Re: [PATCH v6 5/6] dt-bindings: mfd: Add Delta TN48M CPLD drivers bindings

[Rob Herring <robh@xxxxxxxxxx>]

On Sun, Jul 18, 2021 at 11:15:38AM +0200, Robert Marko wrote:
> On Wed, Jul 14, 2021 at 12:25 AM Rob Herring <robh@xxxxxxxxxx> wrote:
> >
> > On Fri, Jun 25, 2021 at 01:46:08PM +0200, Robert Marko wrote:
> > > On Mon, Jun 7, 2021 at 2:33 PM Robert Marko <robert.marko@xxxxxxxxxx> wrote:
> > > >
> > > > Add binding documents for the Delta TN48M CPLD drivers.
> > > >
> > > > Signed-off-by: Robert Marko <robert.marko@xxxxxxxxxx>
> > > > ---
> > > > Changes in v3:
> > > > * Include bindings for reset driver
> > > >
> > > > Changes in v2:
> > > > * Implement MFD as a simple I2C MFD
> > > > * Add GPIO bindings as separate
> > > >
> > > >  .../bindings/gpio/delta,tn48m-gpio.yaml       | 42 +++++++++
> > > >  .../bindings/mfd/delta,tn48m-cpld.yaml        | 90 +++++++++++++++++++
> > > >  .../bindings/reset/delta,tn48m-reset.yaml     | 35 ++++++++
> > > >  3 files changed, 167 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/gpio/delta,tn48m-gpio.yaml
> > > >  create mode 100644 Documentation/devicetree/bindings/mfd/delta,tn48m-cpld.yaml
> > > >  create mode 100644 Documentation/devicetree/bindings/reset/delta,tn48m-reset.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/gpio/delta,tn48m-gpio.yaml b/Documentation/devicetree/bindings/gpio/delta,tn48m-gpio.yaml
> > > > new file mode 100644
> > > > index 000000000000..aca646aecb12
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/gpio/delta,tn48m-gpio.yaml
> > > > @@ -0,0 +1,42 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/gpio/delta,tn48m-gpio.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Delta Networks TN48M CPLD GPIO controller
> > > > +
> > > > +maintainers:
> > > > +  - Robert Marko <robert.marko@xxxxxxxxxx>
> > > > +
> > > > +description: |
> > > > +  This module is part of the Delta TN48M multi-function device. For more
> > > > +  details see ../mfd/delta,tn48m-cpld.yaml.
> > > > +
> > > > +  GPIO controller module provides GPIO-s for the SFP slots.
> > > > +  It is split into 3 controllers, one output only for the SFP TX disable
> > > > +  pins, one input only for the SFP present pins and one input only for
> > > > +  the SFP LOS pins.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    enum:
> > > > +      - delta,tn48m-gpio-sfp-tx-disable
> > > > +      - delta,tn48m-gpio-sfp-present
> > > > +      - delta,tn48m-gpio-sfp-los
> > > > +
> > > > +  reg:
> > > > +    maxItems: 1
> > > > +
> > > > +  "#gpio-cells":
> > > > +    const: 2
> > > > +
> > > > +  gpio-controller: true
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +  - "#gpio-cells"
> > > > +  - gpio-controller
> > > > +
> > > > +additionalProperties: false
> > > > diff --git a/Documentation/devicetree/bindings/mfd/delta,tn48m-cpld.yaml b/Documentation/devicetree/bindings/mfd/delta,tn48m-cpld.yaml
> > > > new file mode 100644
> > > > index 000000000000..2c6e2adf73ca
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/mfd/delta,tn48m-cpld.yaml
> > > > @@ -0,0 +1,90 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/mfd/delta,tn48m-cpld.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Delta Networks TN48M CPLD controller
> > > > +
> > > > +maintainers:
> > > > +  - Robert Marko <robert.marko@xxxxxxxxxx>
> > > > +
> > > > +description: |
> > > > +  Lattice CPLD onboard the TN48M switches is used for system
> > > > +  management.
> > > > +
> > > > +  It provides information about the hardware model, revision,
> > > > +  PSU status etc.
> > > > +
> > > > +  It is also being used as a GPIO expander for the SFP slots and
> > > > +  reset controller for the switch MAC-s and other peripherals.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: delta,tn48m-cpld
> > > > +
> > > > +  reg:
> > > > +    description:
> > > > +      I2C device address.
> > > > +    maxItems: 1
> > > > +
> > > > +  "#address-cells":
> > > > +    const: 1
> > > > +
> > > > +  "#size-cells":
> > > > +    const: 0
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - reg
> > > > +  - "#address-cells"
> > > > +  - "#size-cells"
> > > > +
> > > > +patternProperties:
> > > > +  "^gpio(@[0-9a-f]+)?$":
> > > > +    $ref: ../gpio/delta,tn48m-gpio.yaml
> > > > +
> > > > +  "^reset-controller?$":
> > > > +    $ref: ../reset/delta,tn48m-reset.yaml
> > > > +
> > > > +additionalProperties: false
> > > > +
> > > > +examples:
> > > > +  - |
> > > > +    i2c {
> > > > +        #address-cells = <1>;
> > > > +        #size-cells = <0>;
> > > > +
> > > > +        cpld@41 {
> > > > +            compatible = "delta,tn48m-cpld";
> > > > +            reg = <0x41>;
> > > > +            #address-cells = <1>;
> > > > +            #size-cells = <0>;
> > > > +
> > > > +            gpio@31 {
> > > > +                compatible = "delta,tn48m-gpio-sfp-tx-disable";
> > > > +                reg = <0x31>;
> > > > +                gpio-controller;
> > > > +                #gpio-cells = <2>;
> > > > +            };
> > > > +
> > > > +            gpio@3a {
> > > > +                compatible = "delta,tn48m-gpio-sfp-present";
> > > > +                reg = <0x3a>;
> > > > +                gpio-controller;
> > > > +                #gpio-cells = <2>;
> > > > +            };
> > > > +
> > > > +            gpio@40 {
> > > > +                compatible = "delta,tn48m-gpio-sfp-los";
> > > > +                reg = <0x40>;
> > > > +                gpio-controller;
> > > > +                #gpio-cells = <2>;
> > > > +            };
> > > > +
> > > > +            reset-controller {
> > > > +              compatible = "delta,tn48m-reset";
> > > > +              #reset-cells = <1>;
> > > > +            };
> > > > +        };
> > > > +    };
> > > > diff --git a/Documentation/devicetree/bindings/reset/delta,tn48m-reset.yaml b/Documentation/devicetree/bindings/reset/delta,tn48m-reset.yaml
> > > > new file mode 100644
> > > > index 000000000000..0e5ee8decc0d
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/reset/delta,tn48m-reset.yaml
> > > > @@ -0,0 +1,35 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/reset/delta,tn48m-reset.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Delta Networks TN48M CPLD reset controller
> > > > +
> > > > +maintainers:
> > > > +  - Robert Marko <robert.marko@xxxxxxxxxx>
> > > > +
> > > > +description: |
> > > > +  This module is part of the Delta TN48M multi-function device. For more
> > > > +  details see ../mfd/delta,tn48m-cpld.yaml.
> > > > +
> > > > +  Reset controller modules provides resets for the following:
> > > > +  * 88F7040 SoC
> > > > +  * 88F6820 SoC
> > > > +  * 98DX3265 switch MAC-s
> > > > +  * 88E1680 PHY-s
> > > > +  * 88E1512 PHY
> > > > +  * PoE PSE controller
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: delta,tn48m-reset
> > > > +
> > > > +  "#reset-cells":
> > > > +    const: 1
> > > > +
> > > > +required:
> > > > +  - compatible
> > > > +  - "#reset-cells"
> > > > +
> > > > +additionalProperties: false
> > > > --
> > > > 2.31.1
> > > >
> > >
> > > Are there any issues with the bindings?
> >
> > Yes. Primarily the GPIO function being part of the compatible. I'm
> > surprised Linus W is okay with that.
> 
> I think I already explained this before, having a single compatible
> won't work here.
> Then there would not be anything to know whether its input or output
> only as the pins
> have specific purpose.

The client side should tell the direction. Are you using the SFP 
binding?: Documentation/devicetree/bindings/net/sff,sfp.txt

Specific purpose IOs are not general purpose IOs. Repeating Linus W 
here. Maybe his opinion has evolved...

If the programming model of each instance is different, then different 
compatibles are justified. But describe what the difference is, not the 
connection.

> And knowing the capabilites is a requirment of the GPIO regmap driver
> and the GPIO
> core itself as it exposes that information in a generic manner and
> driver like for the
> SFP bus use that.

Driver details aren't justification for bindings.

> Maybe Linus W can chime in here as well.
> 
> >
> > > The patch series is depending on this as the rest has been reviewed.
> >
> > The bindings have been reviewed too, you just didn't like my comments...
> 
> Sorry, I did not pick that up as after my replies there was no further
> discussion.
> 
> I am really hoping that we can find a middle ground here and get this
> merged as the driver code itself has been revied and ACK-ed.
> 
> Regards,
> Robert
> >
> > Rob
> 
> 
> 
> -- 
> Robert Marko
> Staff Embedded Linux Engineer
> Sartura Ltd.
> Lendavska ulica 16a
> 10000 Zagreb, Croatia
> Email: robert.marko@xxxxxxxxxx
> Web: www.sartura.hr
>