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Date:   Mon, 2 Mar 2020 14:49:49 -0600
From:   Rob Herring <robh@kernel.org>
To:     Tim Harvey <tharvey@gateworks.com>
Cc:     Lee Jones <lee.jones@linaro.org>, Jean Delvare <jdelvare@suse.com>,
        Guenter Roeck <linux@roeck-us.net>,
        linux-hwmon@vger.kernel.org, Frank Rowand <frowand.list@gmail.com>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Robert Jones <rjones@gateworks.com>
Subject: Re: [PATCH v5 1/3] dt-bindings: mfd: Add Gateworks System Controller
 bindings
Message-ID: <20200302204949.GA6649@bogus>
References: <1582577665-13554-1-git-send-email-tharvey@gateworks.com>
 <1582577665-13554-2-git-send-email-tharvey@gateworks.com>
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On Mon, Feb 24, 2020 at 12:54:23PM -0800, Tim Harvey wrote:
> This patch adds documentation of device-tree bindings for the
> Gateworks System Controller (GSC).
> 
> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
> ---
> v5:
>  - resolve dt_binding_check issues
> 
> v4:
>  - move to using pwm<n>_auto_point<m>_{pwm,temp} for FAN PWM
>  - remove unncessary resolution/scaling properties for ADCs
>  - update to yaml
>  - remove watchdog
> 
> v3:
>  - replaced _ with -
>  - remove input bindings
>  - added full description of hwmon
>  - fix unit address of hwmon child nodes
> ---
>  .../devicetree/bindings/mfd/gateworks-gsc.yaml     | 158 +++++++++++++++++++++
>  1 file changed, 158 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
> 
> diff --git a/Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml b/Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
> new file mode 100644
> index 00000000..f7c1a05
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/gateworks-gsc.yaml
> @@ -0,0 +1,158 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/mfd/gateworks-gsc.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Gateworks System Controller multi-function device
> +
> +description: |
> +  The GSC is a Multifunction I2C slave device with the following submodules:
> +   - Watchdog Timer
> +   - GPIO
> +   - Pushbutton controller
> +   - Hardware Monitore with ADC's for temperature and voltage rails and

typo

> +     fan controller
> +
> +maintainers:
> +  - Tim Harvey <tharvey@gateworks.com>
> +  - Robert Jones <rjones@gateworks.com>
> +
> +properties:
> +  $nodename:
> +    pattern: "gsc@[0-9a-f]{1,2}"
> +  compatible:
> +    const: gw,gsc

That's not very specific.

> +
> +  reg:
> +    description: I2C device address
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  interrupt-controller: true
> +
> +  "#interrupt-cells":
> +    const: 1
> +    description: The IRQ number

description is wrong. You can just drop it.

> +
> +  hwmon:

'hwmon' is a Linux thing. I'm suspicious...

> +    type: object
> +    description: Optional Hardware Monitoring module
> +
> +    properties:
> +      compatible:
> +        const: gw,gsc-hwmon
> +
> +      "#address-cells":
> +        const: 1
> +
> +      "#size-cells":
> +        const: 0
> +
> +      gw,fan-base:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        description: The fan controller base address

Shouldn't this be described as a node in the DT or be implied by the 
compatible?

> +
> +    patternProperties:
> +      "^adc@[0-2]$":

There's only one number space at any level. So if you ever need anything 
else at this level, it can't have an address. Just something to 
consider.

> +        type: object
> +        description: |
> +          Properties for a single ADC which can report cooked values
> +          (ie temperature sensor based on thermister), raw values
> +          (ie voltage rail with a pre-scaling resistor divider).
> +
> +        properties:
> +          reg:
> +            description: Register of the ADC
> +            maxItems: 1
> +
> +          label:
> +            description: Name of the ADC input
> +
> +          type:

Very generic property name, but it's not generic. Needs a vendor prefix 
at least.

> +            description: |
> +              temperature in C*10 (temperature),
> +              pre-scaled voltage value (voltage),
> +              or scaled based on an optional resistor divider and optional
> +              offset (voltage-raw)
> +            enum:
> +              - temperature
> +              - voltage
> +              - voltage-raw
> +
> +          gw,voltage-divider:
> +            allOf:
> +              - $ref: /schemas/types.yaml#/definitions/uint32-array
> +            description: values of resistors for divider on raw ADC input
> +            items:
> +              - description: R1
> +              - description: R2

Needs a standard unit suffix. With that, you can drop the type 
reference.

> +
> +          gw,voltage-offset:
> +            $ref: /schemas/types.yaml#/definitions/uint32
> +            description: |
> +              A positive uV voltage offset to apply to a raw ADC
> +              (ie to compensate for a diode drop).

Needs a unit suffix. 

> +
> +        required:
> +          - type
> +          - reg
> +          - label
> +
> +    required:
> +      - compatible
> +      - "#address-cells"
> +      - "#size-cells"
> +
> +required:
> +  - compatible
> +  - reg
> +  - interrupts
> +  - interrupt-controller
> +  - "#interrupt-cells"
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        gsc@20 {
> +            compatible = "gw,gsc";
> +            reg = <0x20>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <4 GPIO_ACTIVE_LOW>;
> +            interrupt-controller;
> +            #interrupt-cells = <1>;
> +
> +            hwmon {
> +                compatible = "gw,gsc-hwmon";
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +                gw,fan-base = <0x2c>;
> +
> +                adc@0 { /* A0: Board Temperature */
> +                    type = "temperature";
> +                    reg = <0x00>;
> +                    label = "temp";
> +                };
> +
> +                adc@2 { /* A1: Input Voltage (raw ADC) */
> +                    type = "voltage-raw";
> +                    reg = <0x02>;
> +                    label = "vdd_vin";
> +                    gw,voltage-divider = <22100 1000>;
> +                    gw,voltage-offset = <800000>;
> +                };
> +
> +                adc@b { /* A2: Battery voltage */
> +                    type = "voltage";
> +                    reg = <0x0b>;
> +                    label = "vdd_bat";
> +                };
> +            };
> +        };
> +    };
> -- 
> 2.7.4
>