watchdog: watchdog_core: Add watchdog registration deferral mechanism
Currently, watchdog subsystem require the misc subsystem to
register a watchdog. This may not be the case in case of an
early registration of a watchdog, which can be required when
the watchdog cannot be disabled.
This patch introduces a deferral mechanism to remove this requirement.
Signed-off-by: Jean-Baptiste Theou <jtheou@adeneo-embedded.us>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index a0438f3..d8b0d33 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -36,6 +36,10 @@
device. The parameter of this routine is the pointer to the registered
watchdog_device structure.
+The watchdog subsystem includes an registration deferral mechanism,
+which allows you to register an watchdog as early as you wish during
+the boot process.
+
The watchdog device structure looks like this:
struct watchdog_device {
@@ -52,6 +56,7 @@
void *driver_data;
struct mutex lock;
unsigned long status;
+ struct list_head deferred;
};
It contains following fields:
@@ -80,6 +85,8 @@
information about the status of the device (Like: is the watchdog timer
running/active, is the nowayout bit set, is the device opened via
the /dev/watchdog interface or not, ...).
+* deferred: entry in wtd_deferred_reg_list which is used to
+ register early initialized watchdogs.
The list of watchdog operations is defined as: