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Message-ID: <d0435ffb-1101-6f1b-b2de-1dc74f6a9543@baylibre.com>
Date: Thu, 26 Apr 2018 10:47:38 +0200
From: Neil Armstrong <narmstrong@...libre.com>
To: Jerome Brunet <jbrunet@...libre.com>,
Carlo Caione <carlo@...one.org>,
Kevin Hilman <khilman@...libre.com>
Cc: Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] clk: meson: add axg audio sclk divider driver
On 25/04/2018 18:33, Jerome Brunet wrote:
> Add a driver to control the clock divider found in the sample clock
> generator of the axg audio clock controller.
>
> The sclk divider accumulates specific features which make the generic
> divider unsuitable to control it:
> - zero based divider (div = val + 1), but zero value gates the clock,
> so minimum divider value is 2.
> - lrclk variant may adjust the duty cycle depending the divider value
> and the 'hi' value.
>
> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
> ---
> drivers/clk/meson/Makefile | 2 +-
> drivers/clk/meson/clkc-audio.h | 8 ++
> drivers/clk/meson/sclk-div.c | 243 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 252 insertions(+), 1 deletion(-)
> create mode 100644 drivers/clk/meson/sclk-div.c
>
> diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
> index 64bb917fe1f0..f51b4754c31b 100644
> --- a/drivers/clk/meson/Makefile
> +++ b/drivers/clk/meson/Makefile
> @@ -4,7 +4,7 @@
>
> obj-$(CONFIG_COMMON_CLK_AMLOGIC) += clk-pll.o clk-mpll.o clk-audio-divider.o
> obj-$(CONFIG_COMMON_CLK_AMLOGIC) += clk-phase.o
> -obj-$(CONFIG_COMMON_CLK_AMLOGIC_AUDIO) += clk-triphase.o
> +obj-$(CONFIG_COMMON_CLK_AMLOGIC_AUDIO) += clk-triphase.o sclk-div.o
> obj-$(CONFIG_COMMON_CLK_MESON8B) += meson8b.o
> obj-$(CONFIG_COMMON_CLK_GXBB) += gxbb.o gxbb-aoclk.o gxbb-aoclk-32k.o
> obj-$(CONFIG_COMMON_CLK_AXG) += axg.o
> diff --git a/drivers/clk/meson/clkc-audio.h b/drivers/clk/meson/clkc-audio.h
> index 286ff1201258..0a7c157ebf81 100644
> --- a/drivers/clk/meson/clkc-audio.h
> +++ b/drivers/clk/meson/clkc-audio.h
> @@ -15,6 +15,14 @@ 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/sclk-div.c b/drivers/clk/meson/sclk-div.c
> new file mode 100644
> index 000000000000..8c0bc914a6d7
> --- /dev/null
> +++ b/drivers/clk/meson/sclk-div.c
> @@ -0,0 +1,243 @@
> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> +/*
> + * Copyright (c) 2018 BayLibre, SAS.
> + * Author: Jerome Brunet <jbrunet@...libre.com>
> + *
> + * Sample clock generator divider:
> + * This HW divider gates with value 0 but is otherwise a zero based divider:
> + *
> + * val >= 1
> + * divider = val + 1
> + *
> + * 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)
> + */
> +
> +#include "clkc-audio.h"
> +
> +static inline struct meson_sclk_div_data *
> +meson_sclk_div_data(struct clk_regmap *clk)
> +{
> + return (struct meson_sclk_div_data *)clk->data;
> +}
> +
> +static int sclk_div_maxval(struct meson_sclk_div_data *sclk)
> +{
> + return (1 << sclk->div.width) - 1;
> +}
> +
> +static int sclk_div_maxdiv(struct meson_sclk_div_data *sclk)
> +{
> + return sclk_div_maxval(sclk) + 1;
> +}
> +
> +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);
> +
> + return clamp(div, 2, maxdiv);
> +}
> +
> +static int sclk_div_bestdiv(struct clk_hw *hw, unsigned long rate,
> + unsigned long *prate,
> + struct meson_sclk_div_data *sclk)
> +{
> + struct clk_hw *parent = clk_hw_get_parent(hw);
> + int bestdiv = 0, i;
> + unsigned long maxdiv, now, parent_now;
> + unsigned long best = 0, best_parent = 0;
> +
> + if (!rate)
> + rate = 1;
> +
> + maxdiv = sclk_div_maxdiv(sclk);
> +
> + if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT))
> + return sclk_div_getdiv(hw, rate, *prate, maxdiv);
> +
> + /*
> + * The maximum divider we can use without overflowing
> + * unsigned long in rate * i below
> + */
> + maxdiv = min(ULONG_MAX / rate, maxdiv);
> +
> + for (i = 2; i <= maxdiv; i++) {
> + /*
> + * It's the most ideal case if the requested rate can be
> + * divided from parent clock without needing to change
> + * parent rate, so return the divider immediately.
> + */
> + if (rate * i == *prate)
> + return i;
> +
> + parent_now = clk_hw_round_rate(parent, rate * i);
> + now = DIV_ROUND_UP_ULL((u64)parent_now, i);
> +
> + if (abs(rate - now) < abs(rate - best)) {
> + bestdiv = i;
> + best = now;
> + best_parent = parent_now;
> + }
> + }
> +
> + if (!bestdiv)
> + bestdiv = sclk_div_maxdiv(sclk);
> + else
> + *prate = best_parent;
> +
> + return bestdiv;
> +}
> +
> +static long sclk_div_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *prate)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> + int div;
> +
> + div = sclk_div_bestdiv(hw, rate, prate, sclk);
> +
> + return DIV_ROUND_UP_ULL((u64)*prate, div);
> +}
> +
> +static void sclk_apply_ratio(struct clk_regmap *clk,
> + struct meson_sclk_div_data *sclk)
> +{
> + unsigned int hi = DIV_ROUND_CLOSEST(sclk->cached_div *
> + sclk->cached_duty.num,
> + sclk->cached_duty.den);
> +
> + if (hi)
> + hi -= 1;
> +
> + meson_parm_write(clk->map, &sclk->hi, hi);
> +}
> +
> +static int sclk_div_set_duty_cycle(struct clk_hw *hw,
> + struct clk_duty *duty)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> +
> + if (MESON_PARM_APPLICABLE(&sclk->hi)) {
> + memcpy(&sclk->cached_duty, duty, sizeof(*duty));
> + sclk_apply_ratio(clk, sclk);
> + }
> +
> + return 0;
> +}
> +
> +static int sclk_div_get_duty_cycle(struct clk_hw *hw,
> + struct clk_duty *duty)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> + int hi;
> +
> + if (!MESON_PARM_APPLICABLE(&sclk->hi)) {
> + duty->num = 1;
> + duty->den = 2;
> + return 0;
> + }
> +
> + hi = meson_parm_read(clk->map, &sclk->hi);
> + duty->num = hi + 1;
> + duty->den = sclk->cached_div;
> + return 0;
> +}
> +
> +static void sclk_apply_divider(struct clk_regmap *clk,
> + struct meson_sclk_div_data *sclk)
> +{
> + if (MESON_PARM_APPLICABLE(&sclk->hi))
> + sclk_apply_ratio(clk, sclk);
> +
> + meson_parm_write(clk->map, &sclk->div, sclk->cached_div - 1);
> +}
> +
> +static int sclk_div_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long prate)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> + unsigned long maxdiv = sclk_div_maxdiv(sclk);
> +
> + sclk->cached_div = sclk_div_getdiv(hw, rate, prate, maxdiv);
> +
> + if (clk_hw_is_enabled(hw))
> + sclk_apply_divider(clk, sclk);
> +
> + return 0;
> +}
> +
> +static unsigned long sclk_div_recalc_rate(struct clk_hw *hw,
> + unsigned long prate)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> +
> + return DIV_ROUND_UP_ULL((u64)prate, sclk->cached_div);
> +}
> +
> +static int sclk_div_enable(struct clk_hw *hw)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> +
> + sclk_apply_divider(clk, sclk);
> +
> + return 0;
> +}
> +
> +static void sclk_div_disable(struct clk_hw *hw)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> +
> + meson_parm_write(clk->map, &sclk->div, 0);
> +}
> +
> +static int sclk_div_is_enabled(struct clk_hw *hw)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> +
> + if (meson_parm_read(clk->map, &sclk->div))
> + return 1;
> +
> + return 0;
> +}
> +
> +static void sclk_div_init(struct clk_hw *hw)
> +{
> + struct clk_regmap *clk = to_clk_regmap(hw);
> + struct meson_sclk_div_data *sclk = meson_sclk_div_data(clk);
> + unsigned int val;
> +
> + val = meson_parm_read(clk->map, &sclk->div);
> +
> + /* if the divider is initially disabled, assume max */
> + if (!val)
> + sclk->cached_div = sclk_div_maxdiv(sclk);
> + else
> + sclk->cached_div = val + 1;
> +
> + sclk_div_get_duty_cycle(hw, &sclk->cached_duty);
> +}
> +
> +const struct clk_ops meson_sclk_div_ops = {
> + .recalc_rate = sclk_div_recalc_rate,
> + .round_rate = sclk_div_round_rate,
> + .set_rate = sclk_div_set_rate,
> + .enable = sclk_div_enable,
> + .disable = sclk_div_disable,
> + .is_enabled = sclk_div_is_enabled,
> + .get_duty_cycle = sclk_div_get_duty_cycle,
> + .set_duty_cycle = sclk_div_set_duty_cycle,
> + .init = sclk_div_init,
> +};
> +EXPORT_SYMBOL_GPL(meson_sclk_div_ops);
>
Acked-by: Neil Armstrong <narmstrong@...libre.com>
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