include/linux/watchdog.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  *      Generic watchdog defines. Derived from..
   4  *
   5  * Berkshire PC Watchdog Defines
   6  * by Ken Hollis <khollis@bitgate.com>
   7  *
   8  */
   9 #ifndef _LINUX_WATCHDOG_H
  10 #define _LINUX_WATCHDOG_H
  11
  12
  13 #include <linux/bitops.h>
  14 #include <linux/cdev.h>
  15 #include <linux/device.h>
  16 #include <linux/kernel.h>
  17 #include <linux/notifier.h>
  18 #include <uapi/linux/watchdog.h>
  19
  20 struct watchdog_ops;
  21 struct watchdog_device;
  22 struct watchdog_core_data;
  23 struct watchdog_governor;
  24
  25 /** struct watchdog_ops - The watchdog-devices operations
  26  *
  27  * @owner:      The module owner.
  28  * @start:      The routine for starting the watchdog device.
  29  * @stop:       The routine for stopping the watchdog device.
  30  * @ping:       The routine that sends a keepalive ping to the watchdog device.
  31  * @status:     The routine that shows the status of the watchdog device.
  32  * @set_timeout:The routine for setting the watchdog devices timeout value (in seconds).
  33  * @set_pretimeout:The routine for setting the watchdog devices pretimeout.
  34  * @get_timeleft:The routine that gets the time left before a reset (in seconds).
  35  * @restart:    The routine for restarting the machine.
  36  * @ioctl:      The routines that handles extra ioctl calls.
  37  *
  38  * The watchdog_ops structure contains a list of low-level operations
  39  * that control a watchdog device. It also contains the module that owns
  40  * these operations. The start and stop function are mandatory, all other
  41  * functions are optional.
  42  */
  43 struct watchdog_ops {
  44         struct module *owner;
  45         /* mandatory operations */
  46         int (*start)(struct watchdog_device *);
  47         int (*stop)(struct watchdog_device *);
  48         /* optional operations */
  49         int (*ping)(struct watchdog_device *);
  50         unsigned int (*status)(struct watchdog_device *);
  51         int (*set_timeout)(struct watchdog_device *, unsigned int);
  52         int (*set_pretimeout)(struct watchdog_device *, unsigned int);
  53         unsigned int (*get_timeleft)(struct watchdog_device *);
  54         int (*restart)(struct watchdog_device *, unsigned long, void *);
  55         long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
  56 };
  57
  58 /** struct watchdog_device - The structure that defines a watchdog device
  59  *
  60  * @id:         The watchdog's ID. (Allocated by watchdog_register_device)
  61  * @parent:     The parent bus device
  62  * @groups:     List of sysfs attribute groups to create when creating the
  63  *              watchdog device.
  64  * @info:       Pointer to a watchdog_info structure.
  65  * @ops:        Pointer to the list of watchdog operations.
  66  * @gov:        Pointer to watchdog pretimeout governor.
  67  * @bootstatus: Status of the watchdog device at boot.
  68  * @timeout:    The watchdog devices timeout value (in seconds).
  69  * @pretimeout: The watchdog devices pre_timeout value.
  70  * @min_timeout:The watchdog devices minimum timeout value (in seconds).
  71  * @max_timeout:The watchdog devices maximum timeout value (in seconds)
  72  *              as configurable from user space. Only relevant if
  73  *              max_hw_heartbeat_ms is not provided.
  74  * @min_hw_heartbeat_ms:
  75  *              Hardware limit for minimum time between heartbeats,
  76  *              in milli-seconds.
  77  * @max_hw_heartbeat_ms:
  78  *              Hardware limit for maximum timeout, in milli-seconds.
  79  *              Replaces max_timeout if specified.
  80  * @reboot_nb:  The notifier block to stop watchdog on reboot.
  81  * @restart_nb: The notifier block to register a restart function.
  82  * @driver_data:Pointer to the drivers private data.
  83  * @wd_data:    Pointer to watchdog core internal data.
  84  * @status:     Field that contains the devices internal status bits.
  85  * @deferred:   Entry in wtd_deferred_reg_list which is used to
  86  *              register early initialized watchdogs.
  87  *
  88  * The watchdog_device structure contains all information about a
  89  * watchdog timer device.
  90  *
  91  * The driver-data field may not be accessed directly. It must be accessed
  92  * via the watchdog_set_drvdata and watchdog_get_drvdata helpers.
  93  *
  94  * The lock field is for watchdog core internal use only and should not be
  95  * touched.
  96  */
  97 struct watchdog_device {
  98         int id;
  99         struct device *parent;
 100         const struct attribute_group **groups;
 101         const struct watchdog_info *info;
 102         const struct watchdog_ops *ops;
 103         const struct watchdog_governor *gov;
 104         unsigned int bootstatus;
 105         unsigned int timeout;
 106         unsigned int pretimeout;
 107         unsigned int min_timeout;
 108         unsigned int max_timeout;
 109         unsigned int min_hw_heartbeat_ms;
 110         unsigned int max_hw_heartbeat_ms;
 111         struct notifier_block reboot_nb;
 112         struct notifier_block restart_nb;
 113         void *driver_data;
 114         struct watchdog_core_data *wd_data;
 115         unsigned long status;
 116 /* Bit numbers for status flags */
 117 #define WDOG_ACTIVE             0       /* Is the watchdog running/active */
 118 #define WDOG_NO_WAY_OUT         1       /* Is 'nowayout' feature set ? */
 119 #define WDOG_STOP_ON_REBOOT     2       /* Should be stopped on reboot */
 120 #define WDOG_HW_RUNNING         3       /* True if HW watchdog running */
 121 #define WDOG_STOP_ON_UNREGISTER 4       /* Should be stopped on unregister */
 122         struct list_head deferred;
 123 };
 124
 125 #define WATCHDOG_NOWAYOUT               IS_BUILTIN(CONFIG_WATCHDOG_NOWAYOUT)
 126 #define WATCHDOG_NOWAYOUT_INIT_STATUS   (WATCHDOG_NOWAYOUT << WDOG_NO_WAY_OUT)
 127
 128 /* Use the following function to check whether or not the watchdog is active */
 129 static inline bool watchdog_active(struct watchdog_device *wdd)
 130 {
 131         return test_bit(WDOG_ACTIVE, &wdd->status);
 132 }
 133
 134 /*
 135  * Use the following function to check whether or not the hardware watchdog
 136  * is running
 137  */
 138 static inline bool watchdog_hw_running(struct watchdog_device *wdd)
 139 {
 140         return test_bit(WDOG_HW_RUNNING, &wdd->status);
 141 }
 142
 143 /* Use the following function to set the nowayout feature */
 144 static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
 145 {
 146         if (nowayout)
 147                 set_bit(WDOG_NO_WAY_OUT, &wdd->status);
 148 }
 149
 150 /* Use the following function to stop the watchdog on reboot */
 151 static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
 152 {
 153         set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
 154 }
 155
 156 /* Use the following function to stop the watchdog when unregistering it */
 157 static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd)
 158 {
 159         set_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status);
 160 }
 161
 162 /* Use the following function to check if a timeout value is invalid */
 163 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
 164 {
 165         /*
 166          * The timeout is invalid if
 167          * - the requested value is larger than UINT_MAX / 1000
 168          *   (since internal calculations are done in milli-seconds),
 169          * or
 170          * - the requested value is smaller than the configured minimum timeout,
 171          * or
 172          * - a maximum hardware timeout is not configured, a maximum timeout
 173          *   is configured, and the requested value is larger than the
 174          *   configured maximum timeout.
 175          */
 176         return t > UINT_MAX / 1000 || t < wdd->min_timeout ||
 177                 (!wdd->max_hw_heartbeat_ms && wdd->max_timeout &&
 178                  t > wdd->max_timeout);
 179 }
 180
 181 /* Use the following function to check if a pretimeout value is invalid */
 182 static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
 183                                                unsigned int t)
 184 {
 185         return t && wdd->timeout && t >= wdd->timeout;
 186 }
 187
 188 /* Use the following functions to manipulate watchdog driver specific data */
 189 static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
 190 {
 191         wdd->driver_data = data;
 192 }
 193
 194 static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
 195 {
 196         return wdd->driver_data;
 197 }
 198
 199 /* Use the following functions to report watchdog pretimeout event */
 200 #if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
 201 void watchdog_notify_pretimeout(struct watchdog_device *wdd);
 202 #else
 203 static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
 204 {
 205         pr_alert("watchdog%d: pretimeout event\n", wdd->id);
 206 }
 207 #endif
 208
 209 /* drivers/watchdog/watchdog_core.c */
 210 void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
 211 extern int watchdog_init_timeout(struct watchdog_device *wdd,
 212                                   unsigned int timeout_parm, struct device *dev);
 213 extern int watchdog_register_device(struct watchdog_device *);
 214 extern void watchdog_unregister_device(struct watchdog_device *);
 215
 216 /* devres register variant */
 217 int devm_watchdog_register_device(struct device *dev, struct watchdog_device *);
 218
 219 #endif  /* ifndef _LINUX_WATCHDOG_H */