1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __TRIGGER_H_
3#define __TRIGGER_H_ 1
4
5#include "asm/bug.h"
6
7/*
8 * Use trigger to model operations which need to be executed when
9 * an event (a signal, for example) is observed.
10 *
11 * States and transits:
12 *
13 *
14 *  OFF--> ON --> READY --(hit)--> HIT
15 *                 ^               |
16 *                 |            (ready)
17 *                 |               |
18 *                  \_____________/
19 *
20 * is_hit and is_ready are two key functions to query the state of
21 * a trigger. is_hit means the event already happen; is_ready means the
22 * trigger is waiting for the event.
23 */
24
25struct trigger {
26	volatile enum {
27		TRIGGER_ERROR		= -2,
28		TRIGGER_OFF		= -1,
29		TRIGGER_ON		= 0,
30		TRIGGER_READY		= 1,
31		TRIGGER_HIT		= 2,
32	} state;
33	const char *name;
34};
35
36#define TRIGGER_WARN_ONCE(t, exp) \
37	WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
38		  t->name, t->state, __func__)
39
40static inline bool trigger_is_available(struct trigger *t)
41{
42	return t->state >= 0;
43}
44
45static inline bool trigger_is_error(struct trigger *t)
46{
47	return t->state <= TRIGGER_ERROR;
48}
49
50static inline void trigger_on(struct trigger *t)
51{
52	TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
53	t->state = TRIGGER_ON;
54}
55
56static inline void trigger_ready(struct trigger *t)
57{
58	if (!trigger_is_available(t))
59		return;
60	t->state = TRIGGER_READY;
61}
62
63static inline void trigger_hit(struct trigger *t)
64{
65	if (!trigger_is_available(t))
66		return;
67	TRIGGER_WARN_ONCE(t, TRIGGER_READY);
68	t->state = TRIGGER_HIT;
69}
70
71static inline void trigger_off(struct trigger *t)
72{
73	if (!trigger_is_available(t))
74		return;
75	t->state = TRIGGER_OFF;
76}
77
78static inline void trigger_error(struct trigger *t)
79{
80	t->state = TRIGGER_ERROR;
81}
82
83static inline bool trigger_is_ready(struct trigger *t)
84{
85	return t->state == TRIGGER_READY;
86}
87
88static inline bool trigger_is_hit(struct trigger *t)
89{
90	return t->state == TRIGGER_HIT;
91}
92
93#define DEFINE_TRIGGER(n) \
94struct trigger n = {.state = TRIGGER_OFF, .name = #n}
95#endif
96