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Message-ID: <cdc50fd9-fbc8-81b2-18b9-94be60eda375@linaro.org>
Date:   Fri, 4 Aug 2023 10:46:12 +0200
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From:   Neil Armstrong <neil.armstrong@linaro.org>
Reply-To: neil.armstrong@linaro.org
Subject: Re: [PATCH v7 3/9] clk: meson: add vclk driver
Content-Language: en-US
To:     Jerome Brunet <jbrunet@baylibre.com>,
        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
References: <20230803-amlogic-v6-4-upstream-dsi-ccf-vim3-v7-0-762219fc5b28@linaro.org>
 <20230803-amlogic-v6-4-upstream-dsi-ccf-vim3-v7-3-762219fc5b28@linaro.org>
 <1j5y5vp88v.fsf@starbuckisacylon.baylibre.com>
Organization: Linaro Developer Services
In-Reply-To: <1j5y5vp88v.fsf@starbuckisacylon.baylibre.com>
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On 04/08/2023 09:33, Jerome Brunet wrote:
> 
> 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.

Ack

thx,
Neil

> 
>>
>> 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 */
>