xref: /linux/tools/perf/util/trigger.h (revision 976e3645923bdd2fe7893aae33fd7a21098bfb28)
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 
25 struct 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 
trigger_is_available(struct trigger * t)40 static inline bool trigger_is_available(struct trigger *t)
41 {
42 	return t->state >= 0;
43 }
44 
trigger_is_error(struct trigger * t)45 static inline bool trigger_is_error(struct trigger *t)
46 {
47 	return t->state <= TRIGGER_ERROR;
48 }
49 
trigger_on(struct trigger * t)50 static inline void trigger_on(struct trigger *t)
51 {
52 	TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
53 	t->state = TRIGGER_ON;
54 }
55 
trigger_ready(struct trigger * t)56 static inline void trigger_ready(struct trigger *t)
57 {
58 	if (!trigger_is_available(t))
59 		return;
60 	t->state = TRIGGER_READY;
61 }
62 
trigger_hit(struct trigger * t)63 static 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 
trigger_off(struct trigger * t)71 static inline void trigger_off(struct trigger *t)
72 {
73 	if (!trigger_is_available(t))
74 		return;
75 	t->state = TRIGGER_OFF;
76 }
77 
trigger_error(struct trigger * t)78 static inline void trigger_error(struct trigger *t)
79 {
80 	t->state = TRIGGER_ERROR;
81 }
82 
trigger_is_ready(struct trigger * t)83 static inline bool trigger_is_ready(struct trigger *t)
84 {
85 	return t->state == TRIGGER_READY;
86 }
87 
trigger_is_hit(struct trigger * t)88 static inline bool trigger_is_hit(struct trigger *t)
89 {
90 	return t->state == TRIGGER_HIT;
91 }
92 
93 #define DEFINE_TRIGGER(n) \
94 struct trigger n = {.state = TRIGGER_OFF, .name = #n}
95 #endif
96