summaryrefslogtreecommitdiff
path: root/include/wdt.h
blob: 9b90fbeeb3a304d44ce1149ffd7d1dc9899cc3c3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
/*
 * Copyright 2017 Google, Inc
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#ifndef _WDT_H_
#define _WDT_H_

/*
 * Implement a simple watchdog uclass. Watchdog is basically a timer that
 * is used to detect or recover from malfunction. During normal operation
 * the watchdog would be regularly reset to prevent it from timing out.
 * If, due to a hardware fault or program error, the computer fails to reset
 * the watchdog, the timer will elapse and generate a timeout signal.
 * The timeout signal is used to initiate corrective action or actions,
 * which typically include placing the system in a safe, known state.
 */

/*
 * Start the timer
 *
 * @dev: WDT Device
 * @timeout_ms: Number of ticks (milliseconds) before timer expires
 * @flags: Driver specific flags. This might be used to specify
 * which action needs to be executed when the timer expires
 * @return: 0 if OK, -ve on error
 */
int wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags);

/*
 * Stop the timer, thus disabling the Watchdog. Use wdt_start to start it again.
 *
 * @dev: WDT Device
 * @return: 0 if OK, -ve on error
 */
int wdt_stop(struct udevice *dev);

/*
 * Reset the timer, typically restoring the counter to
 * the value configured by start()
 *
 * @dev: WDT Device
 * @return: 0 if OK, -ve on error
 */
int wdt_reset(struct udevice *dev);

/*
 * Expire the timer, thus executing its action immediately.
 * This is typically used to reset the board or peripherals.
 *
 * @dev: WDT Device
 * @flags: Driver specific flags
 * @return 0 if OK -ve on error. If wdt action is system reset,
 * this function may never return.
 */
int wdt_expire_now(struct udevice *dev, ulong flags);

/*
 * struct wdt_ops - Driver model wdt operations
 *
 * The uclass interface is implemented by all wdt devices which use
 * driver model.
 */
struct wdt_ops {
	/*
	 * Start the timer
	 *
	 * @dev: WDT Device
	 * @timeout_ms: Number of ticks (milliseconds) before the timer expires
	 * @flags: Driver specific flags. This might be used to specify
	 * which action needs to be executed when the timer expires
	 * @return: 0 if OK, -ve on error
	 */
	int (*start)(struct udevice *dev, u64 timeout_ms, ulong flags);
	/*
	 * Stop the timer
	 *
	 * @dev: WDT Device
	 * @return: 0 if OK, -ve on error
	 */
	int (*stop)(struct udevice *dev);
	/*
	 * Reset the timer, typically restoring the counter to
	 * the value configured by start()
	 *
	 * @dev: WDT Device
	 * @return: 0 if OK, -ve on error
	 */
	int (*reset)(struct udevice *dev);
	/*
	 * Expire the timer, thus executing the action immediately (optional)
	 *
	 * If this function is not provided, a default implementation
	 * will be used, which sets the counter to 1
	 * and waits forever. This is good enough for system level
	 * reset, where the function is not expected to return, but might not be
	 * good enough for other use cases.
	 *
	 * @dev: WDT Device
	 * @flags: Driver specific flags
	 * @return 0 if OK -ve on error. May not return.
	 */
	int (*expire_now)(struct udevice *dev, ulong flags);
};

#endif  /* _WDT_H_ */