Confidential Draft
3/7/00
CS4281 Programming Manual
124
DS308PRM1
13.3.7
I/O Trap Control Register (IOTCR)
Address:
BA0: 58Ch, Read-Write
Default:
00000000h
Definition: Global trapping control, which DMA controller is attached to the legacy trapping, and the type of
legacy support enabled. Global trapping control can also be disabled through the
IISR.GTD
bit
which overrides the
ITD
bit.
Bit Descriptions:
ITE
I/O Trap Enable: Setting this bit enables I/O trapping globally (this avoids having to write each
IOTxxx register to disable each trap range). For trapping to be enabled
ITE
must be set and
IISR.GTD
must be clear.
0 = Global I/O trapping disabled (reset default)
1 = Global I/O trapping enabled - if
IISR.GTD
is clear
EDMA[1:0]Enable DMA Trapping: Defines the DMA trapping logic behavior.
00 = No DMA trapping, use new DMA support (reset default)
01 = CCLS - Legacy DMA - proprietary 8237 trapping enabled via IOTCC.
10 = PC/PCI DMA operation (SB engine supports directly - DMA controller does nothing).
Trapping enabled via IOTPCP.
11 = DDMA Operation and trapping of 00h through 0Fh enabled.
DMA[1:0] DMA Engine Select: binary value of these two bits selects the DMA engine assigned to the
legacy support. Since the DMAn/FIFOm link is inseparable, the
DMA
bits are active in Polled
FIFO and DMA mode if
SSCR.SB
is true.
00 = DMA Engine 0 (reset default)
01 = DMA Engine 1
10 = DMA Engine 2
11 = DMA Engine 3
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
DMA1
DMA0
EDMA1
EDMA0
res
res
res
res
res
res
ITE
D
ra
ft
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