linux-kernel - Re: [PATCH v6 4/5] clk: imx: add imx composite clock

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Message-ID: <20180824074346.crkb2qus76lwva5h@pengutronix.de>
Date:   Fri, 24 Aug 2018 09:43:46 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     Abel Vesa <abel.vesa@....com>
Cc:     Lucas Stach <l.stach@...gutronix.de>,
        Sascha Hauer <kernel@...gutronix.de>,
        Dong Aisheng <aisheng.dong@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Anson Huang <anson.huang@....com>,
        Mark Rutland <mark.rutland@....com>,
        Rob Herring <robh@...nel.org>, devicetree@...r.kernel.org,
        Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-kernel@...r.kernel.org, Abel Vesa <abelvesa@...ux.com>,
        linux-imx@....com, Shawn Guo <shawnguo@...nel.org>,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v6 4/5] clk: imx: add imx composite clock

On Wed, Aug 22, 2018 at 04:48:22PM +0300, Abel Vesa wrote:
> Since a lot of clocks on imx8 are formed by a mux, gate, predivider and
> divider, the idea here is to combine all of those into one composite clock,
> but we need to deal with both predivider and divider at the same time and
> therefore we add the imx_clk_composite_divider_ops and register the composite
> clock with those.
> 
> Signed-off-by: Abel Vesa <abel.vesa@....com>
> Suggested-by: Sascha Hauer <s.hauer@...gutronix.de>
> ---
>  drivers/clk/imx/Makefile        |   1 +
>  drivers/clk/imx/clk-composite.c | 157 ++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/imx/clk.h           |   9 +++
>  3 files changed, 167 insertions(+)
>  create mode 100644 drivers/clk/imx/clk-composite.c
> 
> diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
> index b87513c..4fabb0a 100644
> --- a/drivers/clk/imx/Makefile
> +++ b/drivers/clk/imx/Makefile
> @@ -3,6 +3,7 @@
>  obj-y += \
>  	clk.o \
>  	clk-busy.o \
> +	clk-composite.o \
>  	clk-cpu.o \
>  	clk-fixup-div.o \
>  	clk-fixup-mux.o \
> diff --git a/drivers/clk/imx/clk-composite.c b/drivers/clk/imx/clk-composite.c
> new file mode 100644
> index 0000000..a5c0080
> --- /dev/null
> +++ b/drivers/clk/imx/clk-composite.c
> @@ -0,0 +1,157 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2018 NXP
> + */
> +
> +#include <linux/errno.h>
> +#include <linux/slab.h>
> +#include <linux/clk-provider.h>
> +#include <linux/clk.h>
> +
> +#include "clk.h"
> +
> +#define PCG_PREDIV_SHIFT	16
> +#define PCG_PREDIV_WIDTH	3
> +
> +#define PCG_DIV_SHIFT		0
> +#define PCG_DIV_WIDTH		6
> +
> +#define PCG_PCS_SHIFT		24
> +#define PCG_PCS_MASK		0x7
> +
> +#define PCG_CGC_SHIFT		28
> +
> +static unsigned long imx_clk_composite_divider_recalc_rate(struct clk_hw *hw,
> +						unsigned long parent_rate)
> +{
> +	struct clk_divider *divider = to_clk_divider(hw);
> +	unsigned long prediv_rate;
> +	unsigned int prediv_value;
> +	unsigned int div_value;
> +
> +	prediv_value = clk_readl(divider->reg) >> divider->shift;
> +	prediv_value &= clk_div_mask(divider->width);
> +
> +	prediv_rate = divider_recalc_rate(hw, parent_rate, prediv_value,
> +						divider->table, divider->flags,
> +						divider->width);
> +
> +	div_value = clk_readl(divider->reg) >> PCG_DIV_SHIFT;
> +	div_value &= clk_div_mask(PCG_DIV_WIDTH);
> +
> +	return divider_recalc_rate(hw, prediv_rate, div_value, divider->table,
> +				   divider->flags, PCG_DIV_WIDTH);

This is no table based divider, so divider->table is NULL, right? It's
clearer to just write NULL here instead.

Otherwise this looks good for me now.

Sascha


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