Messages in this thread | | | Date | Fri, 20 Sep 2013 19:59:00 +0200 | Subject | Re: [RFC 5/5] gpiolib: update documentation | From | Linus Walleij <> |
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On Wed, Sep 4, 2013 at 1:29 PM, Alexandre Courbot <acourbot@nvidia.com> wrote:
> +The GPIO framework has quite a bit of history behind it. Currently there exist > +two different (although very similar) ways of using GPIOs: > + > + - The legacy integer-based interface represents GPIOs as integers. This is > + the "historic" way of accessing GPIOs and it was done so because it makes > + GPIOs easy to represent and also allows for the compiler to statically know > + the GPIO number and use fast-paths on GPIOs for which performance matters. > + However, GPIOs can easily be forged this way, and the maximum number of > + GPIOs in the system must be known in advance. Functions of this interface > + are prefixed with "gpio_". > + > + - The new descriptor-based interface represents GPIOs as an opaque pointer. > + This ensures GPIOs are properly acquired before usage, and also does not > + presume anything about their underlying implementation. This interface > + provides get/put functions to acquire GPIOs according to their function for > + a particular device, similarly to e.g. the regulator framework. For these > + reasons, it is the preferred way to access GPIOs. Its functions are prefixed > + with "gpiod_".
I would put all the new style gpiod_* based things on top of the file, and all the old stuff under a separate heading below DEPRECATED LEGACY INTERFACE so it's crystal clear that this is going away.
Yours, Linus Walleij
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