linux-kernel - Re: [3/5] clk: divider: add divider_ro_round

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Message-ID: <f32ed81b-685e-acf6-d2d9-ecd27fd9b8ba@lechnology.com>
Date:   Thu, 11 Jan 2018 17:08:18 -0600
From:   David Lechner <david@...hnology.com>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, Vladimir Zapolskiy <vz@...ia.com>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>
Subject: Re: [3/5] clk: divider: add divider_ro_round_rate helper

On 01/05/2018 11:09 AM, Jerome Brunet wrote:
> Like divider_round_rate, a couple a of driver are doing more or less
> the same operation to round the rate of the divider when it is read-only.
> 
> We can factor this code so let's provide an helper function for this

Perhaps you could also make use of this new helper here (clk-divider.c):

const struct clk_ops clk_divider_ro_ops = {
	.recalc_rate = clk_divider_recalc_rate,
	.round_rate = clk_divider_round_rate,
};
EXPORT_SYMBOL_GPL(clk_divider_ro_ops);

> 
> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
> ---
>   drivers/clk/clk-divider.c    | 43 ++++++++++++++++++++++++++++---------------
>   include/linux/clk-provider.h | 15 +++++++++++++++
>   2 files changed, 43 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
> index a851d3e04c7f..3eb2b27f3513 100644
> --- a/drivers/clk/clk-divider.c
> +++ b/drivers/clk/clk-divider.c
> @@ -344,29 +344,42 @@ long divider_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
>   }
>   EXPORT_SYMBOL_GPL(divider_round_rate_parent);
>   

It is nice to have documentation comments on public functions. Especially
in this case where @prate is an in/out parameter and @table is optional.

> +long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
> +				  unsigned long rate, unsigned long *prate,
> +				  const struct clk_div_table *table, u8 width,
> +				  unsigned long flags, unsigned int val)
> +{
> +	int div;
> +
> +	div = _get_div(table, val, flags, width);
> +
> +	/* Even a read-only clock can propagate a rate change */
> +	if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
> +		if (!parent)
> +			return -EINVAL;
> +
> +		*prate = clk_hw_round_rate(parent, rate * div);
> +	}
> +
> +	return DIV_ROUND_UP_ULL((u64)*prate, div);
> +}
> +EXPORT_SYMBOL_GPL(divider_ro_round_rate_parent);
> +
> +
>   static long clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
>   				unsigned long *prate)
>   {
>   	struct clk_divider *divider = to_clk_divider(hw);
> -	struct clk_hw *hw_parent = clk_hw_get_parent(hw);
> -	int bestdiv;
> +	u32 val;
>   
>   	/* if read only, just return current value */
>   	if (divider->flags & CLK_DIVIDER_READ_ONLY) {
> -		bestdiv = clk_readl(divider->reg) >> divider->shift;
> -		bestdiv &= div_mask(divider->width);
> -		bestdiv = _get_div(divider->table, bestdiv, divider->flags,
> -			divider->width);
> -
> -		/* Even a read-only clock can propagate a rate change */
> -		if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
> -			if (!hw_parent)
> -				return -EINVAL;
> -
> -			*prate = clk_hw_round_rate(hw_parent, rate * bestdiv);
> -		}
> +		val = clk_readl(divider->reg) >> divider->shift;
> +		val &= div_mask(divider->width);
>   
> -		return DIV_ROUND_UP_ULL((u64)*prate, bestdiv);
> +		return divider_ro_round_rate(hw, rate, prate, divider->table,
> +					     divider->width, divider->flags,
> +					     val);
>   	}
>   
>   	return divider_round_rate(hw, rate, prate, divider->table,
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 175a62a15619..eb2c3a035e98 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -417,6 +417,10 @@ long divider_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
>   			       unsigned long rate, unsigned long *prate,
>   			       const struct clk_div_table *table,
>   			       u8 width, unsigned long flags);
> +long divider_ro_round_rate_parent(struct clk_hw *hw, struct clk_hw *parent,
> +				  unsigned long rate, unsigned long *prate,
> +				  const struct clk_div_table *table, u8 width,
> +				  unsigned long flags, unsigned int val);
>   int divider_get_val(unsigned long rate, unsigned long parent_rate,
>   		const struct clk_div_table *table, u8 width,
>   		unsigned long flags);
> @@ -772,6 +776,17 @@ static inline long divider_round_rate(struct clk_hw *hw, unsigned long rate,
>   					 rate, prate, table, width, flags);
>   }
>   

Same here (about documentation comment).

> +static inline long divider_ro_round_rate(struct clk_hw *hw, unsigned long rate,
> +					 unsigned long *prate,
> +					 const struct clk_div_table *table,
> +					 u8 width, unsigned long flags,
> +					 unsigned int val)
> +{
> +	return divider_ro_round_rate_parent(hw, clk_hw_get_parent(hw),
> +					    rate, prate, table, width, flags,
> +					    val);
> +}
> +
>   /*
>    * FIXME clock api without lock protection
>    */
>