Use GPIO directory based on actual device tree path

[VipSaran]

By testing the device tree directory we can detrermine whether to use the "old" /sys/devices/virtual/gpio/gpio%u/%s path or to use the one used after update to kernel 3.18.x: /sys/class/gpio/gpio%u/%s, so both configurations are supported.

[lurch]

I believe this is unnecessary as #6 already contains the fix for this problem.

[olivierrr]

+1

[catskull]

+1

[VipSaran]

updated the fix

[knocte]

@lurch, that fix is worse because it only uses one path, this one checks both.

[lurch]

Nope, #6 is the better fix, as the same path works on all versions of Raspberry Pi, and is in fact the "correct" path to use.
The fact that gpio-admin was ever looking in /sys/devices/virtual/gpio/ in the first place could be considered a bug, as the 'public GPIO interface' is under /sys/class/gpio/ (see e.g. https://www.kernel.org/doc/Documentation/gpio/sysfs.txt), and is what gpio-admin should have been using all along. There was a big discussion about this quite a while ago on the Raspberry Pi forums.

[abuisman]

@VipSaran thanks for your work. Your solution fixes the issues I had with master and #6 .

[ghost]

https://github.com/VipSaran/quick2wire-gpio-admin/blob/fd62bda1f0b3e6ad6ef118035c745afa2cc2e8ca/src/gpio-admin.c