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

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Hi Rob,

> El 10 mar 2021, a las 19:45, Rob Herring <robh+dt@xxxxxxxxxx> escribió:
> 
> On Wed, Mar 10, 2021 at 11:03 AM Álvaro Fernández Rojas
> <noltari@xxxxxxxxx> wrote:
>> 
>> Hi Rob,
>> 
>>> El 10 mar 2021, a las 18:45, Rob Herring <robh+dt@xxxxxxxxxx> escribió:
>>> 
>>> On Wed, Mar 10, 2021 at 5:55 AM Álvaro Fernández Rojas
>>> <noltari@xxxxxxxxx> wrote:
>>>> 
>>>> Add binding documentation for the pincontrol core found in BCM6328 SoCs.
>>>> 
>>>> Signed-off-by: Jonas Gorski <jonas.gorski@xxxxxxxxx>
>>>> Co-developed-by: Jonas Gorski <jonas.gorski@xxxxxxxxx>
>>>> Signed-off-by: Álvaro Fernández Rojas <noltari@xxxxxxxxx>
>>>> ---
>>>> 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@xxxxxxxxx>
>>>> +  - Jonas Gorski <jonas.gorski@xxxxxxxxx>
>>>> +
>>>> +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?
What if you have several controllers inside a syscon?
The root should also have “something" in it?

> 
>> 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?
> 
> 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?

> 
>> 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.
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.

> 
>>        pinctrl: pinctrl {
>>                compatible …
>> 
>>                gpio-controller;
>>                gpio-ranges = <&pinctrl 0 0 32>;
>>                #gpio-cells = <2>;
> 
> I was assuming you have multiple GPIO controllers within 1 pinctlr?
> The pinctrl and gpio could be a single node like above if there's only
> 1 GPIO controller. But I'm still somewhat guessing what the h/w looks
> like because I have to go searching thru the driver to decipher.
> Please describe the h/w in the binding.

GPIO dirout and data rely on 2x u32 registers or a single u64 register.
This is can be either be implemented as a single GPIO controller, or as 2 separate GPIO controllers.
However, since I’m overriding reg_mask_xlate with bcm63xx_reg_mask_xlate I can register it as a single GPIO controller, which makes more sense to me.

> 
> If there's more than 1 GPIO controller, then I'd imagine you have
> something like this:
> 
> pinctrl {
>  ...
>  reg = <base 0x80>;
>  ranges = <0 base 0x80;
>  gpio@4 {
>    reg = <4 4>, <c 4>;
>    reg-names = "dirout", "dat";
>  };
>  gpio@? {};
> 
>  foo-pins {};
> };
> 
>> 
>>                …
>>        };
>> };
>> 
>>> 
>>>> +          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.
> 
> Looks like you have 2 registers to me.

For the GPIO controller there are 4 registers (data high and low, and dirout high and low).
For the pinctrl there are 3 registers (Pinmux high, low and other).

> 
> Rob

Best regards,
Álvaro.



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