Commit 3d3801ef authored by Michael Turquette's avatar Michael Turquette Committed by Stephen Boyd
Browse files

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: 035a61c3 ("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: default avatarMichael Turquette <mturquette@linaro.org>
[arnd@arndb.de: Fix COMMON_CLK=N && HAS_CLK=Y config]
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
[sboyd@codeaurora.org: const arguments to clk_is_match() and
remove unnecessary ternary operation]
Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
parent f55ac065

drivers/clk/clk.c

+26 −0
Original line number Diff line number Diff line
@@ -2169,6 +2169,32 @@ int clk_get_phase(struct clk *clk) 
	return clk_core_get_phase(clk->core);

}



/**

 * 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

include/linux/clk.h

+18 −0
Original line number Diff line number Diff line
@@ -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



/**

CRA Git | Maintained and supported by SUSTech CRA and CCSE