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authorThierry Reding <treding@nvidia.com>2015-01-21 17:13:00 +0100
committerMichael Turquette <mturquette@linaro.org>2015-01-24 16:56:55 -0800
commit4e88f3de89fbb7b5a5a0aca20376b276d26732ac (patch)
tree010afff654b43fd252c9b1482b034781a3cbfaa1 /include/linux/clk.h
parent97bf6af1f928216fd6c5a66e8a57bfa95a659672 (diff)
downloadop-kernel-dev-4e88f3de89fbb7b5a5a0aca20376b276d26732ac.zip
op-kernel-dev-4e88f3de89fbb7b5a5a0aca20376b276d26732ac.tar.gz
clk: Introduce clk_has_parent()
This new function is similar to clk_set_parent(), except that it doesn't actually change the parent. It merely checks that the given parent clock can be a parent for the given clock. A situation where this is useful is to check that a particular setup is valid before switching to it. One specific use-case for this is atomic modesetting in the DRM framework where setting a mode is divided into a check phase where a given configuration is validated before applying changes to the hardware. Cc: Russell King <linux@arm.linux.org.uk> Signed-off-by: Thierry Reding <treding@nvidia.com> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Michael Turquette <mturquette@linaro.org>
Diffstat (limited to 'include/linux/clk.h')
-rw-r--r--include/linux/clk.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/clk.h b/include/linux/clk.h
index c7f258a..ba7e9ed 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -302,6 +302,18 @@ long clk_round_rate(struct clk *clk, unsigned long rate);
int clk_set_rate(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
+ *
+ * This function can be used in drivers that need to check that a clock can be
+ * the parent of another without actually changing the parent.
+ *
+ * Returns true if @parent is a possible parent for @clk, false otherwise.
+ */
+bool clk_has_parent(struct clk *clk, struct clk *parent);
+
+/**
* clk_set_parent - set the parent clock source for this clock
* @clk: clock source
* @parent: parent clock source
@@ -374,6 +386,11 @@ static inline long clk_round_rate(struct clk *clk, unsigned long rate)
return 0;
}
+static inline bool clk_has_parent(struct clk *clk, struct clk *parent)
+{
+ return true;
+}
+
static inline int clk_set_parent(struct clk *clk, struct clk *parent)
{
return 0;
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