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watchdog: renesas_wdt: don't set divider while watchdog is running 

[ Upstream commit e990e12741 ]

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@sang-engineering.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Wolfram Sang 2018-11-07 20:46:02 +01:00 committed by Greg Kroah-Hartman
parent 03a127ef9b
commit 18ddd41b3e
1 changed files with 7 additions and 2 deletions
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9
drivers/watchdog/renesas_wdt.c
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@ -74,12 +74,17 @@ 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();