linux-kernel - Re: [PATCH 8/8] dt: regulator: pwm-regulator: Re-write bindings

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Date:	Fri, 5 Jun 2015 19:47:11 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:	kernel@...inux.com, broonie@...nel.org, lgirdwood@...il.com,
	devicetree@...r.kernel.org
Subject: Re: [PATCH 8/8] dt: regulator: pwm-regulator: Re-write bindings

Whoops, nearly forgot the DT folks.

Sorry chaps.

> * Add support for continuous-voltage mode
> * Put more meat on the bones with regards to voltage-table mode
> * Sort out formatting for ease of consumption
> 
> Signed-off-by: Lee Jones <lee.jones@...aro.org>
> ---
>  .../bindings/regulator/pwm-regulator.txt           | 66 ++++++++++++++++++----
>  1 file changed, 54 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> index ce91f61..9a8269f 100644
> --- a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> +++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> @@ -1,27 +1,69 @@
> -pwm regulator bindings
> +Bindings for the Generic PWM Regulator
> +======================================
> +
> +Currently supports 2 modes of operation:
> +
> +voltage-table:		When in this mode, a voltage table (See below) of predefined
> +			voltage <=> duty-cycle values must be provided via DT.
> +			Limitations are that the regulator can only operate at the
> +			voltages supplied in the table.  Intermediary duty-cycle
> +			values which would normally allow finer grained voltage
> +			selection are ignored and rendered useless.  Although more
> +			control is given to the user if the assumptions made in
> +			continuous-voltage mode do not reign true.
> +
> +continuous-voltage:	This mode uses the regulator's maximum and minimum supplied
> +			voltages specified in the regulator-{min,max}-microvolt
> +			properties to calculate appropriate duty-cycle values.  This
> +			allows for a much more fine grained solution when compared
> +			with voltage-table mode above.  This solution does make an
> +			assumption that a %50 duty-cycle value will cause the
> +			regulator voltage to run at half way between the supplied
> +			max_uV and min_uV values.
>  
>  Required properties:
> -- compatible: Should be "pwm-regulator"
> -- pwms: OF device-tree PWM specification (see PWM binding pwm.txt)
> -- voltage-table: voltage and duty table, include 2 members in each set of
> -  brackets, first one is voltage(unit: uv), the next is duty(unit: percent)
> +--------------------
> +- compatible:		Should be "pwm-regulator"
> +
> +- pwms:			PWM specification (See: ../pwm/pwm.txt)
> +
> +One of these must be provided:
> +- voltage-table: 	Voltage and Duty-Cycle table consisting of 2 cells
> +			    First cell is voltage in microvolts (uV)
> +			    Second cell is duty-cycle in percent (%)
> +
> +- max-duty-cycle:	Maximum Duty-Cycle value -- this will normally be 255 (0xff)
> +			for an 8 bit PMU device
>  
> -Any property defined as part of the core regulator binding defined in
> -regulator.txt can also be used.
> +If both are provided, the current default is voltage-table mode.
>  
> -Example:
> +Any property defined as part of the core regulator binding can also be used.
> +(See: ../regulator/regulator.txt)
> +
> +Continuous Voltage Example:
>  	pwm_regulator {
>  		compatible = "pwm-regulator;
>  		pwms = <&pwm1 0 8448 0>;
> +		regulator-min-microvolt = <1016000>;
> +		regulator-max-microvolt = <1114000>;
> +		regulator-name = "vdd_logic";
> +
> +		max-duty-cycle = <255>; /* 8bit PWM */
> +	};
>  
> +Voltage Table Example:
> +	pwm_regulator {
> +		compatible = "pwm-regulator;
> +		pwms = <&pwm1 0 8448 0>;
> +		regulator-min-microvolt = <1016000>;
> +		regulator-max-microvolt = <1114000>;
> +		regulator-name = "vdd_logic";
> +
> +			      /* Voltage Duty-Cycle */
>  		voltage-table = <1114000 0>,
>  				<1095000 10>,
>  				<1076000 20>,
>  				<1056000 30>,
>  				<1036000 40>,
>  				<1016000 50>;
> -
> -		regulator-min-microvolt = <1016000>;
> -		regulator-max-microvolt = <1114000>;
> -		regulator-name = "vdd_logic";
>  	};

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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