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SubjectRe: [PATCH RFC 1/1] gpio: mcp23s08: convert driver to DT
On Wed, Feb 6, 2013 at 10:31 AM, Lars Poeschel <> wrote:

> The thing that confused me was, that the platform_data for the chip has a
> mandatory "base" member, that sets the linux global gpio number at which the
> chip should appear.

Yes this is common. I think you should look at other drivers
under drivers/gpio using device tree, and how they work around

As stated, as a last resort you can use AUXDATA to anyway assign
a piece of platform data per instance.

In the Nomadik driver, we use the block instance ID and multiply
by a factor of the numbers of GPIOs on each instance.
And luckily the base is zero. Not elegant maybe, but the
global GPIO numberspace is not elegant by nature.

Linus Walleij

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