Messages in this thread | | | From | David Brownell <> | Subject | Re: [patch/rfc 2.6.19-rc5] arch-neutral GPIO calls | Date | Mon, 13 Nov 2006 12:53:00 -0800 |
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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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