#ifndef __TRIGGER_H_#define __TRIGGER_H_ 1 #include "util/debug.h"#include "asm/bug.h" /* * Use trigger to model operations which need to be executed when * an event (a signal, for example) is observed. * * States and transits: * * *  OFF--(on)--> READY --(hit)--> HIT *                 ^               | *                 |            (ready) *                 |               | *                  \_____________/ * * is_hit and is_ready are two key functions to query the state of * a trigger. is_hit means the event already happen; is_ready means the * trigger is waiting for the event. */ struct trigger {	volatile enum {		TRIGGER_ERROR		= -2,		TRIGGER_OFF		= -1,		TRIGGER_READY		= 0,		TRIGGER_HIT		= 1,	} state;	const char *name;}; #define TRIGGER_WARN_ONCE(t, exp) \	WARN_ONCE(t->state != exp, "trigger '%s' state transist error: %d in %s()\n", \		  t->name, t->state, __func__) static inline bool trigger_is_available(struct trigger *t){	return t->state >= 0;} static inline bool trigger_is_error(struct trigger *t){	return t->state <= TRIGGER_ERROR;} static inline void trigger_on(struct trigger *t){	TRIGGER_WARN_ONCE(t, TRIGGER_OFF);	t->state = TRIGGER_READY;} static inline void trigger_ready(struct trigger *t){	if (!trigger_is_available(t))		return;	t->state = TRIGGER_READY;} static inline void trigger_hit(struct trigger *t){	if (!trigger_is_available(t))		return;	TRIGGER_WARN_ONCE(t, TRIGGER_READY);	t->state = TRIGGER_HIT;} static inline void trigger_off(struct trigger *t){	if (!trigger_is_available(t))		return;	t->state = TRIGGER_OFF;} static inline void trigger_error(struct trigger *t){	t->state = TRIGGER_ERROR;} static inline bool trigger_is_ready(struct trigger *t){	return t->state == TRIGGER_READY;} static inline bool trigger_is_hit(struct trigger *t){	return t->state == TRIGGER_HIT;} #define DEFINE_TRIGGER(n) \struct trigger n = {.state = TRIGGER_OFF, .name = #n}#endif