129 lines
3.0 KiB
C
129 lines
3.0 KiB
C
/*
|
|
* arch/xtensa/kernel/time.c
|
|
*
|
|
* Timer and clock support.
|
|
*
|
|
* This file is subject to the terms and conditions of the GNU General Public
|
|
* License. See the file "COPYING" in the main directory of this archive
|
|
* for more details.
|
|
*
|
|
* Copyright (C) 2005 Tensilica Inc.
|
|
*
|
|
* Chris Zankel <chris@zankel.net>
|
|
*/
|
|
|
|
#include <linux/errno.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/time.h>
|
|
#include <linux/clocksource.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/irq.h>
|
|
#include <linux/profile.h>
|
|
#include <linux/delay.h>
|
|
|
|
#include <asm/timex.h>
|
|
#include <asm/platform.h>
|
|
|
|
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
|
|
unsigned long ccount_per_jiffy; /* per 1/HZ */
|
|
unsigned long nsec_per_ccount; /* nsec per ccount increment */
|
|
#endif
|
|
|
|
static cycle_t ccount_read(void)
|
|
{
|
|
return (cycle_t)get_ccount();
|
|
}
|
|
|
|
static struct clocksource ccount_clocksource = {
|
|
.name = "ccount",
|
|
.rating = 200,
|
|
.read = ccount_read,
|
|
.mask = CLOCKSOURCE_MASK(32),
|
|
/*
|
|
* With a shift of 22 the lower limit of the cpu clock is
|
|
* 1MHz, where NSEC_PER_CCOUNT is 1000 or a bit less than
|
|
* 2^10: Since we have 32 bits and the multiplicator can
|
|
* already take up as much as 10 bits, this leaves us with
|
|
* remaining upper 22 bits.
|
|
*/
|
|
.shift = 22,
|
|
};
|
|
|
|
static irqreturn_t timer_interrupt(int irq, void *dev_id);
|
|
static struct irqaction timer_irqaction = {
|
|
.handler = timer_interrupt,
|
|
.flags = IRQF_DISABLED,
|
|
.name = "timer",
|
|
};
|
|
|
|
void __init time_init(void)
|
|
{
|
|
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
|
|
printk("Calibrating CPU frequency ");
|
|
platform_calibrate_ccount();
|
|
printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
|
|
(int)(ccount_per_jiffy/(10000/HZ))%100);
|
|
#endif
|
|
ccount_clocksource.mult =
|
|
clocksource_hz2mult(CCOUNT_PER_JIFFY * HZ,
|
|
ccount_clocksource.shift);
|
|
clocksource_register(&ccount_clocksource);
|
|
|
|
/* Initialize the linux timer interrupt. */
|
|
|
|
setup_irq(LINUX_TIMER_INT, &timer_irqaction);
|
|
set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
|
|
}
|
|
|
|
/*
|
|
* The timer interrupt is called HZ times per second.
|
|
*/
|
|
|
|
irqreturn_t timer_interrupt (int irq, void *dev_id)
|
|
{
|
|
|
|
unsigned long next;
|
|
|
|
next = get_linux_timer();
|
|
|
|
again:
|
|
while ((signed long)(get_ccount() - next) > 0) {
|
|
|
|
profile_tick(CPU_PROFILING);
|
|
#ifndef CONFIG_SMP
|
|
update_process_times(user_mode(get_irq_regs()));
|
|
#endif
|
|
|
|
xtime_update(1); /* Linux handler in kernel/time/timekeeping */
|
|
|
|
/* Note that writing CCOMPARE clears the interrupt. */
|
|
|
|
next += CCOUNT_PER_JIFFY;
|
|
set_linux_timer(next);
|
|
}
|
|
|
|
/* Allow platform to do something useful (Wdog). */
|
|
|
|
platform_heartbeat();
|
|
|
|
/* Make sure we didn't miss any tick... */
|
|
|
|
if ((signed long)(get_ccount() - next) > 0)
|
|
goto again;
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
|
|
void __cpuinit calibrate_delay(void)
|
|
{
|
|
loops_per_jiffy = CCOUNT_PER_JIFFY;
|
|
printk("Calibrating delay loop (skipped)... "
|
|
"%lu.%02lu BogoMIPS preset\n",
|
|
loops_per_jiffy/(1000000/HZ),
|
|
(loops_per_jiffy/(10000/HZ)) % 100);
|
|
}
|
|
#endif
|