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