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Chapter 7. PCI Bus Interface
7-25
PCI Bus Transactions
When the MPC8240 detects an access to the CONFIG_DATA register, it checks the enable
flag and the device number in the CONFIG_ADDR register. If the enable bit is set, and the
device number is not 0b1_1111, the MPC8240 performs a configuration cycle translation
function and runs a configuration-read or configuration-write transaction on the PCI bus.
The device number 0b1_1111 is used for performing interrupt-acknowledge and special-
cycle transactions. See Section 7.4.6, “Other Bus Transactions,” for more information. If
the bus number corresponds to the local PCI bus (bus number = 0x00), the MPC8240
performs a type 0 configuration cycle translation. If the bus number indicates a remote PCI
bus (that is, nonlocal), the MPC8240 performs a type 1 configuration cycle translation.
7.4.5.2.1 Type 0 Configuration Translation
Figure 7-10 shows the type 0 translation function performed on the contents of the
CONFIG_ADDR register to the AD[31:0] signals on the PCI bus during the address phase
of the configuration cycle.
Figure 7-10. Type 0 Configuration Translation
For type 0 configuration cycles, the MPC8240 translates the device number field of the
CONFIG_ADDR register into a unique IDSEL signal for up to 21 different devices. Each
device connects its IDSEL input to one of the AD[31:11] signals. For type 0 configuration
cycles, the MPC8240 translates the device number to IDSEL as shown in Table 7-6.
31 30
24 23
16 15
11 10
8 7
2 1 0
Bus Number
0000000
Reserved
Device Number
Function Number
Register Number
E
00
31
11 10
2 1 0
IDSEL–only one signal high
Function/Register Number
00
Contents of CONFIG_ADDR Register
AD[31:0] Signals
During Address Phase
Содержание MPC8240
Страница 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
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Страница 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Страница 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Страница 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Страница 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Страница 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Страница 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
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 ...
Страница 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Страница 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...