/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _FSM_H_
#define _FSM_H_
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/time.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/atomic.h>
/**
* Define this to get debugging messages.
*/
#define FSM_DEBUG 0
/**
* Define this to get debugging massages for
* timer handling.
*/
#define FSM_TIMER_DEBUG 0
/**
* Define these to record a history of
* Events/Statechanges and print it if a
* action_function is not found.
*/
#define FSM_DEBUG_HISTORY 0
#define FSM_HISTORY_SIZE 40
struct fsm_instance_t;
/**
* Definition of an action function, called by a FSM
*/
typedef void (*fsm_function_t)(struct fsm_instance_t *, int, void *);
/**
* Internal jump table for a FSM
*/
typedef struct {
fsm_function_t *jumpmatrix;
int nr_events;
int nr_states;
const char **event_names;
const char **state_names;
} fsm;
#if FSM_DEBUG_HISTORY
/**
* Element of State/Event history used for debugging.
*/
typedef struct {
int state;
int event;
} fsm_history;
#endif
/**
* Representation of a FSM
*/
typedef struct fsm_instance_t {
fsm *f;
atomic_t state;
char name[16];
void *userdata;
int userint;
wait_queue_head_t wait_q;
#if FSM_DEBUG_HISTORY
int history_index;
int history_size;
fsm_history history[FSM_HISTORY_SIZE];
#endif
} fsm_instance;
/**
* Description of a state-event combination
*/
typedef struct {
int cond_state;
int cond_event;
fsm_function_t function;
} fsm_node;
/**
* Description of a FSM Timer.
*/
typedef struct {
fsm_instance *fi;
struct timer_list tl;
int expire_event;
void *event_arg;
} fsm_timer;
/**
* Creates an FSM
*
* @param name Name of this instance for logging purposes.
* @param state_names An array of names for all states for logging purposes.
* @param event_names An array of names for all events for logging purposes.
* @param nr_states Number of states for this instance.
* @param nr_events Number of events for this instance.
* @param tmpl An array of fsm_nodes, describing this FSM.
* @param tmpl_len Length of the describing array.
* @param order Parameter for allocation of the FSM data structs.
*/
extern fsm_instance *
init_fsm(char *name, const char **state_names,
const char **event_names,
int nr_states, int nr_events, const fsm_node *tmpl,
int tmpl_len, gfp_t order);
/**
* Releases an FSM
*
* @param fi Pointer to an FSM, previously created with init_fsm.
*/
extern void kfree_fsm(fsm_instance *fi);
#if FSM_DEBUG_HISTORY
extern void
fsm_print_history(fsm_instance *fi);
extern void
fsm_record_history(fsm_instance *fi, int state, int event);
#endif
/**
* Emits an event to a FSM.
* If an action function is defined for the current state/event combination,
* this function is called.
*
* @param fi Pointer to FSM which should receive the event.
* @param event The event do be delivered.
* @param arg A generic argument, handed to the action function.
*
* @return 0 on success,
* 1 if current state or event is out of range
* !0 if state and event in range, but no action defined.
*/
static inline int
fsm_event(fsm_instance *fi, int event, void *arg)
{
fsm_function_t r;
int state = atomic_read(&fi->state);
if ((state >= fi->f->nr_states) ||
(event >= fi->f->nr_events) ) {
printk(KERN_ERR "fsm(%s): Invalid state st(%ld/%ld) ev(%d/%ld)\n",
fi->name, (long)state,(long)fi->f->nr_states, event,
(long)fi->f->nr_events);
#if FSM_DEBUG_HISTORY
fsm_print_history(fi);
#endif
return 1;
}
r = fi->f->jumpmatrix[fi->f->nr_states * event + state];
if (r) {
#if FSM_DEBUG
printk(KERN_DEBUG "fsm(%s): state %s event %s\n",
fi->name, fi->f->state_names[state],
fi->f->event_names[event]);
#endif
#if FSM_DEBUG_HISTORY
fsm_record_history(fi, state, event);
#endif
r(fi, event, arg);
return 0;
} else {
#if FSM_DEBUG || FSM_DEBUG_HISTORY
printk(KERN_DEBUG "fsm(%s): no function for event %s in state %s\n",
fi->name, fi->f->event_names[event],
fi->f->state_names[state]);
#endif
#if FSM_DEBUG_HISTORY
fsm_print_history(fi);
#endif
return !0;
}
}
/**
* Modifies the state of an FSM.
* This does <em>not</em> trigger an event or calls an action function.
*
* @param fi Pointer to FSM
* @param state The new state for this FSM.
*/
static inline void
fsm_newstate(fsm_instance *fi, int newstate)
{
atomic_set(&fi->state,newstate);
#if FSM_DEBUG_HISTORY
fsm_record_history(fi, newstate, -1);
#endif
#if FSM_DEBUG
printk(KERN_DEBUG "fsm(%s): New state %s\n", fi->name,
fi->f->state_names[newstate]);
#endif
wake_up(&fi->wait_q);
}
/**
* Retrieves the state of an FSM
*
* @param fi Pointer to FSM
*
* @return The current state of the FSM.
*/
static inline int
fsm_getstate(fsm_instance *fi)
{
return atomic_read(&fi->state);
}
/**
* Retrieves the name of the state of an FSM
*
* @param fi Pointer to FSM
*
* @return The current state of the FSM in a human readable form.
*/
extern const char *fsm_getstate_str(fsm_instance *fi);
/**
* Initializes a timer for an FSM.
* This prepares an fsm_timer for usage with fsm_addtimer.
*
* @param fi Pointer to FSM
* @param timer The timer to be initialized.
*/
extern void fsm_settimer(fsm_instance *fi, fsm_timer *);
/**
* Clears a pending timer of an FSM instance.
*
* @param timer The timer to clear.
*/
extern void fsm_deltimer(fsm_timer *timer);
/**
* Adds and starts a timer to an FSM instance.
*
* @param timer The timer to be added. The field fi of that timer
* must have been set to point to the instance.
* @param millisec Duration, after which the timer should expire.
* @param event Event, to trigger if timer expires.
* @param arg Generic argument, provided to expiry function.
*
* @return 0 on success, -1 if timer is already active.
*/
extern int fsm_addtimer(fsm_timer *timer, int millisec, int event, void *arg);
/**
* Modifies a timer of an FSM.
*
* @param timer The timer to modify.
* @param millisec Duration, after which the timer should expire.
* @param event Event, to trigger if timer expires.
* @param arg Generic argument, provided to expiry function.
*/
extern void fsm_modtimer(fsm_timer *timer, int millisec, int event, void *arg);
#endif /* _FSM_H_ */