[PATCH v3 1/3] Add validation instructions
Add simple instructions for people wanting to validate their schema.
Signed-off-by: Simon Glass sjg@chromium.org ---
(no changes since v1)
README.md | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/README.md b/README.md index 9d2f6e8..d8767fa 100644 --- a/README.md +++ b/README.md @@ -118,6 +118,25 @@ Example: dt-check-compatible -s processed-schema.json vendor,a-compatible ```
+## Testing your changes + +Once you add or change schema, you should test it locally. This assumes that +your system is set up so that 'python' runs Python 3. + +First make sure you don't have any existing dt-schema in your system as this +may interfere: + +``` +sudo apt-get remove dt-schema +pip remove dt-schema +``` + +Then, to validate, use: + +``` +PYTHONPATH=. test/test-dt-validate.py +``` + ## Installing The project and its dependencies can be installed with pip:
Add a motivation and purpose for this new proposed node.
Signed-off-by: Simon Glass sjg@chromium.org ---
(no changes since v1)
dtschema/schemas/firmware.yaml | 83 ++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 dtschema/schemas/firmware.yaml
diff --git a/dtschema/schemas/firmware.yaml b/dtschema/schemas/firmware.yaml new file mode 100644 index 0000000..4439a70 --- /dev/null +++ b/dtschema/schemas/firmware.yaml @@ -0,0 +1,83 @@ +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-clause +# Copyright 2023 Google LLC +# + +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/firmware.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: /firmware Node + +maintainers: + - Simon Glass sjg@chromium.org + +description: | + The '/firmware' node does not represent a real device, but serves as a place + for recording information about the main firmware used on the device, such as + a map of its contents. This is used by the Operating System (OS), user space + programs and possibly other firmware components. Data in the '/firmware' node + does not itself represent the hardware. + + Properties in this node should be common to (and used by) at least two + firmware projects, such as U-Boot and TF-A. Project-specific subnodes can be + used for properties which are specific to a single project. + + Purpose of '/firmware' node + --------------------------- + + Firmware has traditionally been fairly opaque to the OS, with the OS taking + no interest in its contents, version, layout or how it might be updated. This + is less than ideal, since firmware is an important part of the system and + visibility into its operation is every bit as important as visbility into the + OS and user-space programs within the system. + + The traditional approach has been to let firmware deal with firmware, and the + OS deal with everything else. Updating firmware has been handled by firmware. + For example, the UEFI spec defines a way for the OS to post a 'capsule' which + is discovered next time the system boots, permitting firmware updates. But + firmware updates in firmware are highly problematic. They require a reboot + and a sometimes-lengthy wait with a strange-looking interface unfamiliar + to most users. It seems better to make the update as transparent as possible + to the user. As an example of that, ChromeOS has full knowledge of the + firmware version and layout, updates it in the background from user space and + instantly selects the new firmware when the user reboots or logs out. + + A common objection to considering the system holistically is that some parts + of the system are inaccessible to the OS, such as a secure enclave. However + this does not preclude providing visibility into what is present in that + enclave. Firmware-version information is still useful. Firmware updates are + still needed and can still be initiated from user space. + + Another objection is that firmware should provide an interface to the OS, + while keeping its structure private. This thinking is largely driven by + extrapolating from how firmware has been handled in the 'BIOS' days. + It should be considered a degenerate case rather than the norm. As complexity + increases, it creates an artificial boundary between two pieces of the whole. + Mechanisms then need to be invented to cross this unnecessary chasm. An + example of this is Intel's Dynamic Platform and Thermal Framework (DPTF), + which consists of user-space, OS and firmware components all working towards + a shared goal. We need a standard description of these cross-system pieces. + + In order to 'teach the OS about firmware', we need a place to put this + information. That is the purpose of this node. + + In an Open Source world the entire model of firmware needs to adjust to be + more open, more visible and managed just like any other part of the system. + The major goal is to standardise how firmware is presented to the OS and user + space, so that common utilities can be used to manage the entire system, + including the firmware. For example, fwupd can look in this node for + information on how to update the firmware, similar to how VBE works. [1] + It is likely that other purposes will come to light over time. + + [1] https://github.com/fwupd/fwupd/tree/main/plugins/vbe + +properties: + $nodename: + const: firmware + + "#address-cells": true + "#size-cells": true + +additionalProperties: + type: object
With this version I have done with a generic name, in this case 'data', as suggested by Alper Nebi Yasak. This may be controversial, but we may as well have the dicussion now. I assume that there are no other ongoing attempts to define the layout of firmware in devicetree.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v3: Use data,layout for the layout property
Changes in v2: - Reworked significantly based on Alper's comments
dtschema/schemas/firmware/image.yaml | 77 +++++++++++++++++++++ dtschema/schemas/firmware/layout/entry.yaml | 77 +++++++++++++++++++++ 2 files changed, 154 insertions(+) create mode 100644 dtschema/schemas/firmware/image.yaml create mode 100644 dtschema/schemas/firmware/layout/entry.yaml
diff --git a/dtschema/schemas/firmware/image.yaml b/dtschema/schemas/firmware/image.yaml new file mode 100644 index 0000000..cc052e8 --- /dev/null +++ b/dtschema/schemas/firmware/image.yaml @@ -0,0 +1,77 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +# Copyright 2023 Google LLC + +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/firmware/image.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Binman firmware layout + +maintainers: + - Simon Glass sjg@chromium.org + +description: | + The image node provides a layout for firmware, used when packaging firmware + from multiple projects. For now it just supports a very simple set of + features, as a starting point for discussion. + + The Binman tool processes this node to produce a final image which can be + loaded into suitable storage device. Documentation is at: + + https://u-boot.readthedocs.io/en/latest/develop/package/binman.html + + The current image-description format is here: + + https://u-boot.readthedocs.io/en/latest/develop/package/binman.html#image-de... + + It is desirable to reference the image from the storage-device node, perhaps + using an image-desc property: + + spiflash@0 { + compatible = "spidev", "jedec,spi-nor"; + data,layout = <&image>; + }; + + Note that the intention is to change Binman to use whatever schema is agreed + here. + +properties: + $nodename: + pattern: "^[-a-z]+(-[0-9]+)?$" + + compatible: + const: data,image + + "#address-cells": + const: 1 + + "#size-cells": + const: 1 + +required: + - compatible + - "#address-cell" + - "#size-cells" + +additionalProperties: true + +examples: + - | + firmware { + image: image { + compatible = "data,image"; + #address-cells = <1>; + $size-cells = <1>; + + u-boot@0 { + compatible = "data,u-boot"; + reg = <0 0xa0000>; + }; + + atf-bl31@0x100000 { + compatible = "data,atf-bl31"; + reg = <0x100000 0x20000>; + }; + }; + }; diff --git a/dtschema/schemas/firmware/layout/entry.yaml b/dtschema/schemas/firmware/layout/entry.yaml new file mode 100644 index 0000000..29f0dfc --- /dev/null +++ b/dtschema/schemas/firmware/layout/entry.yaml @@ -0,0 +1,77 @@ +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) +# Copyright 2023 Google LLC + +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/firmware/layout/entry.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Image entry + +maintainers: + - Simon Glass sjg@chromium.org + +description: | + The entry node specifies a single entry in the firmware image. + + Entries have a specific type, such as "u-boot" or "atf-bl31". This is provided + using compatible = "data,<type>". + + Note: This definition is intended to be hierarchical, so that entries can + appear in other entries. Schema for that is TBD. + +properties: + compatible: + $ref: /schemas/types.yaml#/definitions/string + + offset: + $ref: /schemas/types.yaml#/definitions/uint32 + description: | + Provides the offset of this entry from the start of its parent section. + + This may be omitted in the description provided by Binman, in which case + the value is calculated as part of image packing. + + size: + $ref: /schemas/types.yaml#/definitions/uint32 + description: | + Provides the size of this entry in bytes. + + This may be omitted in the description provided by Binman, in which case + the value is calculated as part of image packing. + + reg: + description: | + Defines the offset and size of this entry, with reference to its parent + image / section. + + Note This is typically omitted in the description provided to Binman, + since the value is calculated as part of image packing. Separate + properties are provided for the size and offset of an entry, so that it is + easy to specify none, one or both. The `reg` property is the only one that + needs to be looked at once the image has been built. + +required: + - compatible + +additionalProperties: true + +examples: + - | + firmware { + image: image { + compatible = "data,image"; + #address-cells = <1>; + $size-cells = <1>; + + u-boot@0 { + compatible = "data,u-boot"; + reg = <0 0xa0000>; + }; + + atf-bl31@0x100000 { + compatible = "data,atf-bl31"; + reg = <0x100000 0x20000>; + }; + }; + };
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Simon Glass