/*
* Copyright (c) 2001-2004 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/** @addtogroup time
* @{
*/
/**
* @file
* @brief High-level clock interrupt handler.
*
* This file contains the clock() function which is the source
* of preemption. It is also responsible for executing expired
* timeouts.
*/
#include <time/clock.h>
#include <time/timeout.h>
#include <config.h>
#include <synch/spinlock.h>
#include <synch/waitq.h>
#include <func.h>
#include <proc/scheduler.h>
#include <cpu.h>
#include <arch.h>
#include <adt/list.h>
#include <atomic.h>
#include <proc/thread.h>
#include <sysinfo/sysinfo.h>
#include <arch/barrier.h>
#include <mm/frame.h>
#include <ddi/ddi.h>
/* Pointer to variable with uptime */
uptime_t *uptime;
/** Physical memory area of the real time clock */
static parea_t clock_parea;
/* Variable holding fragment of second, so that we would update
* seconds correctly
*/
static unative_t secfrag = 0;
/** Initialize realtime clock counter
*
* The applications (and sometimes kernel) need to access accurate
* information about realtime data. We allocate 1 page with these
* data and update it periodically.
*/
void clock_counter_init(void)
{
void *faddr;
faddr = frame_alloc(ONE_FRAME, FRAME_ATOMIC);
if (!faddr)
panic("Cannot allocate page for clock.");
uptime = (uptime_t *) PA2KA(faddr);
uptime->seconds1 = 0;
uptime->seconds2 = 0;
uptime->useconds = 0;
clock_parea.pbase = (uintptr_t) faddr;
clock_parea.frames = 1;
ddi_parea_register(&clock_parea);
/*
* Prepare information for the userspace so that it can successfully
* physmem_map() the clock_parea.
*/
sysinfo_set_item_val("clock.cacheable", NULL, (unative_t) true);
sysinfo_set_item_val("clock.faddr", NULL, (unative_t) faddr);
}
/** Update public counters
*
* Update it only on first processor
* TODO: Do we really need so many write barriers?
*/
static void clock_update_counters(void)
{
if (CPU->id == 0) {
secfrag += 1000000 / HZ;
if (secfrag >= 1000000) {
secfrag -= 1000000;
uptime->seconds1++;
write_barrier();
uptime->useconds = secfrag;
write_barrier();
uptime->seconds2 = uptime->seconds1;
} else
uptime->useconds += 1000000 / HZ;
}
}
/** Clock routine
*
* Clock routine executed from clock interrupt handler
* (assuming interrupts_disable()'d). Runs expired timeouts
* and preemptive scheduling.
*
*/
{
link_t *l;
timeout_t *h;
timeout_handler_t f;
void *arg;
size_t missed_clock_ticks = CPU->missed_clock_ticks;
unsigned int i;
/*
* To avoid lock ordering problems,
* run all expired timeouts as you visit them.
*/
for (i = 0; i <= missed_clock_ticks; i++) {
clock_update_counters();
spinlock_lock(&CPU->timeoutlock);
while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) {
h = list_get_instance(l, timeout_t, link);
spinlock_lock(&h->lock);
if (h->ticks-- != 0) {
spinlock_unlock(&h->lock);
break;
}
list_remove(l);
f = h->handler;
arg = h->arg;
timeout_reinitialize(h);
spinlock_unlock(&h->lock);
spinlock_unlock(&CPU->timeoutlock);
f(arg);
spinlock_lock(&CPU->timeoutlock);
}
spinlock_unlock(&CPU->timeoutlock);
}
CPU->missed_clock_ticks = 0;
/*
* Do CPU usage accounting and find out whether to preempt THREAD.
*/
if (THREAD) {
uint64_t ticks;
spinlock_lock(&CPU->lock);
CPU->needs_relink += 1 + missed_clock_ticks;
spinlock_unlock(&CPU->lock);
spinlock_lock(&THREAD->lock);
if ((ticks = THREAD->ticks)) {
if (ticks >= 1 + missed_clock_ticks)
THREAD->ticks -= 1 + missed_clock_ticks;
else
THREAD->ticks = 0;
}
spinlock_unlock(&THREAD->lock);
if (!ticks && !PREEMPTION_DISABLED) {
#ifdef CONFIG_UDEBUG
istate_t *istate;
#endif
scheduler();
#ifdef CONFIG_UDEBUG
/*
* Give udebug chance to stop the thread
* before it begins executing userspace code.
*/
istate = THREAD->udebug.uspace_state;
if (istate && istate_from_uspace(istate))
udebug_before_thread_runs();
#endif
}
}
}
/** @}
*/