[PATCH v4 RESEND 1/3] Input: egalax_ts: get gpio from devicetree

[Shawn Guo]

Add LAKML ...

On Wed, Oct 10, 2012 at 09:30:36AM -0700, Dmitry Torokhov wrote:
> Hi Hui,
> 
> On Wed, Oct 10, 2012 at 05:12:01PM +0800, Hui Wang wrote:
> > The irq_to_gpio() is old, most platforms use GENERIC_GPIO framework
> > and don't support this API anymore.
> > 
> > The i.MX6q sabrelite platform equips an egalax touchscreen controller,
> > and this platform already transfered to GENERIC_GPIO framework, to
> > support this driver, we use a more generic way to get gpio.
> 
> Unfortunately this does break the driver for platforms that do still
> support irq_to_gpio and have not transitioned to device tree (yet?).
> It looks like the API suffered from premature deletion...
> 
> I really do not want to add a new platform data structure with only gpio
> in it, is there a better way to detect if irq_to_gpio() (even if only a
> stub) is available?
> 
If CONFIG_ARCH_HAVE_CUSTOM_GPIO_H is not enabled for an architecture,
the irq_to_gpio() in include/linux/gpio.h will tell unavailability by
returning -EINVAL.  But ARM architecture still selects ARCH_HAVE_CUSTOM_GPIO_H
because there are still some platforms having mach/gpio.h.

We may also need a stub irq_to_gpio simply returning -EINVAL into
arch/arm/include/asm/gpio.h when platform does not provide irq_to_gpio,
so that driver can detect if irq_to_gpio() is available.  And that
stub can be removed later when we deselect ARCH_HAVE_CUSTOM_GPIO_H
for ARM architecture.

Shawn