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authorMichael Turquette <mturquette@linaro.org>2015-02-25 09:11:01 -0800
committerStephen Boyd <sboyd@codeaurora.org>2015-03-11 15:56:59 -0700
commit3d3801effda19b21012b5d1981e96cc277df85fd (patch)
treea3255b002f17851376204e909f3e69b5a3c6fc0c
parentf55ac0655a6e42d8299b78c23ee70301f7956d5e (diff)
downloadop-kernel-dev-3d3801effda19b21012b5d1981e96cc277df85fd.zip
op-kernel-dev-3d3801effda19b21012b5d1981e96cc277df85fd.tar.gz
clk: introduce clk_is_match
Some drivers compare struct clk pointers as a means of knowing if the two pointers reference the same clock hardware. This behavior is dubious (drivers must not dereference struct clk), but did not cause any regressions until the per-user struct clk patch was merged. Now the test for matching clk's will always fail with per-user struct clk's. clk_is_match is introduced to fix the regression and prevent drivers from comparing the pointers manually. Fixes: 035a61c314eb ("clk: Make clk API return per-user struct clk instances") Cc: Russell King <linux@arm.linux.org.uk> Cc: Shawn Guo <shawn.guo@linaro.org> Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com> Signed-off-by: Michael Turquette <mturquette@linaro.org> [arnd@arndb.de: Fix COMMON_CLK=N && HAS_CLK=Y config] Signed-off-by: Arnd Bergmann <arnd@arndb.de> [sboyd@codeaurora.org: const arguments to clk_is_match() and remove unnecessary ternary operation] Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
-rw-r--r--drivers/clk/clk.c26
-rw-r--r--include/linux/clk.h18
2 files changed, 44 insertions, 0 deletions
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index b9f85fc2..237f23f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2170,6 +2170,32 @@ int clk_get_phase(struct clk *clk)
}
/**
+ * clk_is_match - check if two clk's point to the same hardware clock
+ * @p: clk compared against q
+ * @q: clk compared against p
+ *
+ * Returns true if the two struct clk pointers both point to the same hardware
+ * clock node. Put differently, returns true if struct clk *p and struct clk *q
+ * share the same struct clk_core object.
+ *
+ * Returns false otherwise. Note that two NULL clks are treated as matching.
+ */
+bool clk_is_match(const struct clk *p, const struct clk *q)
+{
+ /* trivial case: identical struct clk's or both NULL */
+ if (p == q)
+ return true;
+
+ /* true if clk->core pointers match. Avoid derefing garbage */
+ if (!IS_ERR_OR_NULL(p) && !IS_ERR_OR_NULL(q))
+ if (p->core == q->core)
+ return true;
+
+ return false;
+}
+EXPORT_SYMBOL_GPL(clk_is_match);
+
+/**
* __clk_init - initialize the data structures in a struct clk
* @dev: device initializing this clk, placeholder for now
* @clk: clk being initialized
diff --git a/include/linux/clk.h b/include/linux/clk.h
index 8381bbf..68c16a6 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -125,6 +125,19 @@ int clk_set_phase(struct clk *clk, int degrees);
*/
int clk_get_phase(struct clk *clk);
+/**
+ * clk_is_match - check if two clk's point to the same hardware clock
+ * @p: clk compared against q
+ * @q: clk compared against p
+ *
+ * Returns true if the two struct clk pointers both point to the same hardware
+ * clock node. Put differently, returns true if struct clk *p and struct clk *q
+ * share the same struct clk_core object.
+ *
+ * Returns false otherwise. Note that two NULL clks are treated as matching.
+ */
+bool clk_is_match(const struct clk *p, const struct clk *q);
+
#else
static inline long clk_get_accuracy(struct clk *clk)
@@ -142,6 +155,11 @@ static inline long clk_get_phase(struct clk *clk)
return -ENOTSUPP;
}
+static inline bool clk_is_match(const struct clk *p, const struct clk *q)
+{
+ return p == q;
+}
+
#endif
/**
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