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Date:   Fri, 10 Aug 2018 14:27:21 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Yixun Lan <yixun.lan@...ogic.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>, Rob Herring <robh@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Liang Yang <liang.yang@...ogic.com>,
        Jianxin Pan <jianxin.pan@...ogic.com>,
        Qiufang Dai <qiufang.dai@...ogic.com>,
        Jian Hu <jian.hu@...ogic.com>, linux-clk@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/3] clk: meson: add emmc sub clock phase delay driver

On Thu, 2018-08-09 at 15:07 +0800, Yixun Lan wrote:
> Export the emmc sub clock phase delay ops which will be used
> by the emmc sub clock driver itself.
> 
> Signed-off-by: Yixun Lan <yixun.lan@...ogic.com>
> ---
>  drivers/clk/meson/Makefile          |  2 +-
>  drivers/clk/meson/clk-phase-delay.c | 96 +++++++++++++++++++++++++++++
>  drivers/clk/meson/clkc.h            | 13 ++++
>  3 files changed, 110 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/clk/meson/clk-phase-delay.c
> 
> diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
> index 72ec8c40d848..39ce5661b654 100644
> --- a/drivers/clk/meson/Makefile
> +++ b/drivers/clk/meson/Makefile
> @@ -2,7 +2,7 @@
>  # Makefile for Meson specific clk
>  #
>  
> -obj-$(CONFIG_COMMON_CLK_AMLOGIC) += clk-pll.o clk-mpll.o clk-phase.o
> +obj-$(CONFIG_COMMON_CLK_AMLOGIC) += clk-pll.o clk-mpll.o clk-phase.o clk-phase-delay.o
>  obj-$(CONFIG_COMMON_CLK_AMLOGIC_AUDIO)	+= clk-triphase.o sclk-div.o
>  obj-$(CONFIG_COMMON_CLK_MESON_AO) += meson-aoclk.o
>  obj-$(CONFIG_COMMON_CLK_MESON8B) += meson8b.o
> diff --git a/drivers/clk/meson/clk-phase-delay.c b/drivers/clk/meson/clk-phase-delay.c
> new file mode 100644
> index 000000000000..6f226814cfec
> --- /dev/null
> +++ b/drivers/clk/meson/clk-phase-delay.c
> @@ -0,0 +1,96 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Amlogic Meson MMC Sub Clock Controller Driver
> + *
> + * Copyright (c) 2017 Baylibre SAS.
> + * Author: Jerome Brunet <jbrunet@...libre.com>
> + *
> + * Copyright (c) 2018 Amlogic, inc.
> + * Author: Yixun Lan <yixun.lan@...ogic.com>
> + */
> +
> +#include <linux/clk-provider.h>
> +#include "clkc.h"
> +
> +#define SD_EMMC_CLOCK			0

Drop this and use struct parm please.

> +
> +static int meson_clk_phase_delay_get_phase(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct meson_clk_phase_delay_data *ph =
> +		meson_clk_get_phase_delay_data(clk);
> +	unsigned int phase_num = 1 <<  hweight_long(ph->phase_mask);
> +	unsigned long period_ps, p, d;
> +	int degrees;
> +	u32 val;
> +
> +	regmap_read(clk->map, SD_EMMC_CLOCK, &val);
> +	p = (val & ph->phase_mask) >> __ffs(ph->phase_mask);
> +	degrees = p * 360 / phase_num;
> +
> +	if (ph->delay_mask) {
> +		period_ps = DIV_ROUND_UP((unsigned long)NSEC_PER_SEC * 1000,
> +					 clk_hw_get_rate(hw));
> +		d = (val & ph->delay_mask) >> __ffs(ph->delay_mask);
> +		degrees += d * ph->delay_step_ps * 360 / period_ps;
> +		degrees %= 360;
> +	}
> +
> +	return degrees;
> +}
> +
> +static void meson_clk_apply_phase_delay(struct clk_regmap *clk,
> +					unsigned int phase,
> +					unsigned int delay)
> +{
> +	struct meson_clk_phase_delay_data *ph = clk->data;
> +	u32 val;
> +
> +	regmap_read(clk->map, SD_EMMC_CLOCK, &val);
> +
> +	val &= ~ph->phase_mask;
> +	val |= phase << __ffs(ph->phase_mask);
> +
> +	if (ph->delay_mask) {

This imply that delay is delay is optional. In such case, it would be a regular
"phase" and we already have a  driver for this. Please remove all the related
code and make this parameter required for this clock type.

In the future, maybe we'll merge the 2 drivers.

> +		val &= ~ph->delay_mask;
> +		val |= delay << __ffs(ph->delay_mask);
> +	}
> +
> +	regmap_write(clk->map, SD_EMMC_CLOCK, val);
> +}
> +
> +static int meson_clk_phase_delay_set_phase(struct clk_hw *hw, int degrees)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct meson_clk_phase_delay_data *ph =
> +		meson_clk_get_phase_delay_data(clk);
> +	unsigned int phase_num = 1 <<  hweight_long(ph->phase_mask);
> +	unsigned long period_ps, d = 0, r;
> +	u64 p;
> +
> +	p = degrees % 360;
> +
> +	if (!ph->delay_mask) {
> +		p = DIV_ROUND_CLOSEST_ULL(p, 360 / phase_num);
> +	} else {
> +		period_ps = DIV_ROUND_UP((unsigned long)NSEC_PER_SEC * 1000,
> +					 clk_hw_get_rate(hw));
> +
> +		/* First compute the phase index (p), the remainder (r) is the
> +		 * part we'll try to acheive using the delays (d).
> +		 */
> +		r = do_div(p, 360 / phase_num);
> +		d = DIV_ROUND_CLOSEST(r * period_ps,
> +				      360 * ph->delay_step_ps);
> +		d = min(d, ph->delay_mask >> __ffs(ph->delay_mask));
> +	}
> +
> +	meson_clk_apply_phase_delay(clk, p, d);
> +	return 0;
> +}
> +
> +const struct clk_ops meson_clk_phase_delay_ops = {
> +	.get_phase = meson_clk_phase_delay_get_phase,
> +	.set_phase = meson_clk_phase_delay_set_phase,
> +};
> +EXPORT_SYMBOL_GPL(meson_clk_phase_delay_ops);
> diff --git a/drivers/clk/meson/clkc.h b/drivers/clk/meson/clkc.h
> index 24cec16b6038..499834dd34f2 100644
> --- a/drivers/clk/meson/clkc.h
> +++ b/drivers/clk/meson/clkc.h
> @@ -113,6 +113,18 @@ struct clk_regmap _name = {						\
>  	},								\
>  };
>  
> +struct meson_clk_phase_delay_data {
> +	unsigned long			phase_mask;
> +	unsigned long			delay_mask;

Like every other clock drivers in the amlogic directory, please use struct parm
to decribe the fields.

> +	unsigned int			delay_step_ps;
> +};
> +
> +static inline struct meson_clk_phase_delay_data *
> +meson_clk_get_phase_delay_data(struct clk_regmap *clk)
> +{
> +	return (struct meson_clk_phase_delay_data *)clk->data;
> +}
> +
>  /* clk_ops */
>  extern const struct clk_ops meson_clk_pll_ro_ops;
>  extern const struct clk_ops meson_clk_pll_ops;
> @@ -120,5 +132,6 @@ extern const struct clk_ops meson_clk_cpu_ops;
>  extern const struct clk_ops meson_clk_mpll_ro_ops;
>  extern const struct clk_ops meson_clk_mpll_ops;
>  extern const struct clk_ops meson_clk_phase_ops;
> +extern const struct clk_ops meson_clk_phase_delay_ops;
>  
>  #endif /* __CLKC_H */


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