
E-48
DINK32 PowerPC ISA Debugger User’s Manual
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MOTOROLA
MPC8240 EPIC Interrupt Driver
The EPIC registers are in little-endian format. If the system is in big-endian mode, the bytes
must be appropriately swapped by software. DINK32 is written for big-endian mode and
the sample code referred to in this appendix performs the appropriate byte swapping.
E.4.2.1
Embedded Utilities Memory Block (EUMB)
The EUMB is a block of local and PCI memory space allocated to the control and status
registers of the embedded utilities. The embedded utilities are the Messaging Unit (I
2
O),
DMA controller, EPIC, I
2
C, and ATU. The MPC8245 adds the DUART to the EUMB. The
local memory map location of the EUMB is controlled by the embedded utilities memory
block base address register (EUMBBAR). The PCI bus memory map location of the EUMB
is controlled by the peripheral control and status registers base address register
(PCSRBAR). Since EPIC is only accessible from local memory, only the EUMBBAR is of
concern for this appendix.
Please refer to the following sections in the MPC8420 User’s Manual:
Section 3.4 Embedded Utilities Memory Block
Section 4.5 Embedded Utilities Memory Block Base Address Register
Section 4.1 Configuration Register Access
E.4.2.2
EPIC Register Summary
The EPIC register map occupies a 256 Kilobyte range of the EUMB. All EPIC registers are
32 bits wide and reside on 128 bit address boundaries. The EPIC registers are divided into
four distinct areas whose address offsets are based on the EUMB location in local memory
controlled by the value in the EUMBBAR configuration register.
The EPIC address offset map areas:
0x4_1000 - 0x4_10F0: Global EPIC register map
0x4_1100 - 0x4_FFF0: Global timer register map
0x5_0000 - 0x5_FFF0: Interrupt source configuration register map
0x6_0000 - 0x6_0FF0: Processor-related register map
Please refer to Section 11.2 in the MPC8420 User's Manual for the complete EPIC register
address map table and Section 11.9 for all register definitions.
E.4.2.3
EPIC Modes
Pass-Through Mode
This mode provides a mechanism to support alternate interrupt controllers such as the 8259
interrupt controller architecture. Pass-through is the default mode of the EPIC unit.
Mixed Mode
F
n
.