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 * \brief Events handling
35 * This module implements a common system for executing
36 * a user defined action calling a hook function.
38 * NOTE: Generic completion events
40 * Device drivers often need to wait the completion of some event, usually to
41 * allow the hardware to accomplish some asynchronous task.
43 * A common approach is to place a busy wait with a cpu_relax() loop that invokes
44 * the architecture-specific instructions to say that we're not doing much with
47 * Although technically correct, the busy loop degrades the overall system
48 * performance in presence of multiple processes and power consumption.
50 * With the kernel the natural way to implement such wait/complete mechanism is to
51 * use signals via sig_wait() and sig_post()/sig_send().
53 * However, signals in BeRTOS are only available in presence of the kernel (that
54 * is just a compile-time option). This means that each device driver must provide
55 * two different interfaces to implement the wait/complete semantic: one with the
56 * kernel and another without the kernel.
58 * The purpose of the completion events is to provide a generic interface to
59 * implement a synchronization mechanism to block the execution of code until a
60 * specific event happens.
62 * This interface does not depend on the presence of the kernel and it
63 * automatically uses the appropriate event backend to provide the same
64 * behaviour with or without the kernel.
66 * Example usage (wait for a generic device driver initialization):
70 * static void irq_handler(void)
72 * // Completion event has happened, resume the execution of init()
76 * static void init(void)
78 * // Declare the generic completion event
79 * event_initGeneric(&e);
80 * // Submit the hardware initialization request
82 * // Wait for the completion of the event
87 * \author Bernie Innocenti <bernie@codewiz.org>
93 #include <cfg/compiler.h>
94 #include "cfg/cfg_proc.h"
95 #include "cfg/cfg_signal.h"
96 #include "cfg/cfg_timer.h"
98 #include <cpu/power.h> /* cpu_relax() */
101 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
102 #include <kern/signal.h>
110 /// User defined callback type
111 typedef void (*Hook)(void *);
115 void (*action)(struct Event *);
118 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
121 struct Process *sig_proc; /* Process to be signalled */
122 sigbit_t sig_bit; /* Signal to send */
127 Hook func; /* Pointer to softint hook */
128 void *user_data; /* Data to be passed back to user hook */
133 bool completed; /* Generic event completion */
138 void event_hook_ignore(Event *event);
139 void event_hook_signal(Event *event);
140 void event_hook_softint(Event *event);
141 void event_hook_generic(Event *event);
142 void event_hook_generic_timeout(Event *event);
144 /** Initialize the event \a e as a no-op */
145 #define event_initNone(e) \
146 ((e)->action = event_hook_ignore)
148 /** Same as event_initNone(), but returns the initialized event */
149 INLINE Event event_createNone(void);
150 INLINE Event event_createNone(void)
153 e.action = event_hook_ignore;
157 /** Initialize the event \a e with a software interrupt (call function \a f, with parameter \a u) */
158 #define event_initSoftint(e,f,u) \
159 ((e)->action = event_hook_softint,(e)->Ev.Int.func = (f), (e)->Ev.Int.user_data = (u))
161 /** Same as event_initSoftint(), but returns the initialized event */
162 INLINE Event event_createSoftint(Hook func, void *user_data)
165 e.action = event_hook_softint;
166 e.Ev.Int.func = func;
167 e.Ev.Int.user_data = user_data;
171 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
173 /** Initialize the event \a e with a signal (send signal \a s to process \a p) */
174 #define event_initSignal(e,p,s) \
175 ((e)->action = event_hook_signal,(e)->Ev.Sig.sig_proc = (p), (e)->Ev.Sig.sig_bit = (s))
177 /** Same as event_initSignal(), but returns the initialized event */
178 INLINE Event event_createSignal(struct Process *proc, sigbit_t bit)
181 e.action = event_hook_signal;
182 e.Ev.Sig.sig_proc = proc;
183 e.Ev.Sig.sig_bit = bit;
190 * Prevent the compiler from optimizing access to the variable \a x, enforcing
191 * a refetch from memory. This also forbid from reordering successing instances
194 * TODO: move this to cfg/compiler.h
196 #define ACCESS_SAFE(x) (*(volatile typeof(x) *)&(x))
198 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
199 /** Initialize the generic sleepable event \a e */
200 #define event_initGeneric(e) \
201 event_initSignal(e, proc_current(), SIG_SYSTEM5)
203 #define event_initGeneric(e) \
204 ((e)->action = event_hook_generic, (e)->Ev.Gen.completed = false)
208 * Create a generic sleepable event.
210 * \return the properly initialized generic event structure.
212 INLINE Event event_createGeneric(void)
215 event_initGeneric(&e);
220 * Wait the completion of event \a e.
222 INLINE void event_wait(Event *e)
224 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
225 e->Ev.Sig.sig_proc = proc_current();
226 sig_wait(e->Ev.Sig.sig_bit);
228 while (ACCESS_SAFE(e->Ev.Gen.completed) == false)
230 e->Ev.Gen.completed = false;
235 #if CONFIG_TIMER_EVENTS
236 #include <drv/timer.h> /* timer_clock() */
238 /* TODO: move these macros to drv/timer.h */
239 #define TIMER_AFTER(x, y) ((long)(y) - (long)(x) < 0)
240 #define TIMER_BEFORE(x, y) TIMER_AFTER(y, x)
243 * Wait the completion of event \a e or \a timeout elapses.
245 INLINE bool event_waitTimeout(Event *e, ticks_t timeout)
247 #if defined(CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
248 e->Ev.Sig.sig_proc = proc_current();
249 return (sig_waitTimeout(e->Ev.Sig.sig_bit, timeout) & SIG_TIMEOUT) ?
252 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;
265 #endif /* CONFIG_TIMER_EVENTS */
267 /** Trigger an event */
268 INLINE void event_do(struct Event *e)
273 #endif /* KERN_EVENT_H */