Re: [PATCH 1/2] cs5535-gpio: add AMD CS5535/CS5536 GPIO driver support

[Tobias MÃller]

2009/6/13 Andres Salomon <dilinger@xxxxxxxxxxxxxxx>:
> On Thu, 11 Jun 2009 23:35:55 +0200
> Tobias MÃller <Tobias_Mueller@xxxxxxxxx> wrote:
>
>> >> /**
>> >> * Some GPIO pins
>> >> * Â31-29,23 : reserved (always mask out)
>> >> * Â28 Â Â Â : Power Button
>> >> * Â26 Â Â Â : PME#
>> >> * Â22-16 Â Â: LPC
>> >> * Â14,15 Â Â: SMBus
>> >> * Â9,8 Â Â Â: UART1
>> >> * Â7 Â Â Â Â: PCI INTB
>> >> * Â3,4 Â Â Â: UART2/DDC
>> >> * Â2 Â Â Â Â: IDE_IRQ0
>> >> * Â1 Â Â Â Â: AC_BEEP
>> >> * Â0 Â Â Â Â: PCI INTA
>> >> *
>> >> * If a mask was not specified, be conservative and only allow:
>> >> * Â1,2,5,6,10-13,24,25,27
>> >> */
>> >>
>> >> I'll add this in my patch to clear it out.
>> >>
>> >
>> > But why are you being conservative in the first place? ÂIf
>> > something's using GPIOs, unless they're unmapped, you should allow
>> > it to use them without requiring a boot arg.
>> >
>> > For example, OLPC uses GPIO 7 for its DCON IRQ. ÂWith the masking
>> > scheme, OLPC will need to set that mask from the default. ÂI don't
>> > see the point of having the mask at all if other drivers in the
>> > kernel are going to be requesting GPIOs (presumably they know what
>> > they're doing).
>> Hmm... OK, this makes sense. So default mask allow everything exept
>> reserved pins and pin 28 (power button).
>>
>> I think the mask is quite useful if you've critical things on GPIO
>> pins and they should be changeable (especially from userspace and when
>> non-root users are allowed to use userspace gpio).
>
> I agree that it would be useful for userspace, just not for
> kernelspace. ÂIs there a way that you can have it only enforce the
> mask if the request is coming from userspace?

I didn't find a way to find out if a request is coming from userspace, so at
the moment I think it's only possible to set it global.
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