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watchdog: introduce CONFIG_WATCHDOG_OPEN_TIMEOUT 

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>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Rasmus Villemoes 2019-06-05 14:06:43 +00:00 committed by Wim Van Sebroeck
parent 4d1c6a0ec2
commit 487e4e0822
3 changed files with 16 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/watchdog/watchdog-parameters.txt
View File

@ -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 running 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.
-------------------------------------------------

9
drivers/watchdog/Kconfig
View File

@ -58,6 +58,15 @@ config WATCHDOG_HANDLE_BOOT_ENABLED
the watchdog on its own. Thus if your userspace does not start fast
enough your device will reboot.
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".
config WATCHDOG_SYSFS
bool "Read different watchdog information through sysfs"
help

5
drivers/watchdog/watchdog_dev.c
View File

@ -88,7 +88,7 @@ static struct kthread_worker *watchdog_kworker;
static bool handle_boot_enabled =
IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
static unsigned open_timeout;
static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
{
@ -1214,4 +1214,5 @@ MODULE_PARM_DESC(handle_boot_enabled,
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=0)");
"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
__MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");