On 08/05/2012 04:06 AM, Linus Walleij wrote: > On Wed, Aug 1, 2012 at 5:22 PM, Johannes Stezenbach <j...@sig21.net> wrote: > >> I'm currently learning how Linux devicetree support works, >> here is one question I couldn't find an answer for. >> >> I understand that within the devicetree GPIOs are referenced by phandle, >> thus the numbers are irrelevant. However, in sysfs the number is >> what is used to access the GPIO, e.g. for debugging or >> blinkenlight apps. How does this fit together? > > I think it simply does not fit together. > > Grant & me has been claiming the GPIO sysfs interface is a bit > crazy from time to time. > > My long-term plan would be to replace it with /dev/gpio/gpioN > device nodes per-gpiochip and use ioctl etc to control these > beasts instead. However one does not do that overnight, > and my life is too busy, and other refactorings also need to > happen :-/
I can't comment on the sysfs-vs-dev interface location, but I don't think it addresses Johannes' issue; finding out which GPIO IDs are provided by which devices. Perhaps in each device's sysfs node, there should be some information re: which GPIO range it provides. Right now, perhaps a text file with the GPIO base it it. With the new /dev interface you mention above, perhaps a symlink to the /dev file, or a file containing the /dev file's major/minor number. Or, is there such a thing already (other than debugfs's gpio file). -- 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/
