On Fri, Nov 20, 2015 at 03:31:16PM -0800, Stephen Boyd wrote:
> Some qcom based bootloaders identify the dtb blob based on a set
> of device properties like SoC, platform, PMIC, and revisions of
> those components. In downstream kernels, these values are added
> to the different component dtsi files (i.e. pmic dtsi file, SoC
> dtsi file, board dtsi file, etc.) via qcom specific DT
> properties. The dtb files are parsed by a program called dtbTool
> that picks out these properties and creates a table of contents
> binary blob with the property information and some offsets into
> the concatenation of all the dtbs (termed a QCDT image).
>
> The suggestion is to do this via the board compatible string
> instead, because these qcom specific properties are never used by
> the kernel. Add a document describing the format of the
> compatible string that encodes all this information that's
> currently encoded in the qcom,{msm-id,board-id,pmic-id}
> properties in downstream devicetrees. Future bootloaders may be
> updated to look at the compatible field instead of looking for
> the table of contents image. For non-updateable bootloaders, a
> new dtbTool program will parse the compatible string and generate
> a QCDT image from it.
>
> Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxxxxxx>
Much more reasonable now. I do find the '/' in it a bit strange though.
Acked-by: Rob Herring <robh@xxxxxxxxxx>
> ---
> Documentation/devicetree/bindings/arm/qcom.txt | 51 ++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/arm/qcom.txt
>
> diff --git a/Documentation/devicetree/bindings/arm/qcom.txt b/Documentation/devicetree/bindings/arm/qcom.txt
> new file mode 100644
> index 000000000000..3e24518c6678
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/qcom.txt
> @@ -0,0 +1,51 @@
> +QCOM device tree bindings
> +-------------------------
> +
> +Some qcom based bootloaders identify the dtb blob based on a set of
> +device properties like SoC and platform and revisions of those components.
> +To support this scheme, we encode this information into the board compatible
> +string.
> +
> +Each board must specify a top-level board compatible string with the following
> +format:
> +
> + compatible = "qcom,<SoC>[-<soc_version>][-<foundry_id>]-<board>[/<subtype>][-<board_version>]"
> +
> +The 'SoC' and 'board' elements are required. All other elements are optional.
> +
> +The 'SoC' element must be one of the following strings:
> +
> + apq8016
> + apq8074
> + apq8084
> + apq8096
> + msm8916
> + msm8974
> + msm8996
> +
> +The 'board' element must be one of the following strings:
> +
> + cdp
> + liquid
> + dragonboard
> + mtp
> + sbc
> +
> +The 'soc_version' and 'board_version' elements take the form of v<Major>.<Minor>
> +where the minor number may be omitted when it's zero, i.e. v1.0 is the same
> +as v1. If all versions of the 'board_version' elements match, then a
> +wildcard '*' should be used, e.g. 'v*'.
> +
> +The 'foundry_id' and 'subtype' elements are one or more digits from 0 to 9.
> +
> +Examples:
> +
> + "qcom,msm8916-v1-cdp-pm8916-v2.1"
> +
> +A CDP board with an msm8916 SoC, version 1 paired with a pm8916 PMIC of version
> +2.1.
> +
> + "qcom,apq8074-v2.0-2-dragonboard/1-v0.1"
> +
> +A dragonboard board v0.1 of subtype 1 with an apq8074 SoC version 2, made in
> +foundry 2.
> --
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