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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

----------

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

------------------

. Create a subdirectory include/asm/gt64120/.

. 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//gt64120_dep.h file must supply.

. Create a subdirectory arch/mips/gt64120/ 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/ dir.

        1) arch/mips/gt64120//pci.c - it provides bus fixup routine

        2) arch/mips/gt64120//irq.c - it provides enable/disable irqs

                and board irq setup routine (irq_setup)

        3) arch/mips/gt64120//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)