Add qemu 2.4.0

[kvmfornfv.git] / qemu / roms / u-boot / arch / powerpc / cpu / mpc824x / drivers / epic / README

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