Motorola PPC/PMC-8260/DS1, Справочное руководство, Страница: 115 / 150

Memory Map and Devices PowerSPAN II PCI Bus Bridge
PPC/PMC-8260/DS1 5 - 11
PowerSPAN II Configuration
This section describes the basic configuration that needs to be applied by applica-
tions to gain access to the 60x bus from PCI and vice versa.
PCI Lockout
In a PCI system various configuration options are set both by the PPC/PMC-
8260/DS1 itself and by the PCI host independently. For some configuration options
it must be ensured that they have been configured properly on the PPC/PMC-
8260/DS1 before the PCI host gains access to the module.
The PCI lockout mechanism ensures that any access from the PCI bus to the
PPC/PMC-8260/DS1 is retried until all basic resources of the PowerSPAN II have
been configured. The data access is completed normally if the lockout state is left.
Note:
• It must be ensured that the PCI lockout state is ended as soon as possible
after power up. Most PCI systems have a retry limit which may cause
unpredictable results on the host, if reached.
• After ending the PCI lockout state, it does not make sense to set it again for
configuring the PowerSPAN II.
In its factory configuration, the basic settings for the PowerSPAN II are pro-
grammed into the serial E
2
PROM which is loaded at power up. After the serial
download has been completed, the PCI lockout state is left.
17 FF
16
IDR: All interrupts configured as output
18 00
16
PCI_I2O_CTL: I
2
O target image BAR disabled
19...31 00
16
Unused
32...63 00
16
Data elements for long load format (unused)
64...255 00
16
Unused
Table 25: PowerSPAN II Serial E
2
PROM Contents (cont.)
Byte Offset Contents Affected PowerSPAN II Registers