include/linux/watchdog.h

   1 /*
   2  *      Generic watchdog defines. Derived from..
   3  *
   4  * Berkshire PC Watchdog Defines
   5  * by Ken Hollis <khollis@bitgate.com>
   6  *
   7  */
   8 #ifndef _LINUX_WATCHDOG_H
   9 #define _LINUX_WATCHDOG_H
  10
  11
  12 #include <linux/bitops.h>
  13 #include <linux/cdev.h>
  14 #include <linux/device.h>
  15 #include <linux/kernel.h>
  16 #include <linux/notifier.h>
  17 #include <uapi/linux/watchdog.h>
  18
  19 struct watchdog_ops;
  20 struct watchdog_device;
  21 struct watchdog_core_data;
  22
  23 /** struct watchdog_ops - The watchdog-devices operations
  24  *
  25  * @owner:      The module owner.
  26  * @start:      The routine for starting the watchdog device.
  27  * @stop:       The routine for stopping the watchdog device.
  28  * @ping:       The routine that sends a keepalive ping to the watchdog device.
  29  * @status:     The routine that shows the status of the watchdog device.
  30  * @set_timeout:The routine for setting the watchdog devices timeout value (in seconds).
  31  * @get_timeleft:The routine that gets the time left before a reset (in seconds).
  32  * @restart:    The routine for restarting the machine.
  33  * @ioctl:      The routines that handles extra ioctl calls.
  34  *
  35  * The watchdog_ops structure contains a list of low-level operations
  36  * that control a watchdog device. It also contains the module that owns
  37  * these operations. The start and stop function are mandatory, all other
  38  * functions are optional.
  39  */
  40 struct watchdog_ops {
  41         struct module *owner;
  42         /* mandatory operations */
  43         int (*start)(struct watchdog_device *);
  44         int (*stop)(struct watchdog_device *);
  45         /* optional operations */
  46         int (*ping)(struct watchdog_device *);
  47         unsigned int (*status)(struct watchdog_device *);
  48         int (*set_timeout)(struct watchdog_device *, unsigned int);
  49         unsigned int (*get_timeleft)(struct watchdog_device *);
  50         int (*restart)(struct watchdog_device *, unsigned long, void *);
  51         long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
  52 };
  53
  54 /** struct watchdog_device - The structure that defines a watchdog device
  55  *
  56  * @id:         The watchdog's ID. (Allocated by watchdog_register_device)
  57  * @parent:     The parent bus device
  58  * @groups:     List of sysfs attribute groups to create when creating the
  59  *              watchdog device.
  60  * @info:       Pointer to a watchdog_info structure.
  61  * @ops:        Pointer to the list of watchdog operations.
  62  * @bootstatus: Status of the watchdog device at boot.
  63  * @timeout:    The watchdog devices timeout value (in seconds).
  64  * @min_timeout:The watchdog devices minimum timeout value (in seconds).
  65  * @max_timeout:The watchdog devices maximum timeout value (in seconds)
  66  *              as configurable from user space. Only relevant if
  67  *              max_hw_heartbeat_ms is not provided.
  68  * @max_hw_heartbeat_ms:
  69  *              Hardware limit for maximum timeout, in milli-seconds.
  70  *              Replaces max_timeout if specified.
  71  * @reboot_nb:  The notifier block to stop watchdog on reboot.
  72  * @restart_nb: The notifier block to register a restart function.
  73  * @driver_data:Pointer to the drivers private data.
  74  * @wd_data:    Pointer to watchdog core internal data.
  75  * @status:     Field that contains the devices internal status bits.
  76  * @deferred:   Entry in wtd_deferred_reg_list which is used to
  77  *              register early initialized watchdogs.
  78  *
  79  * The watchdog_device structure contains all information about a
  80  * watchdog timer device.
  81  *
  82  * The driver-data field may not be accessed directly. It must be accessed
  83  * via the watchdog_set_drvdata and watchdog_get_drvdata helpers.
  84  *
  85  * The lock field is for watchdog core internal use only and should not be
  86  * touched.
  87  */
  88 struct watchdog_device {
  89         int id;
  90         struct device *parent;
  91         const struct attribute_group **groups;
  92         const struct watchdog_info *info;
  93         const struct watchdog_ops *ops;
  94         unsigned int bootstatus;
  95         unsigned int timeout;
  96         unsigned int min_timeout;
  97         unsigned int max_timeout;
  98         unsigned int max_hw_heartbeat_ms;
  99         struct notifier_block reboot_nb;
 100         struct notifier_block restart_nb;
 101         void *driver_data;
 102         struct watchdog_core_data *wd_data;
 103         unsigned long status;
 104 /* Bit numbers for status flags */
 105 #define WDOG_ACTIVE             0       /* Is the watchdog running/active */
 106 #define WDOG_NO_WAY_OUT         1       /* Is 'nowayout' feature set ? */
 107 #define WDOG_STOP_ON_REBOOT     2       /* Should be stopped on reboot */
 108         struct list_head deferred;
 109 };
 110
 111 #define WATCHDOG_NOWAYOUT               IS_BUILTIN(CONFIG_WATCHDOG_NOWAYOUT)
 112 #define WATCHDOG_NOWAYOUT_INIT_STATUS   (WATCHDOG_NOWAYOUT << WDOG_NO_WAY_OUT)
 113
 114 /* Use the following function to check whether or not the watchdog is active */
 115 static inline bool watchdog_active(struct watchdog_device *wdd)
 116 {
 117         return test_bit(WDOG_ACTIVE, &wdd->status);
 118 }
 119
 120 /* Use the following function to set the nowayout feature */
 121 static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
 122 {
 123         if (nowayout)
 124                 set_bit(WDOG_NO_WAY_OUT, &wdd->status);
 125 }
 126
 127 /* Use the following function to stop the watchdog on reboot */
 128 static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
 129 {
 130         set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
 131 }
 132
 133 /* Use the following function to check if a timeout value is invalid */
 134 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
 135 {
 136         /*
 137          * The timeout is invalid if
 138          * - the requested value is larger than UINT_MAX / 1000
 139          *   (since internal calculations are done in milli-seconds),
 140          * or
 141          * - the requested value is smaller than the configured minimum timeout,
 142          * or
 143          * - a maximum hardware timeout is not configured, a maximum timeout
 144          *   is configured, and the requested value is larger than the
 145          *   configured maximum timeout.
 146          */
 147         return t > UINT_MAX / 1000 || t < wdd->min_timeout ||
 148                 (!wdd->max_hw_heartbeat_ms && wdd->max_timeout &&
 149                  t > wdd->max_timeout);
 150 }
 151
 152 /* Use the following functions to manipulate watchdog driver specific data */
 153 static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
 154 {
 155         wdd->driver_data = data;
 156 }
 157
 158 static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
 159 {
 160         return wdd->driver_data;
 161 }
 162
 163 /* drivers/watchdog/watchdog_core.c */
 164 void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
 165 extern int watchdog_init_timeout(struct watchdog_device *wdd,
 166                                   unsigned int timeout_parm, struct device *dev);
 167 extern int watchdog_register_device(struct watchdog_device *);
 168 extern void watchdog_unregister_device(struct watchdog_device *);
 169
 170 #endif  /* ifndef _LINUX_WATCHDOG_H */