source: SVN/rincon/u-boot/cpu/mpc824x/drivers/epic/README @ 55

Last change on this file since 55 was 55, checked in by Tim Harvey, 22 months ago

rincon: added latest u-boot source

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Signed-off-by: Tim Harvey <tharvey@…>

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Line 
1CONTENT:
2
3   epic.h
4   epic1.c
5   epic2.s
6
7WHAT ARE THESE FILES:
8
9These files contain MPC8240 (Kahlua) EPIC
10driver routines. The driver routines are not
11written for any specific operating system.
12They serves the purpose of code sample, and
13jump-start for using the MPC8240 EPIC unit.
14
15For the reason of correctness of C language
16syntax, these files are compiled by Metaware
17C compiler and assembler.
18
19ENDIAN NOTATION:
20
21The algorithm is designed for big-endian mode,
22software is responsible for byte swapping.
23
24USAGE:
25
261. The host system that is running on MPC8240
27   shall link the files listed here. The memory
28   location of driver routines shall take into
29   account of that driver routines need to run
30   in supervisor mode and they process external
31   interrupts.
32
33   The routine epic_exception shall be called by
34   exception vector at location 0x500, i.e.,
35   603e core external exception vector.
36
372. The host system is responsible for configuring
38   the MPC8240 including Embedded Utilities Memory
39   Block. All EPIC driver functions require the
40   content of Embedded Utilities Memory Block
41   Base Address Register, EUMBBAR, as the first
42   parameter.
43
443. Before EPIC unit of MPC8240 can be used,
45   initialize EPIC unit by calling epicInit
46   with the corresponding parameters.
47
48   The initialization shall disable the 603e
49   core External Exception by calling CoreExtIntDisable( ).
50   Next, call epicInit( ). Last, enable the 603e core
51   External Exception by calling CoreExtIntEnable( ).
52
534. After EPIC unit has been successfully initialized,
54   epicIntSourceSet( ) shall be used to register each
55   external interrupt source. Anytime, an external
56   interrupt source can be disabled or enabled by
57   calling corresponding function, epicIntDisable( ),
58   or epicIntEnable( ).
59
60   Global Timers' resource, base count and frequency,
61   can be changed by calling epicTmFrequencySet( )
62   and epicTmBaseSet( ).
63
64   To stop counting a specific global timer, use
65   the function, epicTmInhibit while epicTmEnable
66   can be used to start counting a timer.
67
685. To mask a set of external interrupts that are
69   are certain level below, epicIntPrioritySet( )
70   can be used. For example, if the processor's
71   current task priority register is set to 0x7,
72   only interrupts of priority 0x8 or higher will
73   be passed to the processor.
74
75   Be careful when using this function. It may
76   corrupt the current interrupt pending, selector,
77   and request registers, resulting an invalid vetor.
78
79   After enabling an interrupt, disable it may also
80   cause an invalid vector. User may consider using
81   the spurious vector interrupt service routine to
82   handle this case.
83
846. The EPIC driver routines contains a set
85   of utilities, Set and Get, for host system
86   to query and modify the desired EPIC source
87   registers.
88
897. Each external interrupt source shall register
90   its interrupt service routine. The routine
91   shall contain all interrupt source specific
92   processes and keep as short as possible.
93
94   Special customized end of interrupt routine
95   is optional. If it is needed, it shall contain
96   the external interrupt source specific end of
97   interrupt process.
98
99   External interrupt exception vector at 0x500
100   shall always call the epicEOI just before
101   rfi instruction. Refer to the routine,
102   epic_exception, for a code sample.
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