From mboxrd@z Thu Jan  1 00:00:00 1970
From: Linus Walleij <linus.walleij@linaro.org>
Subject: Re: [PATCH 3/5] gpio/omap: Add DT support to GPIO driver
Date: Fri, 26 Apr 2013 09:31:46 +0200
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To: Javier Martinez Canillas <martinez.javier@gmail.com>
Cc: Jon Hunter <jon-hunter@ti.com>, Stephen Warren <swarren@wwwdotorg.org>, Grant Likely <grant.likely@secretlab.ca>, Alexandre Courbot <acourbot@nvidia.com>, Stephen Warren <swarren@nvidia.com>, Kevin Hilman <khilman@deeprootsystems.com>, "devicetree-discuss@lists.ozlabs.org" <devicetree-discuss@lists.ozlabs.org>, "linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>

On Wed, Apr 17, 2013 at 2:41 AM, Javier Martinez Canillas
<martinez.javier@gmail.com> wrote:

So:

> +static int omap_gpio_irq_domain_xlate(struct irq_domain *d,
> +                                     struct device_node *ctrlr,
> +                                     const u32 *intspec, unsigned int intsize,
> +                                     irq_hw_number_t *out_hwirq,
> +                                     unsigned int *out_type)
> +{
> +       int ret;
> +       struct gpio_bank *bank = d->host_data;
> +       int gpio = bank->chip.base + intspec[0];
> +
> +       if (WARN_ON(intsize < 2))
> +               return -EINVAL;
> +
> +       ret = gpio_request_one(gpio, GPIOF_IN, ctrlr->full_name);
> +       if (ret)
> +               return ret;

So how to figure out if a device is already requesting this GPIO
on some orthogonal axis?

if (this_gpio_was_hogged_as_input_in_gpiolib) {
   ret = gpio_request_on()...
}

Is my suggestion, then you can explicitly mark which GPIOs
shall have their IRQs implicitly translated to GPIOs and
requested.

Alas, this requires the DTS:es to have this hogging added, but
it is fully backwards-compatible.

Then the applicabl OMAP drivers (like MMC) can be fixed to
do gpio_to_irq() on  their pins instead of using the IRQ
directly.

Yours,
Linus Walleij