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Standard properties of devicetrees.
The #address-cells and #size-cells properties are not inherited from ancestors in the devicetree. They shall be explicitly defined.
A DTSpec-compliant boot program shall supply #address-cells and #size-cells on all nodes that have children.
If missing, a client program should assume a default value of 2 for #address-cells, and a value of 1 for #size-cells.
The reg property describes the address of the device’s resources within the address space defined by its parent bus. Most commonly this means the offsets and lengths of memory-mapped IO register blocks, but may have a different meaning on some bus types. Addresses in the address space defined by the root node are CPU real addresses.
The value is a <prop-encoded-array>, composed of an arbitrary number of pairs of address and length, <address length>. The number of <u32> cells required to specify the address and length are bus-specific and are specified by the #address-cells and #size-cells properties in the parent of the device node. If the parent node specifies a value of 0 for #size-cells, the length field in the value of reg shall be omitted.