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