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From:   Rasmus Villemoes <rasmus.villemoes@prevas.dk>
To:     "linux-watchdog@vger.kernel.org" <linux-watchdog@vger.kernel.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Jonathan Corbet <corbet@lwn.net>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
        Esben Haabendal <esben@haabendal.dk>,
        "martin@hundeboll.net" <martin@hundeboll.net>,
        Rasmus Villemoes <Rasmus.Villemoes@prevas.se>
Subject: [PATCH v9 2/3] watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT
Thread-Topic: [PATCH v9 2/3] watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT
Thread-Index: AQHUscpFh+km+iXtz0aqhI2t954lPQ==
Date:   Mon, 21 Jan 2019 20:45:40 +0000
Message-ID: <20190121204527.5548-3-rasmus.villemoes@prevas.dk>
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This allows setting a default value for the watchdog.open_timeout
commandline parameter via Kconfig.

Some BSPs allow remote updating of the kernel image and root file
system, but updating the bootloader requires physical access. Hence, if
one has a firmware update that requires relaxing the
watchdog.open_timeout a little, the value used must be baked into the
kernel image itself and cannot come from the u-boot environment via the
kernel command line.

Being able to set the initial value in .config doesn't change the fact
that the value on the command line, if present, takes precedence, and is
of course immensely useful for development purposes while one has
console acccess, as well as usable in the cases where one can make a
permanent update of the kernel command line.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
---
 Documentation/watchdog/watchdog-parameters.txt | 8 ++++----
 drivers/watchdog/Kconfig                       | 9 +++++++++
 drivers/watchdog/watchdog_dev.c                | 5 +++--
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/Documentation/watchdog/watchdog-parameters.txt b/Documentation=
/watchdog/watchdog-parameters.txt
index 907c4bb13810..2fdbd07f9791 100644
--- a/Documentation/watchdog/watchdog-parameters.txt
+++ b/Documentation/watchdog/watchdog-parameters.txt
@@ -11,10 +11,10 @@ modules.
 The watchdog core parameter watchdog.open_timeout is the maximum time,
 in seconds, for which the watchdog framework will take care of pinging
 a hardware watchdog until userspace opens the corresponding
-/dev/watchdogN device. A value of 0 (the default) means an infinite
-timeout. Setting this to a non-zero value can be useful to ensure that
-either userspace comes up properly, or the board gets reset and allows
-fallback logic in the bootloader to try something else.
+/dev/watchdogN device. A value of 0 means an infinite timeout. Setting
+this to a non-zero value can be useful to ensure that either userspace
+comes up properly, or the board gets reset and allows fallback logic
+in the bootloader to try something else.
=20
=20
 -------------------------------------------------
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 57f017d74a97..e1de5beb4e80 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -63,6 +63,15 @@ config WATCHDOG_SYSFS
 	  Say Y here if you want to enable watchdog device status read through
 	  sysfs attributes.
=20
+config WATCHDOG_OPEN_TIMEOUT
+	int "Timeout value for opening watchdog device"
+	default 0
+	help
+	  The maximum time, in seconds, for which the watchdog framework takes
+	  care of pinging a hardware watchdog.  A value of 0 means infinite. The
+	  value set here can be overridden by the commandline parameter
+	  "watchdog.open_timeout".
+
 #
 # General Watchdog drivers
 #
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_de=
v.c
index ab2ad20f13eb..b763080741cc 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -88,7 +88,7 @@ static struct kthread_worker *watchdog_kworker;
 static bool handle_boot_enabled =3D
 	IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
=20
-static unsigned open_timeout;
+static unsigned open_timeout =3D CONFIG_WATCHDOG_OPEN_TIMEOUT;
=20
 static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
 {
@@ -1206,4 +1206,5 @@ MODULE_PARM_DESC(handle_boot_enabled,
=20
 module_param(open_timeout, uint, 0644);
 MODULE_PARM_DESC(open_timeout,
-	"Maximum time (in seconds, 0 means infinity) for userspace to take over a=
 running watchdog (default=3D0)");
+	"Maximum time (in seconds, 0 means infinity) for userspace to take over a=
 running watchdog (default=3D"
+	__MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");
--=20
2.20.1