rtc: v3020: fix v3020_mmio_read_bit()

bcb3a167 · Scott Valentine <[email protected]> · 2009-11-11 14:26:49 -08:00

v3020_mmio_read_bit() always returns 0 when left_shift > 7.

v3020_mmio_read_bit()'s return type is (unsigned char).  The code returns
a value masked by (1 << left_shift) that is casted to the return type.  If
left_shift is larger than 7, the cast will always result in a 0 return
value.  The problem was discovered with left_shift = 16, and the included
patch corrects the problem.

The bug was introduced in the last (Apr 3 2009) commit of the file, kernel
versions 2.6.30 and later.

Cc: Alessandro Zummo <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Raphael Assenat <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: bcb3a1676b87effbdeffe8da5c44f63433d158d9
Parents: 61df3337

Changes

1 files changed · +1 −1

File	Status	Add	Del	Content
drivers/rtc/rtc-v3020.c	modified	+1	−1	View file

drivers/rtc/rtc-v3020.c

View file

diff --git a/drivers/rtc/rtc-v3020.c b/drivers/rtc/rtc-v3020.c
index ad16405..423cd5a 100644
--- a/drivers/rtc/rtc-v3020.c
+++ b/drivers/rtc/rtc-v3020.c
@@ -96,7 +96,7 @@ static void v3020_mmio_write_bit(struct v3020 *chip, unsigned char bit)
 
 static unsigned char v3020_mmio_read_bit(struct v3020 *chip)
 {
-	return readl(chip->ioaddress) & (1 << chip->leftshift);
+	return !!(readl(chip->ioaddress) & (1 << chip->leftshift));
 }
 
 static struct v3020_chip_ops v3020_mmio_ops = {