linux-kernel - Re: [PATCH] clk: Add device tree binding to clk-fixed-factor

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Message-ID: <51658BA9.7030508@free-electrons.com>
Date:	Wed, 10 Apr 2013 17:56:25 +0200
From:	Gregory CLEMENT <gregory.clement@...e-electrons.com>
To:	Christian Ruppert <christian.ruppert@...lis.com>
CC:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Mike Turquette <mturquette@...aro.org>,
	linux-doc@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	Rob Herring <rob.herring@...xeda.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Landley <rob@...dley.net>
Subject: Re: [PATCH] clk: Add device tree binding to clk-fixed-factor

Hi Christian,

On 04/10/2013 05:40 PM, Christian Ruppert wrote:
> This patch adds a device tree binding for the simple fixed factor clock
> divider/multiplier of the common clock tree binding.

This patch remind me of something :
http://lists.infradead.org/pipermail/linux-arm-kernel/2012-August/116405.html

Do you have a use case for it, this time?

My version have been hold off waiting for an user for it.
Will you need it for a driver?

Regards,

> 
> Signed-off-by: Christian Ruppert <christian.ruppert@...lis.com>
> ---
>  .../bindings/clock/fixed-factor-clkdiv.txt         |   24 +++++++++++++++
>  drivers/clk/clk-fixed-factor.c                     |   32 ++++++++++++++++++++
>  include/linux/clk-provider.h                       |    1 +
>  3 files changed, 57 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt b/Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt
> new file mode 100644
> index 0000000..352bac4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/fixed-factor-clkdiv.txt
> @@ -0,0 +1,24 @@
> +Device Tree Clock bindings for plat-tb10x
> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible : shall be "fixed-factor-clkdiv"
> +- #clock-cells: from common clock binding; shall be set to 0
> +- clocks: shall be the input parent clock phandle for the clock.
> +- clock-mult: defines the multiplication factor of the output clock frequency
> +  wrt. the input clock frequency.
> +- clock-div: defines the division factor of the output clock frequency wrt.
> +  the input clock frequency.
> +
> +Example:
> +cpu_clk: clkdiv_cpu {	/* CPU clock derived from pll0. 1/2 of pll frequency */
> +	compatible = "fixed-factor-clkdiv";
> +	#clock-cells = <0>;
> +	clocks = <&pll0>;
> +	clock-mult = <1>;
> +	clock-div = <2>;
> +	clock-output-names = "cpu_clk";
> +};
> diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
> index 1ef271e..85e45f1 100644
> --- a/drivers/clk/clk-fixed-factor.c
> +++ b/drivers/clk/clk-fixed-factor.c
> @@ -11,6 +11,7 @@
>  #include <linux/clk-provider.h>
>  #include <linux/slab.h>
>  #include <linux/err.h>
> +#include <linux/of.h>
>  
>  /*
>   * DOC: basic fixed multiplier and divider clock that cannot gate
> @@ -96,3 +97,34 @@ struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
>  
>  	return clk;
>  }
> +
> +#ifdef CONFIG_OF
> +/**
> + * of_fixed_factor_clkdiv_setup() - Set up simple fixed factor clock divider
> + */
> +void of_fixed_factor_clkdiv_setup(struct device_node *node)
> +{
> +	struct clk *clk;
> +	const char *clk_name = node->name;
> +	const char *parent_name;
> +	u32 mult, div;
> +
> +	if (of_property_read_u32(node, "clock-mult", &mult))
> +		return;
> +
> +	if (of_property_read_u32(node, "clock-div", &div))
> +		return;
> +
> +	parent_name = of_clk_get_parent_name(node, 0);
> +
> +	of_property_read_string(node, "clock-output-names", &clk_name);
> +
> +	clk = clk_register_fixed_factor(NULL, clk_name, parent_name, 0,
> +					mult, div);
> +	if (!IS_ERR(clk))
> +		of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +}
> +EXPORT_SYMBOL_GPL(of_fixed_factor_clkdiv_setup);
> +CLK_OF_DECLARE(fixed_clkdiv, "fixed-factor-clkdiv",
> +		of_fixed_factor_clkdiv_setup);
> +#endif
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 7f197d7..d4937cf 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -184,6 +184,7 @@ struct clk *clk_register_fixed_rate(struct device *dev, const char *name,
>  		unsigned long fixed_rate);
>  
>  void of_fixed_clk_setup(struct device_node *np);
> +void of_fixed_factor_clkdiv_setup(struct device_node *node);
>  
>  /**
>   * struct clk_gate - gating clock
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
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