1c4fc09e2SEmmanuel VadotBroadcom BCM47xx Partitions 2c4fc09e2SEmmanuel Vadot=========================== 3c4fc09e2SEmmanuel Vadot 4c4fc09e2SEmmanuel VadotBroadcom is one of hardware manufacturers providing SoCs (BCM47xx) used in 5c4fc09e2SEmmanuel Vadothome routers. Their BCM947xx boards using CFE bootloader have several partitions 6c4fc09e2SEmmanuel Vadotwithout any on-flash partition table. On some devices their sizes and/or 7c4fc09e2SEmmanuel Vadotmeanings can also vary so fixed partitioning can't be used. 8c4fc09e2SEmmanuel Vadot 9c4fc09e2SEmmanuel VadotDiscovering partitions on these devices is possible thanks to having a special 10c4fc09e2SEmmanuel Vadotheader and/or magic signature at the beginning of each of them. They are also 11c4fc09e2SEmmanuel Vadotblock aligned which is important for determinig a size. 12c4fc09e2SEmmanuel Vadot 13c4fc09e2SEmmanuel VadotMost of partitions use ASCII text based magic for determining a type. More 14c4fc09e2SEmmanuel Vadotcomplex partitions (like TRX with its HDR0 magic) may include extra header 15c4fc09e2SEmmanuel Vadotcontaining some details, including a length. 16c4fc09e2SEmmanuel Vadot 17c4fc09e2SEmmanuel VadotA list of supported partitions includes: 18c4fc09e2SEmmanuel Vadot1) Bootloader with Broadcom's CFE (Common Firmware Environment) 19c4fc09e2SEmmanuel Vadot2) NVRAM with configuration/calibration data 20c4fc09e2SEmmanuel Vadot3) Device manufacturer's data with some default values (e.g. SSIDs) 21c4fc09e2SEmmanuel Vadot4) TRX firmware container which can hold up to 4 subpartitions 22c4fc09e2SEmmanuel Vadot5) Backup TRX firmware used after failed upgrade 23c4fc09e2SEmmanuel Vadot 24c4fc09e2SEmmanuel VadotAs mentioned earlier, role of some partitions may depend on extra configuration. 25c4fc09e2SEmmanuel VadotFor example both: main firmware and backup firmware use the same TRX format with 26c4fc09e2SEmmanuel Vadotthe same header. To distinguish currently used firmware a CFE's environment 27c4fc09e2SEmmanuel Vadotvariable "bootpartition" is used. 28c4fc09e2SEmmanuel Vadot 29c4fc09e2SEmmanuel Vadot 30c4fc09e2SEmmanuel VadotDevices using Broadcom partitions described above should should have flash node 31c4fc09e2SEmmanuel Vadotwith a subnode named "partitions" using following properties: 32c4fc09e2SEmmanuel Vadot 33c4fc09e2SEmmanuel VadotRequired properties: 34c4fc09e2SEmmanuel Vadot- compatible : (required) must be "brcm,bcm947xx-cfe-partitions" 35c4fc09e2SEmmanuel Vadot 36c4fc09e2SEmmanuel VadotExample: 37c4fc09e2SEmmanuel Vadot 38c4fc09e2SEmmanuel Vadotflash@0 { 39c4fc09e2SEmmanuel Vadot partitions { 40c4fc09e2SEmmanuel Vadot compatible = "brcm,bcm947xx-cfe-partitions"; 41c4fc09e2SEmmanuel Vadot }; 42c4fc09e2SEmmanuel Vadot}; 43