Where can I find the documentation for the Linux NPU API?

For example the Samsung Galaxy S10 has an Exynos 9820 CPU with integrated NPU. We all know Android is based on Linux. So where can I find the Linux API documentation about how to interact with the NPU? For example there must be a way to get the frequency and core count of the NPU. Maybe they are listed in /proc/cpuinfo? Also I want to load a program into the NPU and execute it. All this must be documented somewhere. Where can I find the Linux NPU documentation? I already know where to find the Android AI documentation. But I am looking for the Linux NPU documentation which is on a lower level.