linux-kernel - Re: [PATCH v2 1/2] dt-bindings: Add power-efuse binding

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Date:   Fri, 11 Mar 2022 09:24:41 -0600
From:   Rob Herring <robh@...nel.org>
To:     Zev Weiss <zev@...ilderbeest.net>
Cc:     devicetree@...r.kernel.org, openbmc@...ts.ozlabs.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>
Subject: Re: [PATCH v2 1/2] dt-bindings: Add power-efuse binding

On Mon, Mar 07, 2022 at 05:18:09PM -0800, Zev Weiss wrote:
> This can be used to describe a power output supplied by a regulator
> device that the system controls.
> 
> Signed-off-by: Zev Weiss <zev@...ilderbeest.net>
> ---
>  .../devicetree/bindings/misc/power-efuse.yaml | 49 +++++++++++++++++++
>  1 file changed, 49 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/misc/power-efuse.yaml
> 
> diff --git a/Documentation/devicetree/bindings/misc/power-efuse.yaml b/Documentation/devicetree/bindings/misc/power-efuse.yaml
> new file mode 100644
> index 000000000000..5f8f0b21af0e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/power-efuse.yaml
> @@ -0,0 +1,49 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/misc/power-efuse.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Generic power efuse device
> +
> +maintainers:
> +  - Zev Weiss <zev@...ilderbeest.net>
> +
> +description: |
> +  This binding describes a physical power output supplied by a
> +  regulator providing efuse functionality (manual on/off control, and
> +  auto-shutoff if current, voltage, or thermal limits are exceeded).
> +
> +  These may be found on systems such as "smart" network PDUs, and
> +  typically supply power to devices entirely separate from the system
> +  described by the device-tree by way of an external connector such as
> +  an Open19 power cable:
> +
> +  https://www.open19.org/marketplace/coolpower-cable-assembly-8ru/

Not really a helpful link...

I still don't understand what the h/w looks like here. At least I now 
understand we're talking a fuse on power rail, not efuses in an SoC 
used as OTP bits or feature disables.

> +
> +properties:
> +  compatible:
> +    const: power-efuse
> +
> +  vout-supply:
> +    description:
> +      phandle to the regulator providing power for the efuse

Vout is a supply to the efuse and not the rail being fused? 

Sorry, I know nothing about how an efuse is implemented so you are going 
to have to explain or draw it.

> +
> +  error-flags-cache-ttl-ms:
> +    description:
> +      The number of milliseconds the vout-supply regulator's error
> +      flags should be cached before re-fetching them.

How does one fetch/read? the error flags?

> +
> +required:
> +  - compatible
> +  - vout-supply
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    efuse {
> +        compatible = "power-efuse";
> +        vout-supply = <&efuse_reg>;
> +        error-flags-cache-ttl-ms = <500>;
> +    };
> -- 
> 2.35.1
> 
>