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References: <20171102065626.21835-1-chunyan.zhang@spreadtrum.com>
 <20171102065626.21835-5-chunyan.zhang@spreadtrum.com> <5625af45-a071-4abf-88ed-f167abff1b73@arm.com>
From:   Chunyan Zhang <zhang.lyra@gmail.com>
Date:   Fri, 3 Nov 2017 20:12:51 +0800
Message-ID: <CAAfSe-uM+xWH3+TcRRO8hSJ6GL9MwSmns9SNTCYSDzVd+5ww8Q@mail.gmail.com>
Subject: Re: [PATCH V3 04/11] clk: sprd: add gate clock support
To:     Julien Thierry <julien.thierry@arm.com>
Cc:     Chunyan Zhang <chunyan.zhang@spreadtrum.com>,
        Stephen Boyd <sboyd@codeaurora.org>,
        Michael Turquette <mturquette@baylibre.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        linux-clk <linux-clk@vger.kernel.org>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>, Mark Brown <broonie@kernel.org>,
        Xiaolong Zhang <xiaolong.zhang@spreadtrum.com>,
        Ben Li <ben.li@spreadtrum.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Orson Zhai <orson.zhai@spreadtrum.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Julien,

On 3 November 2017 at 01:45, Julien Thierry <julien.thierry@arm.com> wrote:
> Hi,
>
>
> On 02/11/17 06:56, Chunyan Zhang wrote:
>>
>> Some clocks on the Spreadtrum's SoCs are just simple gates. Add
>> support for those clocks.
>>
>> Signed-off-by: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
>> ---
>>   drivers/clk/sprd/Makefile |   1 +
>>   drivers/clk/sprd/gate.c   | 106
>> ++++++++++++++++++++++++++++++++++++++++++++++
>>   drivers/clk/sprd/gate.h   |  54 +++++++++++++++++++++++
>>   3 files changed, 161 insertions(+)
>>   create mode 100644 drivers/clk/sprd/gate.c
>>   create mode 100644 drivers/clk/sprd/gate.h
>>
>> diff --git a/drivers/clk/sprd/Makefile b/drivers/clk/sprd/Makefile
>> index 74f4b80..8cd5592 100644
>> --- a/drivers/clk/sprd/Makefile
>> +++ b/drivers/clk/sprd/Makefile
>> @@ -1,3 +1,4 @@
>>   obj-$(CONFIG_SPRD_COMMON_CLK) += clk-sprd.o
>>     clk-sprd-y  += common.o
>> +clk-sprd-y     += gate.o
>> diff --git a/drivers/clk/sprd/gate.c b/drivers/clk/sprd/gate.c
>> new file mode 100644
>> index 0000000..831ef81
>> --- /dev/null
>> +++ b/drivers/clk/sprd/gate.c
>> @@ -0,0 +1,106 @@
>> +/*
>> + * Spreadtrum gate clock driver
>> + *
>> + * Copyright (C) 2017 Spreadtrum, Inc.
>> + * Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
>> + *
>> + * SPDX-License-Identifier: GPL-2.0
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/regmap.h>
>> +
>> +#include "gate.h"
>> +
>> +DEFINE_SPINLOCK(sprd_gate_lock);
>> +EXPORT_SYMBOL_GPL(sprd_gate_lock);
>> +
>> +static void sprd_gate_endisable(const struct sprd_gate *sg, u32 en)
>> +{
>> +       const struct sprd_clk_common *common = &sg->common;
>> +       unsigned long flags = 0;
>> +       unsigned int reg;
>> +       int set = sg->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
>> +
>> +       set ^= en;
>> +
>> +       spin_lock_irqsave(common->lock, flags);
>> +
>> +       sprd_regmap_read(common->regmap, common->reg, &reg);
>> +
>> +       if (set)
>> +               reg |= sg->op_bit;
>> +       else
>> +               reg &= ~sg->op_bit;
>> +
>> +       sprd_regmap_write(common->regmap, common->reg, reg);
>> +
>> +       spin_unlock_irqrestore(common->lock, flags);
>> +}
>> +
>> +static void clk_sc_gate_endisable(const struct sprd_gate *sg, u32 en)
>> +{
>> +       const struct sprd_clk_common *common = &sg->common;
>> +       unsigned long flags = 0;
>> +       int set = sg->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
>> +       unsigned int offset;
>> +
>> +       set ^= en;
>> +
>> +       /*
>> +        * Each set/clear gate clock has three registers:
>> +        * common->reg                  - base register
>> +        * common->reg + offset         - set register
>> +        * common->reg + 2 * offset     - clear register
>> +        */
>> +       offset = set ? sg->sc_offset : sg->sc_offset * 2;
>> +
>> +       spin_lock_irqsave(common->lock, flags);
>> +       sprd_regmap_write(common->regmap, common->reg + offset,
>> sg->op_bit);
>> +       spin_unlock_irqrestore(common->lock, flags);
>> +}
>> +
>> +static void sprd_gate_disable(struct clk_hw *hw)
>> +{
>> +       struct sprd_gate *sg = hw_to_sprd_gate(hw);
>> +
>> +       if (sg->sc_offset)
>> +               clk_sc_gate_endisable(sg, 0);
>> +       else
>> +               sprd_gate_endisable(sg, 0);
>> +}
>> +
>> +static int sprd_gate_enable(struct clk_hw *hw)
>> +{
>> +       struct sprd_gate *sg = hw_to_sprd_gate(hw);
>> +
>> +       if (sg->sc_offset)
>> +               clk_sc_gate_endisable(sg, 1);
>> +       else
>> +               sprd_gate_endisable(sg, 1);
>> +
>> +       return 0;
>> +}
>> +
>> +static int sprd_gate_is_enabled(struct clk_hw *hw)
>> +{
>> +       struct sprd_gate *sg = hw_to_sprd_gate(hw);
>> +       struct sprd_clk_common *common = &sg->common;
>> +       unsigned int reg;
>> +
>> +       sprd_regmap_read(common->regmap, common->reg, &reg);
>> +
>> +       if (sg->flags & CLK_GATE_SET_TO_DISABLE)
>> +               reg ^= sg->op_bit;
>> +
>> +       reg &= sg->op_bit;
>> +
>> +       return reg ? 1 : 0;
>> +}
>> +
>> +const struct clk_ops sprd_gate_ops = {
>> +       .disable        = sprd_gate_disable,
>> +       .enable         = sprd_gate_enable,
>> +       .is_enabled     = sprd_gate_is_enabled,
>> +};
>> +EXPORT_SYMBOL_GPL(sprd_gate_ops);
>
>
> I think it would be better to have a set of ops for each mode,
> sprd_gate_ops and sprd_sc_gate_ops rather than have each function decide
> whether it should use set/clear registers or the base registers.
>
> So you can have a macro SPRD_GATE_CLK that doesn't take an sc_offet and
> selects the sprd_gate_ops and another one that SPRD_SC_GATE_CLK using
> sprd_sc_gate_ops that takes the sc_offset as parameter.
>

That makes more sense, I will revise in the next version.

> Also, I feel keeping enable/disable function separate would be nicer instead
> of having "endisable" functions.

To avoid duplicate code, I prefer to keep the enable and disable
functions together, but I agree that 'endisable' is indeed not good
name for the function, I will revise the name to 'toggle' which I saw
qcom clk drivers use, it might make more sense.

Thanks,
Chunyan

>
> Cheers,
>
>
>> diff --git a/drivers/clk/sprd/gate.h b/drivers/clk/sprd/gate.h
>> new file mode 100644
>> index 0000000..5aeb53c
>> --- /dev/null
>> +++ b/drivers/clk/sprd/gate.h
>> @@ -0,0 +1,54 @@
>> +/*
>> + * Spreadtrum gate clock driver
>> + *
>> + * Copyright (C) 2017 Spreadtrum, Inc.
>> + * Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
>> + *
>> + * SPDX-License-Identifier: GPL-2.0
>> + */
>> +
>> +#ifndef _SPRD_GATE_H_
>> +#define _SPRD_GATE_H_
>> +
>> +#include "common.h"
>> +
>> +struct sprd_gate {
>> +       u32                     op_bit;
>> +       u16                     flags;
>> +       u16                     sc_offset;
>> +
>> +       struct sprd_clk_common  common;
>> +};
>> +
>> +#define SPRD_GATE_CLK(_struct, _name, _parent, _reg, _sc_offset,       \
>> +                     _op_bit, _flags, _gate_flags)                     \
>> +       struct sprd_gate _struct = {                                    \
>> +               .op_bit         = _op_bit,                              \
>> +               .sc_offset      = _sc_offset,                           \
>> +               .flags          = _gate_flags,                          \
>> +               .common = {                                             \
>> +                       .regmap         = NULL,                         \
>> +                       .reg            = _reg,                         \
>> +                       .lock           = &sprd_gate_lock,              \
>> +                       .hw.init        = CLK_HW_INIT(_name,            \
>> +                                                     _parent,          \
>> +                                                     &sprd_gate_ops,   \
>> +                                                     _flags),          \
>> +               }                                                       \
>> +       }
>> +
>> +static inline struct sprd_gate *hw_to_sprd_gate(const struct clk_hw *hw)
>> +{
>> +       struct sprd_clk_common *common = hw_to_sprd_clk_common(hw);
>> +
>> +       return container_of(common, struct sprd_gate, common);
>> +}
>> +
>> +void sprd_gate_helper_disable(struct sprd_clk_common *common, u32 gate);
>> +int sprd_gate_helper_enable(struct sprd_clk_common *common, u32 gate);
>> +int sprd_gate_helper_is_enabled(struct sprd_clk_common *common, u32
>> gate);
>> +
>> +extern const struct clk_ops sprd_gate_ops;
>> +extern spinlock_t sprd_gate_lock;
>> +
>> +#endif /* _SPRD_GATE_H_ */
>>
>
> --
> Julien Thierry

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