The Platform Bus and the Device Tree for Devices That Cannot Be Discovered
Many devices, especially the blocks built into a phone or embedded chip, are not on a bus that can be asked what is present; they are simply wired at fixed addresses. For those, the platform bus is a stand-in bus and a device tree is a data file, loaded at boot, that lists each device's name, addresses and interrupt numbers. The driver code ends up looking the same as a PCI driver, but the information comes from that file instead of from the hardware.
Questions this Concept answers
- Why does the kernel keep a platform bus at all, when the devices on it are not really on a shared bus?
The Device Tree in Embedded Linux
A device tree is a data structure that describes, in a hierarchical, declarative form, the hardware devices available to an embedded processor (whether integrated on-chip or externally connected), de…