linux-kernel - Re: [PATCH 2/3] dt-bindings: spi: Convert sprd ADI bindings to yaml

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Date:   Tue, 24 Aug 2021 12:19:57 -0500
From:   Rob Herring <robh@...nel.org>
To:     Chunyan Zhang <zhang.lyra@...il.com>
Cc:     Mark Brown <broonie@...nel.org>, linux-spi@...r.kernel.org,
        devicetree@...r.kernel.org, Baolin Wang <baolin.wang7@...il.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>,
        Luting Guo <luting.guo@...soc.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] dt-bindings: spi: Convert sprd ADI bindings to yaml

On Tue, Aug 24, 2021 at 05:27:44PM +0800, Chunyan Zhang wrote:
> From: Chunyan Zhang <chunyan.zhang@...soc.com>
> 
> Convert spi-sprd-adi.txt to yaml.
> 
> Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>
> ---
>  .../devicetree/bindings/spi/spi-sprd-adi.txt  | 63 ------------
>  .../devicetree/bindings/spi/sprd,spi-adi.yaml | 99 +++++++++++++++++++
>  2 files changed, 99 insertions(+), 63 deletions(-)
>  delete mode 100644 Documentation/devicetree/bindings/spi/spi-sprd-adi.txt
>  create mode 100644 Documentation/devicetree/bindings/spi/sprd,spi-adi.yaml

[...]

> diff --git a/Documentation/devicetree/bindings/spi/sprd,spi-adi.yaml b/Documentation/devicetree/bindings/spi/sprd,spi-adi.yaml
> new file mode 100644
> index 000000000000..f464fb6033f9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/sprd,spi-adi.yaml
> @@ -0,0 +1,99 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +
> +%YAML 1.2
> +---
> +$id: "http://devicetree.org/schemas/spi/sprd,spi-adi.yaml#"
> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
> +
> +title: Spreadtrum ADI controller
> +
> +maintainers:
> +  - Orson Zhai <orsonzhai@...il.com>
> +  - Baolin Wang <baolin.wang7@...il.com>
> +  - Chunyan Zhang <zhang.lyra@...il.com>
> +
> +description: |
> +  ADI is the abbreviation of Anolog-Digital interface, which is used to access
> +  analog chip (such as PMIC) from digital chip. ADI controller follows the SPI
> +  framework for its hardware implementation is alike to SPI bus and its timing
> +  is compatile to SPI timing.
> +
> +  ADI controller has 50 channels including 2 software read/write channels and
> +  48 hardware channels to access analog chip. For 2 software read/write channels,
> +  users should set ADI registers to access analog chip. For hardware channels,
> +  we can configure them to allow other hardware components to use it independently,
> +  which means we can just link one analog chip address to one hardware channel,
> +  then users can access the mapped analog chip address by this hardware channel
> +  triggered by hardware components instead of ADI software channels.
> +
> +  Thus we introduce one property named "sprd,hw-channels" to configure hardware
> +  channels, the first value specifies the hardware channel id which is used to
> +  transfer data triggered by hardware automatically, and the second value specifies
> +  the analog chip address where user want to access by hardware components.
> +
> +  Since we have multi-subsystems will use unique ADI to access analog chip, when
> +  one system is reading/writing data by ADI software channels, that should be under
> +  one hardware spinlock protection to prevent other systems from reading/writing
> +  data by ADI software channels at the same time, or two parallel routine of setting
> +  ADI registers will make ADI controller registers chaos to lead incorrect results.
> +  Then we need one hardware spinlock to synchronize between the multiple subsystems.
> +
> +  The new version ADI controller supplies multiple master channels for different
> +  subsystem accessing, that means no need to add hardware spinlock to synchronize,
> +  thus change the hardware spinlock support to be optional to keep backward
> +  compatibility.
> +
> +allOf:
> +  - $ref: /spi/spi-controller.yaml#
> +
> +properties:
> +  compatible:
> +    enum:
> +      - sprd,sc9860-adi
> +
> +  reg:
> +    maxItems: 1
> +
> +  hwlocks:
> +    description: Reference to a phandle of a hwlock provider node.

Drop, and add 'maxItems: 1'.

> +
> +  hwlock-names:
> +    description: |
> +      Reference to hwlock name strings defined in the same order
> +      as the hwlocks, should be "adi".

Should be a schema. So drop and add:

const: adi

> +
> +  sprd,hw-channels:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    maxItems: 1

This means 1 uint32.

> +    description: |
> +      This is an array of channel values up to 49 channels.

But this implies 49 entries.

> +      The first value specifies the hardware channel id which is used to
> +      transfer data triggered by hardware automatically, and the second
> +      value specifies the analog chip address where user want to access
> +      by hardware components.

Or 49x2 and that's a uint32-matrix given it's pairs of values. That 
should look something like this:

minItems: 1
maxItems: 49
items:
  items:
    - description: the hardware channel id...
      minimum: ??
      maximum: ?? (range of channel ids?)
    - description: the analog chip address where user want to access...

Rob