linux-kernel - Re: [PATCH v2 2/4] ACPI / gpio: Add support for naming GPIOs

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Date:   Thu, 20 Oct 2016 15:14:42 +0300
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Alexandre Courbot <gnurou@...il.com>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] ACPI / gpio: Add support for naming GPIOs

On Thu, Oct 20, 2016 at 02:06:42PM +0200, Linus Walleij wrote:
> On Thu, Sep 29, 2016 at 3:39 PM, Mika Westerberg
> <mika.westerberg@...ux.intel.com> wrote:
> 
> > DT has property 'gpio-line-names' to name GPIO lines the controller has if
> > present. Use this very same property in ACPI as well to provide nice names
> > for the GPIOS.
> >
> > Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> 
> Oh wait:
> 
> > +static void acpi_gpiochip_set_names(struct acpi_gpio_chip *achip)
> > +{
> > +       struct gpio_chip *chip = achip->chip;
> > +       struct gpio_device *gdev = chip->gpiodev;
> > +       const char **names;
> > +       int ret, i;
> > +
> > +       ret = device_property_read_string_array(chip->parent, "gpio-line-names",
> > +                                               NULL, 0);
> > +       if (ret < 0)
> > +               return;
> > +
> > +       if (ret != gdev->ngpio) {
> > +               dev_warn(chip->parent,
> > +                        "names %d do not match number of GPIOs %d\n", ret,
> > +                        gdev->ngpio);
> > +               return;
> > +       }
> > +
> > +       names = kcalloc(gdev->ngpio, sizeof(*names), GFP_KERNEL);
> > +       if (!names)
> > +               return;
> > +
> > +       ret = device_property_read_string_array(chip->parent, "gpio-line-names",
> > +                                               names, gdev->ngpio);
> > +       if (ret < 0) {
> > +               dev_warn(chip->parent, "Failed to read GPIO line names\n");
> > +               return;
> > +       }
> > +
> > +       /*
> > +        * It is fine to assign the name, it will be allocated as long as
> > +        * the ACPI device exists.
> > +        */
> > +       for (i = 0; i < gdev->ngpio; i++)
> > +               gdev->descs[i].name = names[i];
> > +
> > +       kfree(names);
> > +}
> 
> Wouldn't this entire function work just as fine on device tree?

Now that you mentioned it, yes, I think it should work with DT as well.

> So should this snippet using device_property_* be moved into
> a file like gpiolib-devprop.c+gpiolib.h signature and get used from
> both gpiolib-of.c and gpiolib-acpi.c, replacing the DT-specific
> code in gpiolib-of.c?

Works for me :)