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

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Date:   Fri, 28 Aug 2020 16:00:29 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Al Cooper <alcooperx@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-usb <linux-usb@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 1/3] dt-bindings: Add support for Broadcom USB pin map driver

On Wed, Aug 12, 2020 at 10:20 PM Al Cooper <alcooperx@...il.com> 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.
>
> Signed-off-by: Al Cooper <alcooperx@...il.com>
(...)
> +title: Broadcom USB pin map Controller Device Tree Bindings
> +
> +maintainers:
> +  - Al Cooper <alcooperx@...il.com>
> +
> +properties:
> +  compatible:
> +      items:
> +          - const: brcm,usb-pinmap
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +    description: Must be defined if any out-gpios are specified.
> +
> +  in-gpios:
> +    description: Array of one or more GPIO pins used for input signals.
> +
> +  in-names:
> +    description: Array of input signal names, one per gpio in in-gpios.
> +
> +  in-masks:
> +    description: Array of enable and mask pairs, one per gpio in-gpios.
> +
> +  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>;
> +    };

Wow look at that.

This looks very much like Geert's just invented GPIO aggregator.
But in hardware!

See:
drivers/gpio/gpio-aggregator.c

I think Geert is intending to add bindings to the aggregator, and
while I do think this should be its own driver (in drivers/usb) these
bindings and whatever Geert want to use for the aggregator
should certainly be the same.

Geert what do you think?

Here is the actual driver:
https://lore.kernel.org/linux-usb/20200812202018.49046-3-alcooperx@gmail.com/

Yours,
Linus Walleij