Chapter 4. Configuration Registers
4-1
Chapter 4
Configuration Registers
This chapter describes the programmable configuration registers of the MPC8240. These
registers are generally set up by initialization software following a power-on reset, hard
reset, or error handling routines. All the configuration registers of the MPC8240 are
intrinsically little-endian. In the register descriptions of this chapter, bit 0 is the least
significant bit of the register. This bit numbering is based upon the PCI standard for register
bit order numbering and is opposite from the standard PowerPC bit ordering where bit b0
is the most significant bit of the register.
Reserved bits in the register descriptions are not guaranteed to have predictable values.
Software must preserve the values of reserved bits when writing to a configuration register.
Also, when reading from a configuration register, software should not rely on the value of
any reserved bit remaining consistent. Thus, the values of reserved bit positions must first
be read, merged with the new values for other bit positions, and then written back. Software
should use the transfer size shown in the register bit descriptions throughout this chapter.
4.1 Configuration Register Access
The MPC8240 configuration registers are accessible from the processor core through
memory-mapped configuration ports. The registers are accessed by an indirect method
similar to accessing PCI device configuration registers. A 32-bit register address
0x8000_00nn, where nn is the address offset of the desired configuration register (see
Table 4-2 and Figure 4-1), is written to the CONFIG_ADDR port. Then, the data is
accessed at the CONFIG_DAT port. The locations of these ports are described in Table 4-1.
Table 4-1. Internal Register Access Port Locations
Address Map
CONFIG_ADDR
CONFIG_DAT
A
0x8000_0CF8
0x8000_0CFC–0x8000_0CFF
B
Any word-aligned address within the
range 0xFEC0_0000–0xFEDF_FFFC
*
0xFEE0_0000–0xFEEF_FFFF
1
1
Every word within this range is aliased to the same location
Содержание MPC8240
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Страница 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Страница 516: ...16 14 Watchpoint Trigger Applications ...
Страница 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
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Страница 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...