[PATCH v6 3/3] dt-bindings: mtd: binman-partitions: Add alignment properties

Simon Glass
2023-11-16T17:29:17Z

Add three properties for controlling alignment of partitions, aka
'entries' in binman.

For now there is no explicit mention of hierarchy, so a 'section' is
just the 'binman' node.

These new properties are inputs to the packaging process, but are also
needed if the firmware is repacked, to ensure that alignment
constraints are not violated. Therefore they are provided as part of
the schema.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

Changes in v6:
- Correct schema-validation errors missed due to older dt-schema
(enum fix and reg addition)

Changes in v5:
- Add value ranges
- Consistently mention alignment must be power-of-2
- Mention that alignment refers to bytes

Changes in v2:
- Fix 'a' typo in commit message

.../mtd/partitions/binman-partition.yaml | 54 +++++++++++++++++++
1 file changed, 54 insertions(+)

diff --git a/Documentation/devicetree/bindings/mtd/partitions/binman-partition.yaml b/Documentation/devicetree/bindings/mtd/partitions/binman-partition.yaml
index 83222ac9aa78..2bc80c24bb9b 100644
--- a/Documentation/devicetree/bindings/mtd/partitions/binman-partition.yaml
+++ b/Documentation/devicetree/bindings/mtd/partitions/binman-partition.yaml
@@ -33,6 +33,57 @@ properties:
minItems: 1
maxItems: 2

+ align:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 1
+ maximum: 0x80000000
+ multipleOf: 2
+ description:
+ This sets the alignment of the entry in bytes.
+
+ The entry offset is adjusted so that the entry starts on an aligned
+ boundary within the containing section or image. For example ‘align =
+ <16>’ means that the entry will start on a 16-byte boundary. This may
+ mean that padding is added before the entry. The padding is part of
+ the containing section but is not included in the entry, meaning that
+ an empty space may be created before the entry starts. Alignment
+ must be a power of 2. If ‘align’ is not provided, no alignment is
+ performed.
+
+ align-size:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 1
+ maximum: 0x80000000
+ multipleOf: 2
+ description:
+ This sets the alignment of the entry size in bytes. It must be a power
+ of 2.
+
+ For example, to ensure that the size of an entry is a multiple of 64
+ bytes, set this to 64. While this does not affect the contents of the
+ entry within binman itself (the padding is performed only when its
+ parent section is assembled), the end result is that the entry ends
+ with the padding bytes, so may grow. If ‘align-size’ is not provided,
+ no alignment is performed.
+
+ align-end:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 1
+ maximum: 0x80000000
+ multipleOf: 2
+ description:
+ This sets the alignment (in bytes) of the end of an entry with respect
+ to the containing section. It must be a power of 2.
+
+ Some entries require that they end on an alignment boundary,
+ regardless of where they start. This does not move the start of the
+ entry, so the contents of the entry will still start at the beginning.
+ But there may be padding at the end. While this does not affect the
+ contents of the entry within binman itself (the padding is performed
+ only when its parent section is assembled), the end result is that the
+ entry ends with the padding bytes, so may grow. If ‘align-end’ is not
+ provided, no alignment is performed.
+
additionalProperties: false

examples:
@@ -45,10 +96,13 @@ examples:
partition@100000 {
compatible = "u-boot";
reg = <0x100000 0xf00000>;
+ align-size = <0x1000>;
+ align-end = <0x10000>;
};

partition@200000 {
compatible = "tfa-bl31";
reg = <0x200000 0x100000>;
+ align = <0x4000>;
};
};
--
2.43.0.rc0.421.g78406f8d94-goog