Re: gpio_is_valid()

[Andy Shevchenko <andy.shevchenko@xxxxxxxxx>]

On Mon, Mar 29, 2021 at 5:36 PM Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
>
> On Mon, Mar 29, 2021 at 4:31 PM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> >
> > On Mon, Mar 29, 2021 at 12:50 PM Andy Shevchenko
> > <andy.shevchenko@xxxxxxxxx> wrote:
> >
> > > Anybody to shed a light why we have two stubs of gpio_is_valid() and
> > > one actual declaration?
> > > % git grep -n -w gpio_is_valid -- include/
> > > include/asm-generic/gpio.h:44:static inline bool gpio_is_valid(int number)
> > > include/asm-generic/gpio.h:143:static inline bool gpio_is_valid(int number)
> > > include/linux/gpio.h:109:static inline bool gpio_is_valid(int number)
> >
> > Remnants from "generic GPIO" where some custom platform would have
> > a custom implementation (and semantic!) while using the same
> > API.
> >
> > include/linux/gpio.h:109 - this is just a stub !CONFIG_GPIOLIB
> >
> > include/asm-generic/gpio.h:44 - this one is used if CONFIG_GPIOLIB
> >
> > This is for all "normal" GPIO providers and consumers, end of
> > story.
> >
> > include/asm-generic/gpio.h:143 - this one is used of !CONFIG_GPIOLIB
> > but only <asm/gpio.h> is included, meaning the system has a
> > private implementation of the symbols, not those from GPIOLIB.
>
> Aha, thanks for elaboration!
>
> > It makes sense if you realize there are GPIO drivers that only include
> > <asm/gpio.h> and does not include <linux/gpio.h>. But I wonder if
> > there still are? (Unfortunately I think so, used to be some weird archs
> > and some minor ARM systems.)
>
> The files so far that include asm/gpio.h
>
> Documentation/translations/zh_CN/gpio.txt
> drivers/gpio/Kconfig
> include/asm-generic/gpio.h
> include/linux/gpio.h

Another list (asm-generic/gpio.h)

Documentation/translations/zh_CN/gpio.txt:477:<asm/gpio.h> 包含
<asm-generic/gpio.h>，同时定义三个方法:
MAINTAINERS:7631:F:     include/asm-generic/gpio.h
arch/arm/include/asm/gpio.h:10:#include <asm-generic/gpio.h>
arch/m68k/include/asm/mcfgpio.h:12:#include <asm-generic/gpio.h>
arch/sh/include/asm/gpio.h:19:#include <asm-generic/gpio.h>
drivers/gpio/gpio-davinci.c:26:#include <asm-generic/gpio.h>
drivers/pinctrl/core.c:31:#include <asm-generic/gpio.h>
include/linux/gpio.h:62:#include <asm-generic/gpio.h>

> > Generic GPIO was probably not a very good idea, I think at the time
> > it was a compromise for making custom implementations migrate
> > to the generic implementation over time.
> >
> > I think it is actually gone now! We can probably delete:
> > arch/arm/include/asm/gpio.h
> > include/asm-generic/gpio.h
> >
> > And just move the remaining stubs into <linux/gpio.h>.
> >
> > Interested in the job or should I take a stab at it? :D
>
> I think it's you who understands the area better.
> I missed (I hope *fortunately*) the legacy GPIO APIs.
>
> --
> With Best Regards,
> Andy Shevchenko



-- 
With Best Regards,
Andy Shevchenko