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From:   Jerome Brunet <jbrunet@baylibre.com>
To:     Neil Armstrong <neil.armstrong@linaro.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Kevin Hilman <khilman@baylibre.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jagan Teki <jagan@amarulasolutions.com>,
        Nicolas Belin <nbelin@baylibre.com>
Cc:     linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org,
        linux-arm-kernel@lists.infradead.org,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v7 3/9] clk: meson: add vclk driver
Date:   Fri, 04 Aug 2023 09:33:36 +0200
In-reply-to: <20230803-amlogic-v6-4-upstream-dsi-ccf-vim3-v7-3-762219fc5b28@linaro.org>
Message-ID: <1j5y5vp88v.fsf@starbuckisacylon.baylibre.com>
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On Thu 03 Aug 2023 at 14:03, Neil Armstrong <neil.armstrong@linaro.org> wrote:

> The VCLK and VCLK_DIV clocks have supplementary bits.
>
> The VCLK has a "SOFT RESET" bit to toggle after the whole
> VCLK sub-tree rate has been set, this is implemented in
> the gate enable callback.
>
> The VCLK_DIV clocks as enable and reset bits used to disable
> and reset the divider, associated with CLK_SET_RATE_GATE it ensures
> the rate is set while the divider is disabled and in reset mode.
>
> The VCLK_DIV enable bit isn't implemented as a gate since it's part
> of the divider logic and vendor does this exact sequence to ensure
> the divider is correctly set.

Unless there is reason, I'd prefer if this driver was using 'struct
parm', like the rest of amlogic custom clock drivers, for consistency.

>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  drivers/clk/meson/Kconfig  |   5 ++
>  drivers/clk/meson/Makefile |   1 +
>  drivers/clk/meson/vclk.c   | 146 +++++++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/meson/vclk.h   |  68 +++++++++++++++++++++
>  4 files changed, 220 insertions(+)
>
> diff --git a/drivers/clk/meson/Kconfig b/drivers/clk/meson/Kconfig
> index 135da8f2d0b1..83f629515e96 100644
> --- a/drivers/clk/meson/Kconfig
> +++ b/drivers/clk/meson/Kconfig
> @@ -30,6 +30,10 @@ config COMMON_CLK_MESON_VID_PLL_DIV
>  	tristate
>  	select COMMON_CLK_MESON_REGMAP
>  
> +config COMMON_CLK_MESON_VCLK
> +	tristate
> +	select COMMON_CLK_MESON_REGMAP
> +
>  config COMMON_CLK_MESON_CLKC_UTILS
>  	tristate
>  
> @@ -140,6 +144,7 @@ config COMMON_CLK_G12A
>  	select COMMON_CLK_MESON_EE_CLKC
>  	select COMMON_CLK_MESON_CPU_DYNDIV
>  	select COMMON_CLK_MESON_VID_PLL_DIV
> +	select COMMON_CLK_MESON_VCLK
>  	select MFD_SYSCON
>  	help
>  	  Support for the clock controller on Amlogic S905D2, S905X2 and S905Y2
> diff --git a/drivers/clk/meson/Makefile b/drivers/clk/meson/Makefile
> index cd961cc4f4db..6efeb8c7bd2a 100644
> --- a/drivers/clk/meson/Makefile
> +++ b/drivers/clk/meson/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_COMMON_CLK_MESON_PLL) += clk-pll.o
>  obj-$(CONFIG_COMMON_CLK_MESON_REGMAP) += clk-regmap.o
>  obj-$(CONFIG_COMMON_CLK_MESON_SCLK_DIV) += sclk-div.o
>  obj-$(CONFIG_COMMON_CLK_MESON_VID_PLL_DIV) += vid-pll-div.o
> +obj-$(CONFIG_COMMON_CLK_MESON_VCLK) += vclk.o
>  
>  # Amlogic Clock controllers
>  
> diff --git a/drivers/clk/meson/vclk.c b/drivers/clk/meson/vclk.c
> new file mode 100644
> index 000000000000..0df84403b17f
> --- /dev/null
> +++ b/drivers/clk/meson/vclk.c
> @@ -0,0 +1,146 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023 Neil Armstrong <neil.armstrong@linaro.org>
> + */
> +
> +#include <linux/module.h>
> +#include "vclk.h"
> +
> +/* The VCLK gate has a supplementary reset bit to pulse after ungating */
> +
> +static int clk_regmap_vclk_enable(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_data *vclk = clk_get_regmap_vclk_data(clk);
> +
> +	regmap_set_bits(clk->map, vclk->offset, BIT(vclk->enable_bit_idx));
> +
> +	/* Do a reset pulse */
> +	regmap_set_bits(clk->map, vclk->offset, BIT(vclk->reset_bit_idx));
> +	regmap_clear_bits(clk->map, vclk->offset, BIT(vclk->reset_bit_idx));
> +
> +	return 0;
> +}
> +
> +static void clk_regmap_vclk_disable(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_data *vclk = clk_get_regmap_vclk_data(clk);
> +
> +	regmap_clear_bits(clk->map, vclk->offset, BIT(vclk->enable_bit_idx));
> +}
> +
> +static int clk_regmap_vclk_is_enabled(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_data *vclk = clk_get_regmap_vclk_data(clk);
> +	unsigned int val;
> +
> +	regmap_read(clk->map, vclk->offset, &val);
> +
> +	return val & BIT(vclk->enable_bit_idx) ? 1 : 0;
> +}
> +
> +const struct clk_ops clk_regmap_vclk_ops = {
> +	.enable = clk_regmap_vclk_enable,
> +	.disable = clk_regmap_vclk_disable,
> +	.is_enabled = clk_regmap_vclk_is_enabled,
> +};
> +EXPORT_SYMBOL_GPL(clk_regmap_vclk_ops);
> +
> +/* The VCLK Divider has supplementary reset & enable bits */
> +
> +static unsigned long clk_regmap_vclk_div_recalc_rate(struct clk_hw *hw,
> +						     unsigned long prate)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(clk->map, vclk->offset, &val);
> +	if (ret)
> +		/* Gives a hint that something is wrong */
> +		return 0;
> +
> +	val >>= vclk->shift;
> +	val &= clk_div_mask(vclk->width);
> +
> +	return divider_recalc_rate(hw, prate, val, vclk->table, vclk->flags,
> +				   vclk->width);
> +}
> +
> +static int clk_regmap_vclk_div_determine_rate(struct clk_hw *hw,
> +					      struct clk_rate_request *req)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
> +
> +	return divider_determine_rate(hw, req, vclk->table, vclk->width,
> +				      vclk->flags);
> +}
> +
> +static int clk_regmap_vclk_div_set_rate(struct clk_hw *hw, unsigned long rate,
> +					unsigned long parent_rate)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
> +	unsigned int val;
> +	int ret;
> +
> +	ret = divider_get_val(rate, parent_rate, vclk->table, vclk->width,
> +			      vclk->flags);
> +	if (ret < 0)
> +		return ret;
> +
> +	val = (unsigned int)ret << vclk->shift;
> +	return regmap_update_bits(clk->map, vclk->offset,
> +				  clk_div_mask(vclk->width) << vclk->shift, val);
> +};
> +
> +static int clk_regmap_vclk_div_enable(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
> +
> +	/* Unreset the divider when ungating */
> +	regmap_clear_bits(clk->map, vclk->offset, BIT(vclk->reset_bit_idx));
> +
> +	return regmap_set_bits(clk->map, vclk->offset, BIT(vclk->enable_bit_idx));
> +}
> +
> +static void clk_regmap_vclk_div_disable(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
> +
> +	/* Reset the divider when gating */
> +	regmap_clear_bits(clk->map, vclk->offset, BIT(vclk->enable_bit_idx));
> +
> +	regmap_set_bits(clk->map, vclk->offset, BIT(vclk->reset_bit_idx));
> +}
> +
> +static int clk_regmap_vclk_div_is_enabled(struct clk_hw *hw)
> +{
> +	struct clk_regmap *clk = to_clk_regmap(hw);
> +	struct clk_regmap_vclk_div_data *vclk = clk_get_regmap_vclk_div_data(clk);
> +	unsigned int val;
> +
> +	regmap_read(clk->map, vclk->offset, &val);
> +
> +	return val & BIT(vclk->enable_bit_idx) ? 1 : 0;
> +}
> +
> +const struct clk_ops clk_regmap_vclk_div_ops = {
> +	.recalc_rate = clk_regmap_vclk_div_recalc_rate,
> +	.determine_rate = clk_regmap_vclk_div_determine_rate,
> +	.set_rate = clk_regmap_vclk_div_set_rate,
> +	.enable = clk_regmap_vclk_div_enable,
> +	.disable = clk_regmap_vclk_div_disable,
> +	.is_enabled = clk_regmap_vclk_div_is_enabled,
> +};
> +EXPORT_SYMBOL_GPL(clk_regmap_vclk_div_ops);
> +
> +MODULE_DESCRIPTION("Amlogic vclk clock driver");
> +MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/clk/meson/vclk.h b/drivers/clk/meson/vclk.h
> new file mode 100644
> index 000000000000..90786552a7f3
> --- /dev/null
> +++ b/drivers/clk/meson/vclk.h
> @@ -0,0 +1,68 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2023 Neil Armstrong <neil.armstrong@linaro.org>
> + */
> +
> +#ifndef __VCLK_H
> +#define __VCLK_H
> +
> +#include "clk-regmap.h"
> +
> +/**
> + * struct clk_regmap_vclk_data - vclk regmap backed specific data
> + *
> + * @offset:		offset of the register controlling gate
> + * @enable_bit_idx:	single bit controlling vclk enable
> + * @reset_bit_idx:	single bit controlling vclk reset
> + * @flags:		hardware-specific flags
> + *
> + * Flags:
> + * Same as clk_gate except CLK_GATE_HIWORD_MASK which is ignored
> + */
> +struct clk_regmap_vclk_data {
> +	unsigned int	offset;
> +	u8		enable_bit_idx;
> +	u8		reset_bit_idx;
> +	u8		flags;
> +};
> +
> +static inline struct clk_regmap_vclk_data *
> +clk_get_regmap_vclk_data(struct clk_regmap *clk)
> +{
> +	return (struct clk_regmap_vclk_data *)clk->data;
> +}
> +
> +extern const struct clk_ops clk_regmap_vclk_ops;
> +
> +/**
> + * struct clk_regmap_vclk_div_data - vclk_div regmap back specific data
> + *
> + * @offset:	offset of the register controlling the divider
> + * @shift:	shift to the divider bit field
> + * @width:	width of the divider bit field
> + * @enable_bit_idx:	single bit controlling vclk divider enable
> + * @reset_bit_idx:	single bit controlling vclk divider reset
> + * @table:	array of value/divider pairs, last entry should have div = 0
> + *
> + * Flags:
> + * Same as clk_divider except CLK_DIVIDER_HIWORD_MASK which is ignored
> + */
> +struct clk_regmap_vclk_div_data {
> +	unsigned int	offset;
> +	u8		shift;
> +	u8		width;
> +	u8		enable_bit_idx;
> +	u8		reset_bit_idx;
> +	const struct clk_div_table      *table;
> +	u8		flags;
> +};
> +
> +static inline struct clk_regmap_vclk_div_data *
> +clk_get_regmap_vclk_div_data(struct clk_regmap *clk)
> +{
> +	return (struct clk_regmap_vclk_div_data *)clk->data;
> +}
> +
> +extern const struct clk_ops clk_regmap_vclk_div_ops;
> +
> +#endif /* __VCLK_H */