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From 15a02c1f6dd7c2bb150c61d00ffb33f584ff2288 Mon Sep 17 00:00:00 2001
From: Stephen Boyd <sboyd@codeaurora.org>
Date: Mon, 19 Jan 2015 18:05:28 -0800
Subject: [PATCH] clk: Add __clk_mux_determine_rate_closest
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>
Tested-by: Kenneth Westfield <kwestfie@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
---
drivers/clk/clk.c | 47 +++++++++++++++++++++++++++++++++++---------
include/linux/clk-provider.h | 8 +++++++-
2 files changed, 45 insertions(+), 10 deletions(-)
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -695,14 +695,20 @@ struct clk *__clk_lookup(const char *nam
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;
@@ -730,7 +736,7 @@ long __clk_mux_determine_rate(struct clk
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;
}
@@ -743,8 +749,31 @@ 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)
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -382,6 +382,8 @@ struct clk *clk_register_divider_table(s
* 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;
@@ -396,7 +398,8 @@ 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;
@@ -554,6 +557,9 @@ struct clk *__clk_lookup(const char *nam
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
|