ARM: imx: add common clock support for fixup mux

One register may have several fields to control some clocks. It
is possible that the read/write values of some fields may map to
different real functional values, so writing to the other fields
in the same register may break a working clock tree. A real case
is the aclk_podf field in the register 'CCM Serial Clock Multiplexer
Register 1' of i.MX6Q/SDL SoC. This patch introduces a fixup hook
for multiplexer clock which is called before writing a value to
clock registers to support this kind of multiplexer clocks.

Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

arch/arm/mach-imx/Makefile

@@ -16,7 +16,7 @@ obj-$(CONFIG_SOC_IMX5) += cpu-imx5.o mm-imx5.o clk-imx51-imx53.o ehci-imx5.o $(i
 
 obj-$(CONFIG_COMMON_CLK) += clk-pllv1.o clk-pllv2.o clk-pllv3.o clk-gate2.o \
 			    clk-pfd.o clk-busy.o clk.o \
-			    clk-fixup-div.o
+			    clk-fixup-div.o clk-fixup-mux.o
 
 obj-$(CONFIG_IMX_HAVE_IOMUX_V1) += iomux-v1.o
 obj-$(CONFIG_ARCH_MXC_IOMUX_V3) += iomux-v3.o

arch/arm/mach-imx/clk-fixup-mux.c

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2013 Freescale Semiconductor, Inc.
+ *
+ * The code contained herein is licensed under the GNU General Public
+ * License. You may obtain a copy of the GNU General Public License
+ * Version 2 or later at the following locations:
+ *
+ * http://www.opensource.org/licenses/gpl-license.html
+ * http://www.gnu.org/copyleft/gpl.html
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include "clk.h"
+
+#define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
+
+/**
+ * struct clk_fixup_mux - imx integer fixup multiplexer clock
+ * @mux: the parent class
+ * @ops: pointer to clk_ops of parent class
+ * @fixup: a hook to fixup the write value
+ *
+ * The imx fixup multiplexer clock is a subclass of basic clk_mux
+ * with an addtional fixup hook.
+ */
+struct clk_fixup_mux {
+	struct clk_mux mux;
+	const struct clk_ops *ops;
+	void (*fixup)(u32 *val);
+};
+
+static inline struct clk_fixup_mux *to_clk_fixup_mux(struct clk_hw *hw)
+{
+	struct clk_mux *mux = to_clk_mux(hw);
+
+	return container_of(mux, struct clk_fixup_mux, mux);
+}
+
+static u8 clk_fixup_mux_get_parent(struct clk_hw *hw)
+{
+	struct clk_fixup_mux *fixup_mux = to_clk_fixup_mux(hw);
+
+	return fixup_mux->ops->get_parent(&fixup_mux->mux.hw);
+}
+
+static int clk_fixup_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_fixup_mux *fixup_mux = to_clk_fixup_mux(hw);
+	struct clk_mux *mux = to_clk_mux(hw);
+	unsigned long flags = 0;
+	u32 val;
+
+	spin_lock_irqsave(mux->lock, flags);
+
+	val = readl(mux->reg);
+	val &= ~(mux->mask << mux->shift);
+	val |= index << mux->shift;
+	fixup_mux->fixup(&val);
+	writel(val, mux->reg);
+
+	spin_unlock_irqrestore(mux->lock, flags);
+
+	return 0;
+}
+
+static const struct clk_ops clk_fixup_mux_ops = {
+	.get_parent = clk_fixup_mux_get_parent,
+	.set_parent = clk_fixup_mux_set_parent,
+};
+
+struct clk *imx_clk_fixup_mux(const char *name, void __iomem *reg,
+			      u8 shift, u8 width, const char **parents,
+			      int num_parents, void (*fixup)(u32 *val))
+{
+	struct clk_fixup_mux *fixup_mux;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	if (!fixup)
+		return ERR_PTR(-EINVAL);
+
+	fixup_mux = kzalloc(sizeof(*fixup_mux), GFP_KERNEL);
+	if (!fixup_mux)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clk_fixup_mux_ops;
+	init.parent_names = parents;
+	init.num_parents = num_parents;
+
+	fixup_mux->mux.reg = reg;
+	fixup_mux->mux.shift = shift;
+	fixup_mux->mux.mask = BIT(width) - 1;
+	fixup_mux->mux.lock = &imx_ccm_lock;
+	fixup_mux->mux.hw.init = &init;
+	fixup_mux->ops = &clk_mux_ops;
+	fixup_mux->fixup = fixup;
+
+	clk = clk_register(NULL, &fixup_mux->mux.hw);
+	if (IS_ERR(clk))
+		kfree(fixup_mux);
+
+	return clk;
+}

arch/arm/mach-imx/clk.h

@@ -53,6 +53,10 @@ struct clk *imx_clk_fixup_divider(const char *name, const char *parent,
 				  void __iomem *reg, u8 shift, u8 width,
 				  void (*fixup)(u32 *val));
 
+struct clk *imx_clk_fixup_mux(const char *name, void __iomem *reg,
+			      u8 shift, u8 width, const char **parents,
+			      int num_parents, void (*fixup)(u32 *val));
+
 static inline struct clk *imx_clk_fixed(const char *name, int rate)
 {
 	return clk_register_fixed_rate(NULL, name, NULL, CLK_IS_ROOT, rate);