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    SubjectRe: [patch/rfc 2.6.19-rc5] arch-neutral GPIO calls
    On Monday 13 November 2006 12:26 pm, Bill Gatliff wrote:

    > >Nah; look at arch/arm/plat-omap/gpio.c and ignore the mess, but observe
    > >that what you see there is essentially a bunch of "gpio controller"
    > >classes using the ugly "switch(type)" dispatch scheme instead of the
    > >prettier "type->op()" dispatch scheme. All that stuff needs to be
    > >cleaner, but for now it'd suffice to add a new FPGA typecode.
    > Agreed. But if we add to the machine descriptor, then not only do you
    > not need to touch arch-omap/gpio.c, but you can take that switch
    > statement out, too. Just one less chunk of code to tweak when a new
    > platform is supported.

    Do non-ARM platforms have board/machine descriptors on Linux, though?
    I thought most didn't ...

    One could come up with an implementation that uses GPIO numbers
    as indices into a descriptor array, and using board-specific
    initialization of that array ... just like with IRQs and irq_chip.

    That could lead to heavier weight implementations than I'd prefer
    to see (since GPIOs are a very light weight notion!), but it'd
    certainly provide a more reusable way to add GPIO controllers.

    All behind the API I proposed, note -- no changes needed.

    - Dave

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