/*
* linux/arch/parisc/kernel/time.c
*
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
* Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
* Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
*
* 1994-07-02 Alan Modra
* fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
* 1998-12-20 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/profile.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/param.h>
#include <asm/pdc.h>
#include <asm/led.h>
#include <linux/timex.h>
u64 jiffies_64 = INITIAL_JIFFIES;
EXPORT_SYMBOL(jiffies_64);
/* xtime and wall_jiffies keep wall-clock time */
extern unsigned long wall_jiffies;
static long clocktick; /* timer cycles per tick */
static long halftick;
#ifdef CONFIG_SMP
extern void smp_do_timer(struct pt_regs *regs);
#endif
irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
long now;
long next_tick;
int nticks;
int cpu = smp_processor_id();
profile_tick(CPU_PROFILING, regs);
now = mfctl(16);
/* initialize next_tick to time at last clocktick */
next_tick = cpu_data[cpu].it_value;
/* since time passes between the interrupt and the mfctl()
* above, it is never true that last_tick + clocktick == now. If we
* never miss a clocktick, we could set next_tick = last_tick + clocktick
* but maybe we'll miss ticks, hence the loop.
*
* Variables are *signed*.
*/
nticks = 0;
while((next_tick - now) < halftick) {
next_tick += clocktick;
nticks++;
}
mtctl(next_tick, 16);
cpu_data[cpu].it_value = next_tick;
while (nticks--) {
#ifdef CONFIG_SMP
smp_do_timer(regs);
#else
update_process_times(user_mode(regs));
#endif
if (cpu == 0) {
write_seqlock(&xtime_lock);
do_timer(regs);
write_sequnlock(&xtime_lock);
}
}
#ifdef CONFIG_CHASSIS_LCD_LED
/* Only schedule the led tasklet on cpu 0, and only if it
* is enabled.
*/
if (cpu == 0 && !atomic_read(&led_tasklet.count))
tasklet_schedule(&led_tasklet);
#endif
/* check soft power switch status */
if (cpu == 0 && !atomic_read(&power_tasklet.count))
tasklet_schedule(&power_tasklet);
return IRQ_HANDLED;
}
/*** converted from ia64 ***/
/*
* Return the number of micro-seconds that elapsed since the last
* update to wall time (aka xtime aka wall_jiffies). The xtime_lock
* must be at least read-locked when calling this routine.
*/
static inline unsigned long
gettimeoffset (void)
{
#ifndef CONFIG_SMP
/*
* FIXME: This won't work on smp because jiffies are updated by cpu 0.
* Once parisc-linux learns the cr16 difference between processors,
* this could be made to work.
*/
long last_tick;
long elapsed_cycles;
/* it_value is the intended time of the next tick */
last_tick = cpu_data[smp_processor_id()].it_value;
/* Subtract one tick and account for possible difference between
* when we expected the tick and when it actually arrived.
* (aka wall vs real)
*/
last_tick -= clocktick * (jiffies - wall_jiffies + 1);
elapsed_cycles = mfctl(16) - last_tick;
/* the precision of this math could be improved */
return elapsed_cycles / (PAGE0->mem_10msec / 10000);
#else
return 0;
#endif
}
void
do_gettimeofday (struct timeval *tv)
{
unsigned long flags, seq, usec, sec;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
usec = gettimeoffset();
sec = xtime.tv_sec;
usec += (xtime.tv_nsec / 1000);
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
while (usec >= 1000000) {
usec -= 1000000;
++sec;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);
int
do_settimeofday (struct timespec *tv)
{
time_t wtm_sec, sec = tv->tv_sec;
long wtm_nsec, nsec = tv->tv_nsec;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irq(&xtime_lock);
{
/*
* This is revolting. We need to set "xtime"
* correctly. However, the value in this location is
* the value at the most recent update of wall time.
* Discover what correction gettimeofday would have
* done, and then undo it!
*/
nsec -= gettimeoffset() * 1000;
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
set_normalized_timespec(&xtime, sec, nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
ntp_clear();
}
write_sequnlock_irq(&xtime_lock);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
/*
* XXX: We can do better than this.
* Returns nanoseconds
*/
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies * (1000000000 / HZ);
}
void __init time_init(void)
{
unsigned long next_tick;
static struct pdc_tod tod_data;
clocktick = (100 * PAGE0->mem_10msec) / HZ;
halftick = clocktick / 2;
/* Setup clock interrupt timing */
next_tick = mfctl(16);
next_tick += clocktick;
cpu_data[smp_processor_id()].it_value = next_tick;
/* kick off Itimer (CR16) */
mtctl(next_tick, 16);
if(pdc_tod_read(&tod_data) == 0) {
write_seqlock_irq(&xtime_lock);
xtime.tv_sec = tod_data.tod_sec;
xtime.tv_nsec = tod_data.tod_usec * 1000;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
write_sequnlock_irq(&xtime_lock);
} else {
printk(KERN_ERR "Error reading tod clock\n");
xtime.tv_sec = 0;
xtime.tv_nsec = 0;
}
}
