status of drivers/iio/pulse/tiecap.c

What is the status of drivers/iio/pulse/tiecap.c?

I found some references to it from 2014, e.g., this one
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-February/230125.html
but do not know what has happened with it/why it has not made it into
the kernel.

Cheers
Christoph