Am Dienstag, den 12.01.2010, 04:13 +0100 schrieb hermann pitton:
> Hi!
>
> Am Montag, den 11.01.2010, 11:59 -0700 schrieb Gordon Smith:
> > I need to bit twiddle saa7134 gpio pins from userspace.
> > To use gpio-sysfs, I need a "GPIO number" to export each pin, but I
> > do not know how to find such a number.
> >
> > Card is RTD Embedded Technologies VFG7350 [card=72,autodetected].
> > GPIO uses pcf8574 chip.
> > Kernel is 2.6.30.
> >
> > gpio-sysfs creates
> > /sys/class/gpio/export
> > /sys/class/gpio/import
> > but no gpio<n> entries so far.
> >
> > >From dmesg ("gpiotracking=1")
> > saa7133[0]: board init: gpio is 10000
> > saa7133[0]: gpio: mode=0x0000000 in=0x4011000 out=0x0000000 [pre-init]
> > saa7133[1]: board init: gpio is 10000
> > saa7133[1]: gpio: mode=0x0000000 in=0x4010f00 out=0x0000000 [pre-init]
> >
> > How may I find each "GPIO number" for this board?
> >
> > Thanks in advance for any help.
>
> There are 28 (0-27) gpio pins on each saa713x chip.
>
> Documentation about possible use cases is publicly available via
> nxp.com.
>
> You can do what ever you want with them, but to export them to userland
> seems to be a very bad idea to me.
>
> Likely soon some "advanced hackers" will damage ;) all kind of hardware
> around and others will claim it as being a GNU/Linux problem within the
> same time such stuff appears, and of course it will.
>
> In fact these days, only one to three users are involved hacking on a
> board. It is much cheaper for all involved to give the serial number of
> those than to imagine every day, what all could happen.
>
> For all others not yet active, avoiding any worst case through
> contributing is the way to go.
>
> For the rest, we likely should have some fund, for worst cases, payed by
> themselves.
>
> Cheers,
> Hermann
Hi Trent,
thought there would be straight PROs too, but no reply so far.
If you ever want, could you elaborate a little, what for userspace gpios
can be useful at all and why people eventually also can run into
problems with such pins, since they are "somehow" also under control of
manufacturers. Means they do use them all different within _some_ rules.
Given all the different use cases of gpio pins, for example on the
saa7134 driver, which ones should we eventually export to gpio-sysfs to
try to understand that approach better?
Do we have such pins at all?
Cheers,
Hermann
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