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

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Date:   Thu, 20 Oct 2016 14:06:42 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
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, 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?

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?

Yours,
Linus Walleij