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
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...