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bertos/drv/timer.c

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+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2003, 2004, 2005, 2006 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 2000, 2008 Bernie Innocenti <bernie@codewiz.org>
+ * -->
+ *
+ * \brief Hardware independent timer driver (implementation)
+ *
+ * \author Bernie Innocenti <bernie@codewiz.org>
+ * \author Francesco Sacchi <batt@develer.com>
+ */
+
+#include "timer.h"
+#include "hw/hw_timer.h"
+
+#include "cfg/cfg_timer.h"
+#include "cfg/cfg_wdt.h"
+#include "cfg/cfg_proc.h"
+#include "cfg/cfg_signal.h"
+#include <cfg/os.h>
+#include <cfg/debug.h>
+#include <cfg/module.h>
+
+#include <cpu/attr.h>
+#include <cpu/types.h>
+#include <cpu/irq.h>
+#include <cpu/power.h> // cpu_relax()
+
+#include <kern/proc_p.h> // proc_decQuantun()
+
+/*
+ * Include platform-specific binding code if we're hosted.
+ * Try the CPU specific one for bare-metal environments.
+ */
+#if OS_HOSTED
+	//#include OS_CSOURCE(timer)
+	#include <emul/timer_posix.c>
+#else
+	#ifndef WIZ_AUTOGEN
+		#warning Deprecated: now you should include timer_<cpu> directly in the makefile. Remove this line and the following once done.
+		#include CPU_CSOURCE(timer)
+	#endif
+#endif
+
+/*
+ * Sanity check for config parameters required by this module.
+ */
+#if !defined(CONFIG_KERN) || ((CONFIG_KERN != 0) && CONFIG_KERN != 1)
+	#error CONFIG_KERN must be set to either 0 or 1 in config.h
+#endif
+#if !defined(CONFIG_WATCHDOG) || ((CONFIG_WATCHDOG != 0) && CONFIG_WATCHDOG != 1)
+	#error CONFIG_WATCHDOG must be set to either 0 or 1 in config.h
+#endif
+
+#if CONFIG_WATCHDOG
+	#include <drv/wdt.h>
+#endif
+
+#if defined (CONFIG_KERN_SIGNALS) && CONFIG_KERN_SIGNALS
+	#include <kern/signal.h> /* sig_wait(), sig_check() */
+	#include <kern/proc.h>   /* proc_current() */
+	#include <cfg/macros.h>  /* BV() */
+#endif
+
+
+/**
+ * \def CONFIG_TIMER_STROBE
+ *
+ * This is a debug facility that can be used to
+ * monitor timer interrupt activity on an external pin.
+ *
+ * To use strobes, redefine the macros TIMER_STROBE_ON,
+ * TIMER_STROBE_OFF and TIMER_STROBE_INIT and set
+ * CONFIG_TIMER_STROBE to 1.
+ */
+#if !defined(CONFIG_TIMER_STROBE) || !CONFIG_TIMER_STROBE
+	#define TIMER_STROBE_ON    do {/*nop*/} while(0)
+	#define TIMER_STROBE_OFF   do {/*nop*/} while(0)
+	#define TIMER_STROBE_INIT  do {/*nop*/} while(0)
+#endif
+
+
+/// Master system clock (1 tick accuracy)
+volatile ticks_t _clock;
+
+
+#if CONFIG_TIMER_EVENTS
+
+/**
+ * List of active asynchronous timers.
+ */
+REGISTER static List timers_queue;
+
+/**
+ * This function really does the job. It adds \a timer to \a queue.
+ * \see timer_add for details.
+ */
+INLINE void timer_addToList(Timer *timer, List *queue)
+{
+	/* Inserting timers twice causes mayhem. */
+	ASSERT(timer->magic != TIMER_MAGIC_ACTIVE);
+	DB(timer->magic = TIMER_MAGIC_ACTIVE;)
+
+
+	/* Calculate expiration time for this timer */
+	timer->tick = _clock + timer->_delay;
+
+	/*
+	 * Search for the first node whose expiration time is
+	 * greater than the timer we want to add.
+	 */
+	Timer *node = (Timer *)LIST_HEAD(queue);
+	while (node->link.succ)
+	{
+		/*
+		 * Stop just after the insertion point.
+		 * (this fancy compare takes care of wrap-arounds).
+		 */
+		if (node->tick - timer->tick > 0)
+			break;
+
+		/* Go to next node */
+		node = (Timer *)node->link.succ;
+	}
+
+	/* Enqueue timer request into the list */
+	INSERT_BEFORE(&timer->link, &node->link);
+}
+
+/**
+ * Add the specified timer to the software timer service queue.
+ * When the delay indicated by the timer expires, the timer
+ * device will execute the event associated with it.
+ *
+ * You should not call this function on an already running timer.
+ *
+ * \note Interrupt safe
+ */
+void timer_add(Timer *timer)
+{
+	ATOMIC(timer_addToList(timer, &timers_queue));
+}
+
+/**
+ * Remove a timer from the timers queue before it has expired.
+ *
+ * \note Attempting to remove a timer already expired cause
+ *       undefined behaviour.
+ */
+Timer *timer_abort(Timer *timer)
+{
+	ATOMIC(REMOVE(&timer->link));
+	DB(timer->magic = TIMER_MAGIC_INACTIVE;)
+
+	return timer;
+}
+
+
+INLINE void timer_poll(List *queue)
+{
+	Timer *timer;
+
+	/*
+	 * Check the first timer request in the list and process
+	 * it when it has expired. Repeat this check until the
+	 * first node has not yet expired. Since the list is sorted
+	 * by expiry time, all the following requests are guaranteed
+	 * to expire later.
+	 */
+	while ((timer = (Timer *)LIST_HEAD(queue))->link.succ)
+	{
+		/* This request in list has not yet expired? */
+		if (timer_clock() - timer->tick < 0)
+			break;
+
+		/* Retreat the expired timer */
+		REMOVE(&timer->link);
+		DB(timer->magic = TIMER_MAGIC_INACTIVE;)
+
+		/* Execute the associated event */
+		event_do(&timer->expire);
+	}
+}
+
+/**
+ * Add \a timer to \a queue.
+ * \see synctimer_poll() for details.
+ */
+void synctimer_add(Timer *timer, List *queue)
+{
+	timer_addToList(timer, queue);
+}
+
+/**
+ * Simple synchronous timer based scheduler polling routine.
+ *
+ * Sometimes you would like to have a proper scheduler,
+ * but you can't afford it due to memory constraints.
+ *
+ * This is a simple replacement: you can create events and call
+ * them periodically at specific time intervals.
+ * All you have to do is to set up normal timers, and call synctimer_add()
+ * instead of timer_add() to add the events to your specific queue.
+ * Then, in the main loop or wherever you want, you can call
+ * synctimer_poll() to process expired events. The associated callbacks will be
+ * executed.
+ * As this is done synchronously you don't have to worry about race conditions.
+ * You can kill an event by simply calling synctimer_abort().
+ *
+ */
+void synctimer_poll(List *queue)
+{
+	timer_poll(queue);
+}
+
+#endif /* CONFIG_TIMER_EVENTS */
+
+
+/**
+ * Wait for the specified amount of timer ticks.
+ *
+ * \note Sleeping while preemption is disabled fallbacks to a busy wait sleep.
+ */
+void timer_delayTicks(ticks_t delay)
+{
+	/* We shouldn't sleep with interrupts disabled */
+	IRQ_ASSERT_ENABLED();
+
+#if CONFIG_KERN_SIGNALS
+	Timer t;
+	DB(t.magic = TIMER_MAGIC_INACTIVE;)
+	if (proc_preemptAllowed())
+	{
+		timer_setEvent(&t);
+		timer_setDelay(&t, delay);
+		timer_add(&t);
+		timer_waitEvent(&t);
+	}
+	else
+#endif /* !CONFIG_KERN_SIGNALS */
+	{
+		ticks_t start = timer_clock();
+
+		/* Busy wait */
+		while (timer_clock() - start < delay)
+			cpu_relax();
+	}
+}
+
+
+#if CONFIG_TIMER_UDELAY
+
+/**
+ * Busy wait until the specified amount of high-precision ticks have elapsed.
+ *
+ * \note This function is interrupt safe, the only
+ *       requirement is a running hardware timer.
+ */
+void timer_busyWait(hptime_t delay)
+{
+	hptime_t now, prev = timer_hw_hpread();
+	hptime_t delta;
+
+	for (;;)
+	{
+		now = timer_hw_hpread();
+		/*
+		 * The timer counter may wrap here and "prev" can become
+		 * greater than "now". So, be sure to always evaluate a
+		 * coherent timer difference:
+		 *
+		 * 0     prev            now   TIMER_HW_CNT
+		 * |_____|_______________|_____|
+		 *        ^^^^^^^^^^^^^^^
+		 * delta = now - prev
+		 *
+		 * 0     now             prev  TIMER_HW_CNT
+		 * |_____|_______________|_____|
+		 *  ^^^^^                 ^^^^^
+		 * delta = (TIMER_HW_CNT - prev) + now
+		 *
+		 * NOTE: TIMER_HW_CNT can be any value, not necessarily a power
+		 * of 2. For this reason the "%" operator is not suitable for
+		 * the generic case.
+		 */
+		delta = (now < prev) ? ((hptime_t)TIMER_HW_CNT - prev + now) :
+						(now - prev);
+		if (delta >= delay)
+			break;
+		delay -= delta;
+		prev = now;
+	}
+}
+
+/**
+ * Wait for the specified amount of time (expressed in microseconds).
+ *
+ * \bug In AVR arch the maximum amount of time that can be used as
+ *      delay could be very limited, depending on the hardware timer
+ *      used. Check timer_avr.h, and what register is used as hptime_t.
+ */
+void timer_delayHp(hptime_t delay)
+{
+	if (UNLIKELY(delay > us_to_hptime(1000)))
+	{
+		timer_delayTicks(delay / (TIMER_HW_HPTICKS_PER_SEC / TIMER_TICKS_PER_SEC));
+		delay %= (TIMER_HW_HPTICKS_PER_SEC / TIMER_TICKS_PER_SEC);
+	}
+
+	timer_busyWait(delay);
+}
+#endif /* CONFIG_TIMER_UDELAY */
+
+/**
+ * Timer interrupt handler. Find soft timers expired and
+ * trigger corresponding events.
+ */
+DEFINE_TIMER_ISR
+{
+	/*
+	 * With the Metrowerks compiler, the only way to force the compiler generate
+	 * an interrupt service routine is to put a pragma directive within the function
+	 * body.
+	 */
+	#ifdef __MWERKS__
+	#pragma interrupt saveall
+	#endif
+
+	/*
+	 * On systems sharing IRQ line and vector, this check is needed
+	 * to ensure that IRQ is generated by timer source.
+	 */
+	if (!timer_hw_triggered())
+		return;
+
+	TIMER_STROBE_ON;
+
+	/* Update the master ms counter */
+	++_clock;
+
+	/* Update the current task's quantum (if enabled). */
+	proc_decQuantum();
+
+	#if CONFIG_TIMER_EVENTS
+		timer_poll(&timers_queue);
+	#endif
+
+	/* Perform hw IRQ handling */
+	timer_hw_irq();
+
+	TIMER_STROBE_OFF;
+}
+
+MOD_DEFINE(timer)
+
+/**
+ * Initialize timer
+ */
+void timer_init(void)
+{
+	#if CONFIG_KERN_IRQ
+		MOD_CHECK(irq);
+	#endif
+
+	#if CONFIG_TIMER_EVENTS
+		LIST_INIT(&timers_queue);
+	#endif
+
+	TIMER_STROBE_INIT;
+
+	_clock = 0;
+
+	timer_hw_init();
+
+	MOD_INIT(timer);
+}
+
+
+#if (ARCH & ARCH_EMUL)
+/**
+ * Stop timer (only used by emulator)
+ */
+void timer_cleanup(void)
+{
+	MOD_CLEANUP(timer);
+
+	timer_hw_cleanup();
+
+	// Hmmm... apparently, the demo app does not cleanup properly
+	//ASSERT(LIST_EMPTY(&timers_queue));
+}
+#endif /* ARCH_EMUL */