Re: [patch/rfc 2.6.19-rc5] arch-neutral GPIO calls

H. Peter Anvin
2006-11-12T01:29:55Z

David Brownell wrote:
>
> - Only intended for use with "real" GPIOs that work from IRQ context;
> e.g. pins on a SOC that are controlled by chip register access.
>
> - Doesn't handle I2C or SPI based GPIOs. I think we actually need
> a different API for those "message based" GPIOs, where synchronous
> get/set requires sleeping (and is thus unusable from IRQ context).
> That API could be used for "real" GPIOs; the converse is not true.
>
> - No IORESOURCE_GPIO resource type (could be added though).
>
> - Can be trivially implemented today, on many systems (see partial
> list above) ... no "provider" or gpiochip API necessary.
>
> - Provided in the form of a working patch, with sample implementation;
> known to be viable on multiple architectures and platforms.
>
> - Includes Documentation/gpio.txt
>
> Comments?
>

If this is done, I think it's essential that a "high-level" API (one
that supports message-based GPIO) is provided at the same time. The
"high-level" API should be able to address the GPIOs addressed by the
low-level API. What we do *not* want is a bunch of stuff using the
low-level API when the high-level API would work.

-hpa