linux-kernel - Re: [PATCH v2 05/20] clk: sunxi: Support factor clocks with N multiplier factor starting from 1

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Message-ID: <CAL_JsqLyXwQzd9Oxj9pb49fWqzMjV9=1Nx3i+9bN-rwfEMqwcQ@mail.gmail.com>
Date:	Tue, 17 Jun 2014 16:23:02 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Chen-Yu Tsai <wens@...e.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Rob Herring <robh+dt@...nel.org>,
	Mike Turquette <mturquette@...aro.org>,
	Emilio Lopez <emilio@...pez.com.ar>,
	Linus Walleij <linus.walleij@...aro.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-sunxi@...glegroups.com,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	Luc Verhaegen <libv@...net.be>
Subject: Re: [PATCH v2 05/20] clk: sunxi: Support factor clocks with N
 multiplier factor starting from 1

On Tue, Jun 17, 2014 at 9:52 AM, Chen-Yu Tsai <wens@...e.org> wrote:
> The PLLs on newer Allwinner SoC's, such as the A31 and A23, have a
> N multiplier factor that starts from 1, not 0.
>
> This patch adds an option to the clock driver's config data structures
> to define the difference.
>
> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
> Acked-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
> ---
>  drivers/clk/sunxi/clk-factors.c | 5 ++++-
>  drivers/clk/sunxi/clk-factors.h | 1 +
>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/clk/sunxi/clk-factors.c b/drivers/clk/sunxi/clk-factors.c
> index 3806d97..399cf4d 100644
> --- a/drivers/clk/sunxi/clk-factors.c
> +++ b/drivers/clk/sunxi/clk-factors.c
> @@ -62,7 +62,10 @@ static unsigned long clk_factors_recalc_rate(struct clk_hw *hw,
>                 p = FACTOR_GET(config->pshift, config->pwidth, reg);
>
>         /* Calculate the rate */
> -       rate = (parent_rate * n * (k + 1) >> p) / (m + 1);
> +       if (config->n_from_one)
> +               rate = (parent_rate * (n + 1) * (k + 1) >> p) / (m + 1);
> +       else
> +               rate = (parent_rate * n * (k + 1) >> p) / (m + 1);

This can be simplified and support any base with:

rate = (parent_rate * (n + config->n_base) * (k + 1) >> p) / (m + 1);
--
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