From 86e66604fca053e5ecb2427538aa233637119409 Mon Sep 17 00:00:00 2001
From: Martin Kepplinger <martink@posteo.de>
Date: Thu, 16 Apr 2015 12:45:09 -0700
Subject: [PATCH] drivers/rtc/rtc-x1205.c: use sign_extend32() for sign
 extension

Despite its name, sign_extend32() is safe to use for 8 bit types too.
(See https://lkml.org/lkml/2015/1/18/289).

Signed-off-by: Martin Kepplinger <martink@posteo.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 drivers/rtc/rtc-x1205.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/rtc-x1205.c b/drivers/rtc/rtc-x1205.c
index b1de58e0b3d0..5638b7ba8b06 100644
--- a/drivers/rtc/rtc-x1205.c
+++ b/drivers/rtc/rtc-x1205.c
@@ -22,6 +22,7 @@
 #include <linux/rtc.h>
 #include <linux/delay.h>
 #include <linux/module.h>
+#include <linux/bitops.h>
 
 #define DRV_VERSION "1.0.8"
 
@@ -366,8 +367,7 @@ static int x1205_get_atrim(struct i2c_client *client, int *trim)
 	 * perform sign extension. The formula is
 	 * Catr = (atr * 0.25pF) + 11.00pF.
 	 */
-	if (atr & 0x20)
-		atr |= 0xC0;
+	atr = sign_extend32(atr, 5);
 
 	dev_dbg(&client->dev, "%s: raw atr=%x (%d)\n", __func__, atr, atr);
 
-- 
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