[PATCH 05/10] clk: add clk_set_rate_protect
Jerome Brunet
jbrunet at baylibre.com
Thu May 18 09:37:59 PDT 2017
clk_set_rate_protect is a combination of clk_set_rate and clk_rate_protect
within a critical section. In case where several protecting consumers
compete to set the rate of the same provider, it provides a way to make
sure that at least one of them will be satisfied before the resource is
locked.
This is to avoid the unlikely situation where several consumers protect a
clock provider and none actually get a rate it can work with.
Signed-off-by: Jerome Brunet <jbrunet at baylibre.com>
---
drivers/clk/clk.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/clk.h | 14 ++++++++++++++
2 files changed, 59 insertions(+)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 9c15319bc454..132eb1a2938f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1781,6 +1781,51 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
EXPORT_SYMBOL_GPL(clk_set_rate);
/**
+ * clk_set_rate_protect - specify a new rate and protect it
+ * @clk: the clk whose rate is being changed
+ * @rate: the new rate for clk
+ *
+ * This is a combination of clk_set_rate and clk_rate_protect within
+ * a critical section
+ *
+ * This can be used initially to ensure that at least 1 consumers is
+ * statisfied when several protecting consummers are competing for the
+ * same clock provider.
+ *
+ * The protection is not applied if setting the rate failed.
+ *
+ * Returns 0 on success, -EERROR otherwise.
+ */
+int clk_set_rate_protect(struct clk *clk, unsigned long rate)
+{
+ int ret;
+
+ if (!clk)
+ return 0;
+
+ /* prevent racing with updates to the clock topology */
+ clk_prepare_lock();
+
+ /*
+ * The temporary protection removal is not here, on purpose
+ * This function is meant to be used in instead of clk_rate_protect,
+ * so before the consumer code path protect the clock provider
+ */
+
+ ret = clk_core_set_rate_nolock(clk->core, rate);
+
+ if (!ret) {
+ clk_core_rate_protect(clk->core);
+ clk->protect_count++;
+ }
+
+ clk_prepare_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(clk_set_rate_protect);
+
+/**
* clk_set_rate_range - set a rate range for a clock source
* @clk: clock source
* @min: desired minimum clock rate in Hz, inclusive
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 85d73e02df40..d3c299d23ae7 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -388,6 +388,15 @@ long clk_round_rate(struct clk *clk, unsigned long rate);
int clk_set_rate(struct clk *clk, unsigned long rate);
/**
+ * clk_set_rate_protect - set and protect the clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired clock rate in Hz
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_rate_protect(struct clk *clk, unsigned long rate);
+
+/**
* clk_has_parent - check if a clock is a possible parent for another
* @clk: clock source
* @parent: parent clock source
@@ -506,6 +515,11 @@ static inline int clk_set_rate(struct clk *clk, unsigned long rate)
return 0;
}
+static inline int clk_set_rate_protect(struct clk *clk, unsigned long rate)
+{
+ return 0;
+}
+
static inline long clk_round_rate(struct clk *clk, unsigned long rate)
{
return 0;
--
2.9.4
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