On Mon, Apr 07, 2014 at 08:21:00PM -0700, Guenter Roeck wrote: > On 04/07/2014 07:48 PM, Matthew Garrett wrote: > >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 ?
The SCI is just IRQ 9 - it tells the OS that there's a firmware event, but in itself doesn't say what that event was. This is handled by the platform setting bits in the GPE*_STS registers. The ACPI code reads that and then dispatches the event to the appropriate handler. This will typically be some ACPI code (declared by _Lxx and _Exx methods in the ACPI tables - xx corresponds to the GPE number, L and E whether it's level or edge triggered), but in some cases you want to install a hardcoded event handler. I've only got the 5-series docs to hand, and I can't remember whether that's Panther Point, but you want to look at the definition of GPE0_STS to figure out which hardware events cause which GPEs. GPEs 16 to 31 appear to correspond to GPIO 0 to 15, which is easy enough to handle. > >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. Ok. As long as you don't reprogram anything by default, I think this should be fine. -- Matthew Garrett | mj...@srcf.ucam.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
