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References: <20210518232858.1535403-1-robh@kernel.org> <20210518232858.1535403-5-robh@kernel.org>
 <YKRsPrFMNg5KY55j@pendragon.ideasonboard.com>
In-Reply-To: <YKRsPrFMNg5KY55j@pendragon.ideasonboard.com>
From:   Rob Herring <robh@kernel.org>
Date:   Tue, 18 May 2021 21:10:58 -0500
Message-ID: <CAL_JsqLVZL3RA0SHL08JfwfFgqVhKn8tK_C4jksghrk5TpGNLQ@mail.gmail.com>
Subject: Re: [PATCH 4/6] dt-bindings: i2c: Convert i2c-mux bindings to DT schema
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     devicetree@vger.kernel.org, Peter Rosin <peda@axentia.se>,
        Wolfram Sang <wsa@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Jacopo Mondi <jacopo+renesas@jmondi.org>,
        Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
        Kishon Vijay Abraham I <kishon@ti.com>,
        Lee Jones <lee.jones@linaro.org>,
        =?UTF-8?Q?Niklas_S=C3=B6derlund?= 
        <niklas.soderlund+renesas@ragnatech.se>,
        Roger Quadros <rogerq@ti.com>,
        Jonathan Cameron <jic23@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, May 18, 2021 at 8:39 PM Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Rob,
>
> Thank you for the patch.
>
> On Tue, May 18, 2021 at 06:28:56PM -0500, Rob Herring wrote:
> > As some of the example I2C devices don't have schemas yet, change them to
> > ones that do.
> >
> > Cc: Peter Rosin <peda@axentia.se>
> > Signed-off-by: Rob Herring <robh@kernel.org>
> > ---
> >  .../bindings/i2c/i2c-demux-pinctrl.txt        |   2 +-
> >  .../devicetree/bindings/i2c/i2c-mux-gpio.txt  |   4 +-
> >  .../devicetree/bindings/i2c/i2c-mux-gpmux.txt |  99 --------------
> >  .../bindings/i2c/i2c-mux-gpmux.yaml           | 124 ++++++++++++++++++
> >  .../bindings/i2c/i2c-mux-ltc4306.txt          |   4 +-
> >  .../bindings/i2c/i2c-mux-pinctrl.txt          |   4 +-
> >  .../devicetree/bindings/i2c/i2c-mux-reg.txt   |   4 +-
> >  .../devicetree/bindings/i2c/i2c-mux.txt       |  73 -----------
> >  .../devicetree/bindings/i2c/i2c-mux.yaml      |  87 ++++++++++++
> >  9 files changed, 220 insertions(+), 181 deletions(-)
> >  delete mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt
> >  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.yaml
> >  delete mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux.txt
> >  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
> > index 81b5d55086fa..86b2e433a969 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-demux-pinctrl.txt
> > @@ -27,7 +27,7 @@ Required properties:
> >  - i2c-bus-name: The name of this bus. Also needed as pinctrl-name for the I2C
> >               parents.
> >
> > -Furthermore, I2C mux properties and child nodes. See i2c-mux.txt in this
> > +Furthermore, I2C mux properties and child nodes. See i2c-mux.yaml in this
> >  directory.
> >
> >  Example:
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
> > index 21da3ecbb370..e00d2b9e957a 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.txt
> > @@ -22,8 +22,8 @@ Required properties:
> >  - i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
> >    port is connected to.
> >  - mux-gpios: list of gpios used to control the muxer
> > -* Standard I2C mux properties. See i2c-mux.txt in this directory.
> > -* I2C child bus nodes. See i2c-mux.txt in this directory.
> > +* Standard I2C mux properties. See i2c-mux.yaml in this directory.
> > +* I2C child bus nodes. See i2c-mux.yaml in this directory.
> >
> >  Optional properties:
> >  - idle-state: value to set the muxer to when idle. When no value is
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt
> > deleted file mode 100644
> > index 057083a8ba17..000000000000
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.txt
> > +++ /dev/null
> > @@ -1,99 +0,0 @@
> > -General Purpose I2C Bus Mux
> > -
> > -This binding describes an I2C bus multiplexer that uses a mux controller
> > -from the mux subsystem to route the I2C signals.
> > -
> > -                                  .-----.  .-----.
> > -                                  | dev |  | dev |
> > -    .------------.                '-----'  '-----'
> > -    | SoC        |                   |        |
> > -    |            |          .--------+--------'
> > -    |   .------. |  .------+    child bus A, on MUX value set to 0
> > -    |   | I2C  |-|--| Mux  |
> > -    |   '------' |  '--+---+    child bus B, on MUX value set to 1
> > -    |   .------. |     |    '----------+--------+--------.
> > -    |   | MUX- | |     |               |        |        |
> > -    |   | Ctrl |-|-----+            .-----.  .-----.  .-----.
> > -    |   '------' |                  | dev |  | dev |  | dev |
> > -    '------------'                  '-----'  '-----'  '-----'
> > -
> > -Required properties:
> > -- compatible: i2c-mux
> > -- i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
> > -  port is connected to.
> > -- mux-controls: The phandle of the mux controller to use for operating the
> > -  mux.
> > -* Standard I2C mux properties. See i2c-mux.txt in this directory.
> > -* I2C child bus nodes. See i2c-mux.txt in this directory. The sub-bus number
> > -  is also the mux-controller state described in ../mux/mux-controller.yaml
> > -
> > -Optional properties:
> > -- mux-locked: If present, explicitly allow unrelated I2C transactions on the
> > -  parent I2C adapter at these times:
> > -   + during setup of the multiplexer
> > -   + between setup of the multiplexer and the child bus I2C transaction
> > -   + between the child bus I2C transaction and releasing of the multiplexer
> > -   + during releasing of the multiplexer
> > -  However, I2C transactions to devices behind all I2C multiplexers connected
> > -  to the same parent adapter that this multiplexer is connected to are blocked
> > -  for the full duration of the complete multiplexed I2C transaction (i.e.
> > -  including the times covered by the above list).
> > -  If mux-locked is not present, the multiplexer is assumed to be parent-locked.
> > -  This means that no unrelated I2C transactions are allowed on the parent I2C
> > -  adapter for the complete multiplexed I2C transaction.
> > -  The properties of mux-locked and parent-locked multiplexers are discussed
> > -  in more detail in Documentation/i2c/i2c-topology.rst.
> > -
> > -For each i2c child node, an I2C child bus will be created. They will
> > -be numbered based on their order in the device tree.
> > -
> > -Whenever an access is made to a device on a child bus, the value set
> > -in the relevant node's reg property will be set as the state in the
> > -mux controller.
> > -
> > -Example:
> > -     mux: mux-controller {
> > -             compatible = "gpio-mux";
> > -             #mux-control-cells = <0>;
> > -
> > -             mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
> > -                         <&pioA 1 GPIO_ACTIVE_HIGH>;
> > -     };
> > -
> > -     i2c-mux {
> > -             compatible = "i2c-mux";
> > -             mux-locked;
> > -             i2c-parent = <&i2c1>;
> > -
> > -             mux-controls = <&mux>;
> > -
> > -             #address-cells = <1>;
> > -             #size-cells = <0>;
> > -
> > -             i2c@1 {
> > -                     reg = <1>;
> > -                     #address-cells = <1>;
> > -                     #size-cells = <0>;
> > -
> > -                     ssd1307: oled@3c {
> > -                             compatible = "solomon,ssd1307fb-i2c";
> > -                             reg = <0x3c>;
> > -                             pwms = <&pwm 4 3000>;
> > -                             reset-gpios = <&gpio2 7 1>;
> > -                             reset-active-low;
> > -                     };
> > -             };
> > -
> > -             i2c@3 {
> > -                     reg = <3>;
> > -                     #address-cells = <1>;
> > -                     #size-cells = <0>;
> > -
> > -                     pca9555: pca9555@20 {
> > -                             compatible = "nxp,pca9555";
> > -                             gpio-controller;
> > -                             #gpio-cells = <2>;
> > -                             reg = <0x20>;
> > -                     };
> > -             };
> > -     };
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.yaml
> > new file mode 100644
> > index 000000000000..3e6ea59aea68
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.yaml
> > @@ -0,0 +1,124 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/i2c/i2c-mux-gpmux.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: General Purpose I2C Bus Mux
> > +
> > +maintainers:
> > +  - Peter Rosin <peda@axentia.se>
> > +
> > +description: |+
> > +  This binding describes an I2C bus multiplexer that uses a mux controller
> > +  from the mux subsystem to route the I2C signals.
> > +
> > +                                    .-----.  .-----.
> > +                                    | dev |  | dev |
> > +      .------------.                '-----'  '-----'
> > +      | SoC        |                   |        |
> > +      |            |          .--------+--------'
> > +      |   .------. |  .------+    child bus A, on MUX value set to 0
> > +      |   | I2C  |-|--| Mux  |
> > +      |   '------' |  '--+---+    child bus B, on MUX value set to 1
> > +      |   .------. |     |    '----------+--------+--------.
> > +      |   | MUX- | |     |               |        |        |
> > +      |   | Ctrl |-|-----+            .-----.  .-----.  .-----.
> > +      |   '------' |                  | dev |  | dev |  | dev |
> > +      '------------'                  '-----'  '-----'  '-----'
> > +
> > +
> > +
> > +allOf:
> > +  - $ref: /schemas/i2c/i2c-mux.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    const: i2c-mux
> > +
> > +  i2c-parent:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description:
> > +      The phandle of the I2C bus that this multiplexer's master-side port is
> > +      connected to.
> > +
> > +  mux-controls:
> > +    maxItems: 1
> > +    description:
> > +      The mux-controller states are the I2C sub-bus numbers.
> > +
> > +  mux-locked:
> > +    type: boolean
> > +    description: |
> > +      Explicitly allow unrelated I2C transactions on the parent I2C adapter at
> > +      these times:
> > +       + during setup of the multiplexer
> > +       + between setup of the multiplexer and the child bus I2C transaction
> > +       + between the child bus I2C transaction and releasing of the multiplexer
> > +       + during releasing of the multiplexer
> > +
> > +      However, I2C transactions to devices behind all I2C multiplexers connected
> > +      to the same parent adapter that this multiplexer is connected to are blocked
> > +      for the full duration of the complete multiplexed I2C transaction (i.e.
> > +      including the times covered by the above list).
> > +      If mux-locked is not present, the multiplexer is assumed to be parent-locked.
> > +      This means that no unrelated I2C transactions are allowed on the parent I2C
> > +      adapter for the complete multiplexed I2C transaction.
> > +      The properties of mux-locked and parent-locked multiplexers are discussed
> > +      in more detail in Documentation/i2c/i2c-topology.rst.
> > +
> > +required:
> > +  - compatible
> > +  - i2c-parent
> > +  - mux-controls
> > +
> > +unevaluatedProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    mux: mux-controller {
> > +        compatible = "gpio-mux";
> > +        #mux-control-cells = <0>;
> > +
> > +        mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
> > +                    <&pioA 1 GPIO_ACTIVE_HIGH>;
> > +    };
> > +
> > +    i2c-mux {
> > +        compatible = "i2c-mux";
> > +        mux-locked;
> > +        i2c-parent = <&i2c1>;
> > +
> > +        mux-controls = <&mux>;
> > +
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        i2c@1 {
> > +            reg = <1>;
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            gpio@20 {
> > +                compatible = "nxp,pca9555";
> > +                gpio-controller;
> > +                #gpio-cells = <2>;
> > +                reg = <0x20>;
> > +            };
> > +        };
> > +
> > +        i2c@3 {
> > +            reg = <3>;
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            gpio@20 {
> > +                compatible = "nxp,pca9555";
> > +                gpio-controller;
> > +                #gpio-cells = <2>;
> > +                reg = <0x20>;
> > +            };
> > +        };
> > +    };
> > +...
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-ltc4306.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-ltc4306.txt
> > index 8b1e49cdce3f..29c4550c9782 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux-ltc4306.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-ltc4306.txt
> > @@ -8,8 +8,8 @@ Required Properties:
> >
> >    The following required properties are defined externally:
> >
> > -  - Standard I2C mux properties. See i2c-mux.txt in this directory.
> > -  - I2C child bus nodes. See i2c-mux.txt in this directory.
> > +  - Standard I2C mux properties. See i2c-mux.yaml in this directory.
> > +  - I2C child bus nodes. See i2c-mux.yaml in this directory.
> >
> >  Optional Properties:
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
> > index 33119a98e144..997a287ed3f6 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pinctrl.txt
> > @@ -28,9 +28,9 @@ Also required are:
> >  * Standard pinctrl properties that specify the pin mux state for each child
> >    bus. See ../pinctrl/pinctrl-bindings.txt.
> >
> > -* Standard I2C mux properties. See i2c-mux.txt in this directory.
> > +* Standard I2C mux properties. See i2c-mux.yaml in this directory.
> >
> > -* I2C child bus nodes. See i2c-mux.txt in this directory.
> > +* I2C child bus nodes. See i2c-mux.yaml in this directory.
> >
> >  For each named state defined in the pinctrl-names property, an I2C child bus
> >  will be created. I2C child bus numbers are assigned based on the index into
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
> > index de00d7fc450b..b9d9755e4172 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-reg.txt
> > @@ -7,8 +7,8 @@ Required properties:
> >  - compatible: i2c-mux-reg
> >  - i2c-parent: The phandle of the I2C bus that this multiplexer's master-side
> >    port is connected to.
> > -* Standard I2C mux properties. See i2c-mux.txt in this directory.
> > -* I2C child bus nodes. See i2c-mux.txt in this directory.
> > +* Standard I2C mux properties. See i2c-mux.yaml in this directory.
> > +* I2C child bus nodes. See i2c-mux.yaml in this directory.
> >
> >  Optional properties:
> >  - reg: this pair of <offset size> specifies the register to control the mux.
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.txt b/Documentation/devicetree/bindings/i2c/i2c-mux.txt
> > deleted file mode 100644
> > index b38f58a1c878..000000000000
> > --- a/Documentation/devicetree/bindings/i2c/i2c-mux.txt
> > +++ /dev/null
> > @@ -1,73 +0,0 @@
> > -Common i2c bus multiplexer/switch properties.
> > -
> > -An i2c bus multiplexer/switch will have several child busses that are
> > -numbered uniquely in a device dependent manner.  The nodes for an i2c bus
> > -multiplexer/switch will have one child node for each child bus.
> > -
> > -Optional properties:
> > -- #address-cells = <1>;
> > -   This property is required if the i2c-mux child node does not exist.
> > -
> > -- #size-cells = <0>;
> > -   This property is required if the i2c-mux child node does not exist.
> > -
> > -- i2c-mux
> > -   For i2c multiplexers/switches that have child nodes that are a mixture
> > -   of both i2c child busses and other child nodes, the 'i2c-mux' subnode
> > -   can be used for populating the i2c child busses.  If an 'i2c-mux'
> > -   subnode is present, only subnodes of this will be considered as i2c
> > -   child busses.
> > -
> > -Required properties for the i2c-mux child node:
> > -- #address-cells = <1>;
> > -- #size-cells = <0>;
> > -
> > -Required properties for i2c child bus nodes:
> > -- #address-cells = <1>;
> > -- #size-cells = <0>;
> > -- reg : The sub-bus number.
> > -
> > -Optional properties for i2c child bus nodes:
> > -- Other properties specific to the multiplexer/switch hardware.
> > -- Child nodes conforming to i2c bus binding
> > -
> > -
> > -Example :
> > -
> > -     /*
> > -        An NXP pca9548 8 channel I2C multiplexer at address 0x70
> > -        with two NXP pca8574 GPIO expanders attached, one each to
> > -        ports 3 and 4.
> > -      */
> > -
> > -     mux@70 {
> > -             compatible = "nxp,pca9548";
> > -             reg = <0x70>;
> > -             #address-cells = <1>;
> > -             #size-cells = <0>;
> > -
> > -             i2c@3 {
> > -                     #address-cells = <1>;
> > -                     #size-cells = <0>;
> > -                     reg = <3>;
> > -
> > -                     gpio1: gpio@38 {
> > -                             compatible = "nxp,pca8574";
> > -                             reg = <0x38>;
> > -                             #gpio-cells = <2>;
> > -                             gpio-controller;
> > -                     };
> > -             };
> > -             i2c@4 {
> > -                     #address-cells = <1>;
> > -                     #size-cells = <0>;
> > -                     reg = <4>;
> > -
> > -                     gpio2: gpio@38 {
> > -                             compatible = "nxp,pca8574";
> > -                             reg = <0x38>;
> > -                             #gpio-cells = <2>;
> > -                             gpio-controller;
> > -                     };
> > -             };
> > -     };
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> > new file mode 100644
> > index 000000000000..3aa4d84a6610
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux.yaml
> > @@ -0,0 +1,87 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/i2c/i2c-mux.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Common i2c bus multiplexer/switch properties.
> > +
> > +maintainers:
> > +  - Peter Rosin <peda@axentia.se>
> > +
> > +description: |+
> > +  An i2c bus multiplexer/switch will have several child busses that are numbered
> > +  uniquely in a device dependent manner.  The nodes for an i2c bus
> > +  multiplexer/switch will have one child node for each child bus.
> > +
> > +  For i2c multiplexers/switches that have child nodes that are a mixture of both
> > +  i2c child busses and other child nodes, the 'i2c-mux' subnode can be used for
> > +  populating the i2c child busses.  If an 'i2c-mux' subnode is present, only
> > +  subnodes of this will be considered as i2c child busses.
>
> As I understand this, it means that child nodes corresponding to child
> buses can be either direct children of the I2C mux node, or grouped in a
> i2c-mux node (the same way we optionally group the 'port' nodes in a
> 'ports' node). This doesn't seem to be supported by the bindings below.

I take this as like any MFD. If i2c mux is one of the functions, we'll
have a child node for it. In that case, that device's binding will
define the 'i2c-mux' node and then reference this schema. The fact
that this mentions other nodes being I2C devices is not important and
a somewhat confusing detail. I considered just removing as I don't
think the paragraph is all that useful, but I try not to delete too
much from existing bindings.

Rob