12. Register Descriptions
352
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
12.5.62
PCI I2O Target Image Control Register
This register contains the control information for the PowerSpan II PCI I
2
O Target Image. The lower
4 Kbytes of the image provide the I
2
O Shell Interface - Inbound and Outbound Queues and the Host
Interrupt Status and Mask Registers. I
2
O Message Frames are accessible above the 4-KByte boundary.
The Queues and the Message Frames reside in memory connected to the processor bus.
All PCI transactions claimed by the image are destined for the Processor Bus
The following parameters do not affect Processor Bus transactions generated by I
2
O Shell accesses:
•
TA_EN: no address translation for I
2
O Shell accesses
•
PRKEEP: no read keep for I
2
O Shell accesses
•
END
•
RD_AMT: prefetch amount fixed at 8 bytes for I
2
O Shell accesses.
Register Name: PCI_TI2O_CTL
Register Offset: 0x500
PCI
Bits
Function
PB
Bits
31-24
IMG_EN
TA_EN
BAR_EN
0
BS
0-7
23-16
PowerSpan II Reserved
RTT
8-15
15-08
GBL
CI
0
WTT
16-23
07-00
PRKEEP
END
MRA
0
RD_AMT
24-31
Name
Type
Reset
By
Reset
State
Function
IMG_EN
R/W
PRI_RST
0
Image Enable
The Image Enable bit can be changed with the following
actions:
• initial write to the BA field in the
Base Address Register” on page 257
• register write to IMG_EN
The image enable is cleared by writing a zero to IMG_EN or
writing zero to the BA field in the Px_BSI2O. This effectively
disables I2O functionality.
0 = Disable
1 = Enable