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From 2165bf524da5f5e496d1cdb8c5afae1345ecce1e Mon Sep 17 00:00:00 2001
From: Damien Riegel <damien.riegel@savoirfairelinux.com>
Date: Mon, 16 Nov 2015 12:27:59 -0500
Subject: 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>
---
Documentation/watchdog/watchdog-kernel-api.txt | 19 ++++++++++
drivers/watchdog/watchdog_core.c | 48 ++++++++++++++++++++++++++
include/linux/watchdog.h | 6 ++++
3 files changed, 73 insertions(+)
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -53,6 +53,7 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ struct notifier_block restart_nb;
void *driver_data;
struct mutex lock;
unsigned long status;
@@ -75,6 +76,10 @@ It contains following fields:
* timeout: the watchdog timer's timeout value (in seconds).
* min_timeout: the watchdog timer's minimum timeout value (in seconds).
* max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* restart_nb: notifier block that is registered for machine restart, for
+ internal use only. If a watchdog is capable of restarting the machine, it
+ should define ops->restart. Priority can be changed through
+ watchdog_set_restart_priority.
* bootstatus: status of the device after booting (reported with watchdog
WDIOF_* status bits).
* driver_data: a pointer to the drivers private data of a watchdog device.
@@ -100,6 +105,7 @@ struct watchdog_ops {
unsigned int (*status)(struct watchdog_device *);
int (*set_timeout)(struct watchdog_device *, unsigned int);
unsigned int (*get_timeleft)(struct watchdog_device *);
+ int (*restart)(struct watchdog_device *);
void (*ref)(struct watchdog_device *);
void (*unref)(struct watchdog_device *);
long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
@@ -164,6 +170,8 @@ they are supported. These optional routi
(Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
watchdog's info structure).
* get_timeleft: this routines returns the time that's left before a reset.
+* restart: this routine restarts the machine. It returns 0 on success or a
+ negative errno code for failure.
* ref: the operation that calls kref_get on the kref of a dynamically
allocated watchdog_device struct.
* unref: the operation that calls kref_put on the kref of a dynamically
@@ -231,3 +239,14 @@ the device tree (if the module timeout p
to set the default timeout value as timeout value in the watchdog_device and
then use this function to set the user "preferred" timeout value.
This routine returns zero on success and a negative errno code for failure.
+
+To change the priority of the restart handler the following helper should be
+used:
+
+void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
+
+User should follow the following guidelines for setting the priority:
+* 0: should be called in last resort, has limited restart capabilities
+* 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: highest priority, will preempt all other restart handlers
--- 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 @@ int watchdog_init_timeout(struct watchdo
}
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 @@ static int __watchdog_register_device(st
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 @@ static void __watchdog_unregister_device
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)
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -12,6 +12,7 @@
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/cdev.h>
+#include <linux/notifier.h>
#include <uapi/linux/watchdog.h>
struct watchdog_ops;
@@ -26,6 +27,7 @@ struct watchdog_device;
* @status: The routine that shows the status of the watchdog device.
* @set_timeout:The routine for setting the watchdog devices timeout value (in seconds).
* @get_timeleft:The routine that gets the time left before a reset (in seconds).
+ * @restart: The routine for restarting the machine.
* @ref: The ref operation for dyn. allocated watchdog_device structs
* @unref: The unref operation for dyn. allocated watchdog_device structs
* @ioctl: The routines that handles extra ioctl calls.
@@ -45,6 +47,7 @@ struct watchdog_ops {
unsigned int (*status)(struct watchdog_device *);
int (*set_timeout)(struct watchdog_device *, unsigned int);
unsigned int (*get_timeleft)(struct watchdog_device *);
+ int (*restart)(struct watchdog_device *);
void (*ref)(struct watchdog_device *);
void (*unref)(struct watchdog_device *);
long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
@@ -62,6 +65,7 @@ struct watchdog_ops {
* @timeout: The watchdog devices timeout value (in seconds).
* @min_timeout:The watchdog devices minimum timeout value (in seconds).
* @max_timeout:The watchdog devices maximum timeout value (in seconds).
+ * @restart_nb: The notifier block to register a restart function.
* @driver-data:Pointer to the drivers private data.
* @lock: Lock for watchdog core internal use only.
* @status: Field that contains the devices internal status bits.
@@ -88,6 +92,7 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ struct notifier_block restart_nb;
void *driver_data;
struct mutex lock;
unsigned long status;
@@ -142,6 +147,7 @@ static inline void *watchdog_get_drvdata
}
/* drivers/watchdog/watchdog_core.c */
+void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
extern int watchdog_init_timeout(struct watchdog_device *wdd,
unsigned int timeout_parm, struct device *dev);
extern int watchdog_register_device(struct watchdog_device *);
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