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

["Álvaro Fernández Rojas" <noltari@gmail.com>]

Hi Rob,

> El 11 mar 2021, a las 19:14, Rob Herring <robh+dt@kernel.org> escribió:
> 
> On Thu, Mar 11, 2021 at 10:09 AM Álvaro Fernández Rojas
> <noltari@gmail.com> wrote:
>> 
>> Hi Rob,
>> 
>> El 10/03/2021 a las 21:52, Rob Herring escribió:
>>> On Wed, Mar 10, 2021 at 12:10 PM Álvaro Fernández Rojas
>>> <noltari@gmail.com> wrote:
>>>> 
>>>> Hi Rob,
>>>> 
>>>>> El 10 mar 2021, a las 19:45, Rob Herring <robh+dt@kernel.org> escribió:
>>>>> 
>>>>> On Wed, Mar 10, 2021 at 11:03 AM Álvaro Fernández Rojas
>>>>> <noltari@gmail.com> wrote:
>>>>>> 
>>>>>> Hi Rob,
>>>>>> 
>>>>>>> El 10 mar 2021, a las 18:45, Rob Herring <robh+dt@kernel.org> escribió:
>>>>>>> 
>>>>>>> On Wed, Mar 10, 2021 at 5:55 AM Álvaro Fernández Rojas
>>>>>>> <noltari@gmail.com> wrote:
>>>>>>>> 
>>>>>>>> Add binding documentation for the pincontrol core found in BCM6328 SoCs.
>>>>>>>> 
>>>>>>>> Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com>
>>>>>>>> Co-developed-by: Jonas Gorski <jonas.gorski@gmail.com>
>>>>>>>> Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.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@gmail.com>
>>>>>>>> +  - Jonas Gorski <jonas.gorski@gmail.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@10000080 {
>>>>>>>> +      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)_/¯
>>>>> 
>>>>> I said 'syscon' by itself was not allowed, then asked about the multiple levels.
>>>> 
>>>> Why not?
>>> 
>>> Because 'syscon' alone doesn't mean anything and doesn't describe what
>>> registers it contains. You need something that says this is the XYZ
>>> block in the ABC SoC.
>>> 
>>>> What if you have several controllers inside a syscon?
>>> 
>>> You either just add properties (e.g. just add #clock-cells and it's a
>>> clock provider) or you have child nodes. Which one you do generally
>>> depends on if the providers have DT resources themselves.
>>> 
>>>> The root should also have “something" in it?
>>>> 
>>>>> 
>>>>>> What should I do to document it?
>> 
>> You didn't answer my question about adding documentation...
> 
> You have to document it. Whether it's 1 or 3 schema files depends on
> where we end up, but the top-level one should reference the others if
> it's more than 1 file:
> 
> child-node:
>  type: object
>  $ref: "/schemas/foo/child-node.yaml#"

Can you give me an example of a driver which is documenting that?
I’m sorry, but I still don’t know how to do it properly...

> 
>> An example driver which adds a custom compatible string and doesn't
>> document it:
>> https://github.com/torvalds/linux/blob/a74e6a014c9d4d4161061f770c9b4f98372ac778/Documentation/devicetree/bindings/clock/sprd%2Csc9863a-clk.yaml#L90
> 
> *it Happens.
> 
> Those cases are now blocking my adding a check that they are
> undocumented. There's no shortage of examples of what not to do.
> 
>> 
>>>>>> 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?
>>>>> 
>>>>> It wouldn't be. I wasn't saying the pinctrl and gpio controller are
>>>>> the same node. My suggestion was combining syscon and pinctrl.
>>>> 
>>>> But that wouldn’t be correct if there were more “things” inside the syscon, right?
>>> 
>>> Right.
>>> 
>>>>>> Something like:
>>>>>> syscon {
>>>>> 
>>>>> Again with the syscon. If pinctrl and GPIO are the only functions
>>>>> within this h/w block, then this is not a syscon. You are just abusing
>>>>> that having 'syscon' compatible means you get a regmap created
>>>>> automagically for you. Nothing here looks like a 'system controller'
>>>>> to me. A 'system controller' is a random collection of register bits
>>>>> with functions that don't fit anywhere else.
>>>> 
>>>> pinctrl and GPIO aren’t the only functions within this HW block.
>>>> Maybe I didn’t document/code it properly, but I’m sure I’m not abusing what a system controller is.
>>> 
>>> Okay, that's the detail missing from this patch.
>>> 
>>>> Please, take a look at http://www.datashed.science/misc/bcm/gpl/broadcom-sdk-416L05/shared/opensource/include/bcm963xx/6328_map_part.h:
>>>> typedef struct GpioControl {
>>>>     uint32      GPIODirHi;                  /* 0 */
>>>>     uint32      GPIODir;                    /* 4 */
>>>>     uint32      GPIOioHi;                   /* 8 */
>>>>     uint32      GPIOio;                     /* C */
>>>>     uint32      unused0;                    /* 10 */
>>>>     uint32      SpiSlaveCfg;                /* 14 */
>>>>     uint32      GPIOMode;                   /* 18 */
>>>>     uint64      PinMuxSel;                  /* 1C */
>>>>     uint32      PinMuxSelOther;             /* 24 */
>>>>     uint32      TestControl;                /* 28 */
>>>>     uint32      unused2;                    /* 2C */
>>>>     uint32      RoboSWLEDControl;           /* 30 */
>>>>     uint32      RoboSWLEDLSR;               /* 34 */
>>>>     uint32      unused3;                    /* 38 */
>>>>     uint32      RoboswEphyCtrl;             /* 3C */
>>>>     uint32      RoboswSwitchCtrl;           /* 40 */
>>>>     uint32      RegFileTmCtl;               /* 44 */
>>>>     uint32      RingOscCtrl0;               /* 48 */
>>>>     uint32      RingOscCtrl1;               /* 4C */
>>>>     uint32      unused4[6];                 /* 50 - 64 */
>>>>     uint32      DieRevID;                   /* 68 */
>>>>     uint32      unused5;                    /* 6c */
>>>>     uint32      DiagSelControl;             /* 70 */
>>>>     uint32      DiagReadBack;               /* 74 */
>>>>     uint32      DiagReadBackHi;             /* 78 */
>>>>     uint32      DiagMiscControl;            /* 7c */
>>>> } GpioControl;
>>>> 
>>>> So we’re using GPIODirHi, GPIODir, GPIOioHi and GPIOio registers for GPIO regmap driver.
>>>> And we’re using GPIOMode, PinMuxSel (u64 -> x2 u32), PinMuxSelOther for pinctrl driver.
>>>> And this is for BCM6328, but some of the other SoCs are even more scattered.
>>> 
>>> So based on this I'd do something like this:
>>> 
>>> syscon {
>>>   reg = <base 0x80>;
>>>   ranges = <0 base 0x80>;
>>>   pinctrl@18 {
>>>     reg = <0x18 0x10>;
>>>     foo-pins {};
>>>   gpio@0 {
>>>     reg = <0x0 0x10>;
>>>   };
>>> };
>> 
>> You're missing a "};", so I'm not sure if you want me to go this way (1):
>> syscon {
>>        compatible = "brcm,bcm6328-gpio-regs", "syscon", "simple-mfd";
>>        reg = <0x10000080 0x80>;
>>        ranges = <0 0x10000080 0x80>;
>> 
>>        gpio: gpio@0 {
>>                compatible = "brcm,bcm6328-gpio";
>>                reg = <0x0 0x10>;
>> 
>>                data = <0xc>;
>>                dirout = <0x4>;
>> 
>>                gpio-controller;
>>                gpio-ranges = <&pinctrl 0 0 32>;
>>                #gpio-cells = <2>;
>>        };
>> 
>>        pinctrl: pinctrl@18 {
>>                compatible = "brcm,bcm6328-pinctrl";
>>                reg = <0x18 0x10>;
>> 
>>                foo-pins {};
>>                ...
>>        };
>> };
> 
> This way.
> 
>> 
>> Or this way (2):
>> syscon {
>>        compatible = "brcm,bcm6328-gpio-regs", "syscon", "simple-mfd";
>>        reg = <0x10000080 0x80>;
>>        ranges = <0 0x10000080 0x80>;
>> 
>>        pinctrl: pinctrl@18 {
>>                compatible = "brcm,bcm6328-pinctrl";
>>                reg = <0x0 0x28>;
>> 
>>                gpio: gpio@0 {
> 
> This doesn't make sense IMO because GPIO is not a sub-function of the
> pinctrl h/w. They are peers.

Well, that’s where @Linus and I disagree...

> 
>>                        compatible = "brcm,bcm6328-gpio";
>>                        reg = <0x0 0x10>;
>> 
>>                        data = <0xc>;
>>                        dirout = <0x4>;
>> 
>>                        gpio-controller;
>>                        gpio-ranges = <&pinctrl 0 0 32>;
>>                        #gpio-cells = <2>;
>>                };
>> 
>>                foo-pins {};
>>                ...
>>        };
>> };