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Subject: Re: [PATCH v9 1/4] clk: meson: add one based divider support for sclk
 divider
To:     Jerome Brunet <jbrunet@baylibre.com>,
        Neil Armstrong <narmstrong@baylibre.com>
CC:     Kevin Hilman <khilman@baylibre.com>,
        Carlo Caione <carlo@caione.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, Rob Herring <robh@kernel.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        Yixun Lan <yixun.lan@amlogic.com>,
        Liang Yang <liang.yang@amlogic.com>,
        Jian Hu <jian.hu@amlogic.com>,
        Qiufang Dai <qiufang.dai@amlogic.com>,
        Hanjie Lin <hanjie.lin@amlogic.com>,
        Victor Wan <victor.wan@amlogic.com>,
        <linux-clk@vger.kernel.org>, <linux-amlogic@lists.infradead.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>
References: <1546955444-7549-1-git-send-email-jianxin.pan@amlogic.com>
 <1546955444-7549-2-git-send-email-jianxin.pan@amlogic.com>
 <024e1206ad8c103ef67a72fb2a48cdd5ec634a12.camel@baylibre.com>
From:   Jianxin Pan <jianxin.pan@amlogic.com>
Message-ID: <609bae99-03d4-c338-a594-efae037ebac7@amlogic.com>
Date:   Thu, 24 Jan 2019 17:10:47 +0800
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Hi Jerome,

On 2019/1/22 17:25, Jerome Brunet wrote:
> On Tue, 2019-01-08 at 21:50 +0800, Jianxin Pan wrote:
>> When CLK_DIVIDER_ONE_BASED flag is set, the sclk divider will be:
>> one based divider (div = val), and zero value gates the clock
>>
>> Signed-off-by: Jianxin Pan <jianxin.pan@amlogic.com>
>> ---
>>  drivers/clk/meson/Makefile     |  3 ++-
>>  drivers/clk/meson/clkc-audio.h |  8 ------
>>  drivers/clk/meson/clkc.h       | 10 ++++++-
>>  drivers/clk/meson/sclk-div.c   | 59 ++++++++++++++++++++++++++++-----------
>> ---
>>  4 files changed, 50 insertions(+), 30 deletions(-)
>>
>> diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
>> index a849aa8..acd8694 100644
>> --- a/drivers/clk/meson/Makefile
>> +++ b/drivers/clk/meson/Makefile
>> @@ -4,7 +4,8 @@
>>  
>>  obj-$(CONFIG_COMMON_CLK_AMLOGIC) += clk-pll.o clk-mpll.o clk-phase.o vid-
>> pll-div.o
>>  obj-$(CONFIG_COMMON_CLK_AMLOGIC) += clk-input.o
>> -obj-$(CONFIG_COMMON_CLK_AMLOGIC_AUDIO)	+= clk-triphase.o sclk-div.o
>> +obj-$(CONFIG_COMMON_CLK_AMLOGIC) += sclk-div.o
>> +obj-$(CONFIG_COMMON_CLK_AMLOGIC_AUDIO) += clk-triphase.o
>>  obj-$(CONFIG_COMMON_CLK_MESON_AO) += meson-aoclk.o
>>  obj-$(CONFIG_COMMON_CLK_MESON8B) += meson8b.o
>>  obj-$(CONFIG_COMMON_CLK_GXBB)	 += gxbb.o gxbb-aoclk.o gxbb-aoclk-
>> 32k.o
>> diff --git a/drivers/clk/meson/clkc-audio.h b/drivers/clk/meson/clkc-audio.h
>> index 0a7c157..286ff12 100644
>> --- a/drivers/clk/meson/clkc-audio.h
>> +++ b/drivers/clk/meson/clkc-audio.h
>> @@ -15,14 +15,6 @@ struct meson_clk_triphase_data {
>>  	struct parm ph2;
>>  };
>>  
>> -struct meson_sclk_div_data {
>> -	struct parm div;
>> -	struct parm hi;
>> -	unsigned int cached_div;
>> -	struct clk_duty cached_duty;
>> -};
>> -
>>  extern const struct clk_ops meson_clk_triphase_ops;
>> -extern const struct clk_ops meson_sclk_div_ops;
>>  
>>  #endif /* __MESON_CLKC_AUDIO_H */
>> diff --git a/drivers/clk/meson/clkc.h b/drivers/clk/meson/clkc.h
>> index 6183b22..00b3320 100644
>> --- a/drivers/clk/meson/clkc.h
>> +++ b/drivers/clk/meson/clkc.h
>> @@ -27,6 +27,14 @@ struct parm {
>>  	u8	width;
>>  };
>>  
>> +struct meson_sclk_div_data {
>> +	struct parm div;
>> +	struct parm hi;
>> +	unsigned int cached_div;
>> +	struct clk_duty cached_duty;
>> +	u8 flags;
>> +};
>> +
>>  static inline unsigned int meson_parm_read(struct regmap *map, struct parm
>> *p)
>>  {
>>  	unsigned int val;
>> @@ -118,10 +126,10 @@ struct clk_regmap _name = {				
>> 		\
>>  extern const struct clk_ops meson_clk_mpll_ops;
>>  extern const struct clk_ops meson_clk_phase_ops;
>>  extern const struct clk_ops meson_vid_pll_div_ro_ops;
>> +extern const struct clk_ops meson_sclk_div_ops;
>>  
>>  struct clk_hw *meson_clk_hw_register_input(struct device *dev,
>>  					   const char *of_name,
>>  					   const char *clk_name,
>>  					   unsigned long flags);
>> -
>>  #endif /* __CLKC_H */
>> diff --git a/drivers/clk/meson/sclk-div.c b/drivers/clk/meson/sclk-div.c
>> index bc64019..a6c425b 100644
>> --- a/drivers/clk/meson/sclk-div.c
>> +++ b/drivers/clk/meson/sclk-div.c
>> @@ -4,42 +4,60 @@
>>   * Author: Jerome Brunet <jbrunet@baylibre.com>
>>   *
>>   * Sample clock generator divider:
>> - * This HW divider gates with value 0 but is otherwise a zero based
>> divider:
>> + * This HW divider gates with value 0
>>   *
>>   * val >= 1
>> - * divider = val + 1
>> + * divider = val + 1 if ONE_BASED is not set, otherwise divider = val.
>>   *
>>   * The duty cycle may also be set for the LR clock variant. The duty cycle
>>   * ratio is:
>>   *
>>   * hi = [0 - val]
>> - * duty_cycle = (1 + hi) / (1 + val)
>> + * duty_cycle = (1 + hi) / (1 + val) if ONE_BASED is not set, otherwise:
>> + * duty_cycle = hi / (1 + val)
>>   */
>>  
>> -#include "clkc-audio.h"
>> +#include "clkc.h"
>>  
>> -static inline struct meson_sclk_div_data *
>> -meson_sclk_div_data(struct clk_regmap *clk)
>> +static inline int get_reg(int val, unsigned char flag)
> 
> s/get_reg/sclk_get_reg
OK, I will rename get_reg and get_value in next version.
Thank you for the review.
> 
>>  {
>> -	return (struct meson_sclk_div_data *)clk->data;
>> +	WARN_ON(val < 1);
> 
> I don't think this WARN is justified, especially since you are using this
> function to set the hi value.
OK, it will remove it. Thank you.
> 
>> +	if ((flag & CLK_DIVIDER_ONE_BASED) || !val)
> 
> I don't like that you make a dependency on the generic divider just for this.
> Please make your own flag like MESON_SCLK_ONE_BASED
OK, I will define a new flag MESON_SCLK_ONE_BASED in drivers/clk/meson/clkc.h.
> 
>> +		return val;
>> +	else
>> +		return val - 1;
>> +}
>> +
>> +static inline int get_value(int reg, unsigned char flag)
> 
> s/get_value/sclk_get_divider
OK, I will rename it.
> 
>> +{
>> +	if (flag & CLK_DIVIDER_ONE_BASED)
>> +		return reg;
>> +	else
>> +		return reg + 1;
>>  }
>>  
>> -static int sclk_div_maxval(struct meson_sclk_div_data *sclk)
>> +static inline struct meson_sclk_div_data *
>> +meson_sclk_div_data(struct clk_regmap *clk)
>>  {
>> -	return (1 << sclk->div.width) - 1;
>> +	return (struct meson_sclk_div_data *)clk->data;
>>  }
>>  
>>  static int sclk_div_maxdiv(struct meson_sclk_div_data *sclk)
>>  {
>> -	return sclk_div_maxval(sclk) + 1;
>> +	unsigned int reg = clk_div_mask(sclk->div.width);
> 
> same here, leave the generic divider alone.
>  
> `(1 << sclk->div.width) - 1` was fine to get max register value.
> 
>> +
>> +	return get_value(reg, sclk->flags);
>>  }
>>  
>>  static int sclk_div_getdiv(struct clk_hw *hw, unsigned long rate,
>>  			   unsigned long prate, int maxdiv)
>>  {
>>  	int div = DIV_ROUND_CLOSEST_ULL((u64)prate, rate);
>> +	struct clk_regmap *clk = to_clk_regmap(hw);
>> +	struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
>> +	int mindiv = get_value(1, sclk->flags);
> 
> maxdiv is provided as a param while mindiv is computed inside this function.
> let's be coherent and pick one approach.
OK, I will compute min and max in this function both. 
Thank you for your review.
> 
>>  
>> -	return clamp(div, 2, maxdiv);
>> +	return clamp(div, mindiv, maxdiv);
>>  }
>>  
>>  static int sclk_div_bestdiv(struct clk_hw *hw, unsigned long rate,
>> @@ -47,7 +65,7 @@ static int sclk_div_bestdiv(struct clk_hw *hw, unsigned
>> long rate,
>>  			    struct meson_sclk_div_data *sclk)
>>  {
>>  	struct clk_hw *parent = clk_hw_get_parent(hw);
>> -	int bestdiv = 0, i;
>> +	int bestdiv = 0, i, mindiv;
>>  	unsigned long maxdiv, now, parent_now;
>>  	unsigned long best = 0, best_parent = 0;
>>  
>> @@ -64,8 +82,9 @@ static int sclk_div_bestdiv(struct clk_hw *hw, unsigned
>> long rate,
>>  	 * unsigned long in rate * i below
>>  	 */
>>  	maxdiv = min(ULONG_MAX / rate, maxdiv);
>> +	mindiv = get_value(1, sclk->flags);
>>  
>> -	for (i = 2; i <= maxdiv; i++) {
>> +	for (i = mindiv; i <= maxdiv; i++) {
>>  		/*
>>  		 * It's the most ideal case if the requested rate can be
>>  		 * divided from parent clock without needing to change
>> @@ -111,10 +130,7 @@ static void sclk_apply_ratio(struct clk_regmap *clk,
>>  					    sclk->cached_duty.num,
>>  					    sclk->cached_duty.den);
>>  
>> -	if (hi)
>> -		hi -= 1;
>> -
>> -	meson_parm_write(clk->map, &sclk->hi, hi);
>> +	meson_parm_write(clk->map, &sclk->hi, get_reg(hi, sclk->flags));
>>  }
>>  
>>  static int sclk_div_set_duty_cycle(struct clk_hw *hw,
>> @@ -145,7 +161,7 @@ static int sclk_div_get_duty_cycle(struct clk_hw *hw,
>>  	}
>>  
>>  	hi = meson_parm_read(clk->map, &sclk->hi);
>> -	duty->num = hi + 1;
>> +	duty->num = get_value(hi, sclk->flags);
>>  	duty->den = sclk->cached_div;
>>  	return 0;
>>  }
>> @@ -153,10 +169,13 @@ static int sclk_div_get_duty_cycle(struct clk_hw *hw,
>>  static void sclk_apply_divider(struct clk_regmap *clk,
>>  			       struct meson_sclk_div_data *sclk)
>>  {
>> +	unsigned int div;
>> +
>>  	if (MESON_PARM_APPLICABLE(&sclk->hi))
>>  		sclk_apply_ratio(clk, sclk);
>>  
>> -	meson_parm_write(clk->map, &sclk->div, sclk->cached_div - 1);
>> +	div = get_reg(sclk->cached_div, sclk->flags);
>> +	meson_parm_write(clk->map, &sclk->div, div);
>>  }
>>  
>>  static int sclk_div_set_rate(struct clk_hw *hw, unsigned long rate,
>> @@ -224,7 +243,7 @@ static void sclk_div_init(struct clk_hw *hw)
>>  	if (!val)
>>  		sclk->cached_div = sclk_div_maxdiv(sclk);
>>  	else
>> -		sclk->cached_div = val + 1;
>> +		sclk->cached_div = get_value(val, sclk->flags);
>>  
>>  	sclk_div_get_duty_cycle(hw, &sclk->cached_duty);
>>  }
> 
> 
> .
>