>> 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 > > > Yes, we're already using the /sys/class/gpio interface for all our GPIO > stuff. It does everything we need it to do -- other than change pinmux > settings to make the GPIOs actually work. > > >> 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. > > > Hmm, yes, I found the /sys/kernel/debug/pinctrl interface, but I can't find > any documentation *at all* about what can be written into those files to > change the configuration, despite extensive googling. Do you know of any > documentation or examples? Or is the only option to read the kernel > sources? I'm not aware of anything else other than the pdf I referenced above and the kernel documentation like pinctrl.txt gpio/* etc. Peter _______________________________________________ arm mailing list arm@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/arm
