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 * \addtogroup event_handling
35 * \brief Events handling
37 * This module implements a common system for executing
38 * a user defined action calling a hook function.
41 * Device drivers often need to wait the completion of some event, usually to
42 * allow the hardware to accomplish some asynchronous task.
44 * A common approach is to place a busy wait with a cpu_relax() loop that invokes
45 * the architecture-specific instructions to say that we're not doing much with
48 * Although technically correct, the busy loop degrades the overall system
49 * performance in presence of multiple processes and power consumption.
51 * With the kernel the natural way to implement such wait/complete mechanism is to
52 * use signals via sig_wait() and sig_post()/sig_send().
54 * However, signals in BeRTOS are only available in presence of the kernel (that
55 * is just a compile-time option). This means that each device driver must provide
56 * two different interfaces to implement the wait/complete semantic: one with the
57 * kernel and another without the kernel.
59 * The purpose of the completion events is to provide a generic interface to
60 * implement a synchronization mechanism to block the execution of code until a
61 * specific event happens.
63 * This interface does not depend on the presence of the kernel and it
64 * automatically uses the appropriate event backend to provide the same
65 * behaviour with or without the kernel.
67 * Example usage (wait for a generic device driver initialization):
71 * static void irq_handler(void)
73 * // Completion event has happened, resume the execution of init()
77 * static void init(void)
79 * // Declare the generic completion event
80 * event_initGeneric(&e);
81 * // Submit the hardware initialization request
83 * // Wait for the completion of the event
88 * \author Bernie Innocenti <bernie@codewiz.org>
94 #include <cfg/compiler.h>
95 #include "cfg/cfg_proc.h"
96 #include "cfg/cfg_signal.h"
97 #include "cfg/cfg_timer.h"
99 #include <cpu/power.h> /* cpu_relax() */
102 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
103 #include <kern/signal.h>
111 * \defgroup event_handling Events handling module
116 /// User defined callback type
117 typedef void (*Hook)(void *);
121 void (*action)(struct Event *);
124 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
127 struct Process *sig_proc; /* Process to be signalled */
128 sigbit_t sig_bit; /* Signal to send */
133 Hook func; /* Pointer to softint hook */
134 void *user_data; /* Data to be passed back to user hook */
139 bool completed; /* Generic event completion */
144 void event_hook_ignore(Event *event);
145 void event_hook_signal(Event *event);
146 void event_hook_softint(Event *event);
147 void event_hook_generic(Event *event);
148 void event_hook_generic_timeout(Event *event);
150 /** Initialize the event \a e as a no-op */
151 #define event_initNone(e) \
152 ((e)->action = event_hook_ignore)
154 /** Same as event_initNone(), but returns the initialized event */
155 INLINE Event event_createNone(void);
156 INLINE Event event_createNone(void)
159 e.action = event_hook_ignore;
163 /** Initialize the event \a e with a software interrupt (call function \a f, with parameter \a u) */
164 #define event_initSoftint(e,f,u) \
165 ((e)->action = event_hook_softint,(e)->Ev.Int.func = (f), (e)->Ev.Int.user_data = (u))
167 /** Same as event_initSoftint(), but returns the initialized event */
168 INLINE Event event_createSoftint(Hook func, void *user_data)
171 e.action = event_hook_softint;
172 e.Ev.Int.func = func;
173 e.Ev.Int.user_data = user_data;
177 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
179 /** Initialize the event \a e with a signal (send signal \a s to process \a p) */
180 #define event_initSignal(e,p,s) \
181 ((e)->action = event_hook_signal,(e)->Ev.Sig.sig_proc = (p), (e)->Ev.Sig.sig_bit = (s))
183 /** Same as event_initSignal(), but returns the initialized event */
184 INLINE Event event_createSignal(struct Process *proc, sigbit_t bit)
187 e.action = event_hook_signal;
188 e.Ev.Sig.sig_proc = proc;
189 e.Ev.Sig.sig_bit = bit;
196 * Prevent the compiler from optimizing access to the variable \a x, enforcing
197 * a refetch from memory. This also forbid from reordering successing instances
200 * TODO: move this to cfg/compiler.h
202 #define ACCESS_SAFE(x) (*(volatile typeof(x) *)&(x))
204 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
205 /** Initialize the generic sleepable event \a e */
206 #define event_initGeneric(e) \
207 event_initSignal(e, proc_current(), SIG_SYSTEM5)
209 #define event_initGeneric(e) \
210 ((e)->action = event_hook_generic, (e)->Ev.Gen.completed = false)
214 * Create a generic sleepable event.
216 * \return the properly initialized generic event structure.
218 INLINE Event event_createGeneric(void)
221 event_initGeneric(&e);
226 * Wait the completion of event \a e.
228 * This function releases the CPU the application is configured to use
229 * the kernel, otherwise it's just a busy wait.
230 * \note It's forbidden to use this function inside irq handling functions.
232 INLINE void event_wait(Event *e)
234 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
235 e->Ev.Sig.sig_proc = proc_current();
236 sig_wait(e->Ev.Sig.sig_bit);
238 while (ACCESS_SAFE(e->Ev.Gen.completed) == false)
240 e->Ev.Gen.completed = false;
245 #if CONFIG_TIMER_EVENTS
246 #include <drv/timer.h> /* timer_clock() */
248 /* TODO: move these macros to drv/timer.h */
249 #define TIMER_AFTER(x, y) ((long)(y) - (long)(x) < 0)
250 #define TIMER_BEFORE(x, y) TIMER_AFTER(y, x)
253 * Wait the completion of event \a e or \a timeout elapses.
255 * \note It's forbidden to use this function inside irq handling functions.
257 INLINE bool event_waitTimeout(Event *e, ticks_t timeout)
261 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
262 e->Ev.Sig.sig_proc = proc_current();
263 ret = (sig_waitTimeout(e->Ev.Sig.sig_bit, timeout) & SIG_TIMEOUT) ?
266 ticks_t end = timer_clock() + timeout;
268 while ((ACCESS_SAFE(e->Ev.Gen.completed) == false) ||
269 TIMER_AFTER(timer_clock(), end))
271 ret = e->Ev.Gen.completed;
272 e->Ev.Gen.completed = false;
277 #endif /* CONFIG_TIMER_EVENTS */
282 * Execute the callback function associated with event \a e.
284 * This function can be used also in interrupt routines, but only if the
285 * event was created as a signal or generic event.
287 INLINE void event_do(struct Event *e)
294 #endif /* KERN_EVENT_H */