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103 lines
3.3 KiB
Text
103 lines
3.3 KiB
Text
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CONTENT:
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epic.h
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epic1.c
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epic2.s
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WHAT ARE THESE FILES:
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These files contain MPC8240 (Kahlua) EPIC
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driver routines. The driver routines are not
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written for any specific operating system.
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They serves the purpose of code sample, and
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jump-start for using the MPC8240 EPIC unit.
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For the reason of correctness of C language
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syntax, these files are compiled by Metaware
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C compiler and assembler.
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ENDIAN NOTATION:
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The algorithm is designed for big-endian mode,
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software is responsible for byte swapping.
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USAGE:
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1. The host system that is running on MPC8240
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shall link the files listed here. The memory
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location of driver routines shall take into
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account of that driver routines need to run
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in supervisor mode and they process external
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interrupts.
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The routine epic_exception shall be called by
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exception vector at location 0x500, i.e.,
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603e core external exception vector.
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2. The host system is responsible for configuring
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the MPC8240 including Embedded Utilities Memory
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Block. All EPIC driver functions require the
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content of Embedded Utilities Memory Block
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Base Address Register, EUMBBAR, as the first
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parameter.
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3. Before EPIC unit of MPC8240 can be used,
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initialize EPIC unit by calling epicInit
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with the corresponding parameters.
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The initialization shall disable the 603e
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core External Exception by calling CoreExtIntDisable( ).
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Next, call epicInit( ). Last, enable the 603e core
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External Exception by calling CoreExtIntEnable( ).
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4. After EPIC unit has been successfully initialized,
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epicIntSourceSet( ) shall be used to register each
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external interrupt source. Anytime, an external
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interrupt source can be disabled or enabled by
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calling corresponding function, epicIntDisable( ),
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or epicIntEnable( ).
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Global Timers' resource, base count and frequency,
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can be changed by calling epicTmFrequencySet( )
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and epicTmBaseSet( ).
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To stop counting a specific global timer, use
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the function, epicTmInhibit while epicTmEnable
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can be used to start counting a timer.
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5. To mask a set of external interrupts that are
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are certain level below, epicIntPrioritySet( )
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can be used. For example, if the processor's
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current task priority register is set to 0x7,
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only interrupts of priority 0x8 or higher will
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be passed to the processor.
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Be careful when using this function. It may
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corrupt the current interrupt pending, selector,
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and request registers, resulting an invalid vetor.
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After enabling an interrupt, disable it may also
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cause an invalid vector. User may consider using
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the spurious vector interrupt service routine to
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handle this case.
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6. The EPIC driver routines contains a set
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of utilities, Set and Get, for host system
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to query and modify the desired EPIC source
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registers.
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7. Each external interrupt source shall register
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its interrupt service routine. The routine
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shall contain all interrupt source specific
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processes and keep as short as possible.
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Special customized end of interrupt routine
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is optional. If it is needed, it shall contain
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the external interrupt source specific end of
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interrupt process.
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External interrupt exception vector at 0x500
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shall always call the epicEOI just before
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rfi instruction. Refer to the routine,
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epic_exception, for a code sample.
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