From: Christophe Roullier <christophe.roullier@st.com>
To: <wim@linux-watchdog.org>, <linux@roeck-us.net>,
<mcoquelin.stm32@gmail.com>, <alexandre.torgue@st.com>
Cc: <linux-watchdog@vger.kernel.org>, <christophe.roullier@st.com>,
<linux-kernel@vger.kernel.org>,
<linux-stm32@st-md-mailman.stormreply.com>,
<linux-arm-kernel@lists.infradead.org>
Subject: [PATCH v3 1/1] drivers: watchdog: stm32_iwdg: set WDOG_HW_RUNNING at probe
Date: Fri, 22 Nov 2019 14:22:46 +0100 [thread overview]
Message-ID: <20191122132246.8473-1-christophe.roullier@st.com> (raw)
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>
---
Changes since v2:
According to Guenter
removed intermediate variable
I've tested some config and it is working as expected:
Watchdog enable in Uboot + HANDLE_BOOT_ENABLE is not set + daemon watchdog in userland ON ==> No reset IWDG2
Watchdog enable in Uboot + HANDLE_BOOT_ENABLE is not set ==> Reset IWDG2
Watchdog enable in Uboot + HANDLE_BOOT_ENABLE=y ==> No reset IWDG2
Watchdog enable in Uboot + HANDLE_BOOT_ENABLE=y + daemon watchdog in userland ON puis OFF ==> Reset IWDG2
Watchdog disable in Uboot + HANDLE_BOOT_ENABLE is not set ==> No reset IWDG2
Watchdog disable in Uboot + HANDLE_BOOT_ENABLE=y ==> No reset IWDG2
Watchdog disable in Uboot + HANDLE_BOOT_ENABLE=y + daemon watchdog in userland ON ==> No reset IWDG2
Watchdog disable in Uboot + HANDLE_BOOT_ENABLE=y + daemon watchdog in userland ON puis OFF ==> Reset IWDG2
Thanks,
Christophe
drivers/watchdog/stm32_iwdg.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/watchdog/stm32_iwdg.c b/drivers/watchdog/stm32_iwdg.c
index a3a329011a06..25188d6bbe15 100644
--- 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;
--
2.17.1
next reply other threads:[~2019-11-22 13:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-22 13:22 Christophe Roullier [this message]
2019-11-22 18:15 ` [PATCH v3 1/1] drivers: watchdog: stm32_iwdg: set WDOG_HW_RUNNING at probe Guenter Roeck
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