On 12/15/2014 1:57 PM, Arnd Bergmann wrote:

On Monday 15 December 2014 13:35:47 Ray Jui wrote:

quoted

Like I said previously, dynamic GPIO allocation works fine in the
kernel, as long as all of our GPIO clients in the kernel use gpiod based
API, which is what we will enforce going forward. The only problem is
with some of our customers who use GPIO through sysfs and expect fixed
global GPIO numbers. Thinking about this more, it's probably not that
difficult to add a script for those customers to convert/map the GPIO
numbers based on readings parsed from sysfs, so I guess that's fine.

I think we discussed the user space interface a number of times
in the past, but I forgot the outcome. Either there is already
a way to name gpio lines uniquely in sysfs, or there should be
one.

Can you reach the gpio interfaces using /sys/devices/0001234.bus/1234566.gpiocontroller/...?

	Arnd

We use entries under /sys/class/gpio/ to control GPIOs. All base, label, 
and ngpio info specific to a GPIO controller can be found there.