Add libiio support

[m-kormann]

Industrial I/O (https://wiki.analog.com/software/linux/docs/iio/iio) is a protocol to communicate with integrated devices.

This implementation allows to read sensor data from IIO devices locally or over network.

[bernhard-thiele]

@m-kormann Thanks for offering this PR!

I have no experience with IIO and I will need to get my head around it first. Next days are pretty filled up, so please bear with me if it takes some time.

Seems IIO does similar things like Comedi. From the example, I understand that IIO can be used out-of-the-box on Pinephone and Raspberry Pi. Maybe you could drop a few lines about your motivation for using IIO and how it is positioned to Comedi?

[m-kormann]

You are very welcome!

This example emerged from personal interest when I found that the data of the phone's gyroscope can be sent over network. This opens a lot of applications to real-time models.

From my understanding, Comedi is an interface to measurement with the help of certain hardware (even Soundcards) to measure voltages. It is restricted to the list of drivers available for the certain measurement hardware.

IIO is a layer above the I2C-Bus, which communicates with I/O hardware. As many arduino expansion boards (i.e. gyroscopes, magnetometers, proximity sensors) use I2C, a lot of devices, drivers and usage examples are available in the communities.

[tbeu]

I only checked the header file so far and wondered about the usage of the static storage class which should be avoided. There are also some minor style and cosmetic issues.

@bernhard-thiele Did you find some time for evaluation?

[tbeu]

Some more statics to be avoided.

[tbeu]

@bernhard-thiele Did you find some time for evaluation?

Bump.

Resolved.

[bernhard-thiele]

@bernhard-thiele Did you find some time for evaluation?

No, I only had a superficial view on it. I think it would be cool, but since there was no pressing need to get it in and I have no experience with it, I procrastinated it. My first impression (now some time ago) was that there would be some work needed before it is "feature complete and ready". Unfortunately, at the moment there is not really time for me to work on it, so I'm not sure how to handle it.