diff options
Diffstat (limited to 'Documentation/watchdog/watchdog-kernel-api.txt')
| -rw-r--r-- | Documentation/watchdog/watchdog-kernel-api.txt | 45 |
1 files changed, 7 insertions, 38 deletions
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt index 0a37da76acef..72a009478b15 100644 --- a/Documentation/watchdog/watchdog-kernel-api.txt +++ b/Documentation/watchdog/watchdog-kernel-api.txt @@ -44,7 +44,6 @@ The watchdog device structure looks like this: struct watchdog_device { int id; - struct cdev cdev; struct device *dev; struct device *parent; const struct watchdog_info *info; @@ -56,7 +55,7 @@ struct watchdog_device { 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; }; @@ -66,8 +65,6 @@ It contains following fields: /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. @@ -89,11 +86,10 @@ It contains following fields: * 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. @@ -110,8 +106,8 @@ struct watchdog_ops { 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 *); + void (*ref)(struct watchdog_device *) __deprecated; + void (*unref)(struct watchdog_device *) __deprecated; long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long); }; @@ -120,20 +116,6 @@ driver's operations. This module owner will be used to lock the module when 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 @@ -176,34 +158,21 @@ they are supported. These optional routines/operations are: * 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 - allocated watchdog_device struct. * 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: |