Exporting ioctls from out-of-tree module to userspace

[danielhilst@gmail.com (Daniel Hilst Selli)]

I write an out-of-tree module and now want to export its ioctls to 
userspace by installing a header that my modules includes, I was looking 
for how to do it but can't get it..

I was trying header-y from 
https://www.kernel.org/doc/Documentation/kbuild/makefiles.txt but got: 
make[1]: *** No rule to make target 'headers_install'.  Stop.

Here is what I'm trying: https://gist.github.com/gkos/b0bc4e29a3147b0e6d3b

I see on kernel that usually the exported headers go in 
include/uapi/SOMETHING and are declared on include/uapi/Kbuild.. but 
have no idea if this may work for out-of-tree modules, the 
headers_install exists on linux Makefile so the 'No rule to make target 
'headers_install'' doesn't make sense to me ..

I try follow headers_install target on kernel's Makefile but only got 
frustraded :(

Any idea?

ps: I compiled the module but don't loaded it, so it may have mistakes

Thanks in advance!
Cheers!