clk: add a fixed factor clock

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>
Reviewed-by: Viresh Kumar <viresh.kumar@st.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
[mturquette@linaro.org: constify parent_names in static init macro]
[mturquette@linaro.org: copy/paste bug from mux in static init macro]
[mturquette@linaro.org: fix error handling in clk_register_fixed_factor]
[mturquette@linaro.org: improve division accuracy; thanks to Saravana]
Signed-off-by: Mike Turquette <mturquette@linaro.org>

2 files changed, 43 insertions, 0 deletions

diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index b258532162b8..eb3f84bc5325 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -143,6 +143,26 @@ struct clk {
         DEFINE_CLK(_name, clk_mux_ops, _flags, _parent_names,   \
                         _parents);
 
+#define DEFINE_CLK_FIXED_FACTOR(_name, _parent_name,            \
+                                _parent_ptr, _flags,            \
+                                _mult, _div)                    \
+        static struct clk _name;                                \
+        static const char *_name##_parent_names[] = {           \
+                _parent_name,                                   \
+        };                                                      \
+        static struct clk *_name##_parents[] = {                \
+                _parent_ptr,                                    \
+        };                                                      \
+        static struct clk_fixed_factor _name##_hw = {           \
+                .hw = {                                         \
+                        .clk = &_name,                          \
+                },                                              \
+                .mult = _mult,                                  \
+                .div = _div,                                    \
+        };                                                      \
+        DEFINE_CLK(_name, clk_fixed_factor_ops, _flags,         \
+                        _name##_parent_names, _name##_parents);
+
 /**
  * __clk_init - initialize the data structures in a struct clk
  * @dev:        device initializing this clk, placeholder for now
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 5db3412106b3..c1c23b9ec368 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -277,6 +277,29 @@ struct clk *clk_register_mux(struct device *dev, const char *name,
                 u8 clk_mux_flags, spinlock_t *lock);
 
 /**
+ * struct clk_fixed_factor - fixed multiplier and divider clock
+ *
+ * @hw:         handle between common and hardware-specific interfaces
+ * @mult:       multiplier
+ * @div:        divider
+ *
+ * Clock with a fixed multiplier and divider. The output frequency is the
+ * parent clock rate divided by div and multiplied by mult.
+ * Implements .recalc_rate, .set_rate and .round_rate
+ */
+
+struct clk_fixed_factor {
+        struct clk_hw   hw;
+        unsigned int    mult;
+        unsigned int    div;
+};
+
+extern struct clk_ops clk_fixed_factor_ops;
+struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
+                const char *parent_name, unsigned long flags,
+                unsigned int mult, unsigned int div);
+
+/**
  * clk_register - allocate a new clock, register it and return an opaque cookie
  * @dev: device that is registering this clock
  * @hw: link to hardware-specific clock data