linux-sg2042/Documentation/mips/GT64120.README

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README for arch/mips/gt64120 directory and subdirectories
Jun Sun, jsun@mvista.com or jsun@junsun.net
01/27, 2001
MOTIVATION
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Many MIPS boards share the same system controller (or CPU companian chip),
such as GT-64120. It is highly desirable to let these boards share
the same controller code instead of duplicating them.
This directory is meant to hold all MIPS boards that use GT-64120 or GT-64120A.
HOW TO ADD A BOARD
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. Create a subdirectory include/asm/gt64120/<board>.
. Create a file called gt64120_dep.h under that directory.
. Modify include/asm/gt64120/gt64120.h file to include the new gt64120_dep.h
based on config options. The board-dep section is at the end of
include/asm/gt64120/gt64120.h file. There you can find all required
definitions include/asm/gt64120/<board>/gt64120_dep.h file must supply.
. Create a subdirectory arch/mips/gt64120/<board> directory to hold
board specific routines.
. The GT-64120 common code is supplied under arch/mips/gt64120/common directory.
It includes:
1) arch/mips/gt64120/pci.c -
common PCI routine, include the top-level pcibios_init()
2) arch/mips/gt64120/irq.c -
common IRQ routine, include the top-level do_IRQ()
[This part really belongs to arch/mips/kernel. jsun]
3) arch/mips/gt64120/gt_irq.c -
common IRQ routines for GT-64120 chip. Currently it only handles
the timer interrupt.
. Board-specific routines are supplied under arch/mips/gt64120/<board> dir.
1) arch/mips/gt64120/<board>/pci.c - it provides bus fixup routine
2) arch/mips/gt64120/<board>/irq.c - it provides enable/disable irqs
and board irq setup routine (irq_setup)
3) arch/mips/gt64120/<board>/int-handler.S -
The first-level interrupt dispatching routine.
4) a bunch of other "normal" stuff (setup, prom, dbg_io, reset, etc)
. Follow other "normal" procedure to modify configuration files, etc.
TO-DO LIST
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. Expand arch/mips/gt64120/gt_irq.c to handle all GT-64120 interrupts.
We probably need to introduce GT_IRQ_BASE in board-dep header file,
which is used the starting irq_nr for all GT irqs.
A function, gt64120_handle_irq(), will be added so that the first-level
irq dispatcher will call this function if it detects an interrupt
from GT-64120.
. More support for GT-64120 PCI features (2nd PCI bus, perhaps)