From: Sascha Hauer <s.hauer@pengutronix.de>

Having fixed factors/dividers in hardware is a common pattern, so
add a basic clock type doing this. It basically describes a fixed
factor clock using a nominator and a denominator.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
Sascha,

I have this patch in my set, because i need this to get SPEAr stuff pushed by
Mike. I have updated your original patch, with all the review comments you got
on it. Please check see if i have corrupted something.

 drivers/clk/Makefile           |    2 +-
 drivers/clk/clk-fixed-factor.c |   94 ++++++++++++++++++++++++++++++++++++++++
 include/linux/clk-private.h    |   20 ++++++++
 include/linux/clk-provider.h   |   23 ++++++++++
 4 files changed, 138 insertions(+), 1 deletions(-)
 create mode 100644 drivers/clk/clk-fixed-factor.c

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 1f736bc..24aa714 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile

@@ -1,4 +1,4 @@
 
 obj-$(CONFIG_CLKDEV_LOOKUP)	+= clkdev.o
 obj-$(CONFIG_COMMON_CLK)	+= clk.o clk-fixed-rate.o clk-gate.o \
-				   clk-mux.o clk-divider.o
+				   clk-mux.o clk-divider.o clk-fixed-factor.o

diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
new file mode 100644
index 0000000..7453efe
--- /dev/null
+++ b/drivers/clk/clk-fixed-factor.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Standard functionality for the common clock API.
+ */
+#include <linux/module.h>
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+
+/*
+ * DOC: basic fixed multiplier and divider clock that cannot gate
+ *
+ * Traits of this clock:
+ * prepare - clk_prepare only ensures that parents are prepared
+ * enable - clk_enable only ensures that parents are enabled
+ * rate - rate is fixed.  clk->rate = parent->rate / div * mult
+ * parent - fixed parent.  No clk_set_parent support
+ */
+
+#define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)
+
+static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
+
+	return (parent_rate / fix->div) * fix->mult;
+}
+
+static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
+				unsigned long *prate)
+{
+	struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
+
+	if (prate) {
+		unsigned long best_parent;
+		best_parent = (rate / fix->mult) * fix->div;
+		*prate = __clk_round_rate(__clk_get_parent(hw->clk),
+				best_parent);
+		return (*prate / fix->div) * fix->mult;
+	} else {
+		return (__clk_get_rate(__clk_get_parent(hw->clk)) / fix->div) *
+			fix->mult;
+	}
+}