[PATCH] pxa: fix gpio_to_irq() for GPIOs on expander chips

[Marc Zyngier]

On Wed, 23 Dec 2009 04:07:34 -0500
Haojian Zhuang <haojian.zhuang at gmail.com> wrote:

> I not prefer the patch in that link
> (http://www.spinics.net/lists/arm-kernel/msg53803.html). I think
> gpio_to_irq() macro is enough. When we handle gpio expander, we could
> implement an independant gpio_to_irq() function in expander driver.
> It's like Marc's patch
> ((http://www.spinics.net/lists/arm-kernel/msg79587.html).

I'm not sure I really get it. In my patch, the pca953x_gpio_to_irq()
function can only be called from __gpio_to_irq(). As such, it is only
useful with Philipp's patch when used on PXA.

> In platform driver, we can declare the relationship directly in below.
> 
>  static struct pca953x_platform_data gpio_exp[] = {
>         [0] = {
>                .gpio_base      = PXA_GPIO_IRQ_NUM,
>                .irq_base       = PXA_GPIO_IRQ_BASE + PXA_GPIO_IRQ_NUM,
>         },
>         [1] = {
>                .gpio_base      = PXA_GPIO_IRQ_NUM + 16,
>                .irq_base       = PXA_GPIO_IRQ_BASE + PXA_GPIO_IRQ_NUM + 16,
>         },
>  };
> 
> But I don't suggest to append ARCH_NR_GPIOS in gpio.h. Could it be
> appended into platform driver only? Since not each platform have more
> than 256 GPIOs.

We could mimic what s3c2410 does to provide some extra GPIO space for
platforms that require it (arch/arm/mach-s3c2410/include/mach/gpio.h):

#define ARCH_NR_GPIOS   (256 + CONFIG_S3C24XX_GPIO_EXTRA)

	M.
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