4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2003, 2004, 2005 Develer S.r.l. (http://www.develer.com/)
30 * Copyright 1999, 2001, 2003 Bernie Innocenti <bernie@codewiz.org>
33 * \defgroup event_handling Event handling module
37 * \brief Events handling
39 * This module implements a common system for executing
40 * a user defined action calling a hook function.
43 * Device drivers often need to wait the completion of some event, usually to
44 * allow the hardware to accomplish some asynchronous task.
46 * A common approach is to place a busy wait with a cpu_relax() loop that invokes
47 * the architecture-specific instructions to say that we're not doing much with
50 * Although technically correct, the busy loop degrades the overall system
51 * performance in presence of multiple processes and power consumption.
53 * With the kernel the natural way to implement such wait/complete mechanism is to
54 * use signals via sig_wait() and sig_post()/sig_send().
56 * However, signals in BeRTOS are only available in presence of the kernel (that
57 * is just a compile-time option). This means that each device driver must provide
58 * two different interfaces to implement the wait/complete semantic: one with the
59 * kernel and another without the kernel.
61 * The purpose of the completion events is to provide a generic interface to
62 * implement a synchronization mechanism to block the execution of code until a
63 * specific event happens.
65 * This interface does not depend on the presence of the kernel and it
66 * automatically uses the appropriate event backend to provide the same
67 * behaviour with or without the kernel.
69 * Example usage (wait for a generic device driver initialization):
73 * static void irq_handler(void)
75 * // Completion event has happened, resume the execution of init()
79 * static void init(void)
81 * // Declare the generic completion event
82 * event_initGeneric(&e);
83 * // Submit the hardware initialization request
85 * // Wait for the completion of the event
90 * Example usage: wait multiple generic events via event_select()
95 * void event_notifier(void)
97 * Event *evs[] = { &ev1, &ev2 };
99 * event_initGeneric(&ev1);
100 * event_initGeneric(&ev2);
104 * int id = event_select(evs, countof(evs),
108 * kprintf("no IRQ\n");
111 * kprintf("IRQ %d happened\n", id);
115 * void irq1_handler(void)
120 * // notify the completion of event 1
124 * void irq2_handler(void)
129 * // notify the completion of event 2
134 * \author Bernie Innocenti <bernie@codewiz.org>
140 #include <cfg/compiler.h>
141 #include "cfg/cfg_proc.h"
142 #include "cfg/cfg_signal.h"
143 #include "cfg/cfg_timer.h"
145 #include <cpu/power.h> /* cpu_relax() */
148 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
149 #include <kern/signal.h>
156 /// User defined callback type
157 typedef void (*Hook)(void *);
161 void (*action)(struct Event *);
164 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
167 struct Process *sig_proc; /* Process to be signalled */
168 sigbit_t sig_bit; /* Signal to send */
173 struct Process *sig_proc; /* Process to be signalled */
174 Signal sig; /* Signal structure */
179 Hook func; /* Pointer to softint hook */
180 void *user_data; /* Data to be passed back to user hook */
185 bool completed; /* Generic event completion */
190 void event_hook_ignore(Event *event);
191 void event_hook_signal(Event *event);
192 void event_hook_softint(Event *event);
193 void event_hook_generic(Event *event);
194 void event_hook_generic_signal(Event *event);
196 /** Initialize the event \a e as a no-op */
197 #define event_initNone(e) \
198 ((e)->action = event_hook_ignore)
200 /** Same as event_initNone(), but returns the initialized event */
201 INLINE Event event_createNone(void);
202 INLINE Event event_createNone(void)
205 e.action = event_hook_ignore;
209 /** Initialize the event \a e with a software interrupt (call function \a f, with parameter \a u) */
210 #define event_initSoftint(e,f,u) \
211 ((e)->action = event_hook_softint,(e)->Ev.Int.func = (f), (e)->Ev.Int.user_data = (u))
213 /** Same as event_initSoftint(), but returns the initialized event */
214 INLINE Event event_createSoftint(Hook func, void *user_data)
217 e.action = event_hook_softint;
218 e.Ev.Int.func = func;
219 e.Ev.Int.user_data = user_data;
223 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
225 /** Initialize the event \a e with a signal (send signal \a s to process \a p) */
226 #define event_initSignal(e,p,s) \
227 ((e)->action = event_hook_signal,(e)->Ev.Sig.sig_proc = (p), (e)->Ev.Sig.sig_bit = (s))
229 /** Same as event_initSignal(), but returns the initialized event */
230 INLINE Event event_createSignal(struct Process *proc, sigbit_t bit)
233 e.action = event_hook_signal;
234 e.Ev.Sig.sig_proc = proc;
235 e.Ev.Sig.sig_bit = bit;
241 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
242 /** Initialize the generic sleepable event \a e */
243 #define event_initGeneric(e) \
244 ((e)->action = event_hook_generic_signal, \
245 (e)->Ev.SigGen.sig_proc = proc_current(), \
246 (e)->Ev.SigGen.sig.wait = 0, (e)->Ev.SigGen.sig.recv = 0)
248 #define event_initGeneric(e) \
249 ((e)->action = event_hook_generic, (e)->Ev.Gen.completed = false)
253 * Signal used to implement generic events.
255 #define EVENT_GENERIC_SIGNAL SIG_SYSTEM5
258 * Create a generic sleepable event.
260 * \return the properly initialized generic event structure.
262 INLINE Event event_createGeneric(void)
265 event_initGeneric(&e);
270 * Wait the completion of event \a e.
272 * This function releases the CPU the application is configured to use
273 * the kernel, otherwise it's just a busy wait.
274 * \note It's forbidden to use this function inside irq handling functions.
276 INLINE void event_wait(Event *e)
278 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
279 e->Ev.Sig.sig_proc = proc_current();
280 sig_waitSignal(&e->Ev.SigGen.sig, EVENT_GENERIC_SIGNAL);
282 while (ACCESS_SAFE(e->Ev.Gen.completed) == false)
284 e->Ev.Gen.completed = false;
290 * Wait for multiple events
292 * On success return the offset in the \a evs vector of the Event that
293 * happened, -1 if the timeout expires.
295 * NOTE: timeout == 0 means no timeout.
297 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
298 INLINE int event_select(Event **evs, int n, ticks_t timeout)
300 sigmask_t mask = (1 << n) - 1;
303 ASSERT(n <= SIG_USER_MAX);
304 for (i = 0; i < n; i++)
307 /* Map each event to a distinct signal bit */
308 event_initSignal(e, proc_current(), 1 << i);
310 mask = timeout ? sig_waitTimeout(mask, timeout) : sig_wait(mask);
311 i = UINT8_LOG2(mask);
313 return i < n ? i : -1;
316 INLINE int event_select(Event **evs, int n, ticks_t timeout)
318 ticks_t end = timer_clock() + timeout;
323 for (i = 0; i < n; i++)
326 if (ACCESS_SAFE(e->Ev.Gen.completed) == true)
328 e->Ev.Gen.completed = false;
333 if (timeout && TIMER_AFTER(timer_clock(), end))
342 #if CONFIG_TIMER_EVENTS
343 #include <drv/timer.h> /* timer_clock() */
346 * Wait the completion of event \a e or \a timeout elapses.
348 * \note It's forbidden to use this function inside irq handling functions.
350 INLINE bool event_waitTimeout(Event *e, ticks_t timeout)
354 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
355 e->Ev.Sig.sig_proc = proc_current();
356 ret = (sig_waitTimeoutSignal(&e->Ev.SigGen.sig,
357 EVENT_GENERIC_SIGNAL, timeout) & SIG_TIMEOUT) ?
360 ticks_t end = timer_clock() + timeout;
362 while ((ACCESS_SAFE(e->Ev.Gen.completed) == false) ||
363 TIMER_AFTER(timer_clock(), end))
365 ret = e->Ev.Gen.completed;
366 e->Ev.Gen.completed = false;
371 #endif /* CONFIG_TIMER_EVENTS */
376 * Execute the callback function associated with event \a e.
378 * This function can be used also in interrupt routines, but only if the
379 * event was created as a signal or generic event.
381 INLINE void event_do(struct Event *e)
388 #endif /* KERN_EVENT_H */