Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1#ifndef __TRIGGER_H_
2#define __TRIGGER_H_ 1
3
4#include "util/debug.h"
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_READY = 0,
30 TRIGGER_HIT = 1,
31 } state;
32 const char *name;
33};
34
35#define TRIGGER_WARN_ONCE(t, exp) \
36 WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \
37 t->name, t->state, __func__)
38
39static inline bool trigger_is_available(struct trigger *t)
40{
41 return t->state >= 0;
42}
43
44static inline bool trigger_is_error(struct trigger *t)
45{
46 return t->state <= TRIGGER_ERROR;
47}
48
49static inline void trigger_on(struct trigger *t)
50{
51 TRIGGER_WARN_ONCE(t, TRIGGER_OFF);
52 t->state = TRIGGER_READY;
53}
54
55static inline void trigger_ready(struct trigger *t)
56{
57 if (!trigger_is_available(t))
58 return;
59 t->state = TRIGGER_READY;
60}
61
62static inline void trigger_hit(struct trigger *t)
63{
64 if (!trigger_is_available(t))
65 return;
66 TRIGGER_WARN_ONCE(t, TRIGGER_READY);
67 t->state = TRIGGER_HIT;
68}
69
70static inline void trigger_off(struct trigger *t)
71{
72 if (!trigger_is_available(t))
73 return;
74 t->state = TRIGGER_OFF;
75}
76
77static inline void trigger_error(struct trigger *t)
78{
79 t->state = TRIGGER_ERROR;
80}
81
82static inline bool trigger_is_ready(struct trigger *t)
83{
84 return t->state == TRIGGER_READY;
85}
86
87static inline bool trigger_is_hit(struct trigger *t)
88{
89 return t->state == TRIGGER_HIT;
90}
91
92#define DEFINE_TRIGGER(n) \
93struct trigger n = {.state = TRIGGER_OFF, .name = #n}
94#endif