linux-kernel - Re: [PATCH v4 2/2] counter: add IRQ or GPIO based pulse counter

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Message-ID: <CACRpkdYSdtwSZxicJ1Rxp_XkK1BstpnzMcV0JqXg+cac_+gSSw@mail.gmail.com>
Date:   Thu, 28 Jan 2021 09:24:08 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     Rob Herring <robh+dt@...nel.org>,
        William Breathitt Gray <vilhelm.gray@...il.com>,
        Ahmad Fatoum <a.fatoum@...gutronix.de>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        David Jander <david@...tonic.nl>,
        Robin van der Gracht <robin@...tonic.nl>,
        linux-iio <linux-iio@...r.kernel.org>
Subject: Re: [PATCH v4 2/2] counter: add IRQ or GPIO based pulse counter

Hi Oleksij,

thanks for your patch!

On Tue, Jan 26, 2021 at 2:15 PM Oleksij Rempel <o.rempel@...gutronix.de> wrote:

> +       priv->irq = platform_get_irq(pdev,  0);
> +       if (priv->irq < 0) {
> +               dev_err(dev, "failed to map GPIO to IRQ: %d\n", priv->irq);
> +               return priv->irq;
> +       }
> +
> +       priv->gpio = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);
> +       if (IS_ERR(priv->gpio))
> +               return dev_err_probe(dev, PTR_ERR(priv->gpio), "failed to get gpio\n");

I would attempt to get the IRQ from the GPIO if not defined explicitly
in the device tree.

priv->gpio = devm_gpiod_get_optional(...)
if (priv->gpio) {
    /* Attempt to look up IRQ */
    irq = gpiod_to_irq(priv->irq);
}
priv->irq = platfform_get_irq(...)
if (priv->irq < 0 && irq > 0) {
    /* Use the GPIO-related IRQ */
    priv->irq = irq;
} else if (priv->irq < 0) {
   /* Error */
}

This way the example in the device tree binding which only defines
a GPIO and no interrupt will work if the GPIO chip provides an
IRQ mapping.

Yours.
Linus Walleij