clk: mxs: add mxs specific clocks

Add mxs specific clocks, pll, reference clock (PFD), integer divider
and fractional divider.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>

drivers/clk/mxs/clk-ref.c

@@ -0,0 +1,154 @@
+/*
+ * Copyright 2012 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.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include "clk.h"
+
+/**
+ * struct clk_ref - mxs reference clock
+ * @hw: clk_hw for the reference clock
+ * @reg: register address
+ * @idx: the index of the reference clock within the same register
+ *
+ * The mxs reference clock sources from pll.  Every 4 reference clocks share
+ * one register space, and @idx is used to identify them.  Each reference
+ * clock has a gate control and a fractional * divider.  The rate is calculated
+ * as pll rate  * (18 / FRAC), where FRAC = 18 ~ 35.
+ */
+struct clk_ref {
+	struct clk_hw hw;
+	void __iomem *reg;
+	u8 idx;
+};
+
+#define to_clk_ref(_hw) container_of(_hw, struct clk_ref, hw)
+
+static int clk_ref_enable(struct clk_hw *hw)
+{
+	struct clk_ref *ref = to_clk_ref(hw);
+
+	writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + CLR);
+
+	return 0;
+}
+
+static void clk_ref_disable(struct clk_hw *hw)
+{
+	struct clk_ref *ref = to_clk_ref(hw);
+
+	writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + SET);
+}
+
+static unsigned long clk_ref_recalc_rate(struct clk_hw *hw,
+					 unsigned long parent_rate)
+{
+	struct clk_ref *ref = to_clk_ref(hw);
+	u64 tmp = parent_rate;
+	u8 frac = (readl_relaxed(ref->reg) >> (ref->idx * 8)) & 0x3f;
+
+	tmp *= 18;
+	do_div(tmp, frac);
+
+	return tmp;
+}
+
+static long clk_ref_round_rate(struct clk_hw *hw, unsigned long rate,
+			       unsigned long *prate)
+{
+	unsigned long parent_rate = *prate;
+	u64 tmp = parent_rate;
+	u8 frac;
+
+	tmp = tmp * 18 + rate / 2;
+	do_div(tmp, rate);
+	frac = tmp;
+
+	if (frac < 18)
+		frac = 18;
+	else if (frac > 35)
+		frac = 35;
+
+	tmp = parent_rate;
+	tmp *= 18;
+	do_div(tmp, frac);
+
+	return tmp;
+}
+
+static int clk_ref_set_rate(struct clk_hw *hw, unsigned long rate,
+			    unsigned long parent_rate)
+{
+	struct clk_ref *ref = to_clk_ref(hw);
+	unsigned long flags;
+	u64 tmp = parent_rate;
+	u32 val;
+	u8 frac, shift = ref->idx * 8;
+
+	tmp = tmp * 18 + rate / 2;
+	do_div(tmp, rate);
+	frac = tmp;
+
+	if (frac < 18)
+		frac = 18;
+	else if (frac > 35)
+		frac = 35;
+
+	spin_lock_irqsave(&mxs_lock, flags);
+
+	val = readl_relaxed(ref->reg);
+	val &= ~(0x3f << shift);
+	val |= frac << shift;
+	writel_relaxed(val, ref->reg);
+
+	spin_unlock_irqrestore(&mxs_lock, flags);
+
+	return 0;
+}
+
+static const struct clk_ops clk_ref_ops = {
+	.enable		= clk_ref_enable,
+	.disable	= clk_ref_disable,
+	.recalc_rate	= clk_ref_recalc_rate,
+	.round_rate	= clk_ref_round_rate,
+	.set_rate	= clk_ref_set_rate,
+};
+
+struct clk *mxs_clk_ref(const char *name, const char *parent_name,
+			void __iomem *reg, u8 idx)
+{
+	struct clk_ref *ref;
+	struct clk *clk;
+	struct clk_init_data init;
+
+	ref = kzalloc(sizeof(*ref), GFP_KERNEL);
+	if (!ref)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &clk_ref_ops;
+	init.flags = 0;
+	init.parent_names = (parent_name ? &parent_name: NULL);
+	init.num_parents = (parent_name ? 1 : 0);
+
+	ref->reg = reg;
+	ref->idx = idx;
+	ref->hw.init = &init;
+
+	clk = clk_register(NULL, &ref->hw);
+	if (IS_ERR(clk))
+		kfree(ref);
+
+	return clk;
+}