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PCI Bus Controller
Freescale Semiconductor
22-35
number to select one of the IDSEL lines. If the bus number is not equal to its secondary bus, but is within
the range of buses subordinate to the bridge, the bridge claims and passes that access through as a Type 1
access.
Figure 22-39. PCI-to-PCI Bridge Determining Match to Secondary or Subordinate Bus
22.4.1.5.4
Address Decoding
For positive address decoding, an address hits when the address on the address bus matches an assigned
address range. Multiple devices on the same PCI bus may use positive address decoding, though no
overlap in the assigned address ranges can occur. The PCI controller only implements positive address
decoding.
For subtractive address decoding, an address hits when the address on the address bus does not match any
address range for any of the PCI devices on the bus. Only one device on a PCI bus may use subtractive
address decoding, and its use is optional.
22.4.2
Configuration Interface
The PCI bus protocol requires the implementation of a standardized set of registers for most devices on
the PCI bus. The PCI controller implements a Type 0 Configuration register set or header. These registers,
discussed in
Section 22.3.1, “PCI Type 0 Configuration Registers,”
are primarily intended to be read or
written by the PCI configuring master at initialization time through the PCI bus. The PCI controller
provides internal access to these registers through an internal bus interface. As with most of the PCI
controller registers, they are accessible by software in the address space at offsets. Internal accesses to the
Type 0 configuration header do not require PCI arbitration when they are accessed internally and are
allowed to execute regardless of whether any write data is posted in the PCI Controller.
If the PCI controller is the host device or configuring master, the internal bus interface configures the PCI
Controller. An external master would configure the PCI controller through the external PCI bus.
More information on the standard PCI configuration register is in the
PCI Local Bus Specification,
Revision 2.2
.
PCI
Bridge
PCI
Bridge
Secondary
Bus
Subordinate
Bus
Primary
Bus
ColdFire
Device 0.0
.
Device 1.0
Device 0.1
Device 1.1
Device 0.2
Device 1.2
Device 2.2
Device 3.2
Responds
to Type 0
Responds
to Type 0
Processor
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 ...