Re: [PATCH 2/5] dt-bindings: Add bindings for the Analog Devices ADP5585

From: Laurent Pinchart
Date: Tue May 21 2024 - 15:43:30 EST

Hi Krzysztof,

On Tue, May 21, 2024 at 09:05:50PM +0200, Krzysztof Kozlowski wrote:
> On 20/05/2024 21:59, Laurent Pinchart wrote:
> > The ADP5585 is a 10/11 input/output port expander with a built in keypad
> > matrix decoder, programmable logic, reset generator, and PWM generator.
> > These bindings model the device as an MFD, and support the GPIO expander
> > and PWM functions.
> >
> > These bindings support the GPIO and PWM functions.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > ---
> > I've limited the bindings to GPIO and PWM as I lack hardware to design,
> > implement and test the rest of the features the chip supports.
> > ---
> > .../bindings/gpio/adi,adp5585-gpio.yaml | 36 ++++++
> > .../devicetree/bindings/mfd/adi,adp5585.yaml | 117 ++++++++++++++++++
> > .../bindings/pwm/adi,adp5585-pwm.yaml | 35 ++++++
> > MAINTAINERS | 7 ++
> > 4 files changed, 195 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/gpio/adi,adp5585-gpio.yaml
> > create mode 100644 Documentation/devicetree/bindings/mfd/adi,adp5585.yaml
> > create mode 100644 Documentation/devicetree/bindings/pwm/adi,adp5585-pwm.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/gpio/adi,adp5585-gpio.yaml b/Documentation/devicetree/bindings/gpio/adi,adp5585-gpio.yaml
> > new file mode 100644
> > index 000000000000..210e4d53e764
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/gpio/adi,adp5585-gpio.yaml
> > @@ -0,0 +1,36 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/gpio/adi,adp5585-gpio.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices ADP5585 GPIO Expander
> > +
> > +maintainers:
> > + - Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > +
> > +description: |
> > + The Analog Devices ADP5585 has up to 11 GPIOs represented by a "gpio" child
> > + node of the parent MFD device. See
> > + Documentation/devicetree/bindings/mfd/adi,adp5585.yaml for further details as
> > + well as an example.
> > +
> > +properties:
> > + compatible:
> > + const: adi,adp5585-gpio
> > +
> > + gpio-controller: true
> > +
> > + '#gpio-cells':
> > + const: 2
> > +
> > + gpio-reserved-ranges: true
>
> There are no resources here, so new compatible is not really warranted.
> Squash the node into parent.

Child nodes seem (to me) to be the standard way to model functions in
MFD devices. Looking at mfd_add_device(), for OF-based systems, the
function iterates over child nodes. I don't mind going a different
routes, could you indicate what you have in mind, perhaps pointing to an
existing driver as an example ?

> > +
> > +required:
> > + - compatible
> > + - gpio-controller
> > + - "#gpio-cells"
> > +
> > +additionalProperties: false
> > +
> > +...
> > diff --git a/Documentation/devicetree/bindings/mfd/adi,adp5585.yaml b/Documentation/devicetree/bindings/mfd/adi,adp5585.yaml
> > new file mode 100644
> > index 000000000000..217c038b2842
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mfd/adi,adp5585.yaml
> > @@ -0,0 +1,117 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/mfd/adi,adp5585.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices ADP5585 Keypad Decoder and I/O Expansion
> > +
> > +maintainers:
> > + - Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > +
> > +description: |
>
> Do not need '|' unless you need to preserve formatting.
>
> > + The ADP5585 is a 10/11 input/output port expander with a built in keypad
> > + matrix decoder, programmable logic, reset generator, and PWM generator.
> > +
> > +properties:
> > + compatible:
> > + items:
> > + - enum:
> > + - adi,adp5585-00 # Default
> > + - adi,adp5585-01 # 11 GPIOs
> > + - adi,adp5585-02 # No pull-up resistors by default on special pins
> > + - adi,adp5585-03 # Alternate I2C address
> > + - adi,adp5585-04 # Pull-down resistors on all pins by default
> > + - const: adi,adp5585
> > +
> > + reg:
> > + maxItems: 1
> > +
> > + interrupts:
> > + maxItems: 1
> > +
> > + vdd-supply: true
> > +
> > + gpio:
> > + $ref: /schemas/gpio/adi,adp5585-gpio.yaml
> > +
> > + pwm:
> > + $ref: /schemas/pwm/adi,adp5585-pwm.yaml
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - gpio
> > + - pwm
> > +
> > +allOf:
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + const: adi,adp5585-01
> > + then:
> > + properties:
> > + gpio:
> > + properties:
> > + gpio-reserved-ranges: false
>
> This also points to fact your child node is pointless. It does not stand
> on its own...

That doesn't make the child pointless just for that reason. There are
numerous examples of child nodes that don't stand on their own.

> > + else:
> > + properties:
> > + gpio:
> > + properties:
> > + gpio-reserved-ranges:
> > + items:
> > + - const: 5
> > + - const: 1
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + i2c {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + mfd@34 {
> > + compatible = "adi,adp5585-00", "adi,adp5585";
> > + reg = <0x34>;
> > +
> > + gpio {
> > + compatible = "adi,adp5585-gpio";
> > + gpio-controller;
> > + #gpio-cells = <2>;
> > + gpio-reserved-ranges = <5 1>;
> > + };
> > +
> > + pwm {
> > + compatible = "adi,adp5585-pwm";
> > + #pwm-cells = <3>;
> > + };
> > + };
> > + };
> > +
> > + - |
> > + i2c {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + mfd@34 {
> > + compatible = "adi,adp5585-01", "adi,adp5585";
> > + reg = <0x34>;
> > +
> > + vdd-supply = <&reg_3v3>;
> > +
> > + gpio {
> > + compatible = "adi,adp5585-gpio";
> > + gpio-controller;
> > + #gpio-cells = <2>;
>
> Different by one property? So just keep one example, unless there are
> more differences.

I found the two examples useful during development of the binding to
test the gpio-reserved-ranges rule (I got it wrong in the first place,
and the dt schema validator told me), but I'm fine dropping one of the
two.

> > + };
> > +
> > + pwm {
> > + compatible = "adi,adp5585-pwm";
> > + #pwm-cells = <3>;
> > + };
> > + };
> > + };
> > +
> > +...
> > diff --git a/Documentation/devicetree/bindings/pwm/adi,adp5585-pwm.yaml b/Documentation/devicetree/bindings/pwm/adi,adp5585-pwm.yaml
> > new file mode 100644
> > index 000000000000..351a9d5da566
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pwm/adi,adp5585-pwm.yaml
> > @@ -0,0 +1,35 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/pwm/adi,adp5585-pwm.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices ADP5585 PWM Generator
> > +
> > +maintainers:
> > + - Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > +
> > +description: |
>
> Do not need '|' unless you need to preserve formatting.
>
> > + The Analog Devices ADP5585 generates a PWM output with configurable frequency
> > + and duty cycle represented by a "pwm" child node of the parent MFD device.
> > + See Documentation/devicetree/bindings/mfd/adi,adp5585.yaml for further
> > + details as well as an example.
> > +
> > +allOf:
> > + - $ref: /schemas/pwm/pwm.yaml#
> > +
> > +properties:
> > + compatible:
> > + enum:
> > + - adi,adp5585-pwm
> > +
> > + "#pwm-cells":
> > + const: 3
>
> Also no resources, so this can be part of the parent node.

I'll sure follow the same design for the GPIO and PWM functions :-)
Let's answer the above question first.

--
Regards,

Laurent Pinchart