linux-kernel - Re: [PATCH] clk: add flags to distinguish xtal clocks

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Message-ID: <20131110113716.GN26440@lukather>
Date:	Sun, 10 Nov 2013 12:37:16 +0100
From:	Maxime Ripard <maxime.ripard@...e-electrons.com>
To:	Felipe Balbi <balbi@...com>
Cc:	mturquette@...aro.org, james.hogan@...tec.com,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	luca@...lho.fi,
	Linux ARM Kernel Mailing List 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] clk: add flags to distinguish xtal clocks

Hi Felipe,

On Fri, Nov 08, 2013 at 12:00:48PM -0600, Felipe Balbi wrote:
> From: Luciano Coelho <luca@...lho.fi>
> 
> Add a flag that indicate whether the clock is a crystal or not.
> 
> Additionally, parse a new device tree binding in clk-fixed-rate to set
> this flag.
> 
> If clock-xtal isn't set, the clock framework will assume clock to be
> generated by an oscillator.  There's only one user for this binding
> right now which is Texas Instruments' WiLink devices which need to know
> details about the clock in order to initialize the underlying WiFi HW
> correctly.
> 
> Signed-off-by: Luciano Coelho <luca@...lho.fi>
> Signed-off-by: Felipe Balbi <balbi@...com>
> ---
> 
> Dropped CLK_IS_TYPE_DEFINED flag and just assume that if the flag
> isn't there, default behavior will be taken.
> 
>  Documentation/devicetree/bindings/clock/fixed-clock.txt | 1 +
>  drivers/clk/clk-fixed-rate.c                            | 6 +++++-
>  include/linux/clk-provider.h                            | 1 +
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/clock/fixed-clock.txt b/Documentation/devicetree/bindings/clock/fixed-clock.txt
> index 0b1fe78..3036dfe 100644
> --- a/Documentation/devicetree/bindings/clock/fixed-clock.txt
> +++ b/Documentation/devicetree/bindings/clock/fixed-clock.txt
> @@ -12,6 +12,7 @@ Required properties:
>  Optional properties:
>  - gpios : From common gpio binding; gpio connection to clock enable pin.
>  - clock-output-names : From common clock binding.
> +- clock-xtal: true when a clock is provided by a crystal
>  
>  Example:
>  	clock {
> diff --git a/drivers/clk/clk-fixed-rate.c b/drivers/clk/clk-fixed-rate.c
> index 1ed591a..5db9bf0 100644
> --- a/drivers/clk/clk-fixed-rate.c
> +++ b/drivers/clk/clk-fixed-rate.c
> @@ -91,13 +91,17 @@ void of_fixed_clk_setup(struct device_node *node)
>  	struct clk *clk;
>  	const char *clk_name = node->name;
>  	u32 rate;
> +	unsigned long flags = CLK_IS_ROOT;
>  
>  	if (of_property_read_u32(node, "clock-frequency", &rate))
>  		return;
>  
> +	if (of_property_read_bool(node, "clock-xtal"))
> +		flags |= CLK_IS_TYPE_XTAL;
> +

Introducing a new compatible instead of a property would make more
sense here I think.

Do you have a reason not to do so?

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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