12. Register Descriptions
357
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
12.5.64
I2O Control and Status Register
Register Name: I2O_CSR
Register Offset: 0x508
PCI
Bits
Function
PB
Bits
31-24
PowerSpan II Reserved
0-7
23-16
PowerSpan II Reserved
8-15
15-08
PowerSpan II Reserved
16-23
07-00
HOPL_SIZE
EMTR
OFL
IPL
XI
2
O_
EN
I
2
O_EN
24-31
I
Name
Type
Reset
By
Reset
State
Function
HOPL_SIZE
[2:0]
R/W
PRI_RST
0
Host Outbound Post List Size
Specifies the size of the Host Outbound Post List
circular FIFO in the Host memory. The IOP must
program this field when PowerSpan II extended
Outbound Option support is enable (see
EMTR
R/W
PRI_RST
0
Empty FIFO Read Response
The Empty FIFO Read Response bit determines the
PowerSpan II response to an IOP read of the
Inbound Post List Bottom Pointer Register” on
page 365
“I2O Outbound Free List Bottom
. If the EMTR bit is set, a
read from either of these registers when their
corresponding FIFO is empty will return 0xffff_ffff as
read data to the IOP. If the bit is not set, the contents of
the corresponding Pointer Register will be returned as
read data.
0 = return pointer on read when FIFO empty
1 = return 0xFFFF_FFFF on read when FIFO empty
OFL
R
PRI_RST
0
Outbound Free List
Indicates status of the Outbound Free List FIFO. If this
bit is set, at least one Outbound Message Frame is
available in Host memory.
0 = empty
1 = not empty