Intel GD82559ER - Manual (Page 54)

GD82559ER — Networking Silicon
48 Datasheet
7.1.2 PCI Command Register
The 82559ER Command register at word address 04h in the PCI configuration space provides
control over the 82559ER’s ability to generate and respond to PCI cycles
. If a 0His written to this
register, the 82559ER is logically disconnected from the PCI bus for all accesses except
configuration accesses
. The format of this register is shown in the figure below.
Note that bits three, five, seven, and nine are set to 0b. The table below describes the bits of the PCI
Command register.
Figure 18. PCI Command Register
Reserved
SERR# Enable
Parity Error Response
Memory Write and Invalidate Enable
Bus Master Enable
Memory Space
IO space
0 0 0 0
10 15 0 1 2 3 4 5 6 7 8 9
Table 5. PCI Command Register Bits
Bits Name Description
15:10 Reserved These bits are reserved and should be set to 000000b.
8 SERR# Enable
This bit controls a device’s ability to enable the SERR# driver. A value of 0b
disables the SERR# driver. A value of 1b enables the SERR# driver. This
bit must be set to report address parity errors. In the 82559ER, this bit is
configurable and has a default value of 0b.
6 Parity Error Control
This bit controls a device’s response to parity errors. A value of 0b causes
the device to ignore any parity errors that it detects and continue normal
operation. A value of 1b causes the device to take normal action when a
parity error is detected. This bit must be set to 0b after RST# is asserted. In
the 82559ER, this bit is configurable and has a default value of 0b.
4
Memory Write and
Invalidate Enable
This bit controls a device’s ability to use the Memory Write and Invalidate
command. A value of 0b disables the device from using the Memory Write
and Invalidate Enable command. A value of 1b enables the device to use
the Memory Write and Invalidate command. In the 82559ER, this bit is
configurable and has a default value of 0b.
2 Bus Master
This bit controls a device’s ability to act as a master on the PCI bus. A
value of 0b disables the device from generating PCI accesses. A value of
1b allows the device to behave as a bus master. In the 82559ER, this bit is
configurable and has a default value of 0b.
1 Memory Space
This bit controls a device’s response to the memory space accesses. A
value of 0b disables the device response. A value of 1b allows the device
to respond to memory space accesses. In the 82559ER, this bit is
configurable and its default value of 0b.
0 I/O Space
This bit controls a device’s response to the I/O space accesses
.
A value of
0b disables the device response. A value of 1b allows the device to
respond to I/O space accesses. In the 82559ER, this bit is configurable and
the default value of 0b.