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authorSimon Horman <horms+renesas@verge.net.au>2019-03-25 19:35:53 +0300
committerGeert Uytterhoeven <geert+renesas@glider.be>2019-04-02 10:50:48 +0300
commitcb8be119d21d8a0affc3598a928dd0baf5da238f (patch)
treea9cad79fb039220cd64061c02f34afc3eecb5a84 /include/linux/math64.h
parente0836e36384321ab1b4af05ab441c0c59a972596 (diff)
downloadlinux-cb8be119d21d8a0affc3598a928dd0baf5da238f.tar.xz
math64: New DIV64_U64_ROUND_CLOSEST helper
Provide DIV64_U64_ROUND_CLOSEST helper which performs division rounded to the closest integer using an unsigned 64bit dividend and divisor. This will be used in a follow-up patch to allow calculation of clock divisors with high frequency parents in the R-Car Gen3 CPG MSSR driver where overflow occurs if either the dividend or divisor is 32bit. Signed-off-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Diffstat (limited to 'include/linux/math64.h')
-rw-r--r--include/linux/math64.h13
1 files changed, 13 insertions, 0 deletions
diff --git a/include/linux/math64.h b/include/linux/math64.h
index bb2c84afb80c..65bef21cdddb 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -284,4 +284,17 @@ static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
#define DIV64_U64_ROUND_UP(ll, d) \
({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })
+/**
+ * DIV64_U64_ROUND_CLOSEST - unsigned 64bit divide with 64bit divisor rounded to nearest integer
+ * @dividend: unsigned 64bit dividend
+ * @divisor: unsigned 64bit divisor
+ *
+ * Divide unsigned 64bit dividend by unsigned 64bit divisor
+ * and round to closest integer.
+ *
+ * Return: dividend / divisor rounded to nearest integer
+ */
+#define DIV64_U64_ROUND_CLOSEST(dividend, divisor) \
+ ({ u64 _tmp = (divisor); div64_u64((dividend) + _tmp / 2, _tmp); })
+
#endif /* _LINUX_MATH64_H */