From cb8be119d21d8a0affc3598a928dd0baf5da238f Mon Sep 17 00:00:00 2001 From: Simon Horman Date: Mon, 25 Mar 2019 17:35:53 +0100 Subject: 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 Signed-off-by: Geert Uytterhoeven --- include/linux/math64.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'include/linux/math64.h') 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 */ -- cgit v1.2.3