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Message-ID: <54426665-90c5-4355-a174-f512004e11e5@linaro.org>
Date: Sat, 20 Jan 2024 14:32:17 +0100
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Subject: Re: [PATCH 2/2] dt-bindings: hwinfo: Add Qualcomm's board-id types
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To: Amrit Anand <quic_amrianan@quicinc.com>, robh+dt@kernel.org,
 krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, agross@kernel.org,
 andersson@kernel.org
Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-arm-msm@vger.kernel.org, kernel@quicinc.com,
 Elliot Berman <quic_eberman@quicinc.com>
References: <1705749649-4708-1-git-send-email-quic_amrianan@quicinc.com>
 <1705749649-4708-3-git-send-email-quic_amrianan@quicinc.com>
From: Konrad Dybcio <konrad.dybcio@linaro.org>
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In-Reply-To: <1705749649-4708-3-git-send-email-quic_amrianan@quicinc.com>
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On 20.01.2024 12:20, Amrit Anand wrote:
> Qualcomm based DT uses two or three different identifiers. The SoC
> based idenfier which signifies chipset and the revision for those
> chipsets. The board based identifier is used to distinguish different
> boards (e.g. IDP, MTP) along with the different types of same boards.
> The PMIC attached to the board can also be used as a identifier for
> device tree.
> 
> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
> Signed-off-by: Amrit Anand <quic_amrianan@quicinc.com>
> ---
>  .../devicetree/bindings/hwinfo/qcom,board-id.yaml  | 86 ++++++++++++++++++++++
>  include/dt-bindings/arm/qcom,ids.h                 | 68 +++++++++++++++--
>  2 files changed, 146 insertions(+), 8 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> 
> diff --git a/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> new file mode 100644
> index 0000000..807f134
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwinfo/qcom,board-id.yaml
> @@ -0,0 +1,86 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/hwinfo/qcom,board-id.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: QCOM Board Identifier for Devicetree Selection
> +
> +maintainers:
> +  - Amrit Anand <quic_amrianan@quicinc.com>
> +  - Elliot Berman <quic_eberman@quicinc.com>
> +
> +description: |

The '|'s are unnecessary in both commits, IIRC they're used for
preserving formatting which we don't really need for non-styled
plaintext

> +  Qualcomm uses two and sometimes three hardware identifiers to describe
> +  its boards
> +      - a SoC identifier is used to match chipsets (e.g. sm8550 vs sm8450)
> +      - a board identifier is used to match board form factor (e.g. MTP, QRD,
> +        ADP, CRD)
> +      - a PMIC identifier is occasionally used when different PMICs are used
> +        for a given board/SoC combination.
> +  Each field and helper macros are defined at::
> +      - include/dt-bindings/arm/qcom,ids.h
> +
> +  For example,
> +    / {
> +        #board-id-cells = <2>;
> +        board-id = <456 0>, <457 0>, <10 0>;
> +        board-id-types = "qcom,soc-id", "qcom,soc-id", "qcom,board-id";
> +     }
> +
> +allOf:
> +  - $ref: board-id.yaml#
> +
> +properties:
> +  board-id:
> +    minItems: 2

I believe some older platforms match exclusively based on socid, so
perhaps 1 would be okay as well.

[...]

> +examples:
> +   - |
> +     #include <dt-bindings/arm/qcom,ids.h>
> +     / {
> +         model = "Qualcomm Technologies, Inc. sc7280 IDP SKU1 platform";
> +         compatible = "qcom,sc7280-idp", "google,senor", "qcom,sc7280";
> +
> +         #board-id-cells = <2>;
> +         board-id = <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(1)>,
> +                    <QCOM_SOC_ID(SC7280) QCOM_SOC_REVISION(2)>,
> +                    <QCOM_BOARD_ID(IDP, 1, 0) QCOM_BOARD_SUBTYPE(UFS, ANY, 1)>;
> +         board-id-types = "qcom,soc-id",
> +                          "qcom,soc-id",
> +                          "qcom,board-id";

So, would the matching here would be:

loop over disctinct board-id-types
	check if there's at least 1 match for all of them
		use this dtb if that's the case

stop booting / "best guess match"

?

[...]

> +#define QCOM_BOARD_ID_MTP		0x8
> +#define QCOM_BOARD_ID_DRAGONBOARD	0x10
> +#define QCOM_BOARD_ID_QRD		0x11
> +#define QCOM_BOARD_ID_HDK		0x1F
> +#define QCOM_BOARD_ID_ATP		0x21
> +#define QCOM_BOARD_ID_IDP		0x22
> +#define QCOM_BOARD_ID_SBC		0x24
> +#define QCOM_BOARD_ID_QXR		0x26
> +#define QCOM_BOARD_ID_CRD		0x28

Missing ADP/QCP/Ride (if they're separate)

Konrad