From: Brian Norris <computersforpeace@xxxxxxxxx>
Currently the only documented partitioning is "fixed-partitions" but
there are more methods in use that we may want to support in the future.
Mention them and make it clear Fixed Partitions are just a single case.
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
Signed-off-by: Rafał Miłecki <rafal@xxxxxxxxxx>
---
This is based on Brian's patch:
[RFC PATCH 3/7] doc: dt: mtd: partition: add on-flash format binding
V1: Dropped "Section B: On-Flash Partition Tables" with Google's FMAP as this
patchset doesn't add that new parser.
V2: Add "We currently only document a binding for fixed layouts." part
V3: Extend description of 'partitions' subnode - thanks Florian
---
.../devicetree/bindings/mtd/partition.txt | 32 ++++++++++++++++++----
1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/mtd/partition.txt b/Documentation/devicetree/bindings/mtd/partition.txt
index 81a224da63be..36f3b769a626 100644
--- a/Documentation/devicetree/bindings/mtd/partition.txt
+++ b/Documentation/devicetree/bindings/mtd/partition.txt
@@ -1,29 +1,49 @@
-Representing flash partitions in devicetree
+Flash partitions in device tree
+===============================
-Partitions can be represented by sub-nodes of an mtd device. This can be used
+Flash devices can be partitioned into one or more functional ranges (e.g. "boot
+code", "nvram", "kernel").
+
+Different devices may be partitioned in a different ways. Some may use a fixed
+flash layout set at production time. Some may use on-flash table that describes
+the geometry and naming/purpose of each functional region. It is also possible
+to see these methods mixed.
+
+To assist system software in locating partitions, we allow describing which
+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.
+
+
+Fixed Partitions
+================
+
+Partitions can be represented by sub-nodes of a flash device. This can be used
on platforms which have strong conventions about which portions of a flash are
used for what purposes, but which don't use an on-flash partition table such
as RedBoot.
-The partition table should be a subnode of the mtd node and should be named
+The partition table should be a subnode of the flash node and should be named
'partitions'. This node should have the following property:
- compatible : (required) must be "fixed-partitions"
Partitions are then defined in subnodes of the partitions node.
-For backwards compatibility partitions as direct subnodes of the mtd device are
+For backwards compatibility partitions as direct subnodes of the flash device are
supported. This use is discouraged.
NOTE: also for backwards compatibility, direct subnodes that have a compatible
string are not considered partitions, as they may be used for other bindings.
#address-cells & #size-cells must both be present in the partitions subnode of the
-mtd device. There are two valid values for both:
+flash device. There are two valid values for both:
<1>: for partitions that require a single 32-bit cell to represent their
size/address (aka the value is below 4 GiB)
<2>: for partitions that require two 32-bit cells to represent their
size/address (aka the value is 4 GiB or greater).
Required properties:
-- reg : The partition's offset and size within the mtd bank.
+- reg : The partition's offset and size within the flash
Optional properties:
- label : The label / name for this partition. If omitted, the label is taken
--
2.11.0
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