watchdog: sp805: fix restart handler

The restart handler is missing two things, first, the registers
has to be unlocked and second there is no synchronization for the
write_relaxed() calls.

This was tested on a custom board with the NXP LS1028A SoC.

Fixes: 6c5c0d48b686c ("watchdog: sp805: add restart handler")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200327162450.28506-1-michael@walle.cc
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
index 53e0492..190d26e 100644 (file)
--- a/drivers/watchdog/sp805_wdt.c
+++ b/drivers/watchdog/sp805_wdt.c
@@ -137,10 +137,14 @@ wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
 {
        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 
+       writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
        writel_relaxed(0, wdt->base + WDTCONTROL);
        writel_relaxed(0, wdt->base + WDTLOAD);
        writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
 
+       /* Flush posted writes. */
+       readl_relaxed(wdt->base + WDTLOCK);
+
        return 0;
 }