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Message-ID: <90994df6-9d7d-686f-8668-a1cf5267aa16@gmail.com>
Date: Thu, 11 Mar 2021 18:09:29 +0100
From: Álvaro Fernández Rojas <noltari@...il.com>
To: Rob Herring <robh+dt@...nel.org>
Cc: Linus Walleij <linus.walleij@...aro.org>,
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 10/03/2021 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...
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
>>>> 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 {};
...
};
};
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 {
compatible = "brcm,bcm6328-gpio";
reg = <0x0 0x10>;
data = <0xc>;
dirout = <0x4>;
gpio-controller;
gpio-ranges = <&pinctrl 0 0 32>;
#gpio-cells = <2>;
};
foo-pins {};
...
};
};
>
> If things are more scattered within gpio or pinctrl, then maybe you
> need multiple reg entries. Whether the OS uses 'reg' and mmio or a
> regmap from the syscon is up to you. That's independent of the
> binding.
>
>>>> 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.
>
> I think 1 makes more sense.
>
> Rob
>
Best regards,
Álvaro.
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