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/*
* This file is part of the coreboot project.
*
* This program 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; version 2 of the License.
*
* 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.
*/
#include <stdint.h>
#include <console/console.h>
#include <delay.h>
#include <thread.h>
#include <cpu/x86/msr.h>
#include <cpu/x86/lapic.h>
void init_timer(void)
{
/* Set the APIC timer to no interrupts and periodic mode */
lapic_write(LAPIC_LVTT, (LAPIC_LVT_TIMER_PERIODIC | LAPIC_LVT_MASKED));
/* Set the divider to 1, no divider */
lapic_write(LAPIC_TDCR, LAPIC_TDR_DIV_1);
/* Set the initial counter to 0xffffffff */
lapic_write(LAPIC_TMICT, 0xffffffff);
}
void udelay(u32 usecs)
{
u32 start, value, ticks, timer_fsb;
if (!thread_yield_microseconds(usecs))
return;
timer_fsb = get_timer_fsb();
if (!timer_fsb || (lapic_read(LAPIC_LVTT) &
(LAPIC_LVT_TIMER_PERIODIC | LAPIC_LVT_MASKED)) !=
(LAPIC_LVT_TIMER_PERIODIC | LAPIC_LVT_MASKED)) {
init_timer();
timer_fsb = get_timer_fsb();
}
/* Calculate the number of ticks to run, our FSB runs at timer_fsb Mhz
*/
ticks = usecs * timer_fsb;
start = lapic_read(LAPIC_TMCCT);
do {
value = lapic_read(LAPIC_TMCCT);
} while ((start - value) < ticks);
}
#if CONFIG(LAPIC_MONOTONIC_TIMER)
#include <timer.h>
static struct monotonic_counter {
int initialized;
struct mono_time time;
uint32_t last_value;
} mono_counter;
void timer_monotonic_get(struct mono_time *mt)
{
uint32_t current_tick;
uint32_t usecs_elapsed;
uint32_t timer_fsb;
if (!mono_counter.initialized) {
init_timer();
timer_fsb = get_timer_fsb();
/* An FSB frequency of 200Mhz provides a 20 second polling
* interval between timer_monotonic_get() calls before wrap
* around occurs. */
if (timer_fsb > 200)
printk(BIOS_WARNING,
"apic timer freq (%d) may be too fast.\n",
timer_fsb);
mono_counter.last_value = lapic_read(LAPIC_TMCCT);
mono_counter.initialized = 1;
}
timer_fsb = get_timer_fsb();
current_tick = lapic_read(LAPIC_TMCCT);
/* Note that the APIC timer counts down. */
usecs_elapsed = (mono_counter.last_value - current_tick) / timer_fsb;
/* Update current time and tick values only if a full tick occurred. */
if (usecs_elapsed) {
mono_time_add_usecs(&mono_counter.time, usecs_elapsed);
mono_counter.last_value = current_tick;
}
/* Save result. */
*mt = mono_counter.time;
}
#endif
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