Message-ID: <9d7b3a35-6d21-4b7a-8669-cf3610467cad@linaro.org>
Date: Mon, 5 Feb 2024 18:27:05 +0100
From: neil.armstrong@...aro.org
To: Jerome Brunet <jbrunet@...libre.com>
Cc: Michael Turquette <mturquette@...libre.com>,
 Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>, Kevin Hilman <khilman@...libre.com>,
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Jagan Teki <jagan@...rulasolutions.com>, Nicolas Belin
 <nbelin@...libre.com>, Vinod Koul <vkoul@...nel.org>,
 Kishon Vijay Abraham I <kishon@...nel.org>, Remi Pommarel
 <repk@...plefau.lt>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-amlogic@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
 linux-phy@...ts.infradead.org, Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v9 07/12] clk: meson: add vclk driver

On 27/11/2023 17:24, Jerome Brunet wrote:
> 
> On Mon 27 Nov 2023 at 17:14, Neil Armstrong <neil.armstrong@...aro.org> wrote:
> 
>> On 24/11/2023 15:41, Jerome Brunet wrote:
>>> On Fri 24 Nov 2023 at 09:41, Neil Armstrong <neil.armstrong@...aro.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.
>>>>
>>>> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
>>>> ---
>>>>    drivers/clk/meson/Kconfig  |   5 ++
>>>>    drivers/clk/meson/Makefile |   1 +
>>>>    drivers/clk/meson/vclk.c   | 141 +++++++++++++++++++++++++++++++++++++++++++++
>>>>    drivers/clk/meson/vclk.h   |  51 ++++++++++++++++
>>>>    4 files changed, 198 insertions(+)
>>>>
>>>> diff --git a/drivers/clk/meson/Kconfig b/drivers/clk/meson/Kconfig
>>>> index 29ffd14d267b..59a40a49f8e1 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
>>> This particular line belong in the next patch
>>>
>>>>    	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 9ee4b954c896..9ba43fe7a07a 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..47f08a52b49f
>>>> --- /dev/null
>>>> +++ b/drivers/clk/meson/vclk.c
>>>> @@ -0,0 +1,141 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * Copyright (c) 2023 Neil Armstrong <neil.armstrong@...aro.org>
>>>> + */
>>>> +
>>>> +#include <linux/module.h>
>>>> +#include "vclk.h"
>>>> +
>>>> +/* The VCLK gate has a supplementary reset bit to pulse after ungating */
>>>> +
>>>> +static inline struct clk_regmap_vclk_data *
>>>> +clk_get_regmap_vclk_data(struct clk_regmap *clk)
>>>> +{
>>>> +	return (struct clk_regmap_vclk_data *)clk->data;
>>>> +}
>>>> +
>>>> +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);
>>>> +
>>>> +	meson_parm_write(clk->map, &vclk->enable, 1);
>>>> +
>>>> +	/* Do a reset pulse */
>>>> +	meson_parm_write(clk->map, &vclk->reset, 1);
>>>> +	meson_parm_write(clk->map, &vclk->reset, 0);
>>>> +
>>>> +	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);
>>>> +
>>>> +	meson_parm_write(clk->map, &vclk->enable, 0);
>>>> +}
>>>> +
>>>> +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);
>>>> +
>>>> +	return meson_parm_read(clk->map, &vclk->enable);
>>>> +}
>>>> +
>>>> +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);
>>> s/clk_regmap_vclk/meson_vclk at least for what is exported, ideally most
>>> all the code.
>>> I get clk_regmap_ comes from code copied from clk_regmap.c.
>>> The reason the this part is different (and not using parm) if that when
>>> I converted amlogic to regmap, I hope we could make this generic,
>>> possibly converging between aml and qcom (which was the only other
>>> platform using regmap for clock at the time). This is why clk_regmap.c
>>> is a bit different from the other driver.
>>> For the aml specific drivers, best to look at the mpll or cpu-dyndiv one.
>>>
>>>> +
>>>> +/* The VCLK Divider has supplementary reset & enable bits */
>>>> +
>>>> +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;
>>>> +}
>>>> +
>>>> +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);
>>>> +
>>>> +	return divider_recalc_rate(hw, prate, meson_parm_read(clk->map, &vclk->div),
>>>> +				   vclk->table, vclk->flags, vclk->div.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->div.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);
>>>> +	int ret;
>>>> +
>>>> +	ret = divider_get_val(rate, parent_rate, vclk->table, vclk->div.width,
>>>> +			      vclk->flags);
>>>> +	if (ret < 0)
>>>> +		return ret;
>>>> +
>>>> +	meson_parm_write(clk->map, &vclk->div, ret);
>>>> +
>>>> +	return 0;
>>>> +};
>>>> +
>>>> +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 */
>>>> +	meson_parm_write(clk->map, &vclk->reset, 0);
>>>> +	meson_parm_write(clk->map, &vclk->enable, 1);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +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 */
>>>> +	meson_parm_write(clk->map, &vclk->enable, 0);
>>>> +	meson_parm_write(clk->map, &vclk->reset, 1);
>>>> +}
>>>> +
>>>> +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);
>>>> +
>>>> +	return meson_parm_read(clk->map, &vclk->enable);
>>>> +}
>>>> +
>>>> +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@...aro.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..4f25d7ad2717
>>>> --- /dev/null
>>>> +++ b/drivers/clk/meson/vclk.h
>>
>> Is vclk.c/h ok ? clk-vclk doesn't look pretty, but I can switch to it to
>> keep files organized.
> 
> I don't have a strong opinion about it.
> I would have suggested vclk-div.c/h - like sclk ... but you do have gate
> ops in there, so ... :/
> 
> This made me realize that one does not really go without the other.
> It is more a coherent block, isn't it ?
> Would it make more sense to have these 2 merged in a single clk_ops ?

No those a 2 separate blocks, one is for VCLK clock input and the other is for the DIV
block, and the reset isn't used in the same way so I can't merge them.

> 
> It's bit late to point this out, sorry about that.
> 
> I let you decide whether to merge the ops or not and which name to pick.
> 
> If you keep them separated, meson_vclk_gate_ops instead of just
> meson_vclk_ops, to make things clear.

Ack

> 
>>
>> Neil
>>
>>>> @@ -0,0 +1,51 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>>> +/*
>>>> + * Copyright (c) 2023 Neil Armstrong <neil.armstrong@...aro.org>
>>>> + */
>>>> +
>>>> +#ifndef __VCLK_H
>>>> +#define __VCLK_H
>>> This is too generic.
>>> Please add the MESON prefix like the other clock driver please.
>>>
>>>> +
>>>> +#include "clk-regmap.h"
>>>> +#include "parm.h"
>>>> +
>>>> +/**
>>>> + * struct clk_regmap_vclk_data - vclk regmap backed specific data
>>>> + *
>>>> + * @enable:	vclk enable field
>>>> + * @reset:	vclk reset field
>>>> + * @flags:	hardware-specific flags
>>>> + *
>>>> + * Flags:
>>>> + * Same as clk_gate except CLK_GATE_HIWORD_MASK which is ignored
>>>> + */
>>>> +struct clk_regmap_vclk_data {
>>>> +	struct parm enable;
>>>> +	struct parm reset;
>>>> +	u8 flags;
>>>> +};
>>>> +
>>>> +extern const struct clk_ops clk_regmap_vclk_ops;
>>>> +
>>>> +/**
>>>> + * struct clk_regmap_vclk_div_data - vclk_div regmap back specific data
>>>> + *
>>>> + * @div:	divider field
>>>> + * @enable:	vclk divider enable field
>>>> + * @reset:	vclk divider reset field
>>>> + * @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 {
>>>> +	struct parm div;
>>>> +	struct parm enable;
>>>> +	struct parm reset;
>>>> +	const struct clk_div_table *table;
>>>> +	u8 flags;
>>>> +};
>>>> +
>>>> +extern const struct clk_ops clk_regmap_vclk_div_ops;
>>>> +
>>>> +#endif /* __VCLK_H */
>>>
> 
> 

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