tree 3cc2d4bbfbeebc7c74cd00a494a0ce7258c3d6aa
parent e7e432b468029e9f9f665d6a0b6c6e11bf5107ea
author Matt Spinler <spinler@us.ibm.com> 1503346639 -0500
committer Patrick Williams <patrick@stwcx.xyz> 1505845600 +0000

Add GPIO class

This class will be used for accessing GPIOs off of the
UCD90160 to check for PGOOD faults, and also later for
isolating GPU overtemps and PGOOD faults down to the specific
GPU that failed.

The FileDescriptor class is used by the GPIO class to manage
the lifetime of the GPIO file handles.

The class only supports reading a GPIO value.  At this point
there is no requirement for doing writes.

This class was copied from phosphor-gpio-monitor/gpio-util.

Change-Id: Iee276aed67e1cba549c3070c08238ab5f621c320
Signed-off-by: Matt Spinler <spinler@us.ibm.com>