CPC700 User’s Manual—Preliminary
1-5
Processor to PLB Interface
The CPC700 provides an interface to attach a 60x or 7xx processor to the internal PLB and to provide the
processor with a low latency access path to local memory. Through this interface, the processor may
access the PCI bus, local memory, external peripherals, and internal peripherals (UARTs, I2Cs, Timers,
and interrupt controller).
Processor interface features:
• Supports PowerPC 603e, 740, and 750 families.
• One level processor address pipelining.
• Support for processor “no-DRTRY” mode.
• Processor bus arbiter arbitrates between local processor and internal snoop engine.
• L1 cache coherency support during PCI access to local memory.
• 32-byte write buffer to memory.
• 32-byte write buffer to PLB.
• lwarx/stwx. support (reservation cancelling snoops).
• Address only cycle support.
• External MCP_REQ input may be programmed to drive MCP to processor.
• Error tracking/status for processor transactions.
• Provides low latency access path to local memory.
Address Map Support
The CPC700 incorporates a simple fixed processor address map that serves the PowerPC family of pro-
cessors. The address map has provisions for ROM, RAM, and I/O. Mapping does not require flexibility
because the CPC700 has the ability to map primary and secondary resources independently. This map-
ping can be performed solely from the processor side or from a combination of the processor and the PCI
side. This mechanism lets the same fixed secondary resources become flexible to the primary side, while
providing local processor operating space stability.
Through the use of “Mapping Port Windows,” either the PowerPC or PCI can gain access to the other
side’s resources. There are three local windows available to the PowerPC to access PCI memory. These
windows can be programmed to powers of 2 boundaries, are variable in size, and may be used to access
any location in a 64-bit PCI address space yet are invisible to the PCI bus.
PCI to local processor memory access “Port Windows” are handled in the PCI standard method, through
the programming of the Base Address Registers (BARs) in PCI configuration space. These registers are
defined to allow the PowerPC processor to request allocation of resources on the PCI side. There are
some fundamental differences though, that differentiate the CPC700 from other embedded solutions. The
first of these differences is that the PowerPC can program the size of the allocation as well as the type: I/O
or Memory. The second difference is that the actual location allocated by the host is translated to the Pow-
erPC space via secondary registers allowing the PowerPC to maintain its local allocation independent of
PCI mappings.
There are two BARs available in the CPC700 for this function.
Содержание CPC700
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Страница 10: ...Table of Contents x Table of Contents...
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Страница 246: ...I 11 2 JTAG...
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