From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
[ Upstream commit e990e12741877e9bfac402ca468f4007a75f6e2a ]
The datasheet says we must stop the timer before changing the clock
divider. This can happen when the restart handler is called while the
watchdog is running.
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Wim Van Sebroeck <wim@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/watchdog/renesas_wdt.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index 88d81feba4e6..d01efd342dc0 100644
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -77,12 +77,17 @@ static int rwdt_init_timeout(struct watchdog_device *wdev)
static int rwdt_start(struct watchdog_device *wdev)
{
struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
+ u8 val;
pm_runtime_get_sync(wdev->parent);
- rwdt_write(priv, 0, RWTCSRB);
- rwdt_write(priv, priv->cks, RWTCSRA);
+ /* Stop the timer before we modify any register */
+ val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
+ rwdt_write(priv, val, RWTCSRA);
+
rwdt_init_timeout(wdev);
+ rwdt_write(priv, priv->cks, RWTCSRA);
+ rwdt_write(priv, 0, RWTCSRB);
while (readb_relaxed(priv->base + RWTCSRA) & RWTCSRA_WRFLG)
cpu_relax();
--
2.19.1
