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 function is 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 	/* optional operations */
48 	int (*stop)(struct watchdog_device *);
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 */
watchdog_active(struct watchdog_device * wdd)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  */
watchdog_hw_running(struct watchdog_device * wdd)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 */
watchdog_set_nowayout(struct watchdog_device * wdd,bool nowayout)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 */
watchdog_stop_on_reboot(struct watchdog_device * wdd)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 */
watchdog_stop_on_unregister(struct watchdog_device * wdd)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 */
watchdog_timeout_invalid(struct watchdog_device * wdd,unsigned int t)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 */
watchdog_pretimeout_invalid(struct watchdog_device * wdd,unsigned int t)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 */
watchdog_set_drvdata(struct watchdog_device * wdd,void * data)186 static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
187 {
188 	wdd->driver_data = data;
189 }
190 
watchdog_get_drvdata(struct watchdog_device * wdd)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
watchdog_notify_pretimeout(struct watchdog_device * wdd)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 int watchdog_set_last_hw_keepalive(struct watchdog_device *, unsigned int);
214 
215 /* devres register variant */
216 int devm_watchdog_register_device(struct device *dev, struct watchdog_device *);
217 
218 #endif  /* ifndef _LINUX_WATCHDOG_H */
219