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Message-Id: <3DED7410-5FCB-403D-BFB5-B8694133DADA@gmail.com>
Date: Thu, 11 Mar 2021 19:34:46 +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 11 mar 2021, a las 19:14, Rob Herring <robh+dt@...nel.org> escribió:
>
> On Thu, Mar 11, 2021 at 10:09 AM Álvaro Fernández Rojas
> <noltari@...il.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@...il.com> wrote:
>>>>
>>>> Hi Rob,
>>>>
>>>>> El 10 mar 2021, a las 19:45, Rob Herring <robh+dt@...nel.org> escribió:
>>>>>
>>>>> On Wed, Mar 10, 2021 at 11:03 AM Álvaro Fernández Rojas
>>>>> <noltari@...il.com> wrote:
>>>>>>
>>>>>> 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)_/¯
>>>>>
>>>>> 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 {};
>> ...
>> };
>> };
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