[PATCH] watchdog: sunplus: fix sp_wdt_restart spin loop and timeout

[Andrew Gaylard <ag@ffroot.co.za>]

sp_wdt_restart() returns immediately after writing WDT_RESUME. The
kernel continues executing and the watchdog kthread could pet the
watchdog before the short timeout expired, preventing reset.

Add a spin loop so no other CPU can pet the watchdog while waiting for
the reset. Set the restart timeout to ~1.5s.

Signed-off-by: Andrew Gaylard <ag@ffroot.co.za>
---
 drivers/watchdog/sunplus_wdt.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/sunplus_wdt.c b/drivers/watchdog/sunplus_wdt.c
index e5212f3d2e24..b44dcc307634 100644
--- a/drivers/watchdog/sunplus_wdt.c
+++ b/drivers/watchdog/sunplus_wdt.c
@@ -61,10 +61,16 @@ static int sp_wdt_restart(struct watchdog_device *wdev,
 
 	writel(WDT_STOP, base + WDT_CTRL);
 	writel(WDT_UNLOCK, base + WDT_CTRL);
-	writel(0x0001, base + WDT_CNT);
+	writel(0x20F5, base + WDT_CNT);	/* ~1.5s at 90kHz */
 	writel(WDT_LOCK, base + WDT_CTRL);
 	writel(WDT_RESUME, base + WDT_CTRL);
 
+	/* Spin until the watchdog resets us. This prevents any other CPU
+	 * from petting the watchdog.
+	 */
+	while (1)
+		cpu_relax();
+
 	return 0;
 }
 
-- 
2.53.0