linux-kernel - [PATCH v8 1/6] math64: New DIV_U64_ROUND

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Message-Id: <20220211191238.2142-2-kabel@kernel.org>
Date:   Fri, 11 Feb 2022 20:12:33 +0100
From:   Marek Behún <kabel@...nel.org>
To:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Gregory Clement <gregory.clement@...tlin.com>
Cc:     Pali Rohár <pali@...nel.org>,
        linux-clk@...r.kernel.org, linux-serial@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Marek Behún <kabel@...nel.org>
Subject: [PATCH v8 1/6] math64: New DIV_U64_ROUND_CLOSEST helper

From: Pali Rohár <pali@...nel.org>

Provide DIV_U64_ROUND_CLOSEST helper which uses div_u64 to perform
division rounded to the closest integer using unsigned 64bit
dividend and unsigned 32bit divisor.

Signed-off-by: Pali Rohár <pali@...nel.org>
Reviewed-by: Marek Behún <kabel@...nel.org>
Signed-off-by: Marek Behún <kabel@...nel.org>
---
Changes since v7:
- added Marek's Reviewed-by tag
---
 include/linux/math64.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/math64.h b/include/linux/math64.h
index 2928f03d6d46..a14f40de1dca 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -300,6 +300,19 @@ u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div);
 #define DIV64_U64_ROUND_CLOSEST(dividend, divisor)	\
 	({ u64 _tmp = (divisor); div64_u64((dividend) + _tmp / 2, _tmp); })
 
+/*
+ * DIV_U64_ROUND_CLOSEST - unsigned 64bit divide with 32bit divisor rounded to nearest integer
+ * @dividend: unsigned 64bit dividend
+ * @divisor: unsigned 32bit divisor
+ *
+ * Divide unsigned 64bit dividend by unsigned 32bit divisor
+ * and round to closest integer.
+ *
+ * Return: dividend / divisor rounded to nearest integer
+ */
+#define DIV_U64_ROUND_CLOSEST(dividend, divisor)	\
+	({ u32 _tmp = (divisor); div_u64((u64)(dividend) + _tmp / 2, _tmp); })
+
 /*
  * DIV_S64_ROUND_CLOSEST - signed 64bit divide with 32bit divisor rounded to nearest integer
  * @dividend: signed 64bit dividend
-- 
2.34.1