Representing and addressing devices

Each device is given at least one node in a DT. Some properties are common to many device types, especially devices sitting on a bus known to the kernel (SPI, I2C, platform, MDIO, and so on). These properties are reg, #address-cells, and #size-cells. The purpose of these properties is device addressing on the bus they sit on. That said, the main addressing property is reg, which is a generic property whose meaning depends on the bus the device sits on. The # (hash) that prefixes size-cell and address-cell can be translated into length.

Each addressable device gets a reg property that is a list of tuples in the form reg = <address0 size0 [address1size1] [address2size2] ... >, where each tuple represents an address range used by the device. #size-cells indicates how many 32-bit cells are used to represent size, and may be 0 if size is not relevant. On the other hand, #address-cells indicates how many 32-bit cells are used to represent the address. In...