Re: [PATCH V3 05/11] clk: sprd: add mux clock support

From: Julien Thierry
Date: Thu Nov 02 2017 - 14:22:33 EST



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@xxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxxxx>
+ *
+ * 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