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SubjectRe: [PATCH V3 05/11] clk: sprd: add mux clock support
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On 02/11/17 18:11, Julien Thierry wrote:
> 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@spreadtrum.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@spreadtrum.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, &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;

Oops, meant to say "return num_parents - 1;" on that last line.

--
Julien Thierry

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