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Message-ID: <CAL_JsqK_00BQ4DkO8KUF1+TzxwCfU-=9tck7gdFL3Fh6mktHMg@mail.gmail.com>
Date: Thu, 11 Mar 2021 11:14:20 -0700
From: Rob Herring <robh+dt@...nel.org>
To: Álvaro Fernández Rojas <noltari@...il.com>
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
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#"
> 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.
> 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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