struct watchdog_device {
int id;
- struct cdev cdev;
struct device *dev;
struct device *parent;
const struct watchdog_info *info;
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ struct notifier_block reboot_nb;
+ struct notifier_block restart_nb;
void *driver_data;
- struct mutex lock;
+ struct watchdog_core_data *wd_data;
unsigned long status;
struct list_head deferred;
};
/dev/watchdog0 cdev (dynamic major, minor 0) as well as the old
/dev/watchdog miscdev. The id is set automatically when calling
watchdog_register_device.
-* cdev: cdev for the dynamic /dev/watchdog<id> device nodes. This
- field is also populated by watchdog_register_device.
* dev: device under the watchdog class (created by watchdog_register_device).
* parent: set this to the parent device (or NULL) before calling
watchdog_register_device.
* 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).
+* reboot_nb: notifier block that is registered for reboot notifications, for
+ internal use only. If the driver calls watchdog_stop_on_reboot, watchdog core
+ will stop the watchdog on such notifications.
+* 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.
This data should only be accessed via the watchdog_set_drvdata and
watchdog_get_drvdata routines.
-* lock: Mutex for WatchDog Timer Driver Core internal use only.
+* wd_data: a pointer to watchdog core internal data.
* status: this field contains a number of status bits that give extra
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, ...).
+ running/active, or is the nowayout bit set).
* deferred: entry in wtd_deferred_reg_list which is used to
register early initialized watchdogs.
unsigned int (*status)(struct watchdog_device *);
int (*set_timeout)(struct watchdog_device *, unsigned int);
unsigned int (*get_timeleft)(struct watchdog_device *);
- void (*ref)(struct watchdog_device *);
- void (*unref)(struct watchdog_device *);
+ int (*restart)(struct watchdog_device *);
+ void (*ref)(struct watchdog_device *) __deprecated;
+ void (*unref)(struct watchdog_device *) __deprecated;
long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
};
the watchdog is active. (This to avoid a system crash when you unload the
module and /dev/watchdog is still open).
-If the watchdog_device struct is dynamically allocated, just locking the module
-is not enough and a driver also needs to define the ref and unref operations to
-ensure the structure holding the watchdog_device does not go away.
-
-The simplest (and usually sufficient) implementation of this is to:
-1) Add a kref struct to the same structure which is holding the watchdog_device
-2) Define a release callback for the kref which frees the struct holding both
-3) Call kref_init on this kref *before* calling watchdog_register_device()
-4) Define a ref operation calling kref_get on this kref
-5) Define a unref operation calling kref_put on this kref
-6) When it is time to cleanup:
- * Do not kfree() the struct holding both, the last kref_put will do this!
- * *After* calling watchdog_unregister_device() call kref_put on the kref
-
Some operations are mandatory and some are optional. The mandatory operations
are:
* start: this is a pointer to the routine that starts the watchdog timer
(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.
-* 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
- allocated watchdog_device struct.
+* restart: this routine restarts the machine. It returns 0 on success or a
+ negative errno code for failure.
* ioctl: if this routine is present then it will be called first before we do
our own internal ioctl call handling. This routine should return -ENOIOCTLCMD
if a command is not supported. The parameters that are passed to the ioctl
call are: watchdog_device, cmd and arg.
+The 'ref' and 'unref' operations are no longer used and deprecated.
+
The status bits should (preferably) be set with the set_bit and clear_bit alike
bit-operations. The status bits that are defined are:
* WDOG_ACTIVE: this status bit indicates whether or not a watchdog timer device
is active or not. When the watchdog is active after booting, then you should
set this status bit (Note: when you register the watchdog timer device with
this bit set, then opening /dev/watchdog will skip the start operation)
-* WDOG_DEV_OPEN: this status bit shows whether or not the watchdog device
- was opened via /dev/watchdog.
- (This bit should only be used by the WatchDog Timer Driver Core).
-* WDOG_ALLOW_RELEASE: this bit stores whether or not the magic close character
- has been sent (so that we can support the magic close feature).
- (This bit should only be used by the WatchDog Timer Driver Core).
* WDOG_NO_WAY_OUT: this bit stores the nowayout setting for the watchdog.
If this bit is set then the watchdog timer will not be able to stop.
-* WDOG_UNREGISTERED: this bit gets set by the WatchDog Timer Driver Core
- after calling watchdog_unregister_device, and then checked before calling
- any watchdog_ops, so that you can be sure that no operations (other then
- unref) will get called after unregister, even if userspace still holds a
- reference to /dev/watchdog
To set the WDOG_NO_WAY_OUT status bit (before registering your watchdog
timer device) you can either:
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 disable the watchdog on reboot, the user must call the following helper:
+
+static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd);
+
+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
projects / cascardo / linux.git / blobdiff