drivers: watchdog: stm32_iwdg: set WDOG_HW_RUNNING at probe

If the watchdog hardware is already enabled during the boot process,
when the Linux watchdog driver loads, it should start/reset the watchdog
and tell the watchdog framework. As a result, ping can be generated from
the watchdog framework (if CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set),
until the userspace watchdog daemon takes over control

Fixes:4332d113c66a ("watchdog: Add STM32 IWDG driver")

Signed-off-by: Christophe Roullier <christophe.roullier@st.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20191122132246.8473-1-christophe.roullier@st.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
index a3a3290..25188d6 100644 (file)
--- a/drivers/watchdog/stm32_iwdg.c
+++ b/drivers/watchdog/stm32_iwdg.c
@@ -262,6 +262,24 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
        watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
        watchdog_init_timeout(wdd, 0, dev);
 
+       /*
+        * In case of CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set
+        * (Means U-Boot/bootloaders leaves the watchdog running)
+        * When we get here we should make a decision to prevent
+        * any side effects before user space daemon will take care of it.
+        * The best option, taking into consideration that there is no
+        * way to read values back from hardware, is to enforce watchdog
+        * being run with deterministic values.
+        */
+       if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) {
+               ret = stm32_iwdg_start(wdd);
+               if (ret)
+                       return ret;
+
+               /* Make sure the watchdog is serviced */
+               set_bit(WDOG_HW_RUNNING, &wdd->status);
+       }
+
        ret = devm_watchdog_register_device(dev, wdd);
        if (ret)
                return ret;