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/*
* linux/arch/ia64/kernel/time.c
*
* Copyright (C) 1998-2001 Hewlett-Packard Co
* Copyright (C) 1998-2000 Stephane Eranian <eranian@hpl.hp.com>
* Copyright (C) 1999-2001 David Mosberger <davidm@hpl.hp.com>
* Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
* Copyright (C) 1999-2000 VA Linux Systems
* Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <asm/delay.h>
#include <asm/efi.h>
#include <asm/hw_irq.h>
#include <asm/ptrace.h>
#include <asm/sal.h>
#include <asm/system.h>
extern rwlock_t xtime_lock;
extern unsigned long wall_jiffies;
extern unsigned long last_time_offset;
#ifdef CONFIG_IA64_DEBUG_IRQ
unsigned long last_cli_ip;
#endif
static void
do_profile (unsigned long ip)
{
extern unsigned long prof_cpu_mask;
extern char _stext;
if (!((1UL << smp_processor_id()) & prof_cpu_mask))
return;
if (prof_buffer && current->pid) {
ip -= (unsigned long) &_stext;
ip >>= prof_shift;
/*
* Don't ignore out-of-bounds IP values silently, put them into the last
* histogram slot, so if present, they will show up as a sharp peak.
*/
if (ip > prof_len - 1)
ip = prof_len - 1;
atomic_inc((atomic_t *) &prof_buffer[ip]);
}
}
/*
* Return the number of micro-seconds that elapsed since the last update to jiffy. The
* xtime_lock must be at least read-locked when calling this routine.
*/
static inline unsigned long
gettimeoffset (void)
{
unsigned long elapsed_cycles, lost = jiffies - wall_jiffies;
unsigned long now, last_tick;
# define time_keeper_id 0 /* smp_processor_id() of time-keeper */
last_tick = (cpu_data(time_keeper_id)->itm_next
- (lost + 1)*cpu_data(time_keeper_id)->itm_delta);
now = ia64_get_itc();
if ((long) (now - last_tick) < 0) {
# if 1
printk("CPU %d: now < last_tick (now=0x%lx,last_tick=0x%lx)!\n",
smp_processor_id(), now, last_tick);
# endif
return last_time_offset;
}
elapsed_cycles = now - last_tick;
return (elapsed_cycles*local_cpu_data->usec_per_cyc) >> IA64_USEC_PER_CYC_SHIFT;
}
void
do_settimeofday (struct timeval *tv)
{
write_lock_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!
*/
tv->tv_usec -= gettimeoffset();
tv->tv_usec -= (jiffies - wall_jiffies) * (1000000 / HZ);
while (tv->tv_usec < 0) {
tv->tv_usec += 1000000;
tv->tv_sec--;
}
xtime = *tv;
time_adjust = 0; /* stop active adjtime() */
time_status |= STA_UNSYNC;
time_maxerror = NTP_PHASE_LIMIT;
time_esterror = NTP_PHASE_LIMIT;
}
write_unlock_irq(&xtime_lock);
}
void
do_gettimeofday (struct timeval *tv)
{
unsigned long flags, usec, sec, old;
read_lock_irqsave(&xtime_lock, flags);
{
usec = gettimeoffset();
/*
* Ensure time never goes backwards, even when ITC on different CPUs are
* not perfectly synchronized.
*/
do {
old = last_time_offset;
if (usec <= old) {
usec = old;
break;
}
} while (cmpxchg(&last_time_offset, old, usec) != old);
sec = xtime.tv_sec;
usec += xtime.tv_usec;
}
read_unlock_irqrestore(&xtime_lock, flags);
while (usec >= 1000000) {
usec -= 1000000;
++sec;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
}
static void
timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
unsigned long new_itm;
new_itm = local_cpu_data->itm_next;
if (!time_after(ia64_get_itc(), new_itm))
printk("Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
ia64_get_itc(), new_itm);
while (1) {
/*
* Do kernel PC profiling here. We multiply the instruction number by
* four so that we can use a prof_shift of 2 to get instruction-level
* instead of just bundle-level accuracy.
*/
if (!user_mode(regs))
do_profile(regs->cr_iip + 4*ia64_psr(regs)->ri);
#ifdef CONFIG_SMP
smp_do_timer(regs);
#endif
new_itm += local_cpu_data->itm_delta;
if (smp_processor_id() == 0) {
/*
* Here we are in the timer irq handler. We have irqs locally
* disabled, but we don't know if the timer_bh is running on
* another CPU. We need to avoid to SMP race by acquiring the
* xtime_lock.
*/
write_lock(&xtime_lock);
do_timer(regs);
local_cpu_data->itm_next = new_itm;
write_unlock(&xtime_lock);
} else
local_cpu_data->itm_next = new_itm;
if (time_after(new_itm, ia64_get_itc()))
break;
}
do {
/*
* If we're too close to the next clock tick for comfort, we increase the
* saftey margin by intentionally dropping the next tick(s). We do NOT update
* itm.next because that would force us to call do_timer() which in turn would
* let our clock run too fast (with the potentially devastating effect of
* losing monotony of time).
*/
while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
new_itm += local_cpu_data->itm_delta;
ia64_set_itm(new_itm);
/* double check, in case we got hit by a (slow) PMI: */
} while (time_after_eq(ia64_get_itc(), new_itm));
}
/*
* Encapsulate access to the itm structure for SMP.
*/
void __init
ia64_cpu_local_tick (void)
{
int cpu = smp_processor_id();
unsigned long shift = 0, delta;
/* arrange for the cycle counter to generate a timer interrupt: */
ia64_set_itv(IA64_TIMER_VECTOR);
delta = local_cpu_data->itm_delta;
/*
* Stagger the timer tick for each CPU so they don't occur all at (almost) the
* same time:
*/
if (cpu) {
unsigned long hi = 1UL << ia64_fls(cpu);
shift = (2*(cpu - hi) + 1) * delta/hi/2;
}
local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
ia64_set_itm(local_cpu_data->itm_next);
}
void __init
ia64_init_itm (void)
{
unsigned long platform_base_freq, itc_freq, drift;
struct pal_freq_ratio itc_ratio, proc_ratio;
long status;
/*
* According to SAL v2.6, we need to use a SAL call to determine the platform base
* frequency and then a PAL call to determine the frequency ratio between the ITC
* and the base frequency.
*/
status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM, &platform_base_freq, &drift);
if (status != 0) {
printk("SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
} else {
status = ia64_pal_freq_ratios(&proc_ratio, 0, &itc_ratio);
if (status != 0)
printk("PAL_FREQ_RATIOS failed with status=%ld\n", status);
}
if (status != 0) {
/* invent "random" values */
printk("SAL/PAL failed to obtain frequency info---inventing reasonably values\n");
platform_base_freq = 100000000;
itc_ratio.num = 3;
itc_ratio.den = 1;
}
if (platform_base_freq < 40000000) {
printk("Platform base frequency %lu bogus---resetting to 75MHz!\n",
platform_base_freq);
platform_base_freq = 75000000;
}
if (!proc_ratio.den)
proc_ratio.den = 1; /* avoid division by zero */
if (!itc_ratio.den)
itc_ratio.den = 1; /* avoid division by zero */
itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
printk("CPU %d: base freq=%lu.%03luMHz, ITC ratio=%lu/%lu, ITC freq=%lu.%03luMHz\n",
smp_processor_id(),
platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
local_cpu_data->itc_freq = itc_freq;
local_cpu_data->cyc_per_usec = (itc_freq + 500000) / 1000000;
local_cpu_data->usec_per_cyc = ((1000000UL<<IA64_USEC_PER_CYC_SHIFT)
+ itc_freq/2)/itc_freq;
/* Setup the CPU local timer tick */
ia64_cpu_local_tick();
}
static struct irqaction timer_irqaction = {
handler: timer_interrupt,
flags: SA_INTERRUPT,
name: "timer"
};
void __init
time_init (void)
{
register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
efi_gettimeofday((struct timeval *) &xtime);
ia64_init_itm();
}
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