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Message-ID: <532aed43-03bf-ea26-bdc2-d7deb1093f53@arm.com>
Date: Thu, 2 Nov 2017 18:11:05 +0000
From: Julien Thierry <julien.thierry@....com>
To: Chunyan Zhang <chunyan.zhang@...eadtrum.com>,
Stephen Boyd <sboyd@...eaurora.org>,
Michael Turquette <mturquette@...libre.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>
Cc: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>, linux-clk@...r.kernel.org,
devicetree@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Mark Brown <broonie@...nel.org>,
Xiaolong Zhang <xiaolong.zhang@...eadtrum.com>,
Ben Li <ben.li@...eadtrum.com>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Orson Zhai <orson.zhai@...eadtrum.com>,
Chunyan Zhang <zhang.lyra@...il.com>
Subject: Re: [PATCH V3 05/11] clk: sprd: add mux clock support
Hi,
On 02/11/17 06:56, Chunyan Zhang wrote:
> This patch adds clock multiplexor support for Spreadtrum platforms,
> the mux clocks also can be found in sprd composite clocks, so
> provides two helpers that can be reused later on.
>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@...eadtrum.com>
> ---
> drivers/clk/sprd/Makefile | 1 +
> drivers/clk/sprd/mux.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++
> drivers/clk/sprd/mux.h | 65 ++++++++++++++++++++++++++++++++++
> 3 files changed, 155 insertions(+)
> create mode 100644 drivers/clk/sprd/mux.c
> create mode 100644 drivers/clk/sprd/mux.h
>
> diff --git a/drivers/clk/sprd/Makefile b/drivers/clk/sprd/Makefile
> index 8cd5592..cee36b5 100644
> --- a/drivers/clk/sprd/Makefile
> +++ b/drivers/clk/sprd/Makefile
> @@ -2,3 +2,4 @@ obj-$(CONFIG_SPRD_COMMON_CLK) += clk-sprd.o
>
> clk-sprd-y += common.o
> clk-sprd-y += gate.o
> +clk-sprd-y += mux.o
> diff --git a/drivers/clk/sprd/mux.c b/drivers/clk/sprd/mux.c
> new file mode 100644
> index 0000000..5a344e0
> --- /dev/null
> +++ b/drivers/clk/sprd/mux.c
> @@ -0,0 +1,89 @@
> +/*
> + * Spreadtrum multiplexer clock driver
> + *
> + * Copyright (C) 2017 Spreadtrum, Inc.
> + * Author: Chunyan Zhang <chunyan.zhang@...eadtrum.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/regmap.h>
> +
> +#include "mux.h"
> +
> +DEFINE_SPINLOCK(sprd_mux_lock);
> +EXPORT_SYMBOL_GPL(sprd_mux_lock);
> +
> +u8 sprd_mux_helper_get_parent(const struct sprd_clk_common *common,
> + const struct sprd_mux_internal *mux)
> +{
> + unsigned int reg;
> + u8 parent;
> + int num_parents;
> + int i;
> +
> + sprd_regmap_read(common->regmap, common->reg, ®);
> + parent = reg >> mux->shift;
> + parent &= (1 << mux->width) - 1;
> +
> + if (mux->table) {
> + num_parents = clk_hw_get_num_parents(&common->hw);
> +
> + for (i = 0; i < num_parents; i++)
> + if (parent == mux->table[i] ||
> + (i < (num_parents - 1) && parent > mux->table[i] &&
> + parent < mux->table[i + 1]))
> + return i;
> + if (i == num_parents)
> + return i - 1;
The if branch is not necessary since you only get there when the loop
has finished, so the condition is always true. And the loop can be
simplified to:
for (i = 0; i < num_parents - 1; i++)
if (parent >= mux->table[i] && parent < mux->table[i + 1])
return i;
return num_parents;
> + }
> +
> + return parent;
> +}
> +EXPORT_SYMBOL_GPL(sprd_mux_helper_get_parent);
> +
> +static u8 sprd_mux_get_parent(struct clk_hw *hw)
> +{
> + struct sprd_mux *cm = hw_to_sprd_mux(hw);
> +
> + return sprd_mux_helper_get_parent(&cm->common, &cm->mux);
> +}
> +
> +int sprd_mux_helper_set_parent(const struct sprd_clk_common *common,
> + const struct sprd_mux_internal *mux,
> + u8 index)
> +{
> + unsigned long flags = 0;
> + unsigned int reg;
> +
> + if (mux->table)
> + index = mux->table[index];
> +
> + spin_lock_irqsave(common->lock, flags);
> +
> + sprd_regmap_read(common->regmap, common->reg, ®);
> + reg &= ~GENMASK(mux->width + mux->shift - 1, mux->shift);
> + sprd_regmap_write(common->regmap, common->reg,
> + reg | (index << mux->shift));
> +
> + spin_unlock_irqrestore(common->lock, flags);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(sprd_mux_helper_set_parent);
> +
> +static int sprd_mux_set_parent(struct clk_hw *hw, u8 index)
> +{
> + struct sprd_mux *cm = hw_to_sprd_mux(hw);
> +
> + return sprd_mux_helper_set_parent(&cm->common, &cm->mux, index);
> +}
> +
> +const struct clk_ops sprd_mux_ops = {
> + .get_parent = sprd_mux_get_parent,
> + .set_parent = sprd_mux_set_parent,
> + .determine_rate = __clk_mux_determine_rate,
> +};
> +EXPORT_SYMBOL_GPL(sprd_mux_ops);
Same as with the other patch, I'd recommend have one set of ops for
direct mux and another one for a mux using a table to map the parents.
Keeping functions for both modes separate.
Cheers,
> diff --git a/drivers/clk/sprd/mux.h b/drivers/clk/sprd/mux.h
> new file mode 100644
> index 0000000..148ca8c
> --- /dev/null
> +++ b/drivers/clk/sprd/mux.h
> @@ -0,0 +1,65 @@
> +/*
> + * Spreadtrum multiplexer clock driver
> + *
> + * Copyright (C) 2017 Spreadtrum, Inc.
> + * Author: Chunyan Zhang <chunyan.zhang@...eadtrum.com>
> + *
> + * SPDX-License-Identifier: GPL-2.0
> + */
> +
> +#ifndef _SPRD_MUX_H_
> +#define _SPRD_MUX_H_
> +
> +#include "common.h"
> +
> +struct sprd_mux_internal {
> + u8 shift;
> + u8 width;
> + const u8 *table;
> +};
> +
> +struct sprd_mux {
> + struct sprd_mux_internal mux;
> + struct sprd_clk_common common;
> +};
> +
> +#define _SPRD_MUX_CLK(_shift, _width, _table) \
> + { \
> + .shift = _shift, \
> + .width = _width, \
> + .table = _table, \
> + }
> +
> +#define SPRD_MUX_CLK(_struct, _name, _parents, _table, \
> + _reg, _shift, _width, \
> + _flags) \
> + struct sprd_mux _struct = { \
> + .mux = _SPRD_MUX_CLK(_shift, _width, _table), \
> + .common = { \
> + .regmap = NULL, \
> + .reg = _reg, \
> + .lock = &sprd_mux_lock, \
> + .hw.init = CLK_HW_INIT_PARENTS(_name, \
> + _parents, \
> + &sprd_mux_ops, \
> + _flags), \
> + } \
> + }
> +
> +static inline struct sprd_mux *hw_to_sprd_mux(const struct clk_hw *hw)
> +{
> + struct sprd_clk_common *common = hw_to_sprd_clk_common(hw);
> +
> + return container_of(common, struct sprd_mux, common);
> +}
> +
> +extern const struct clk_ops sprd_mux_ops;
> +extern spinlock_t sprd_mux_lock;
> +
> +u8 sprd_mux_helper_get_parent(const struct sprd_clk_common *common,
> + const struct sprd_mux_internal *mux);
> +int sprd_mux_helper_set_parent(const struct sprd_clk_common *common,
> + const struct sprd_mux_internal *mux,
> + u8 index);
> +
> +#endif /* _SPRD_MUX_H_ */
>
--
Julien Thierry
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