On Wed, 9 May 2018 10:17:28 +0200 Rafał Miłecki <zajec5@xxxxxxxxx> wrote: > From: Rafał Miłecki <rafal@xxxxxxxxxx> > > Broadcom based home router devices use partitions which have to be > discovered in a specific way. They are not fixed and there is not any > standard partition table. This commit adds and describes a new custom > binding for such devices. > > Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx> Applied both. Thanks, Boris > --- > This commit documents a new binding for describing partitions. Just as a > reminder: we agreed to use "compatible" for that purpose to avoid > /guessing/. There are too many cases, devices and /formats/ to just > blindly try every possible parser. > > This was e.g. described by Boris in his patchset 2+ years ago: > [RFC PATCH 0/7] mtd: partitions: add of_match_table support > http://lists.infradead.org/pipermail/linux-mtd/2015-December/064076.html > > Quote: > > (2) we can't just scan for all supported parsers (like the block system does), since > > there is a wide diversity of "formats" (no standardization), and it is not > > always safe or efficient to attempt to do so, particularly since many of > > them allow their data structures to be placed anywhere on the flash, and > > so require scanning the entire flash device to find them. > > I believe this solution was also acked back then by Rob: > [RFC PATCH 3/7] doc: dt: mtd: partition: add on-flash format binding > http://lists.infradead.org/pipermail/linux-mtd/2015-December/064100.html > > V2: Move documentation to the new brcm,bcm947xx-cfe-partitions.txt file > as suggested by Rob (we don't want to bloat partition.txt). > Slightly update commit message. > --- > .../devicetree/bindings/mtd/partition.txt | 2 +- > .../partitions/brcm,bcm947xx-cfe-partitions.txt | 42 ++++++++++++++++++++++ > 2 files changed, 43 insertions(+), 1 deletion(-) > create mode 100644 Documentation/devicetree/bindings/mtd/partitions/brcm,bcm947xx-cfe-partitions.txt > > diff --git a/Documentation/devicetree/bindings/mtd/partition.txt b/Documentation/devicetree/bindings/mtd/partition.txt > index 36f3b769a626..a8f382642ba9 100644 > --- a/Documentation/devicetree/bindings/mtd/partition.txt > +++ b/Documentation/devicetree/bindings/mtd/partition.txt > @@ -14,7 +14,7 @@ method is used for a given flash device. To describe the method there should be > a subnode of the flash device that is named 'partitions'. It must have a > 'compatible' property, which is used to identify the method to use. > > -We currently only document a binding for fixed layouts. > +Available bindings are listed in the "partitions" subdirectory. > > > Fixed Partitions > diff --git a/Documentation/devicetree/bindings/mtd/partitions/brcm,bcm947xx-cfe-partitions.txt b/Documentation/devicetree/bindings/mtd/partitions/brcm,bcm947xx-cfe-partitions.txt > new file mode 100644 > index 000000000000..1d61a029395e > --- /dev/null > +++ b/Documentation/devicetree/bindings/mtd/partitions/brcm,bcm947xx-cfe-partitions.txt > @@ -0,0 +1,42 @@ > +Broadcom BCM47xx Partitions > +=========================== > + > +Broadcom is one of hardware manufacturers providing SoCs (BCM47xx) used in > +home routers. Their BCM947xx boards using CFE bootloader have several partitions > +without any on-flash partition table. On some devices their sizes and/or > +meanings can also vary so fixed partitioning can't be used. > + > +Discovering partitions on these devices is possible thanks to having a special > +header and/or magic signature at the beginning of each of them. They are also > +block aligned which is important for determinig a size. > + > +Most of partitions use ASCII text based magic for determining a type. More > +complex partitions (like TRX with its HDR0 magic) may include extra header > +containing some details, including a length. > + > +A list of supported partitions includes: > +1) Bootloader with Broadcom's CFE (Common Firmware Environment) > +2) NVRAM with configuration/calibration data > +3) Device manufacturer's data with some default values (e.g. SSIDs) > +4) TRX firmware container which can hold up to 4 subpartitions > +5) Backup TRX firmware used after failed upgrade > + > +As mentioned earlier, role of some partitions may depend on extra configuration. > +For example both: main firmware and backup firmware use the same TRX format with > +the same header. To distinguish currently used firmware a CFE's environment > +variable "bootpartition" is used. > + > + > +Devices using Broadcom partitions described above should should have flash node > +with a subnode named "partitions" using following properties: > + > +Required properties: > +- compatible : (required) must be "brcm,bcm947xx-cfe-partitions" > + > +Example: > + > +flash@0 { > + partitions { > + compatible = "brcm,bcm947xx-cfe-partitions"; > + }; > +}; -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
