lkml.org 
[lkml]   [2017]   [Nov]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH V3 05/11] clk: sprd: add mux clock support
    On 3 November 2017 at 02:22, Julien Thierry <julien.thierry@arm.com> wrote:
    >
    >
    > 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.

    Yes, that makes the code nicer, and thanks to your reminder, I even
    make it more clean by moving the check for 'mux->table' up.


    Thanks,
    Chunyan

    >
    > --
    > Julien Thierry

    \
     
     \ /
      Last update: 2017-11-03 13:14    [W:6.467 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site