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>
diff --git a/drivers/rtc/rtc-x1205.c b/drivers/rtc/rtc-x1205.c
index b1de58e..5638b7b 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 @@
* 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);