/*
* Copyright (c) 2001-2004 Jakub Jermar
* Copyright (c) 2022 Jiří Zárevúcky
* 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 kernel_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 <halt.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 <barrier.h>
#include <mm/frame.h>
#include <ddi/ddi.h>
#include <arch/cycle.h>
#include <preemption.h>
/* Pointer to variable with uptime */
uptime_t *uptime;
/** Physical memory area of the real time clock */
static parea_t clock_parea;
/** 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)
{
uintptr_t faddr = frame_alloc(1, FRAME_LOWMEM | FRAME_ATOMIC, 0);
if (faddr == 0)
panic("Cannot allocate page for clock.");
uptime = (uptime_t *) PA2KA(faddr);
uptime->seconds1 = 0;
uptime->seconds2 = 0;
uptime->useconds = 0;
ddi_parea_init(&clock_parea);
clock_parea.pbase = faddr;
clock_parea.frames = 1;
clock_parea.unpriv = true;
clock_parea.mapped = false;
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.faddr", NULL, (sysarg_t) faddr);
}
/** Update public counters
*
* Update it only on first processor
*/
static void clock_update_counters(uint64_t current_tick)
{
if (CPU->id == 0) {
uint64_t usec = (1000000 / HZ) * current_tick;
sysarg_t secs = usec / 1000000;
sysarg_t usecs = usec % 1000000;
uptime->seconds1 = secs;
write_barrier();
uptime->useconds = usecs;
write_barrier();
uptime->seconds2 = secs;
}
}
static void cpu_update_accounting(void)
{
// FIXME: get_cycle() is unimplemented on several platforms
uint64_t now = get_cycle();
atomic_time_increment(&CPU->busy_cycles, now - CPU_LOCAL->last_cycle);
CPU_LOCAL->last_cycle = now;
}
/** Clock routine
*
* Clock routine executed from clock interrupt handler
* (assuming interrupts_disable()'d). Runs expired timeouts
* and preemptive scheduling.
*
*/
void clock(void)
{
size_t missed_clock_ticks = CPU_LOCAL->missed_clock_ticks;
CPU_LOCAL->missed_clock_ticks = 0;
CPU_LOCAL->current_clock_tick += missed_clock_ticks + 1;
uint64_t current_clock_tick = CPU_LOCAL->current_clock_tick;
clock_update_counters(current_clock_tick);
/* Account CPU usage */
cpu_update_accounting();
/*
* To avoid lock ordering problems,
* run all expired timeouts as you visit them.
*
*/
irq_spinlock_lock(&CPU->timeoutlock, false);
link_t *cur;
while ((cur = list_first(&CPU->timeout_active_list)) != NULL) {
timeout_t *timeout = list_get_instance(cur, timeout_t, link);
if (current_clock_tick <= timeout->deadline) {
break;
}
list_remove(cur);
timeout_handler_t handler = timeout->handler;
void *arg = timeout->arg;
atomic_bool *finished = &timeout->finished;
irq_spinlock_unlock(&CPU->timeoutlock, false);
handler(arg);
/* Signal that the handler is finished. */
atomic_store_explicit(finished, true, memory_order_release);
irq_spinlock_lock(&CPU->timeoutlock, false);
}
irq_spinlock_unlock(&CPU->timeoutlock, false);
/*
* Do CPU usage accounting and find out whether to preempt THREAD.
*
*/
if (THREAD) {
if (current_clock_tick >= CPU_LOCAL->preempt_deadline && PREEMPTION_ENABLED) {
thread_yield();
#ifdef CONFIG_UDEBUG
/*
* Give udebug chance to stop the thread
* before it begins executing userspace code.
*/
istate_t *istate = THREAD->udebug.uspace_state;
if ((istate) && (istate_from_uspace(istate)))
udebug_before_thread_runs();
#endif
}
}
}
/** @}
*/