tree 02cd38c7c4c4d25d0610db811c611cd77e7589c2
parent 7bd5fcf356d7ba99a3648ad4b905078806fe27ec
author Matt Spinler <spinler@us.ibm.com> 1519409899 -0600
committer Matt Spinler <spinler@us.ibm.com> 1519666995 -0600

Make it possible to choose the target interface

The current code will always try to add a FanSpeed
interface if an <X>_target sysfs file is present, and
a FanPwm interface if a pwm<X> file is present.

For devices that have both types of files, it will
create both interfaces, and since each have a Target
property, it can cause REST calls which get these
properties to return the wrong one, as they can't
select the interface to use.

To fix this, allow a TARGET_MODE environment variable
to be specified to select which target to try to create,
either RPM or PWM.  If TARGET_MODE isn't there, default
to the current behavior of creating an interface for
whichever sysfs file type is exposed, so the code doesn't
limit what is created.

Tested: Set TARGET_MODE to RPM and then PWM in the config
        file, and ensure only the 1 interface is created.
        Remove that entry from the config file, and ensure
        it still works as it does today.

Change-Id: I2983e514c86c8d4fb785648520a913339daf6c8f
Signed-off-by: Matt Spinler <spinler@us.ibm.com>