math64: New DIV64_U64_ROUND_CLOSEST helper (cb8be119) · Commits · 戴 / test

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>

include/linux/math64.h

+13 −0

Original line number	Original line	Diff line number	Diff line
	@@ -284,4 +284,17 @@ static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor)
	#define DIV64_U64_ROUND_UP(ll, d) \		#define DIV64_U64_ROUND_UP(ll, d) \
	({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); })		({ 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 */		#endif /* _LINUX_MATH64_H */

Admin message