TC1796
System Units (Vol. 1 of 2)
On-Chip System Buses and Bus Bridges
User’s Manual
6-15
V2.0, 2007-07
Buses, V2.0
6.3
Local Memory to FPI Bus Interface (LFI Bridge)
6.3.1
Functional Overview
The LFI Bridge is a bi-directional bus bridge between the DLMB and the System
Peripheral FPI Bus (SPB). The bridge supports all transactions types of both the
LMB Bus and FPI Bus.
The bridge is not direction-transparent; this means that the master TAG of a bus master
is not forwarded to the other side of the bridge and is replaced instead by the master TAG
of the LFI Bridge itself.
In order to avoid deadlocks, priority is given to transactions initiated either by PCP, DMA,
or by Cerberus.
The bridge supports the pipelining of both connected buses. Therefore, no additional
delay is created except for bus protocol conversions.
Address Translation
Addresses of SPB transfers (initiated either by the PCP, DMA controller, or Cerberus)
via the LFI Bridge that address a DLMB or PLMB slave device are translated into a
DLMB address according
Bus Errors at Writes via the LFI Bridge
When a write operation has been initiated and directed to the LFI Bridge by a SPB bus
master, the LFI Bridge handles the write transaction at the LMBs (DLMB and PLMB)
autonomously. If the write operation at the LMB results in a bus error, the BCU of the
corresponding LMB detects the bus error and generates a LMB bus error interrupt. There
is no bus error generated at the SPB side in this case because of the nature of a posted
write operation.
Table 6-6
SPB to DLMB Address Translation
Transaction
Destination
SPB Access Range
Translated DLMB Address
SBRAM/SRAM
E800 0000
H
- E800 FFFF
H
C000 0000
H
- C000 FFFF
H
Reserved
E801 0000
H
- E83F FFFF
H
C001 0000
H
- C03F FFFF
H
DMI LDRAM and
DPRAM
E840 0000
H
- E840 FFFF
H
D000 0000
H
- D000 FFFF
H
Reserved
E841 0000
H
- E84F FFFF
H
D0010000
H
- D00F FFFF
H
PMI SPRAM
E850 0000
H
- E850 BFFF
H
D400 0000
H
- D400 BFFF
H
Reserved
E850 C000
H
- E85F FFFF
H
D400 C000
H
- D40F FFFF
H