linux-kernel - [PATCH] powerpc/time: Define div128_by_32() static and _

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Message-ID: <50810349bf1eee378fbeab72a36e4b6553a60c3d.1738749246.git.christophe.leroy@csgroup.eu>
Date: Wed,  5 Feb 2025 10:54:26 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Naveen N Rao <naveen@...nel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/time: Define div128_by_32() static and __init

div128_by_32() used to be called from outside time.c in the old days
but since v2.6.15 it hasn't been used outside time.c

$ git grep div128_by_32 v2.6.14
v2.6.14:arch/ppc64/kernel/iSeries_setup.c:	div128_by_32(1024 * 1024, 0, tb_ticks_per_sec, &divres);
v2.6.14:arch/ppc64/kernel/pmac_time.c:	div128_by_32( 1024*1024, 0, tb_ticks_per_sec, &divres );
v2.6.14:arch/ppc64/kernel/time.c:				div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
v2.6.14:arch/ppc64/kernel/time.c:	div128_by_32(1024*1024, 0, tb_ticks_per_sec, &divres);
v2.6.14:arch/ppc64/kernel/time.c:	div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
v2.6.14:arch/ppc64/kernel/time.c:	div128_by_32( 1024*1024, 0, new_tb_ticks_per_sec, &divres );
v2.6.14:arch/ppc64/kernel/time.c:void div128_by_32( unsigned long dividend_high, unsigned long dividend_low,
v2.6.14:include/asm-ppc64/time.h:void div128_by_32( unsigned long dividend_high, unsigned long dividend_low,

$ git grep div128_by_32 v2.6.15
v2.6.15:arch/powerpc/kernel/time.c:				div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
v2.6.15:arch/powerpc/kernel/time.c:	div128_by_32(1024*1024, 0, tb_ticks_per_sec, &res);
v2.6.15:arch/powerpc/kernel/time.c:	div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
v2.6.15:arch/powerpc/kernel/time.c:	div128_by_32(1024*1024, 0, new_tb_ticks_per_sec, &divres);
v2.6.15:arch/powerpc/kernel/time.c:void div128_by_32(u64 dividend_high, u64 dividend_low,
v2.6.15:include/asm-powerpc/time.h:extern void div128_by_32(u64 dividend_high, u64 dividend_low,

Move it above its only caller which is time_init() and define it
static and __init.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/time.h |  3 --
 arch/powerpc/kernel/time.c      | 65 ++++++++++++++++-----------------
 2 files changed, 32 insertions(+), 36 deletions(-)

diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 9bdd8080299b..f8885586efaf 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -89,9 +89,6 @@ static inline unsigned long tb_ticks_since(unsigned long tstamp)
 #define mulhdu(x, y)	mul_u64_u64_shr(x, y, 64)
 #endif
 
-extern void div128_by_32(u64 dividend_high, u64 dividend_low,
-			 unsigned divisor, struct div_result *dr);
-
 extern void secondary_cpu_time_init(void);
 extern void __init time_init(void);
 
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 0727332ad86f..0be53642501b 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -901,6 +901,38 @@ void secondary_cpu_time_init(void)
 	register_decrementer_clockevent(smp_processor_id());
 }
 
+/*
+ * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
+ * result.
+ */
+static __init void div128_by_32(u64 dividend_high, u64 dividend_low,
+				unsigned int divisor, struct div_result *dr)
+{
+	unsigned long a, b, c, d;
+	unsigned long w, x, y, z;
+	u64 ra, rb, rc;
+
+	a = dividend_high >> 32;
+	b = dividend_high & 0xffffffff;
+	c = dividend_low >> 32;
+	d = dividend_low & 0xffffffff;
+
+	w = a / divisor;
+	ra = ((u64)(a - (w * divisor)) << 32) + b;
+
+	rb = ((u64)do_div(ra, divisor) << 32) + c;
+	x = ra;
+
+	rc = ((u64)do_div(rb, divisor) << 32) + d;
+	y = rb;
+
+	do_div(rc, divisor);
+	z = rc;
+
+	dr->result_high = ((u64)w << 32) + x;
+	dr->result_low  = ((u64)y << 32) + z;
+}
+
 /* This function is only called on the boot processor */
 void __init time_init(void)
 {
@@ -974,39 +1006,6 @@ void __init time_init(void)
 	enable_sched_clock_irqtime();
 }
 
-/*
- * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
- * result.
- */
-void div128_by_32(u64 dividend_high, u64 dividend_low,
-		  unsigned divisor, struct div_result *dr)
-{
-	unsigned long a, b, c, d;
-	unsigned long w, x, y, z;
-	u64 ra, rb, rc;
-
-	a = dividend_high >> 32;
-	b = dividend_high & 0xffffffff;
-	c = dividend_low >> 32;
-	d = dividend_low & 0xffffffff;
-
-	w = a / divisor;
-	ra = ((u64)(a - (w * divisor)) << 32) + b;
-
-	rb = ((u64) do_div(ra, divisor) << 32) + c;
-	x = ra;
-
-	rc = ((u64) do_div(rb, divisor) << 32) + d;
-	y = rb;
-
-	do_div(rc, divisor);
-	z = rc;
-
-	dr->result_high = ((u64)w << 32) + x;
-	dr->result_low  = ((u64)y << 32) + z;
-
-}
-
 /* We don't need to calibrate delay, we use the CPU timebase for that */
 void calibrate_delay(void)
 {
-- 
2.47.0