Re: [PATCH v5 1/3] clk: meson: add emmc sub clock phase delay driver

[Jerome Brunet]

On Thu, 2018-10-18 at 13:07 +0800, Jianxin Pan wrote:
> From: Yixun Lan <yixun.lan@xxxxxxxxxxx>
> 
> 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@xxxxxxxxxxx>
> Signed-off-by: Jianxin Pan <jianxin.pan@xxxxxxxxxxx>
> ---
>  drivers/clk/meson/Makefile          |  2 +-
>  drivers/clk/meson/clk-phase-delay.c | 79 +++++++++++++++++++++++++++++++++++++
>  drivers/clk/meson/clkc.h            | 13 ++++++
>  3 files changed, 93 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 72ec8c4..39ce566 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 0000000..b9573a7
> --- /dev/null
> +++ b/drivers/clk/meson/clk-phase-delay.c
> @@ -0,0 +1,79 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Amlogic Meson MMC Sub Clock Controller Driver
> + *
> + * Copyright (c) 2017 Baylibre SAS.
> + * Author: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
> + *
> + * Copyright (c) 2018 Amlogic, inc.
> + * Author: Yixun Lan <yixun.lan@xxxxxxxxxxx>
> + */
> +
> +#include <linux/clk-provider.h>
> +#include "clkc.h"
> +
> +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 long period_ps, p, d;
> +	int degrees;
> +	u32 val;
> +
> +	regmap_read(clk->map, ph->phase.reg_off, &val);
> +	p = PARM_GET(ph->phase.width, ph->phase.shift, val);

there is an helper for this: meson_parm_read()

> +	degrees = p * 360 / (1 << (ph->phase.width));
> +
> +	period_ps = DIV_ROUND_UP((unsigned long)NSEC_PER_SEC * 1000,
> +				 clk_hw_get_rate(hw));
> +
> +	d = PARM_GET(ph->delay.width, ph->delay.shift, val);
> +	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)

This helper function is a bit overkill.
simply call meson_parm_write() twice in meson_clk_phase_delay_set_phase().

> +{
> +	struct meson_clk_phase_delay_data *ph = clk->data;
> +	u32 val;
> +
> +	regmap_read(clk->map, ph->delay.reg_off, &val);
> +	val = PARM_SET(ph->phase.width, ph->phase.shift, val, phase);
> +	val = PARM_SET(ph->delay.width, ph->delay.shift, val, delay);
> +	regmap_write(clk->map, ph->delay.reg_off, 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 long period_ps, d = 0, r;
> +	u64 p;
> +
> +	p = degrees % 360;
> +	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 / (1 << (ph->phase.width)));
> +	d = DIV_ROUND_CLOSEST(r * period_ps,
> +			      360 * ph->delay_step_ps);
> +	d = min(d, PMASK(ph->delay.width));
> +
> +	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 6b96d55..3309d78 100644
> --- a/drivers/clk/meson/clkc.h
> +++ b/drivers/clk/meson/clkc.h
> @@ -105,6 +105,18 @@ struct clk_regmap _name = {						\
>  	},								\
>  };
>  
> +struct meson_clk_phase_delay_data {
> +	struct parm			phase;
> +	struct parm			delay;
> +	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;
> @@ -112,5 +124,6 @@ struct clk_regmap _name = {						\
>  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 */