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Subject[PATCH 5.4 81/96] drivers: watchdog: stm32_iwdg: set WDOG_HW_RUNNING at probe
Date
From: Christophe Roullier <christophe.roullier@st.com>

commit 85fdc63fe256b595f923a69848cd99972ff446d8 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/watchdog/stm32_iwdg.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

--- a/drivers/watchdog/stm32_iwdg.c
+++ b/drivers/watchdog/stm32_iwdg.c
@@ -262,6 +262,24 @@ static int stm32_iwdg_probe(struct platf
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;

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