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authorScott Valentine <svalentine@concentris-systems.com>2009-11-11 17:26:49 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2009-11-12 10:25:59 -0500
commitbcb3a1676b87effbdeffe8da5c44f63433d158d9 (patch)
tree179eaa6692cad02a1e2b4c15a6919061aa06dd8d /drivers/rtc/rtc-v3020.c
parent61df33370c52633b47d794f5e024eb15ca9a2efe (diff)
rtc: v3020: fix v3020_mmio_read_bit()
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 <a.zummo@towertech.it> Cc: Paul Gortmaker <p_gortmaker@yahoo.com> Cc: Raphael Assenat <raph@8d.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/rtc/rtc-v3020.c')
-rw-r--r--drivers/rtc/rtc-v3020.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-v3020.c b/drivers/rtc/rtc-v3020.c
index ad164056feb6..423cd5a30b10 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)
96 96
97static unsigned char v3020_mmio_read_bit(struct v3020 *chip) 97static unsigned char v3020_mmio_read_bit(struct v3020 *chip)
98{ 98{
99 return readl(chip->ioaddress) & (1 << chip->leftshift); 99 return !!(readl(chip->ioaddress) & (1 << chip->leftshift));
100} 100}
101 101
102static struct v3020_chip_ops v3020_mmio_ops = { 102static struct v3020_chip_ops v3020_mmio_ops = {