watchdog: core: add restart handler support
Many watchdog drivers implement the same code to register a restart
handler. This patch provides a generic way to set such a function.
The patch adds a new restart watchdog operation. If a restart priority
greater than 0 is needed, the driver can call
watchdog_set_restart_priority to set it.
Suggested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 873f139..88a34ef 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -32,6 +32,7 @@
#include <linux/types.h> /* For standard types */
#include <linux/errno.h> /* For the -ENODEV/... values */
#include <linux/kernel.h> /* For printk/panic/... */
+#include <linux/reboot.h> /* For restart handler */
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/init.h> /* For __init/__exit/... */
#include <linux/idr.h> /* For ida_* macros */
@@ -137,6 +138,41 @@
}
EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+static int watchdog_restart_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
+ restart_nb);
+
+ int ret;
+
+ ret = wdd->ops->restart(wdd);
+ if (ret)
+ return NOTIFY_BAD;
+
+ return NOTIFY_DONE;
+}
+
+/**
+ * watchdog_set_restart_priority - Change priority of restart handler
+ * @wdd: watchdog device
+ * @priority: priority of the restart handler, should follow these guidelines:
+ * 0: use watchdog's restart function as last resort, has limited restart
+ * capabilies
+ * 128: default restart handler, use if no other handler is expected to be
+ * available and/or if restart is sufficient to restart the entire system
+ * 255: preempt all other handlers
+ *
+ * If a wdd->ops->restart function is provided when watchdog_register_device is
+ * called, it will be registered as a restart handler with the priority given
+ * here.
+ */
+void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
+{
+ wdd->restart_nb.priority = priority;
+}
+EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
+
static int __watchdog_register_device(struct watchdog_device *wdd)
{
int ret, id = -1, devno;
@@ -202,6 +238,15 @@
return ret;
}
+ if (wdd->ops->restart) {
+ wdd->restart_nb.notifier_call = watchdog_restart_notifier;
+
+ ret = register_restart_handler(&wdd->restart_nb);
+ if (ret)
+ dev_warn(wdd->dev, "Cannot register restart handler (%d)\n",
+ ret);
+ }
+
return 0;
}
@@ -238,6 +283,9 @@
if (wdd == NULL)
return;
+ if (wdd->ops->restart)
+ unregister_restart_handler(&wdd->restart_nb);
+
devno = wdd->cdev.dev;
ret = watchdog_dev_unregister(wdd);
if (ret)