linux-kernel - Re: [PATCH v3 1/4] dt-bindings: w1: document generic onewire and DS2760 bindings

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Message-ID: <20180705233245.GA16422@rob-hp-laptop>
Date:   Thu, 5 Jul 2018 17:32:45 -0600
From:   Rob Herring <robh@...nel.org>
To:     Daniel Mack <daniel@...que.org>
Cc:     zbr@...emap.net, mark.rutland@....com, szabolcs.gyurko@....hu,
        sre@...nel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        robert.jarzmik@...e.fr
Subject: Re: [PATCH v3 1/4] dt-bindings: w1: document generic onewire and
 DS2760 bindings

On Wed, Jul 04, 2018 at 06:44:08AM +0200, Daniel Mack wrote:
> This patch adds a generic w1 bindings document that merely describes how
> slave deviceses are grouped under master nodes. It also adds a specific
> binding for the ds2760 battery monitor.
> 
> Signed-off-by: Daniel Mack <daniel@...que.org>
> ---
>  .../bindings/power/supply/maxim,ds2760.txt    | 29 +++++++++++++++++++

This has grown enough now, you should probably make it a separate 
patch.

>  .../devicetree/bindings/w1/w1-gpio.txt        | 11 +++++--
>  Documentation/devicetree/bindings/w1/w1.txt   | 25 ++++++++++++++++
>  3 files changed, 62 insertions(+), 3 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/power/supply/maxim,ds2760.txt
>  create mode 100644 Documentation/devicetree/bindings/w1/w1.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/supply/maxim,ds2760.txt b/Documentation/devicetree/bindings/power/supply/maxim,ds2760.txt
> new file mode 100644
> index 000000000000..a39d1ada48f2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/supply/maxim,ds2760.txt
> @@ -0,0 +1,29 @@
> +Devicetree bindings for Maxim DS2760
> +====================================
> +
> +The ds2760 is a w1 slave device and must hence have its sub-node in DT
> +under a w1 bus master node.
> +
> +The device exposes a power supply, so the details described in
> +Documentation/devicetree/bindings/power/supply/power_supply.txt apply.
> +
> +Required properties:
> +- compatible: must be "maxim,ds2760"
> +
> +Optional properties:
> +- power-supplies:	Refers to one or more power supplies connected to
> +			this battery.
> +- maxim,pmod-enabled:	This boolean property enables the DS2760 to enter
> +			sleep mode when the DQ line goes low for greater
> +			than 2 seconds and leave sleep Mode when the DQ
> +			line goes high.
> +- maxim,cache-time:	Time im milliseconds to cache the data for. When

Add unit suffix as defined in property-units.txt.

> +			this time expires, the values are read again from
> +			the hardware. Defaults to 1000.
> +- maxim,rated-capacity:	The rated capacity of the battery, in mAh.

Seems like this should be common.

> +			If not specified, the value stored in the
> +			non-volatile chip memory is used.
> +- maxim,current-accumulator:
> +			The current accumulator value in mAh.
> +			If not specified, the value stored in the
> +			non-volatile chip memory is used.

This would be updated periodically while running and then restored after 
a power cycle or reboot to maintain the battery level across power 
cycle? I don't think that belongs in DT as we don't really define 
whether a DT can be updated persistently.
 
> diff --git a/Documentation/devicetree/bindings/w1/w1-gpio.txt b/Documentation/devicetree/bindings/w1/w1-gpio.txt
> index 6e09c35d9f1a..3d6554eac240 100644
> --- a/Documentation/devicetree/bindings/w1/w1-gpio.txt
> +++ b/Documentation/devicetree/bindings/w1/w1-gpio.txt
> @@ -13,10 +13,15 @@ Optional properties:
>   - linux,open-drain: if specified, the data pin is considered in
>  		     open-drain mode.
>  
> +Also refer to the generic w1.txt document.
> +
>  Examples:
>  
> -	onewire@0 {
> +	onewire {
>  		compatible = "w1-gpio";
> -		gpios = <&gpio 126 0>, <&gpio 105 0>;
> -	};
> +		gpios = <&gpio 0 GPIO_ACTIVE_HIGH>;
>  
> +		battery {
> +			// ...
> +		};
> +	};
> diff --git a/Documentation/devicetree/bindings/w1/w1.txt b/Documentation/devicetree/bindings/w1/w1.txt
> new file mode 100644
> index 000000000000..bee18f7070ec
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/w1/w1.txt
> @@ -0,0 +1,25 @@
> +Generic devicetree bindings for onewire (w1) busses
> +===================================================
> +
> +Onewire busses are described through nodes of their master bus controller.
> +Slave devices are listed as sub-nodes of such master devices. For now, only
> +one slave is allowed per bus master.
> +
> +
> +Example:
> +
> +	charger: charger {
> +		compatible = "gpio-charger";
> +		charger-type = "mains";
> +		gpios = <&gpio 1 GPIO_ACTIVE_LOW>;
> +	};
> +
> +	onewire@0 {

Drop the unit-address.

> +		compatible = "w1-gpio";
> +		gpios = <&gpio 100 0>, <&gpio 101 0>;
> +
> +		battery {
> +			compatible = "maxim,ds2760";
> +			power-supplies = <&charger>;
> +		};
> +	};
> -- 
> 2.17.1
>