1 #ifndef _FSM_H_
2 #define _FSM_H_
3
4 #include <linux/kernel.h>
5 #include <linux/types.h>
6 #include <linux/timer.h>
7 #include <linux/time.h>
8 #include <linux/slab.h>
9 #include <linux/sched.h>
10 #include <linux/string.h>
11 #include <linux/atomic.h>
12
13 /**
14 * Define this to get debugging messages.
15 */
16 #define FSM_DEBUG 0
17
18 /**
19 * Define this to get debugging massages for
20 * timer handling.
21 */
22 #define FSM_TIMER_DEBUG 0
23
24 /**
25 * Define these to record a history of
26 * Events/Statechanges and print it if a
27 * action_function is not found.
28 */
29 #define FSM_DEBUG_HISTORY 0
30 #define FSM_HISTORY_SIZE 40
31
32 struct fsm_instance_t;
33
34 /**
35 * Definition of an action function, called by a FSM
36 */
37 typedef void (*fsm_function_t)(struct fsm_instance_t *, int, void *);
38
39 /**
40 * Internal jump table for a FSM
41 */
42 typedef struct {
43 fsm_function_t *jumpmatrix;
44 int nr_events;
45 int nr_states;
46 const char **event_names;
47 const char **state_names;
48 } fsm;
49
50 #if FSM_DEBUG_HISTORY
51 /**
52 * Element of State/Event history used for debugging.
53 */
54 typedef struct {
55 int state;
56 int event;
57 } fsm_history;
58 #endif
59
60 /**
61 * Representation of a FSM
62 */
63 typedef struct fsm_instance_t {
64 fsm *f;
65 atomic_t state;
66 char name[16];
67 void *userdata;
68 int userint;
69 wait_queue_head_t wait_q;
70 #if FSM_DEBUG_HISTORY
71 int history_index;
72 int history_size;
73 fsm_history history[FSM_HISTORY_SIZE];
74 #endif
75 } fsm_instance;
76
77 /**
78 * Description of a state-event combination
79 */
80 typedef struct {
81 int cond_state;
82 int cond_event;
83 fsm_function_t function;
84 } fsm_node;
85
86 /**
87 * Description of a FSM Timer.
88 */
89 typedef struct {
90 fsm_instance *fi;
91 struct timer_list tl;
92 int expire_event;
93 void *event_arg;
94 } fsm_timer;
95
96 /**
97 * Creates an FSM
98 *
99 * @param name Name of this instance for logging purposes.
100 * @param state_names An array of names for all states for logging purposes.
101 * @param event_names An array of names for all events for logging purposes.
102 * @param nr_states Number of states for this instance.
103 * @param nr_events Number of events for this instance.
104 * @param tmpl An array of fsm_nodes, describing this FSM.
105 * @param tmpl_len Length of the describing array.
106 * @param order Parameter for allocation of the FSM data structs.
107 */
108 extern fsm_instance *
109 init_fsm(char *name, const char **state_names,
110 const char **event_names,
111 int nr_states, int nr_events, const fsm_node *tmpl,
112 int tmpl_len, gfp_t order);
113
114 /**
115 * Releases an FSM
116 *
117 * @param fi Pointer to an FSM, previously created with init_fsm.
118 */
119 extern void kfree_fsm(fsm_instance *fi);
120
121 #if FSM_DEBUG_HISTORY
122 extern void
123 fsm_print_history(fsm_instance *fi);
124
125 extern void
126 fsm_record_history(fsm_instance *fi, int state, int event);
127 #endif
128
129 /**
130 * Emits an event to a FSM.
131 * If an action function is defined for the current state/event combination,
132 * this function is called.
133 *
134 * @param fi Pointer to FSM which should receive the event.
135 * @param event The event do be delivered.
136 * @param arg A generic argument, handed to the action function.
137 *
138 * @return 0 on success,
139 * 1 if current state or event is out of range
140 * !0 if state and event in range, but no action defined.
141 */
142 static inline int
fsm_event(fsm_instance * fi,int event,void * arg)143 fsm_event(fsm_instance *fi, int event, void *arg)
144 {
145 fsm_function_t r;
146 int state = atomic_read(&fi->state);
147
148 if ((state >= fi->f->nr_states) ||
149 (event >= fi->f->nr_events) ) {
150 printk(KERN_ERR "fsm(%s): Invalid state st(%ld/%ld) ev(%d/%ld)\n",
151 fi->name, (long)state,(long)fi->f->nr_states, event,
152 (long)fi->f->nr_events);
153 #if FSM_DEBUG_HISTORY
154 fsm_print_history(fi);
155 #endif
156 return 1;
157 }
158 r = fi->f->jumpmatrix[fi->f->nr_states * event + state];
159 if (r) {
160 #if FSM_DEBUG
161 printk(KERN_DEBUG "fsm(%s): state %s event %s\n",
162 fi->name, fi->f->state_names[state],
163 fi->f->event_names[event]);
164 #endif
165 #if FSM_DEBUG_HISTORY
166 fsm_record_history(fi, state, event);
167 #endif
168 r(fi, event, arg);
169 return 0;
170 } else {
171 #if FSM_DEBUG || FSM_DEBUG_HISTORY
172 printk(KERN_DEBUG "fsm(%s): no function for event %s in state %s\n",
173 fi->name, fi->f->event_names[event],
174 fi->f->state_names[state]);
175 #endif
176 #if FSM_DEBUG_HISTORY
177 fsm_print_history(fi);
178 #endif
179 return !0;
180 }
181 }
182
183 /**
184 * Modifies the state of an FSM.
185 * This does <em>not</em> trigger an event or calls an action function.
186 *
187 * @param fi Pointer to FSM
188 * @param state The new state for this FSM.
189 */
190 static inline void
fsm_newstate(fsm_instance * fi,int newstate)191 fsm_newstate(fsm_instance *fi, int newstate)
192 {
193 atomic_set(&fi->state,newstate);
194 #if FSM_DEBUG_HISTORY
195 fsm_record_history(fi, newstate, -1);
196 #endif
197 #if FSM_DEBUG
198 printk(KERN_DEBUG "fsm(%s): New state %s\n", fi->name,
199 fi->f->state_names[newstate]);
200 #endif
201 wake_up(&fi->wait_q);
202 }
203
204 /**
205 * Retrieves the state of an FSM
206 *
207 * @param fi Pointer to FSM
208 *
209 * @return The current state of the FSM.
210 */
211 static inline int
fsm_getstate(fsm_instance * fi)212 fsm_getstate(fsm_instance *fi)
213 {
214 return atomic_read(&fi->state);
215 }
216
217 /**
218 * Retrieves the name of the state of an FSM
219 *
220 * @param fi Pointer to FSM
221 *
222 * @return The current state of the FSM in a human readable form.
223 */
224 extern const char *fsm_getstate_str(fsm_instance *fi);
225
226 /**
227 * Initializes a timer for an FSM.
228 * This prepares an fsm_timer for usage with fsm_addtimer.
229 *
230 * @param fi Pointer to FSM
231 * @param timer The timer to be initialized.
232 */
233 extern void fsm_settimer(fsm_instance *fi, fsm_timer *);
234
235 /**
236 * Clears a pending timer of an FSM instance.
237 *
238 * @param timer The timer to clear.
239 */
240 extern void fsm_deltimer(fsm_timer *timer);
241
242 /**
243 * Adds and starts a timer to an FSM instance.
244 *
245 * @param timer The timer to be added. The field fi of that timer
246 * must have been set to point to the instance.
247 * @param millisec Duration, after which the timer should expire.
248 * @param event Event, to trigger if timer expires.
249 * @param arg Generic argument, provided to expiry function.
250 *
251 * @return 0 on success, -1 if timer is already active.
252 */
253 extern int fsm_addtimer(fsm_timer *timer, int millisec, int event, void *arg);
254
255 /**
256 * Modifies a timer of an FSM.
257 *
258 * @param timer The timer to modify.
259 * @param millisec Duration, after which the timer should expire.
260 * @param event Event, to trigger if timer expires.
261 * @param arg Generic argument, provided to expiry function.
262 */
263 extern void fsm_modtimer(fsm_timer *timer, int millisec, int event, void *arg);
264
265 #endif /* _FSM_H_ */
266