linux-kernel - Re: [PATCH v2 1/5] gpio: add support to get local gpio number

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Date:   Thu, 28 Nov 2019 13:49:42 +0100
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Support Opensource <support.opensource@...semi.com>,
        Lee Jones <lee.jones@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Steve Twiss <stwiss.opensource@...semi.com>,
        Adam.Thomson.Opensource@...semi.com,
        linux-devicetree <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, kernel@...gutronix.de
Subject: Re: [PATCH v2 1/5] gpio: add support to get local gpio number

On 19-11-28 11:46, Bartosz Golaszewski wrote:
> śr., 27 lis 2019 o 14:59 Marco Felsch <m.felsch@...gutronix.de> napisał(a):
> >
> > Sometimes consumers needs to know the gpio-chip local gpio number of a
> > 'struct gpio_desc' for further configuration. This is often the case for
> > mfd devices.
> >
> 
> We already have this support. It's just a matter of exporting it, so
> maybe adjust the commit message to not be confusing.

Therefore I mentioned the consumers.

> That being said: I'm not really a fan of this - the whole idea of gpio
> descriptors was to make them opaque and their hardware offsets
> irrelevant. :(

I know therefore I added a driver local helper but this wasn't the way
Linus wanted to go..

> > Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> > ---
> >  drivers/gpio/gpiolib.c        |  6 ++++++
> >  include/linux/gpio/consumer.h | 10 ++++++++++
> >  2 files changed, 16 insertions(+)
> >
> > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> > index 104ed299d5ea..7709648313fc 100644
> > --- a/drivers/gpio/gpiolib.c
> > +++ b/drivers/gpio/gpiolib.c
> > @@ -4377,6 +4377,12 @@ int gpiod_count(struct device *dev, const char *con_id)
> >  }
> >  EXPORT_SYMBOL_GPL(gpiod_count);
> >
> > +int gpiod_to_offset(struct gpio_desc *desc)
> 
> Maybe call it: gpiod_desc_to_offset()?

The function name is proposed by Linus too so Linus what's your
oppinion?

Regards,
  Marco

> > +{
> > +       return gpio_chip_hwgpio(desc);
> > +}
> > +EXPORT_SYMBOL_GPL(gpiod_to_offset);
> > +
> >  /**
> >   * gpiod_get - obtain a GPIO for a given GPIO function
> >   * @dev:       GPIO consumer, can be NULL for system-global GPIOs
> > diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
> > index b70af921c614..e2178c3bf7fd 100644
> > --- a/include/linux/gpio/consumer.h
> > +++ b/include/linux/gpio/consumer.h
> > @@ -60,6 +60,9 @@ enum gpiod_flags {
> >  /* Return the number of GPIOs associated with a device / function */
> >  int gpiod_count(struct device *dev, const char *con_id);
> >
> > +/* Get the local chip offset from a global desc */
> > +int gpiod_to_offset(struct gpio_desc *desc);
> > +
> >  /* Acquire and dispose GPIOs */
> >  struct gpio_desc *__must_check gpiod_get(struct device *dev,
> >                                          const char *con_id,
> > @@ -189,6 +192,13 @@ static inline int gpiod_count(struct device *dev, const char *con_id)
> >         return 0;
> >  }
> >
> > +static inline int gpiod_to_offset(struct gpio_desc *desc)
> > +{
> > +       /* GPIO can never have been requested */
> > +       WARN_ON(desc);
> > +       return 0;
> > +}
> > +
> >  static inline struct gpio_desc *__must_check gpiod_get(struct device *dev,
> >                                                        const char *con_id,
> >                                                        enum gpiod_flags flags)
> > --
> > 2.20.1
> >