[WATCHDOG] max63xx: be careful when disabling the watchdog

When shutting down the watchdog timer, special care must be taken
not to overwrite other bits in the register, as it may be shared
with other peripherals.

For example, on the Arcom Vulcan, the register is shared between
the watchdog and the PCI reset line...

Signed-off-by: Marc Zyngier <maz@misterjones.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/watchdog/max63xx_wdt.c b/drivers/watchdog/max63xx_wdt.c
index 75f3a83c0361..3053ff05ca41 100644
--- a/drivers/watchdog/max63xx_wdt.c
+++ b/drivers/watchdog/max63xx_wdt.c
@@ -154,9 +154,14 @@ static void max63xx_wdt_enable(struct max63xx_timeout *entry)
 
 static void max63xx_wdt_disable(void)
 {
+	u8 val;
+
 	spin_lock(&io_lock);
 
-	__raw_writeb(3, wdt_base);
+	val = __raw_readb(wdt_base);
+	val &= ~MAX6369_WDSET;
+	val |= 3;
+	__raw_writeb(val, wdt_base);
 
 	spin_unlock(&io_lock);