – Modem SGD R Ch Current Count..RO
31-24 Current Modem SGD Read Channel Index
This field reports the index the SGD engine is
currently processing.
23-0 Current Modem SGD Read Channel Count
This field reports the count remaining in the current
entry being processed. For example, if 10 bytes of a
30-byte count have been transferred, this field would
read 20 to indicate 20 bytes remaining.
Modem SGD Table Format
63
62 61 60-56 55-32 31-0
EOL FLAG STOP -reserved- Base Base
Count Address
[23:0] [31:0]