watchdog: sch311x_wdt: Fix Polarity when starting watchdog

Some motherboards like the Advantech ARK3400 documentation
use a non-inverted GPIO pin. We fix this by assuming that
the BIOS will set the Polarity bit for the GPIO correctly
at startup and we keep the Bit-setting intact when we start
and stop the watchdog.

Reported-by: Jean-François Deverge <jf.deverge@gmail.com>
Signed-off-by: Dave Mueller <d.mueller@elsoft.ch>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/watchdog/sch311x_wdt.c b/drivers/watchdog/sch311x_wdt.c
index f8477002b728..9681ada0f252 100644
--- a/drivers/watchdog/sch311x_wdt.c
+++ b/drivers/watchdog/sch311x_wdt.c
@@ -136,6 +136,8 @@ static void sch311x_wdt_set_timeout(int t)
 
 static void sch311x_wdt_start(void)
 {
+        unsigned char t;
+
         spin_lock(&sch311x_wdt_data.io_lock);
 
         /* set watchdog's timeout */
@@ -149,7 +151,8 @@ static void sch311x_wdt_start(void)
          * Bit 4-6  (Reserved)
          * Bit 7,   Output Type: 0 = Push Pull Bit, 1 = Open Drain
          */
-        outb(0x0e, sch311x_wdt_data.runtime_reg + GP60);
+        t = inb(sch311x_wdt_data.runtime_reg + GP60);
+        outb((t & ~0x0d) | 0x0c, sch311x_wdt_data.runtime_reg + GP60);
 
         spin_unlock(&sch311x_wdt_data.io_lock);
 
@@ -157,10 +160,13 @@ static void sch311x_wdt_start(void)
 
 static void sch311x_wdt_stop(void)
 {
+        unsigned char t;
+
         spin_lock(&sch311x_wdt_data.io_lock);
 
         /* stop the watchdog */
-        outb(0x01, sch311x_wdt_data.runtime_reg + GP60);
+        t = inb(sch311x_wdt_data.runtime_reg + GP60);
+        outb((t & ~0x0d) | 0x01, sch311x_wdt_data.runtime_reg + GP60);
         /* disable timeout by setting it to 0 */
         sch311x_wdt_set_timeout(0);