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author | Thierry Reding <treding@nvidia.com> | 2015-01-21 19:13:00 +0300 |
---|---|---|
committer | Michael Turquette <mturquette@linaro.org> | 2015-01-25 03:56:55 +0300 |
commit | 4e88f3de89fbb7b5a5a0aca20376b276d26732ac (patch) | |
tree | 010afff654b43fd252c9b1482b034781a3cbfaa1 /include/linux | |
parent | 97bf6af1f928216fd6c5a66e8a57bfa95a659672 (diff) | |
download | linux-4e88f3de89fbb7b5a5a0aca20376b276d26732ac.tar.xz |
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')
-rw-r--r-- | include/linux/clk.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/clk.h b/include/linux/clk.h index c7f258a81761..ba7e9eda4347 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; |