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    SubjectRe: New resources - pls, explain :-(
    On Wed, Aug 11, 1999, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

    >Its cute but if you think harder the implementation would suck
    >
    >> right thing" for that bus. One could add "bigendian_writel()" and
    >> "littleendian_writel()" to satisfy the Linus constraint of making
    >> unusual usage of writel() obvious.
    >
    >So every I/O has an if in it. Nothing like stalling the pipeline before we
    >probably stall on I/O writes to make things twice as painful.

    And what about simply having a struct io_bus containing function pointers
    to read/write and ioremap routines ? This way, we could hide all the i/o
    range offset issues when using several busses (we do have such problems
    with the ppc, especially with IDE, see recent discussion of linuxppc-dev
    mailing list). Each driver would have an bus structure associated with
    the device, eventually provided by the resource tree, and the only
    overhead of i/os could be the indirect function call.

    For the endian issue (which I think is a non-issue) , most of the time,
    the endian is known at compile time and could get be resolved by macros.
    If it's not the case, then just add two sets of i/o function pointers in
    the bus structure.

    Also, each bus stucture (let's call this a bus driver) can have it's own
    alloc/dealloc range functions associated, and eventually generic
    notifiers for hotswap.

    I beleive we can build some kind of "device-tree" which would be made of
    a virtual root, containing busses, containing resources trees. Looks a
    bit like Open Firmware ;-)

    --
    Perso. e-mail: <mailto:bh40@calva.net>
    Work e-mail: <mailto:benh@mipsys.com>
    BenH. Web : <http://calvaweb.calvacom.fr/bh40/>




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