new file mode 100644
@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/layouts/nvmem-layout.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NVMEM (Non Volatile Memory) layouts
+
+maintainers:
+ - Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+ - Michael Walle <michael@walle.cc>
+ - Miquel Raynal <miquel.raynal@bootlin.com>
+
+description: |
+ Most NVMEM layouts are static and thus do not require additional description
+ besides the bytes/bits offset and length. Other layouts can be less statically
+ define and might require dynamic reading of the NVMEM device in order to
+ perform their parsing. The nvmem-layout container is here to describe these.
+
+properties:
+ compatible: true
+
+ '#address-cells': false
+
+ '#size-cells': false
+
+required:
+ - compatible
+
+unevaluatedProperties: false
@@ -39,6 +39,13 @@ properties:
when it's driven low (logical '0') to allow writing.
maxItems: 1
+ nvmem-layout:
+ $ref: /schemas/nvmem/layouts/nvmem-layout.yaml
+ description:
+ Alternative to the statically defined nvmem cells, this
+ container may reference more advanced (dynamic) layout
+ parsers.
+
patternProperties:
"@[0-9a-f]+(,[0-7])?$":
type: object
The nvmem devices description works like this: * Most cases (EEPROM & co): eeprom@x { compatible = "<eeprom-compatible>"; ... }; * MTD case: flash@y { compatible = "<flash-compatible>"; ... otp { compatible = "user-otp"; /* or "factory-otp" */ ... }; }; In the former case, the nvmem device is "eeprom@x", while in the latter case the nvmem device is "otp". Nvmem devices can produce nvmem cells. The current way to describe nvmem cells is to locate them by providing their static byte and bit offset and length. These information are stored in subnodes of the nvmem device. It is now a fact that such description does not fit more advanced use cases where the location or the size of the cells may vary. There are currently three known situations which require being described differently: Kontron's SL28 VPD, ONIE's TLV table and U-Boot's environment variables. Hence, we need a way to describe the parsers that must be used in order to make the dynamic discovery of the nvmem cells. This new description must fit both use cases (the generic situation and the MTD case). Let's create in both cases a container node named nvmem-layout whose content will depend on the parser. Right now nvmem-layout.yaml is "empty", but references to additional layout parser bindings will be inserted in the near future. The final goal being something that looks like: * Most cases (EEPROM & co): eeprom@x { compatible = "<eeprom-compatible>"; ... nvmem-layout { compatible = "<parser-compatible>"; ... }; }; * MTD case: flash@y { compatible = "<flash-compatible>"; ... otp { compatible = "user-otp"; /* or "factory-otp" */ ... nvmem-layout { compatible = "<parser-compatible>"; ... }; }; }; Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com> --- .../bindings/nvmem/layouts/nvmem-layout.yaml | 30 +++++++++++++++++++ .../devicetree/bindings/nvmem/nvmem.yaml | 7 +++++ 2 files changed, 37 insertions(+) create mode 100644 Documentation/devicetree/bindings/nvmem/layouts/nvmem-layout.yaml