linux-kernel - Re: [RFC 1/3] devfreq: dt-bindings: Document Exynos3250 devfreq driver

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Date:	Mon, 08 Dec 2014 05:06:53 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	박경민 <kyungmin.park@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Russell King <linux@....linux.org.uk>,
	최찬우 <cw00.choi@...sung.com>
Cc:	Marek Szyprowski <m.szyprowski@...sung.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>
Subject: Re: [RFC 1/3] devfreq: dt-bindings: Document Exynos3250 devfreq driver

>   
>  Add documentation for bindings used by Exynos3250 devfreq driver.
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> ---
>  .../bindings/arm/samsung/exynos3250-devfreq.txt    | 66 ++++++++++++++++++++++
>  1 file changed, 66 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt b/Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt
> new file mode 100644
> index 000000000000..047955e9e371
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/samsung/exynos3250-devfreq.txt
> @@ -0,0 +1,66 @@
> +Samsung Exynos3250 devfreq driver
> +=================================
> +
> +The driver support changing frequencies and voltage for:
> + - memory controller and bus,
> + - peripheral buses (left and right).
> +
> +Memory controller and bus
> +=========================
> +Required properties:
> + - compatible : should be "samsung,exynos3250-busfreq-mif"
> + - reg : two sets (offset and length of the register) for PPMU registers
> +	used by this devfreq driver
> + - clock-names : one clock of name "dmc" to manage frequency
> + - clocks : phandle and specifier for clock listed in clock-names property
> + - vdd_mif-supply : phandle to MIF voltage regulator
> +
> +Peripheral buses
> +================
> +Required properties:
> + - compatible : should be "samsung,exynos3250-busfreq-int"
> + - reg : two sets (offset and length of the register) for PPMU registers
> +	used by this devfreq driver
> + - clock-names : names for PPMU clocks and bus clocks to manage frequencies;
> +	All following clock names (and corresponding phandles) must be
> +	provided:
> +	- "ppmu_left", "ppmu_right",
> +	- "aclk_400", "aclk_266", "aclk_200", "aclk_160", "aclk_gdl", "aclk_gdr", "mfc";
> + - clocks : phandles and specifiers for clocks listed in clock-names property
> + - vdd_mif-supply : phandle to INT voltage regulator
> +
> +Example
> +=======
> +	busfreq_mif: busfreq@...A0000 {
> +		compatible = "samsung,exynos3250-busfreq-mif";
> +		reg = <0x106A0000 0x2000>, <0x106B0000 0x2000>;
> +		clocks = <&cmu_dmc CLK_DIV_DMC>;
> +		clock-names = "dmc";
> +		vdd_mif-supply = <&buck1_reg>;
> +		status = "okay";
> +	};

The hardware you are binding hereby is "Exynos PPMU".
You may consider to bind PPMU (DMC PPMU or BUS PPMU whichever hardware
you want to use) with DT and then let exynos bus devfreq driver use
the already-bound devices if found, ... in principle.
In other words or point of view, you may implement PPMU driver in
devfreq class device driver so that you let it bind PPMU device with DT.
It may be done similarly with the device below.


Cheers,
MyungJoo.


> +
> +	busfreq_int: busfreq@...A0000 {
> +		compatible = "samsung,exynos3250-busfreq-int";
> +		reg = <0x116A0000 0x2000>, <0x112A0000 0x2000>;
> +		clocks = <&cmu CLK_PPMULEFT>,
> +			<&cmu CLK_PPMURIGHT>,
> +			<&cmu CLK_DIV_ACLK_400_MCUISP>,
> +			<&cmu CLK_DIV_ACLK_266>,
> +			<&cmu CLK_DIV_ACLK_200>,
> +			<&cmu CLK_DIV_ACLK_160>,
> +			<&cmu CLK_DIV_GDL>,
> +			<&cmu CLK_DIV_GDR>,
> +			<&cmu CLK_DIV_MFC>;
> +		clock-names = "ppmuleft",
> +			"ppmuright",
> +			"aclk_400",
> +			"aclk_266",
> +			"aclk_200",
> +			"aclk_160",
> +			"aclk_gdl",
> +			"aclk_gdr",
> +			"mfc";
> +		vdd_int-supply = <&buck3_reg>;
> +		status = "okay";
> +	};
> -- 
> 1.9.1
>