IDT PCI Bus Interface
PCI Register Description
79RC32438 User Reference Manual
10 - 6
November 4, 2002
Notes
Read Value:
Previous value written
Write Effect:
Modify value
EAP
Description:
Enable Arbiter Parking
. When this bit is set and the PCI bus interface is configured to operate
in PCI host mode with an internal arbiter, then PCI bus parking is enabled. Enabling bus parking
causes the internal PCI arbiter to “park” the bus on the last master granted the bus as long as no
other master requests the bus.
Initial Value:
0x0
(A warm reset does not modify this field except under the following conditions: the warm
reset occurs as a result of the assertion of the PCI reset signal and the RC32438 is operat-
ing in PCI satellite mode. When a warm reset occurs under the above conditions, this field
takes on its initial value.)
Read Value:
Previous value written
Write Effect:
Modify value
PCIM
Description:
PCI Mode
. This field indicates the PCI operating mode selected during boot configuration.
0x0 - Disabled (EN bit in PCIC register is cleared)
0x1 - PCI satellite mode with PCI target not ready
0x2 - PCI satellite mode with suspended CPU execution
0x3 - PCI host mode with external arbiter
0x4 - PCI host mode with internal arbiter using fixed priority arbitration algorithm
0x5 - PCI host mode with internal arbiter using round robin arbitration algorithm
0x6 - reserved
0x7 - reserved
Initial Value:
See PCI mode boot configuration in Table 3.3 of Chapter 3.
Read Value:
Status
Write Effect:
Read-only
IGM
Description:
Idle Grant Mode
. This bit controls the operation of the internal arbiter when the PCI interface is
configured to operate in a PCI host mode with internal arbiter. When the internal arbiter is used
and this bit is cleared, the arbiter operates in a static idle grant mode. This means that once a
grant is asserted when the PCI bus is idle, the grant will remain asserted until the requested
transaction completes or 16 PCI clock cycles have elapsed. When the internal arbiter is used
and this bit is set, the arbiter operates in a dynamic idle grant mode. This means that while the
PCI bus is idle, the arbiter may take away a grant from one master and pass it to another.
Initial Value:
0x0
Read Value:
Previous value written
Write Effect:
Modify value