1*4882a593SmuzhiyunBroadcom BCM47xx Partitions
2*4882a593Smuzhiyun===========================
3*4882a593Smuzhiyun
4*4882a593SmuzhiyunBroadcom is one of hardware manufacturers providing SoCs (BCM47xx) used in
5*4882a593Smuzhiyunhome routers. Their BCM947xx boards using CFE bootloader have several partitions
6*4882a593Smuzhiyunwithout any on-flash partition table. On some devices their sizes and/or
7*4882a593Smuzhiyunmeanings can also vary so fixed partitioning can't be used.
8*4882a593Smuzhiyun
9*4882a593SmuzhiyunDiscovering partitions on these devices is possible thanks to having a special
10*4882a593Smuzhiyunheader and/or magic signature at the beginning of each of them. They are also
11*4882a593Smuzhiyunblock aligned which is important for determinig a size.
12*4882a593Smuzhiyun
13*4882a593SmuzhiyunMost of partitions use ASCII text based magic for determining a type. More
14*4882a593Smuzhiyuncomplex partitions (like TRX with its HDR0 magic) may include extra header
15*4882a593Smuzhiyuncontaining some details, including a length.
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17*4882a593SmuzhiyunA list of supported partitions includes:
18*4882a593Smuzhiyun1) Bootloader with Broadcom's CFE (Common Firmware Environment)
19*4882a593Smuzhiyun2) NVRAM with configuration/calibration data
20*4882a593Smuzhiyun3) Device manufacturer's data with some default values (e.g. SSIDs)
21*4882a593Smuzhiyun4) TRX firmware container which can hold up to 4 subpartitions
22*4882a593Smuzhiyun5) Backup TRX firmware used after failed upgrade
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24*4882a593SmuzhiyunAs mentioned earlier, role of some partitions may depend on extra configuration.
25*4882a593SmuzhiyunFor example both: main firmware and backup firmware use the same TRX format with
26*4882a593Smuzhiyunthe same header. To distinguish currently used firmware a CFE's environment
27*4882a593Smuzhiyunvariable "bootpartition" is used.
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29*4882a593Smuzhiyun
30*4882a593SmuzhiyunDevices using Broadcom partitions described above should should have flash node
31*4882a593Smuzhiyunwith a subnode named "partitions" using following properties:
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33*4882a593SmuzhiyunRequired properties:
34*4882a593Smuzhiyun- compatible : (required) must be "brcm,bcm947xx-cfe-partitions"
35*4882a593Smuzhiyun
36*4882a593SmuzhiyunExample:
37*4882a593Smuzhiyun
38*4882a593Smuzhiyunflash@0 {
39*4882a593Smuzhiyun	partitions {
40*4882a593Smuzhiyun		compatible = "brcm,bcm947xx-cfe-partitions";
41*4882a593Smuzhiyun	};
42*4882a593Smuzhiyun};
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