Date:	Fri, 25 Oct 2013 21:03:44 +0100
From:	Grant Likely <grant.likely@...aro.org>
To:	Chanwoo Choi <cw00.choi@...sung.com>, anton@...msg.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Cc:	dwmw2@...radead.org, rob.herring@...xeda.com,
	myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
	cw00.choi@...sung.com
Subject: Re: [PATCH 3/4] charger-manager: Add device tree binding for charger-manager

On Tue, 22 Oct 2013 21:51:56 +0900, Chanwoo Choi <cw00.choi@...sung.com> wrote:
> This patch add binding file for charger-manager that this framework enables to
> control and multiple chargers and to monitor charging event.
> 
> Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> Signed-off-by: Myungjoo Ham <myungjoo.ham@...sung.com>
> ---
>  .../devicetree/bindings/power/charger-manager.txt  | 106 +++++++++++++++++++++
>  1 file changed, 106 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power/charger-manager.txt
> 
> diff --git a/Documentation/devicetree/bindings/power/charger-manager.txt b/Documentation/devicetree/bindings/power/charger-manager.txt
> new file mode 100644
> index 0000000..b22c5526
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/power/charger-manager.txt
> @@ -0,0 +1,106 @@
> +Charger-manager framework
> +
> +THe devicetree bindings are for the charger-manager to control charging feature.
> +
> +This framework enables to control and multiple chargers and to monitor charging
> +event in the context of suspend-to-RAM with an interface combining the chargers.
> +
> +Required Properties:
> +- compatible:		Must be "charger-manager".
> +- psy-name:		The name of power-supply class for charger-manager.
> +- polling-mode:		Determine which polling mode will be used.
> +- polling-invertal-ms:	Interval in millisecond at which charger-manager will
> +			monitor battery health.
> +- fullbatt-vchkdrop-ms
> +- fullbatt-vchkdrop-uV:	Check voltage drop afer the battery is fully charged.
> +			If it has dropped more than fullbatt_vchkdrop_uV after
> +			fullbatt_vchkdrop_ms, charger-manager will restart
> +			charging.
> +- fullbatt-uV:		The standard voltage in microvolt for checking
> +			fully charged. If VBATT >= fullbatt_uV, it is assumed to
> +			be full.
> +- fullbatt-soc:		The standard SOC(State Of Charger) for checking
> +			fully charged. If state of Charge >= fullbatt_soc, it is
> +			assumed to be full.
> +- fullbatt-full-capacity: The standard capacity for checking fully charged.
> +			If full capacity of battery >= fullbatt_full_capacity,
> +			it is assumed to be full.
> +- battery-present:	Specify where information for existance of battery
> +			can be obtained.
> +- measure-battery-temp:	Whether to measure battery or not
> +
> +- charging-max-duration-minute:		Maximum possible duration for charging.
> +			If whole charging duration exceed 'charging-max-duration
> +			-ms', charger-manager stop charging.
> +- discharging-max-duration-minute:	Maximum possible duration for
> +			discharging with charger cable after full-batt. If
> +			discharging duration exceed 'discharging-max-duration-
> +			ms', charger-manager start charging.
> +- psy-fuelgauge-name:	The name of power-supply for fuel gauge
> +- io-channels:		The iio channel data for ADC
> +- iio-adc-overheat:	The value of the highest ADC for temperature
> +- iio-adc-cold:		The value of the lowest ADC for temperature
> +- psy-chargers:		Arrary of power-supply name for chargers.
> +- charger-regulators:	Array of charger regulators. It include charger cable
> +			data which need cable-name/extcon-name/min-current-uA
> +			max-current-uA. When cable is attached/detached,
> +			charger-manager change current limit of regulator
> +			according to min-current-uA/max-current-uA.

The documentation for the above properties needs to specify what the
values actually mean. For example, "polling-mode" is documented as
"Determine which polling mode will be used". Huh? What is the difference
between a value of 0 or 1? What values are valid? What do they mean?

As it stands I suspect that the binding is a direct translation from the
existing pdata structure. That probably isn't really what you want. Some
of the properties above do make sense and are documented correctly (ie.
fullbatt-*), but others don't make sense and probably shouldn't be part
of the generic binding (ie. io-channels sounds like something device
specific).

I'll defer to the regulators people on what does and does not make
sense.

g.

> +
> +Examples: adding charger-desc data in dts file
> +
> +charger-manager@ {
> +	compatible = "charger-manager";
> +
> +	psy-name = "battery";
> +
> +	polling-mode = <2>;		/* Polling external power */
> +	polling-interval-ms = <30000>;	/* Polling period */
> +
> +	fullbatt-vchkdrop-ms = <30000>;
> +	fullbatt-vchkdrop-uV = <150000>;
> +	fullbatt-uV = <420000>;
> +	fullbatt-soc = <100>;
> +	fullbatt-full-capacity = <0>;
> +
> +	battery-present = <3>;		/* CM_CHARGER_STAT */
> +
> +	measure-battery-temp;
> +
> +	charging-max-duration-minute = <360>;
> +	discharging-max-duration-minute = <90>;
> +
> +	psy-fuelgauge-name = "max17040";
> +
> +	io-channels = <&adc 2>;
> +	iio-adc-overheat = <2500>;
> +	iio-adc-cold = <0>;
> +
> +	psy-chargers {
> +		psy-charger-max14577 {
> +			psy-charger-name = "max14577-charger";
> +		};
> +	};
> +
> +	charger-regulators {
> +		charger-vinchg1 {
> +			regulator-name = "vinchg1";
> +
> +			charger-cables {
> +				cable-USB {
> +					cable-name = "USB";
> +					extcon-name = "max14577-muic";
> +					min-current-uA = <475000>;
> +					max-current-uA = <500000>;
> +				};
> +
> +				cable-TA {
> +					cable-name = "TA";
> +					extcon-name = "max14577-muic";
> +					min-current-uA = <650000>;
> +					max-current-uA = <675000>;
> +				};
> +			};
> +		};
> +	};
> +};
> -- 
> 1.8.0
> 

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