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PCI Bus Controller
Freescale Semiconductor
22-31
22.4.1.4
PCI Bus Commands
PCI supports a number of different commands. The initiator on the PCI_CBE[3:0] signals during the
address phase of a PCI transaction presents these commands.
Table 22-26. PCI Bus Commands
PCI_CBE[3:0]
PCI Bus
Command
PCI Controller
Supports as
Initiator
PCI Controller
Supports as
Target
Definition
0000
INTERRUPT
ACKNOWLEDGE
Yes
No
The
INTERRUPT
ACKNOWLEDGE
command is a read (implicitly
addressing an external interrupt controller). Only one
device on the PCI bus should respond to the
INTERRUPT
ACKNOWLEDGE
command.
0001
SPECIAL
CYCLE
Yes
No
The
SPECIAL
CYCLE
command provides a mechanism to
broadcast select messages to all devices on the PCI bus.
0010
I
/
O
READ
Yes
No
The
I
/
O
READ
command accesses agents mapped into the
PCI I/O space.
0011
I
/
O
WRITE
Yes
No
The
I
/
O
WRITE
command accesses agents mapped into the
PCI I/O space.
0100
Reserved
No
No
—
0101
Reserved
No
No
—
0110
MEMORY
-
READ
Yes
Yes
The
MEMORY
READ
command accesses agents mapped into
PCI memory space.
0111
MEMORY
-
WRITE
Yes
Yes
The
MEMORY
WRITE
command accesses agents mapped
into PCI memory space.
1000
Reserved
No
No
—
1001
Reserved
No
No
—
1010
CONFIGURATION
READ
Yes
Yes
The
CONFIGURATION
READ
command accesses the 256 byte
configuration space of a PCI agent.
1011
CONFIGURATION
WRITE
Yes
Yes
The
CONFIGURATION
WRITE
command accesses the 256
byte configuration space of a PCI agent.
1100
MEMORY
READ
MULTIPLE
Yes
Yes
For the PCI controller as master, the
MEMORY
READ
MULTIPLE
command functions the same as the
MEMORY
READ
command.
For the PCI controller as target, the
MEMORY
READ
MULTIPLE
command causes an internal bus burst and can prefetch an
additional three bursts worth of data when addressed to
prefetchable space and when PCITCR1[PID] clears.
Internal bus prefetching only applies to PCI reads in the
address range for BAR1–5.
Cache line wrap implements if internal bus is the
transaction initiator and also wraps.
1101
DUAL
ADDRESS
CYCLE
No
No
The
DUAL
ADDRESS
CYCLE
command transfers a 64-bit
address (in two 32-bit address cycles) to 64-bit addressable
devices. This device does not respond to this command.
Summary of Contents for MCF54455
Page 33: ...xxviii Freescale Semiconductor ...
Page 67: ...Freescale Semiconductor 1 ...
Page 125: ...Freescale Semiconductor 1 ...
Page 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Page 173: ...Cache 6 28 Freescale Semiconductor ...
Page 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Page 207: ...Power Management 9 16 Freescale Semiconductor ...
Page 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Page 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Page 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Page 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Page 601: ...Freescale Semiconductor 1 ...
Page 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Page 843: ...Freescale Semiconductor 1 ...
Page 921: ...Revision History A 6 Freescale Semiconductor ...