linux-kernel - Re: [PATCH v6 04/15] dt-bindings: add BCM6328 pincontroller binding documentation

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Message-Id: <A2B4813E-4177-4969-9119-A40B39A36948@gmail.com>
Date:   Wed, 10 Mar 2021 19:03:20 +0100
From:   Álvaro Fernández Rojas <noltari@...il.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Cc:     Michael Walle <michael@...le.cc>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Jonas Gorski <jonas.gorski@...il.com>,
        Necip Fazil Yildiran <fazilyildiran@...il.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 04/15] dt-bindings: add BCM6328 pincontroller binding
 documentation

Hi Rob,

> El 10 mar 2021, a las 18:45, Rob Herring <robh+dt@...nel.org> escribió:
> 
> On Wed, Mar 10, 2021 at 5:55 AM Álvaro Fernández Rojas
> <noltari@...il.com> wrote:
>> 
>> Add binding documentation for the pincontrol core found in BCM6328 SoCs.
>> 
>> Signed-off-by: Jonas Gorski <jonas.gorski@...il.com>
>> Co-developed-by: Jonas Gorski <jonas.gorski@...il.com>
>> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
>> ---
>> v6: add changes suggested by Rob Herring
>> v5: change Documentation to dt-bindings in commit title
>> v4: no changes
>> v3: add new gpio node
>> v2: remove interrupts
>> 
>> .../pinctrl/brcm,bcm6328-pinctrl.yaml         | 174 ++++++++++++++++++
>> 1 file changed, 174 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/pinctrl/brcm,bcm6328-pinctrl.yaml
>> 
>> diff --git a/Documentation/devicetree/bindings/pinctrl/brcm,bcm6328-pinctrl.yaml b/Documentation/devicetree/bindings/pinctrl/brcm,bcm6328-pinctrl.yaml
>> new file mode 100644
>> index 000000000000..471f6efa1754
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/pinctrl/brcm,bcm6328-pinctrl.yaml
>> @@ -0,0 +1,174 @@
>> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
>> +%YAML 1.2
>> +---
>> +$id: http://devicetree.org/schemas/pinctrl/brcm,bcm6328-pinctrl.yaml#
>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Broadcom BCM6328 pin controller
>> +
>> +maintainers:
>> +  - Álvaro Fernández Rojas <noltari@...il.com>
>> +  - Jonas Gorski <jonas.gorski@...il.com>
>> +
>> +description: |+
>> +  The pin controller node should be the child of a syscon node.
>> +
>> +  Refer to the the bindings described in
>> +  Documentation/devicetree/bindings/mfd/syscon.yaml
>> +
>> +properties:
>> +  compatible:
>> +    const: brcm,bcm6328-pinctrl
>> +
>> +  gpio:
>> +    type: object
>> +    properties:
>> +      compatible:
>> +        const: brcm,bcm6328-gpio
>> +
>> +      data:
>> +        $ref: /schemas/types.yaml#/definitions/uint32
>> +        description: |
>> +          Offset in the register map for the data register (in bytes).
>> +
>> +      dirout:
>> +        $ref: /schemas/types.yaml#/definitions/uint32
>> +        description: |
>> +          Offset in the register map for the dirout register (in bytes).
>> +
>> +      gpio-controller: true
>> +
>> +      "#gpio-cells":
>> +        const: 2
>> +
>> +      gpio-ranges:
>> +        maxItems: 1
>> +
>> +    required:
>> +      - gpio-controller
>> +      - gpio-ranges
>> +      - '#gpio-cells'
>> +
>> +    additionalProperties: false
>> +
>> +patternProperties:
>> +  '^.*-pins$':
>> +    if:
>> +      type: object
>> +    then:
>> +      properties:
>> +        function:
>> +          $ref: "pinmux-node.yaml#/properties/function"
>> +          enum: [ serial_led_data, serial_led_clk, inet_act_led, pcie_clkreq,
>> +                  led, ephy0_act_led, ephy1_act_led, ephy2_act_led,
>> +                  ephy3_act_led, hsspi_cs1, usb_device_port, usb_host_port ]
>> +
>> +        pins:
>> +          $ref: "pinmux-node.yaml#/properties/pins"
>> +          enum: [ gpio6, gpio7, gpio11, gpio16, gpio17, gpio18, gpio19,
>> +                  gpio20, gpio25, gpio26, gpio27, gpio28, hsspi_cs1,
>> +                  usb_port1 ]
>> +
>> +required:
>> +  - compatible
>> +  - gpio
>> +
>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    gpio_cntl@...00080 {
>> +      compatible = "brcm,bcm6328-gpio-controller", "syscon", "simple-mfd";
> 
> You just added "brcm,bcm6328-gpio-controller", it would need to be documented.

I just added that because you requested me to do it ¯\_(ツ)_/¯
What should I do to document it?
I still don’t get most of this .yaml stuff...

> 
>> +      reg = <0x10000080 0x80>;
>> +
>> +      pinctrl: pinctrl {
>> +        compatible = "brcm,bcm6328-pinctrl";
>> +
>> +        gpio {
>> +          compatible = "brcm,bcm6328-gpio";
> 
> I'm still trying to understand why you need 3 levels of nodes here?
> The gpio controller contains a pin controller plus other undefined
> functions (because of 'syscon') and the pin controller contains a gpio
> controller?

In previous versions the gpio controller was registered along with the pin controller, but @Linus requested me to register the gpio pin controller ranges through device tree by using gpio-ranges and I decided to use this approach, which was already used by other pin controllers.
However, there aren’t any pinctrl drivers using gpio-regmap, so this is kind of new…

> 
> I think "brcm,bcm6328-gpio-controller" and "brcm,bcm6328-pinctrl"
> should be a single node.

I agree, but does it make sense to add gpio-ranges to a pinctrl node referencing itself?
Something like:
syscon {
	pinctrl: pinctrl {
		compatible …

		gpio-controller;
		gpio-ranges = <&pinctrl 0 0 32>;
		#gpio-cells = <2>;

		…
	};
};

> 
>> +          data = <0xc>;
>> +          dirout = <0x4>;
> 
> This looks similar to the brcm,bcm6345-gpio.txt binding which then
> uses the gpio-mmio driver. Defining addresses with 'reg' is much
> preferred over custom properties. That binding also captures the bank
> size.

It’s similar, but Linus requested to use gpio regmap because we had a large amount of registers, so we’re not using it.

> 
> Rob

Best regards,
Álvaro.