[PATCH 1/7] clk: Add __clk_mux_determine_rate_closest

Stephen Boyd
2014-11-20T00:10:54Z

Some clock drivers want to find the closest rate on the input of
a mux instead of a rate that's less than or equal to the desired
rate. Add a generic mux function to support this.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
drivers/clk/clk.c | 47 +++++++++++++++++++++++++++++++++++---------
include/linux/clk-provider.h | 9 +++++++--
2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 4896ae9e23da..675f37a7329f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -700,14 +700,20 @@ struct clk *__clk_lookup(const char *name)
return NULL;
}

-/*
- * Helper for finding best parent to provide a given frequency. This can be used
- * directly as a determine_rate callback (e.g. for a mux), or from a more
- * complex clock that may combine a mux with other operations.
- */
-long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
- unsigned long *best_parent_rate,
- struct clk **best_parent_p)
+static bool mux_is_better_rate(unsigned long rate, unsigned long now,
+ unsigned long best, unsigned long flags)
+{
+ if (flags & CLK_MUX_ROUND_CLOSEST)
+ return abs(now - rate) < abs(best - rate);
+
+ return now <= rate && now > best;
+}
+
+static long
+clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk **best_parent_p,
+ unsigned long flags)
{
struct clk *clk = hw->clk, *parent, *best_parent = NULL;
int i, num_parents;
@@ -735,7 +741,7 @@ long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
parent_rate = __clk_round_rate(parent, rate);
else
parent_rate = __clk_get_rate(parent);
- if (parent_rate <= rate && parent_rate > best) {
+ if (mux_is_better_rate(rate, parent_rate, best, flags)) {
best_parent = parent;
best = parent_rate;
}
@@ -748,8 +754,31 @@ out:

return best;
}
+
+/*
+ * Helper for finding best parent to provide a given frequency. This can be used
+ * directly as a determine_rate callback (e.g. for a mux), or from a more
+ * complex clock that may combine a mux with other operations.
+ */
+long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk **best_parent_p)
+{
+ return clk_mux_determine_rate_flags(hw, rate, best_parent_rate,
+ best_parent_p, 0);
+}
EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);

+long __clk_mux_determine_rate_closest(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk **best_parent_p)
+{
+ return clk_mux_determine_rate_flags(hw, rate, best_parent_rate,
+ best_parent_p,
+ CLK_MUX_ROUND_CLOSEST);
+}
+EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest);
+
/*** clk api ***/

void __clk_unprepare(struct clk *clk)
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index be21af149f11..446faed3f79f 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -383,6 +383,8 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
* register, and mask of mux bits are in higher 16-bit of this register.
* While setting the mux bits, higher 16-bit should also be updated to
* indicate changing mux bits.
+ * CLK_MUX_ROUND_CLOSEST - Use the parent rate that is closest to the desired
+ * frequency.
*/
struct clk_mux {
struct clk_hw hw;
@@ -397,7 +399,8 @@ struct clk_mux {
#define CLK_MUX_INDEX_ONE BIT(0)
#define CLK_MUX_INDEX_BIT BIT(1)
#define CLK_MUX_HIWORD_MASK BIT(2)
-#define CLK_MUX_READ_ONLY BIT(3) /* mux setting cannot be changed */
+#define CLK_MUX_READ_ONLY BIT(3) /* mux can't be changed */
+#define CLK_MUX_ROUND_CLOSEST BIT(4)

extern const struct clk_ops clk_mux_ops;
extern const struct clk_ops clk_mux_ro_ops;
@@ -555,7 +558,9 @@ struct clk *__clk_lookup(const char *name);
long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *best_parent_rate,
struct clk **best_parent_p);
-
+long __clk_mux_determine_rate_closest(struct clk_hw *hw, unsigned long rate,
+ unsigned long *best_parent_rate,
+ struct clk **best_parent_p);
/*
* FIXME clock api without lock protection
*/