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 * \author Bernie Innocenti <bernie@codewiz.org>
96 #include <cfg/compiler.h>
97 #include "cfg/cfg_proc.h"
98 #include "cfg/cfg_signal.h"
99 #include "cfg/cfg_timer.h"
101 #include <cpu/power.h> /* cpu_relax() */
104 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
105 #include <kern/signal.h>
112 /// User defined callback type
113 typedef void (*Hook)(void *);
117 void (*action)(struct Event *);
120 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
123 struct Process *sig_proc; /* Process to be signalled */
124 sigbit_t sig_bit; /* Signal to send */
129 Hook func; /* Pointer to softint hook */
130 void *user_data; /* Data to be passed back to user hook */
135 bool completed; /* Generic event completion */
140 void event_hook_ignore(Event *event);
141 void event_hook_signal(Event *event);
142 void event_hook_softint(Event *event);
143 void event_hook_generic(Event *event);
144 void event_hook_generic_timeout(Event *event);
146 /** Initialize the event \a e as a no-op */
147 #define event_initNone(e) \
148 ((e)->action = event_hook_ignore)
150 /** Same as event_initNone(), but returns the initialized event */
151 INLINE Event event_createNone(void);
152 INLINE Event event_createNone(void)
155 e.action = event_hook_ignore;
159 /** Initialize the event \a e with a software interrupt (call function \a f, with parameter \a u) */
160 #define event_initSoftint(e,f,u) \
161 ((e)->action = event_hook_softint,(e)->Ev.Int.func = (f), (e)->Ev.Int.user_data = (u))
163 /** Same as event_initSoftint(), but returns the initialized event */
164 INLINE Event event_createSoftint(Hook func, void *user_data)
167 e.action = event_hook_softint;
168 e.Ev.Int.func = func;
169 e.Ev.Int.user_data = user_data;
173 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
175 /** Initialize the event \a e with a signal (send signal \a s to process \a p) */
176 #define event_initSignal(e,p,s) \
177 ((e)->action = event_hook_signal,(e)->Ev.Sig.sig_proc = (p), (e)->Ev.Sig.sig_bit = (s))
179 /** Same as event_initSignal(), but returns the initialized event */
180 INLINE Event event_createSignal(struct Process *proc, sigbit_t bit)
183 e.action = event_hook_signal;
184 e.Ev.Sig.sig_proc = proc;
185 e.Ev.Sig.sig_bit = bit;
191 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
192 /** Initialize the generic sleepable event \a e */
193 #define event_initGeneric(e) \
194 event_initSignal(e, proc_current(), SIG_SYSTEM5)
196 #define event_initGeneric(e) \
197 ((e)->action = event_hook_generic, (e)->Ev.Gen.completed = false)
201 * Create a generic sleepable event.
203 * \return the properly initialized generic event structure.
205 INLINE Event event_createGeneric(void)
208 event_initGeneric(&e);
213 * Wait the completion of event \a e.
215 * This function releases the CPU the application is configured to use
216 * the kernel, otherwise it's just a busy wait.
217 * \note It's forbidden to use this function inside irq handling functions.
219 INLINE void event_wait(Event *e)
221 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
222 e->Ev.Sig.sig_proc = proc_current();
223 sig_wait(e->Ev.Sig.sig_bit);
225 while (ACCESS_SAFE(e->Ev.Gen.completed) == false)
227 e->Ev.Gen.completed = false;
232 #if CONFIG_TIMER_EVENTS
233 #include <drv/timer.h> /* timer_clock() */
235 /* TODO: move these macros to drv/timer.h */
236 #define TIMER_AFTER(x, y) ((long)(y) - (long)(x) < 0)
237 #define TIMER_BEFORE(x, y) TIMER_AFTER(y, x)
240 * Wait the completion of event \a e or \a timeout elapses.
242 * \note It's forbidden to use this function inside irq handling functions.
244 INLINE bool event_waitTimeout(Event *e, ticks_t timeout)
248 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
249 e->Ev.Sig.sig_proc = proc_current();
250 ret = (sig_waitTimeout(e->Ev.Sig.sig_bit, timeout) & SIG_TIMEOUT) ?
253 ticks_t end = timer_clock() + timeout;
255 while ((ACCESS_SAFE(e->Ev.Gen.completed) == false) ||
256 TIMER_AFTER(timer_clock(), end))
258 ret = e->Ev.Gen.completed;
259 e->Ev.Gen.completed = false;
264 #endif /* CONFIG_TIMER_EVENTS */
269 * Execute the callback function associated with event \a e.
271 * This function can be used also in interrupt routines, but only if the
272 * event was created as a signal or generic event.
274 INLINE void event_do(struct Event *e)
281 #endif /* KERN_EVENT_H */