illumos gate

The amdf17nbdf driver originally was written with dual purposes. The first was to provide a temperature sensor for AMD Zen family platforms. Secondly, it was to provide a foundation for additional work such as dealing with the memory controller and other aspects of the system. The combination of the northbridge and data fabric PCI devices that are bound to the driver are useful for providing access to two different services:

• The System Management Network
• Direct and Indirect access to the Data Fabric

As I started looking at adding additional functionality, we needed to consider even more PCI devices and mapping them together. Rather than try and continuing to push functionality into the amdf17nbdf driver directly, I instead decided to transform it into a nexus driver that provides services and concretely can provide access to services for child devices.

This distinction makes it much easier for us to actually separate out the act of amalgamating all of the different per-processor die PCI devices and the actual child devices which would provide services such as temperature services, memory controller data, etc.

This will create three drivers as a result:

• amdzen: The Nexus driver itself
• amdzen_stub: A driver that will attach to the PCI devices on the system that constitute the northbridge and data fabric.
• smntemp: A child device of amdzen that provides sensor access through the SMN.