linux-kernel - Re: [PATCH 1/3] dt-bindings: Add support for Broadcom USB pin map driver

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Message-ID: <CAOGqxeXWXkRD=agGL45D0sGe64TUBBq=OtibkX8AkiC5g0sWww@mail.gmail.com>
Date:   Tue, 25 Aug 2020 08:26:46 -0400
From:   Alan Cooper <alcooperx@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     ": Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        BCM Kernel Feedback <bcm-kernel-feedback-list@...adcom.com>,
        DTML <devicetree@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "moderated list:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 1/3] dt-bindings: Add support for Broadcom USB pin map driver

On Mon, Aug 24, 2020 at 7:30 PM Rob Herring <robh@...nel.org> wrote:
>
> On Wed, Aug 12, 2020 at 04:20:16PM -0400, Al Cooper wrote:
> > Add DT bindings for the Broadcom USB pin map driver. This driver allows
> > some USB input and output signals to be mapped to any GPIO instead
> > of the normal dedicated pins to/from the XHCI controller.
>
> Is this a driver or h/w block because bindings are for h/w blocks?

This is a hardware block. I'll remove "driver" from the description.

>
> >
> > Signed-off-by: Al Cooper <alcooperx@...il.com>
> > ---
> >  .../bindings/usb/brcm,usb-pinmap.yaml         | 63 +++++++++++++++++++
> >  1 file changed, 63 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/usb/brcm,usb-pinmap.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/usb/brcm,usb-pinmap.yaml b/Documentation/devicetree/bindings/usb/brcm,usb-pinmap.yaml
> > new file mode 100644
> > index 000000000000..19cf6ad36373
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/usb/brcm,usb-pinmap.yaml
> > @@ -0,0 +1,63 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/usb/brcm,usb-pinmap.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Broadcom USB pin map Controller Device Tree Bindings
> > +
> > +maintainers:
> > +  - Al Cooper <alcooperx@...il.com>
> > +
> > +properties:
> > +  compatible:
> > +      items:
> > +          - const: brcm,usb-pinmap
>
> 2 space indentation please.

Fixed.

>
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +    description: Must be defined if any out-gpios are specified.
>
> 'dependencies' can express this in schema.

Okay.

>
> > +
> > +  in-gpios:
> > +    description: Array of one or more GPIO pins used for input signals.
>
> You need to define how many GPIOs are valid.

I tried to avoid doing this because there is a possibility that future
chips will have a few more signals added and the driver was written so
new signals can be added entirely in device tree without any changes
to the driver. If this is unacceptable, I can add the current max in
and out valid gpios.

>
> > +
> > +  in-names:
> > +    description: Array of input signal names, one per gpio in in-gpios.
>
> No, this isn't how we name GPIOs. The part before '-gpios' is how.

This is the meant to be a description of how each gpio is being used
to help with error messages in the driver.
What if I use "brcmstb,in-functions" instead?

>
> > +
> > +  in-masks:
> > +    description: Array of enable and mask pairs, one per gpio in-gpios.
>
> Needs a vendor prefix.

I'll change it to "brcmstb,in-masks"

>
> > +
> > +  out-gpios:
> > +    description: Array of one or more GPIO pins used for output signals.
> > +
> > +  out-names:
> > +    description: Array of output signal names, one per gpio in out-gpios.
> > +
> > +  out-masks:
> > +    description: Array of enable, value, changed and clear masks, one
> > +      per gpio in out-gpios.
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    usb_pinmap: usb-pinmap@...00d0 {
> > +        compatible = "brcm,usb-pinmap";
> > +        reg = <0x22000d0 0x4>;
> > +        in-gpios = <&gpio 18 0>, <&gpio 19 0>;
> > +        in-names = "VBUS", "PWRFLT";
> > +        in-masks = <0x8000 0x40000 0x10000 0x80000>;
> > +        out-gpios = <&gpio 20 0>;
> > +        out-names = "PWRON";
> > +        out-masks = <0x20000 0x800000 0x400000 0x200000>;
> > +        interrupts = <0x0 0xb2 0x4>;
> > +    };
> > +
> > +...
> > --
> > 2.17.1
> >