Re: [PATCH v3 1/2] dt-bindings: arm: qcom: document qcom,msm-id and qcom,board-id

[Krzysztof Kozlowski]

On 22/06/2022 13:56, Konrad Dybcio wrote:
> 
> 
> On 22.06.2022 13:48, Krzysztof Kozlowski wrote:
>> The top level qcom,msm-id and qcom,board-id properties are utilized by
>> bootloaders on Qualcomm MSM platforms to determine which device tree
>> should be used and passed to the kernel.
>>
>> The commit b32e592d3c28 ("devicetree: bindings: Document qcom board
>> compatible format") from 2015 was a consensus during discussion about
>> upstreaming qcom,msm-id and qcom,board-id fields.  There are however still
>> problems with that consensus:
>> 1. It was reached 7 years ago but it turned out its implementation did
>>    not reach all possible products.
>>
>> 2. Initially additional tool (dtbTool) was needed for parsing these
>>    fields to create a QCDT image consisting of multiple DTBs, later the
>>    bootloaders were improved and they use these qcom,msm-id and
>>    qcom,board-id properties directly.
>>
>> 3. Extracting relevant information from the board compatible requires
>>    this additional tool (dtbTool), which makes the build process more
>>    complicated and not easily reproducible (DTBs are modified after the
>>    kernel build).
>>
>> 4. Some versions of Qualcomm bootloaders expect these properties even
>>    when booting with a single DTB.  The community is stuck with these
>>    bootloaders thus they require properties in the DTBs.
>>
>> Since several upstreamed Qualcomm SoC-based boards require these
>> properties to properly boot and the properties are reportedly used by
>> bootloaders, document them.
>>
>> Link: https://lore.kernel.org/r/a3c932d1-a102-ce18-deea-18cbbd05ecab@xxxxxxxxxx/
>> Co-developed-by: Kumar Gala <galak@xxxxxxxxxxxxxx>
>> Signed-off-by: Kumar Gala <galak@xxxxxxxxxxxxxx>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
>> ---
>>  .../devicetree/bindings/arm/qcom.yaml         | 121 ++++++++++++++++++
>>  include/dt-bindings/arm/qcom,ids.h            |  30 +++++
>>  2 files changed, 151 insertions(+)
>>  create mode 100644 include/dt-bindings/arm/qcom,ids.h
>>
>> diff --git a/Documentation/devicetree/bindings/arm/qcom.yaml b/Documentation/devicetree/bindings/arm/qcom.yaml
>> index 6c38c1387afd..431e3ff31d75 100644
>> --- a/Documentation/devicetree/bindings/arm/qcom.yaml
>> +++ b/Documentation/devicetree/bindings/arm/qcom.yaml
>> @@ -403,6 +403,127 @@ properties:
>>                - qcom,sm8450-qrd
>>            - const: qcom,sm8450
>>  
>> +  # Board compatibles go above
>> +
>> +  qcom,msm-id:
>> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
>> +    minItems: 1
>> +    maxItems: 8
>> +    items:
>> +      items:
>> +        - description: |
>> +            MSM chipset ID - an exact match value consisting of two bitfields::
>> +             - bits 0-15  - The unique MSM chipset ID
>> +             - bits 16-31 - Reserved; should be 0
>> +        - description: |
>> +            Hardware revision ID - a chipset specific 32-bit ID representing
>> +            the version of the chipset.  It is best a match value - the
>> +            bootloader will look for the closest possible match.
>> +    deprecated: true
>> +    description:
>> +      The MSM chipset and hardware revision use by Qualcomm bootloaders.  It
>> +      can optionally be an array of these to indicate multiple hardware that
>> +      use the same device tree.  It is expected that the bootloader will use
>> +      this information at boot-up to decide which device tree to use when given
>> +      multiple device trees, some of which may not be compatible with the
>> +      actual hardware.  It is the bootloader's responsibility to pass the
>> +      correct device tree to the kernel.
>> +      The property is deprecated.
>> +
>> +  qcom,board-id:
>> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
>> +    minItems: 1
>> +    maxItems: 8
>> +    items:
>> +      oneOf:
>> +        - maxItems: 2
>> +          items:
>> +            - description: |
>> +                Board ID consisting of three bitfields::
>> +                  - bits 31-24 - Unused
>> +                  - bits 23-16 - Platform Version Major
>> +                  - bits 15-8  - Platform Version Minor
>> +                  - bits 7-0   - Platform Type
>> +                Platform Type field is an exact match value.  The
>> +                Platform Major/Minor field is a best match.  The bootloader will
>> +                look for the closest possible match.
>> +            - description: |
>> +                Subtype ID unique to a Platform Type/Chipset ID.  For a given
>> +                Platform Type, there will typically only be a single board and the
>> +                subtype_id will be 0.  However in some cases board variants may
>> +                need to be distinguished by different subtype_id values.
>> +        # OnePlus uses a variant of board-id with four elements:
>> +        - minItems: 4
>> +          items:
>> +            - const: 8
>> +            - const: 0
>> +            - description: OnePlus board ID
>> +            - description: OnePlus subtype ID
>> +    deprecated: true
>> +    description:
>> +      The board type and revision information.  It can optionally be an array
>> +      of these to indicate multiple boards that use the same device tree.  It
>> +      is expected that the bootloader will use this information at boot-up to
>> +      decide which device tree to use when given multiple device trees, some of
>> +      which may not be compatible with the actual hardware.  It is the
>> +      bootloader's responsibility to pass the correct device tree to the
>> +      kernel
>> +      The property is deprecated.
>> +
>> +allOf:
>> +  # Explicit allow-list for older SoCs. The legacy properties are not allowed
>> +  # on newer SoCs.
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            enum:
>> +              - qcom,apq8026
>> +              - qcom,apq8094
>> +              - qcom,apq8096
>> +              - qcom,msm8992
>> +              - qcom,msm8994
>> +              - qcom,msm8996
>> +              - qcom,msm8998
>> +              - qcom,sdm630
>> +              - qcom,sdm632
>> +              - qcom,sdm845
>> +              - qcom,sdx55
>> +              - qcom,sdx65
>> +              - qcom,sm6125
>> +              - qcom,sm6350
>> +              - qcom,sm7225
>> +              - qcom,sm8150
>> +              - qcom,sm8250
>> +    then:
>> +      properties:
>> +        qcom,board-id: true
>> +        qcom,msm-id: true
>> +    else:
>> +      properties:
>> +        qcom,board-id: false
>> +        qcom,msm-id: false
>> +
>> +  - if:
>> +      properties:
>> +        compatible:
>> +          contains:
>> +            enum:
>> +              - oneplus,cheeseburger
>> +              - oneplus,dumpling
>> +              - oneplus,enchilada
>> +              - oneplus,fajita
>> +    then:
>> +      properties:
>> +        qcom,board-id:
>> +          items:
>> +            minItems: 4
>> +    else:
>> +      properties:
>> +        qcom,board-id:
>> +          items:
>> +            maxItems: 2
>> +
>>  additionalProperties: true
>>  
>>  ...
>> diff --git a/include/dt-bindings/arm/qcom,ids.h b/include/dt-bindings/arm/qcom,ids.h
>> new file mode 100644
>> index 000000000000..df4a07b898cc
>> --- /dev/null
>> +++ b/include/dt-bindings/arm/qcom,ids.h
>> @@ -0,0 +1,30 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) 2015, The Linux Foundation. All rights reserved.
>> + * Copyright (c) 2022 Linaro Ltd
>> + * Author: Krzysztof Kozlowski <krzk@xxxxxxxxxx> based on previous work of Kumar Gala.
>> + */
>> +#ifndef _DT_BINDINGS_ARM_QCOM_IDS_H
>> +#define _DT_BINDINGS_ARM_QCOM_IDS_H
>> +
>> +/* qcom,msm-id */
>> +#define QCOM_ID_APQ8026				199
>> +#define QCOM_ID_MSM8916				206
>> +#define QCOM_ID_MSM8994				207
>> +#define QCOM_ID_MSM8996				246
>> +#define QCOM_ID_APQ8016				247
>> +#define QCOM_ID_MSM8216				248
>> +#define QCOM_ID_MSM8116				249
>> +#define QCOM_ID_MSM8616				250
>> +#define QCOM_ID_MSM8998				292
>> +#define QCOM_ID_SDM845				321
> These are the same ones used in the qcom socid driver. Perhaps they can be exported from there?
> 

I can actually use the bindings in the socid driver. Less code.

Best regards,
Krzysztof