1c66ec88fSEmmanuel VadotFlash partitions in device tree 2c66ec88fSEmmanuel Vadot=============================== 3c66ec88fSEmmanuel Vadot 4c66ec88fSEmmanuel VadotFlash devices can be partitioned into one or more functional ranges (e.g. "boot 5c66ec88fSEmmanuel Vadotcode", "nvram", "kernel"). 6c66ec88fSEmmanuel Vadot 7c66ec88fSEmmanuel VadotDifferent devices may be partitioned in a different ways. Some may use a fixed 8c66ec88fSEmmanuel Vadotflash layout set at production time. Some may use on-flash table that describes 9c66ec88fSEmmanuel Vadotthe geometry and naming/purpose of each functional region. It is also possible 10c66ec88fSEmmanuel Vadotto see these methods mixed. 11c66ec88fSEmmanuel Vadot 12c66ec88fSEmmanuel VadotTo assist system software in locating partitions, we allow describing which 13c66ec88fSEmmanuel Vadotmethod is used for a given flash device. To describe the method there should be 14c66ec88fSEmmanuel Vadota subnode of the flash device that is named 'partitions'. It must have a 15c66ec88fSEmmanuel Vadot'compatible' property, which is used to identify the method to use. 16c66ec88fSEmmanuel Vadot 17c66ec88fSEmmanuel VadotWhen a single partition is represented with a DT node (it depends on a used 18c66ec88fSEmmanuel Vadotformat) it may also be described using above rules ('compatible' and optionally 19c66ec88fSEmmanuel Vadotsome extra properties / subnodes). It allows describing more complex, 20c66ec88fSEmmanuel Vadothierarchical (multi-level) layouts and should be used if there is some 21c66ec88fSEmmanuel Vadotsignificant relation between partitions or some partition internally uses 22c66ec88fSEmmanuel Vadotanother partitioning method. 23c66ec88fSEmmanuel Vadot 24c66ec88fSEmmanuel VadotAvailable bindings are listed in the "partitions" subdirectory. 25c66ec88fSEmmanuel Vadot 26c66ec88fSEmmanuel Vadot 27*5def4c47SEmmanuel VadotDeprecated: partitions defined in flash node 28*5def4c47SEmmanuel Vadot============================================ 29c66ec88fSEmmanuel Vadot 30c66ec88fSEmmanuel VadotFor backwards compatibility partitions as direct subnodes of the flash device are 31c66ec88fSEmmanuel Vadotsupported. This use is discouraged. 32c66ec88fSEmmanuel VadotNOTE: also for backwards compatibility, direct subnodes that have a compatible 33c66ec88fSEmmanuel Vadotstring are not considered partitions, as they may be used for other bindings. 34