Functional Description
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2-31
2
.
Figure 2-6. PCI Spread I/O Address Translation
Spread I/O addressing allows each PCI device’s I/O registers to reside on
a different PPC memory page, so device drivers can be protected from
each other using memory page protection.
All I/O accesses must be performed within natural word boundaries. Any
I/O access that is not contained within a natural word boundary results in
unpredictable operation. For example, an I/O transfer of four bytes starting
at address $80000010 is considered a valid transfer. An I/O transfer of four
bytes starting at address $80000011 is considered an invalid transfer since
it crosses the natural word boundary at address $80000013/$80000014.
Generating PCI Configuration Cycles
The PHB uses configuration Mechanism #1 as defined in the PCI Local
Bus Specification 2.1 to generate configuration cycles. Please refer to this
specification for a complete description of this function.
Configuration Mechanism #1 uses an address register/data register format.
Performing a configuration access is a two step process. The first step is to
place the address of the configuration cycle within the
CONFIG_ADDRESS register. Note that this action does not generate any
cycles on the PCI bus.
1915 9702
PPC A Offset
31
12 11
5 4
0
31
0
PCI Address
25 24
0 0 0 0 0 0 0
0 0 0 0 0 0 0
5 4
Summary of Contents for MVME5100 Series
Page 1: ...MVME5100 Single Board Computer Programmer s Reference Guide V5100A PG2 September 2001 Edition ...
Page 16: ...xvi ...
Page 20: ...xx ...
Page 28: ...xxviii ...
Page 62: ...1 34 Computer Group Literature Center Web Site Product Data and Memory Maps 1 ...
Page 278: ...3 88 Computer Group Literature Center Web Site System Memory Controller SMC 3 ...
Page 288: ...4 10 Computer Group Literature Center Web Site Hawk Programming Details 4 ...
Page 320: ...Index IN 12 Computer Group Literature Center Web Site I N D E X ...