linux-kernel - [PATCH] rtc-pcf2123: use sign_extend32() for sign extension

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Date:	Mon, 18 Apr 2016 12:17:44 +0200
From:	Martin Kepplinger <martink@...teo.de>
To:	a.zummo@...ertech.it, alexandre.belloni@...e-electrons.com
Cc:	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org,
	Martin Kepplinger <martink@...teo.de>
Subject: [PATCH] rtc-pcf2123: use sign_extend32() for sign extension

Signed-off-by: Martin Kepplinger <martink@...teo.de>
---
 drivers/rtc/rtc-pcf2123.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-pcf2123.c b/drivers/rtc/rtc-pcf2123.c
index f22e060..b4478cc 100644
--- a/drivers/rtc/rtc-pcf2123.c
+++ b/drivers/rtc/rtc-pcf2123.c
@@ -96,7 +96,7 @@
 #define CD_TMR_TE		BIT(3)	/* Countdown timer enable */
 
 /* PCF2123_REG_OFFSET BITS */
-#define OFFSET_SIGN_BIT		BIT(6)	/* 2's complement sign bit */
+#define OFFSET_SIGN_BIT		6	/* 2's complement sign bit */
 #define OFFSET_COARSE		BIT(7)	/* Coarse mode offset */
 #define OFFSET_STEP		(2170)	/* Offset step in parts per billion */
 
@@ -217,7 +217,7 @@ static int pcf2123_read_offset(struct device *dev, long *offset)
 	if (reg & OFFSET_COARSE)
 		reg <<= 1; /* multiply by 2 and sign extend */
 	else
-		reg |= (reg & OFFSET_SIGN_BIT) << 1; /* sign extend only */
+		reg = sign_extend32(reg, OFFSET_SIGN_BIT);
 
 	*offset = ((long)reg) * OFFSET_STEP;
 
-- 
2.1.4