linux-kernel - Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation

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Message-ID: <20180916135721.rhu3rn4fsrmmgnbf@earth.universe>
Date:   Sun, 16 Sep 2018 15:57:21 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Baolin Wang <baolin.wang@...aro.org>,
        Craig Tatlor <ctatlor97@...il.com>
Cc:     robh+dt@...nel.org, mark.rutland@....com, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        yuanjiang.yu@...soc.com, broonie@...nel.org
Subject: Re: [PATCH 1/2] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge
 unit documentation

Hi,

On Wed, Sep 12, 2018 at 03:29:38PM +0800, Baolin Wang wrote:
> This patch adds the binding documentation for Spreadtrum SC27XX series PMICs
> fuel gauge unit device, which is used to calculate the battery capacity.
> 
> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>
> ---
>  .../devicetree/bindings/power/supply/sc27xx-fg.txt |   55 ++++++++++++++++++++
>  1 file changed, 55 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> new file mode 100644
> index 0000000..7447bae
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/supply/sc27xx-fg.txt
> @@ -0,0 +1,55 @@
> +Spreadtrum SC27XX PMICs Fuel Gauge Unit Power Supply Bindings
> +
> +Required properties:
> +- compatible: Should be one of the following:
> +  "sprd,sc2720-fgu",
> +  "sprd,sc2721-fgu",
> +  "sprd,sc2723-fgu",
> +  "sprd,sc2730-fgu",
> +  "sprd,sc2731-fgu".
> +- reg: The address offset of fuel gauge unit.
> +- bat-detect-gpio: GPIO for battery detection.
> +- io-channels: Specify the IIO ADC channel to get temperature.
> +- io-channel-names: Should be "bat-temp".
> +- sprd,inner-resist: Specify the the battery inner resistance (mOhm).

This should be a property of the battery.without the sprd, prefix.

> +- sprd,ocv-cap-table: Provide the battery capacity percent with corresponding
> +  open circuit voltage (ocv) of the battery, which is used to look up current
> +  battery capacity according to current baterry ocv values.

This should also be part of the battery binding. I just reviewed a
patchset for the Qualcomm Battery Monitoring System, which needs the
same functionality. The Qualcomm binding is more advanced, but
should also support this simpler case. Thus I think it makes sense
to use its description as base for adding support for this feature
to Documentation/devicetree/bindings/power/supply/battery.txt

-- Sebastian

> +- monitored-battery: Phandle of battery characteristics devicetree node.
> +  The fuel gauge uses the following battery properties:
> +- charge-full-design-microamp-hours: battery design capacity.
> +- constant-charge-voltage-max-microvolt: maximum constant input voltage.
> +  See Documentation/devicetree/bindings/power/supply/battery.txt
> +
> +Example:
> +
> +	bat: battery {
> +		compatible = "simple-battery";
> +		charge-full-design-microamp-hours = <1900000>;
> +		constant-charge-voltage-max-microvolt = <4350000>;
> +		......
> +	};
> +
> +	sc2731_pmic: pmic@0 {
> +		compatible = "sprd,sc2731";
> +		reg = <0>;
> +		spi-max-frequency = <26000000>;
> +		interrupts = <GIC_SPI 31 IRQ_TYPE_LEVEL_HIGH>;
> +		interrupt-controller;
> +		#interrupt-cells = <2>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +
> +		fgu@a00 {
> +			compatible = "sprd,sc2731-fgu";
> +			reg = <0xa00>;
> +			bat-detect-gpio = <&pmic_eic 9 GPIO_ACTIVE_HIGH>;
> +			io-channels = <&pmic_adc 5>;
> +			io-channel-names = "bat-temp";
> +			sprd,inner-resist = <250>;
> +			sprd,ocv-cap-table = <4185 100>, <4113 95>, <4066 90>, <4022 85>, <3983 80>, <3949 75>, <3917 70>,
> +				<3889 65>, <3864 60>, <3835 55>, <3805 50>, <3787 45>, <3777 40>, <3773 35>, <3770 30>,
> +				<3765 25>, <3752 20>, <3724 15>, <3680 10>, <3605 5>, <3400 0>;
> +			monitored-battery = <&bat>;
> +		};
> +	};
> -- 
> 1.7.9.5
> 

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