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OF-nodes, Fwnodes, Swnodes, Devlinks, Properties - Understanding How Devices Are Modeled in Linux - Bartosz Golaszewski, Qualcomm
The linux kernel driver model has grown over the years and acquired several different mechanisms for passing device configuration data to platform drivers. This configuration can come from firmware (device-tree, ACPI) or from the kernel code itself (board-files, MFD, auxiliary drivers).
For a less experienced driver developer, the different APIs that are used to access device properties can be quite confusing and lead to questions: should I use the OF routines? Maybe fwnode or the generic device properties? What are software nodes in this model and what even is a device property? How are devices linked according to their provider-consumer relationship and their probe order ensured, if at all?
This talk will discuss the history and evolution of device properties - from legacy, custom platform data structures, through the introduction of the open-firmware API and its generalization to firmware nodes alongside other fwnode implementations up to the generic device property API. It will also touch on the devlinks and how they tie into this model.
The goal of this beginner/intermediate level talk is to give a clear picture of how device configuration should be handled in the kernel.