Hi Peter, > We have several pieces of software that make use of the /sys/class/gpio > userspace interface to the GPIO subsystem. > > One important prerequisite to being able to use the userspace GPIO interface > is to be able to put the corresponding package pins into GPIO mode, by > modifying the chip's mux settings. > > With Fedora 19 on the Pandaboard, we were able to achieve this by poking > around in /sys/kernel/debug/omap_mux. However, when running Fedora 20, this > directory is empty. My assumption is that this functionality has been > subsumed by the pinctrl subsystem in recent kernels. Unfortunately, there > doesn't seem to be any documented userspace API. > > I'd greatly appreciate it if someone could give me some pointers about how > to deal with this issue! Recently, sorry don't remember which kernel, most of the gpio stuff moved over to the gpiolib interface which changed some of the user space access but it at least appears to be documented in Documentation/gpio/sysfs.txt and at least on my Panda-es running 3.15rc3 there is /sys/class/gpio/export interface which is I suspect what you'll >From the pinctl PoV looking at a presentation [1] on the topic I'm not sure there is a userspace API yet according to page 18, although there's been quite some water under the bridge since 3.9 but it might be that the gpiolib stuff above is all you need. But if you do need the pinctrl stuff there's a bunch of options in /sys/kernel/debug/pinctrl/ and the files in there map out how the pins are currently mapped and there's means to change them there too. I've not had time to play with any of the above but hopefully it gives you enough of a start/help. Peter [1] http://www.df.lth.se/~triad/papers/pincontrol-gpio-update.pdf _______________________________________________ arm mailing list arm@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/arm
