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 struct watchdog_device {
95 int id;
96 struct device *parent;
97 const struct attribute_group **groups;
98 const struct watchdog_info *info;
99 const struct watchdog_ops *ops;
100 const struct watchdog_governor *gov;
101 unsigned int bootstatus;
102 unsigned int timeout;
103 unsigned int pretimeout;
104 unsigned int min_timeout;
105 unsigned int max_timeout;
106 unsigned int min_hw_heartbeat_ms;
107 unsigned int max_hw_heartbeat_ms;
108 struct notifier_block reboot_nb;
109 struct notifier_block restart_nb;
110 void *driver_data;
111 struct watchdog_core_data *wd_data;
112 unsigned long status;
113 /* Bit numbers for status flags */
114 #define WDOG_ACTIVE 0 /* Is the watchdog running/active */
115 #define WDOG_NO_WAY_OUT 1 /* Is 'nowayout' feature set ? */
116 #define WDOG_STOP_ON_REBOOT 2 /* Should be stopped on reboot */
117 #define WDOG_HW_RUNNING 3 /* True if HW watchdog running */
118 #define WDOG_STOP_ON_UNREGISTER 4 /* Should be stopped on unregister */
119 struct list_head deferred;
120 };
121
122 #define WATCHDOG_NOWAYOUT IS_BUILTIN(CONFIG_WATCHDOG_NOWAYOUT)
123 #define WATCHDOG_NOWAYOUT_INIT_STATUS (WATCHDOG_NOWAYOUT << WDOG_NO_WAY_OUT)
124
125 /* Use the following function to check whether or not the watchdog is active */
126 static inline bool watchdog_active(struct watchdog_device *wdd)
127 {
128 return test_bit(WDOG_ACTIVE, &wdd->status);
129 }
130
131 /*
132 * Use the following function to check whether or not the hardware watchdog
133 * is running
134 */
135 static inline bool watchdog_hw_running(struct watchdog_device *wdd)
136 {
137 return test_bit(WDOG_HW_RUNNING, &wdd->status);
138 }
139
140 /* Use the following function to set the nowayout feature */
141 static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool nowayout)
142 {
143 if (nowayout)
144 set_bit(WDOG_NO_WAY_OUT, &wdd->status);
145 }
146
147 /* Use the following function to stop the watchdog on reboot */
148 static inline void watchdog_stop_on_reboot(struct watchdog_device *wdd)
149 {
150 set_bit(WDOG_STOP_ON_REBOOT, &wdd->status);
151 }
152
153 /* Use the following function to stop the watchdog when unregistering it */
154 static inline void watchdog_stop_on_unregister(struct watchdog_device *wdd)
155 {
156 set_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status);
157 }
158
159 /* Use the following function to check if a timeout value is invalid */
160 static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
161 {
162 /*
163 * The timeout is invalid if
164 * - the requested value is larger than UINT_MAX / 1000
165 * (since internal calculations are done in milli-seconds),
166 * or
167 * - the requested value is smaller than the configured minimum timeout,
168 * or
169 * - a maximum hardware timeout is not configured, a maximum timeout
170 * is configured, and the requested value is larger than the
171 * configured maximum timeout.
172 */
173 return t > UINT_MAX / 1000 || t < wdd->min_timeout ||
174 (!wdd->max_hw_heartbeat_ms && wdd->max_timeout &&
175 t > wdd->max_timeout);
176 }
177
178 /* Use the following function to check if a pretimeout value is invalid */
179 static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
180 unsigned int t)
181 {
182 return t && wdd->timeout && t >= wdd->timeout;
183 }
184
185 /* Use the following functions to manipulate watchdog driver specific data */
186 static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
187 {
188 wdd->driver_data = data;
189 }
190
191 static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
192 {
193 return wdd->driver_data;
194 }
195
196 /* Use the following functions to report watchdog pretimeout event */
197 #if IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)
198 void watchdog_notify_pretimeout(struct watchdog_device *wdd);
199 #else
200 static inline void watchdog_notify_pretimeout(struct watchdog_device *wdd)
201 {
202 pr_alert("watchdog%d: pretimeout event\n", wdd->id);
203 }
204 #endif
205
206 /* drivers/watchdog/watchdog_core.c */
207 void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority);
208 extern int watchdog_init_timeout(struct watchdog_device *wdd,
209 unsigned int timeout_parm, struct device *dev);
210 extern int watchdog_register_device(struct watchdog_device *);
211 extern void watchdog_unregister_device(struct watchdog_device *);
212
213 /* devres register variant */
214 int devm_watchdog_register_device(struct device *dev, struct watchdog_device *);
215
216 #endif /* ifndef _LINUX_WATCHDOG_H */