Re: Adding interrupt support to gpio-ich driver (possibly via SCI)

[Guenter Roeck]

On 04/07/2014 07:48 PM, Matthew Garrett wrote:
> On Fri, Apr 04, 2014 at 09:25:50AM -0700, Guenter Roeck wrote:
>
> > Is there a clean way to use any of those to implement interrupt support
> > for this driver ? I thought about hijacking the SCI interrupt by registering
> > an interrupt handler with acpi_install_sci_handler(), but that would restrict
> > the driver to kernel only (or the acpi function would have to be exported),
> > and I have no idea if it would work or, more importantly, if it would be
> > the best approach to solve the problem, or if the result would be acceptable.
> > I can figure out the "working" part, but that would not help much if I would
> > have to carry the patch locally because it is not acceptable for upstream
> > integration.
>
> You shouldn't need to install an SCI handler - the way the hardware will
> generate an SCI is to raise a GPE. If you know which GPE the device
> raises (my recollection is that for most Intel chipsets it's GPIO number
> + 0x10) then you can just call acpi_install_gpe_handler(). The problem

Sounds good. Do you by any chance have a pointer to some documentation
explaining this in some more detail ?

> is that the firmware may well already be using some of those GPIOs, and
> there's no easy way to tell. Checking the interrupt configuration isn't
> sufficient, since some of them may just be used as outputs.
The gpio-ich driver already has some magic to detect that condition - I
noticed that I can not request all GPIO pins on all hardware. Either case,
the gpio pins I am interested in are well defined on the hardware I am
dealing with, so I can be sure I won't step on some unexpected use.

Thanks!

Guenter

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/