Open source != free software.

The difference between open source and free software is mostly in the political camp the word comes from. Read the OSI definition of open source if you don't believe:

> https://opensource.org/osd-annotated

The reasons why "free software" people don't like the word "open source" are indeed political:

> https://www.gnu.org/philosophy/open-source-misses-the-point....

For software for which the source code is available, but does not give the four freedoms:

> https://www.gnu.org/philosophy/free-sw.html#content

it is common to use the word "shared source" (originally devised by Microsoft):

> https://en.wikipedia.org/wiki/Shared_source

Kernel driver of proprietary AMDGPU-PRO are licensed exactly same way as modules in mainline kernel. Most of them dual-licensed under MIT and GPL so BSD and other projects can use them.

But it is free software. It resides in the kernel tree: https://git.kernel.org/cgit/linux/kernel/git/stable/linux-st...