2 * linux/arch/ia64/kernel/time.c
4 * Copyright (C) 1998-2003 Hewlett-Packard Co
5 * Stephane Eranian <eranian@hpl.hp.com>
6 * David Mosberger <davidm@hpl.hp.com>
7 * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
8 * Copyright (C) 1999-2000 VA Linux Systems
9 * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
12 #include <linux/cpu.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/profile.h>
17 #include <linux/sched.h>
18 #include <linux/time.h>
19 #include <linux/interrupt.h>
20 #include <linux/efi.h>
21 #include <linux/timex.h>
22 #include <linux/timekeeper_internal.h>
23 #include <linux/platform_device.h>
24 #include <linux/cputime.h>
26 #include <asm/machvec.h>
27 #include <asm/delay.h>
28 #include <asm/hw_irq.h>
29 #include <asm/ptrace.h>
31 #include <asm/sections.h>
33 #include "fsyscall_gtod_data.h"
35 static u64 itc_get_cycles(struct clocksource *cs);
37 struct fsyscall_gtod_data_t fsyscall_gtod_data;
39 struct itc_jitter_data_t itc_jitter_data;
41 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
43 #ifdef CONFIG_IA64_DEBUG_IRQ
45 unsigned long last_cli_ip;
46 EXPORT_SYMBOL(last_cli_ip);
50 static struct clocksource clocksource_itc = {
53 .read = itc_get_cycles,
54 .mask = CLOCKSOURCE_MASK(64),
55 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
57 static struct clocksource *itc_clocksource;
59 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
61 #include <linux/kernel_stat.h>
63 extern u64 cycle_to_nsec(u64 cyc);
65 void vtime_flush(struct task_struct *tsk)
67 struct thread_info *ti = task_thread_info(tsk);
71 account_user_time(tsk, cycle_to_nsec(ti->utime));
74 account_guest_time(tsk, cycle_to_nsec(ti->gtime));
77 account_idle_time(cycle_to_nsec(ti->idle_time));
80 delta = cycle_to_nsec(ti->stime);
81 account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
84 if (ti->hardirq_time) {
85 delta = cycle_to_nsec(ti->hardirq_time);
86 account_system_index_time(tsk, delta, CPUTIME_IRQ);
89 if (ti->softirq_time) {
90 delta = cycle_to_nsec(ti->softirq_time));
91 account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
103 * Called from the context switch with interrupts disabled, to charge all
104 * accumulated times to the current process, and to prepare accounting on
107 void arch_vtime_task_switch(struct task_struct *prev)
109 struct thread_info *pi = task_thread_info(prev);
110 struct thread_info *ni = task_thread_info(current);
112 ni->ac_stamp = pi->ac_stamp;
113 ni->ac_stime = ni->ac_utime = 0;
117 * Account time for a transition between system, hard irq or soft irq state.
118 * Note that this function is called with interrupts enabled.
120 static __u64 vtime_delta(struct task_struct *tsk)
122 struct thread_info *ti = task_thread_info(tsk);
123 __u64 now, delta_stime;
125 WARN_ON_ONCE(!irqs_disabled());
127 now = ia64_get_itc();
128 delta_stime = now - ti->ac_stamp;
134 void vtime_account_system(struct task_struct *tsk)
136 struct thread_info *ti = task_thread_info(tsk);
137 __u64 stime = vtime_delta(tsk);
139 if ((tsk->flags & PF_VCPU) && !irq_count())
141 else if (hardirq_count())
142 ti->hardirq_time += stime;
143 else if (in_serving_softirq())
144 ti->softirq_time += stime;
148 EXPORT_SYMBOL_GPL(vtime_account_system);
150 void vtime_account_idle(struct task_struct *tsk)
152 struct thread_info *ti = task_thread_info(tsk);
154 ti->idle_time += vtime_delta(tsk);
157 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
160 timer_interrupt (int irq, void *dev_id)
162 unsigned long new_itm;
164 if (cpu_is_offline(smp_processor_id())) {
168 platform_timer_interrupt(irq, dev_id);
170 new_itm = local_cpu_data->itm_next;
172 if (!time_after(ia64_get_itc(), new_itm))
173 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
174 ia64_get_itc(), new_itm);
176 profile_tick(CPU_PROFILING);
179 update_process_times(user_mode(get_irq_regs()));
181 new_itm += local_cpu_data->itm_delta;
183 if (smp_processor_id() == time_keeper_id)
186 local_cpu_data->itm_next = new_itm;
188 if (time_after(new_itm, ia64_get_itc()))
192 * Allow IPIs to interrupt the timer loop.
200 * If we're too close to the next clock tick for
201 * comfort, we increase the safety margin by
202 * intentionally dropping the next tick(s). We do NOT
203 * update itm.next because that would force us to call
204 * xtime_update() which in turn would let our clock run
205 * too fast (with the potentially devastating effect
206 * of losing monotony of time).
208 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
209 new_itm += local_cpu_data->itm_delta;
210 ia64_set_itm(new_itm);
211 /* double check, in case we got hit by a (slow) PMI: */
212 } while (time_after_eq(ia64_get_itc(), new_itm));
217 * Encapsulate access to the itm structure for SMP.
220 ia64_cpu_local_tick (void)
222 int cpu = smp_processor_id();
223 unsigned long shift = 0, delta;
225 /* arrange for the cycle counter to generate a timer interrupt: */
226 ia64_set_itv(IA64_TIMER_VECTOR);
228 delta = local_cpu_data->itm_delta;
230 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
234 unsigned long hi = 1UL << ia64_fls(cpu);
235 shift = (2*(cpu - hi) + 1) * delta/hi/2;
237 local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
238 ia64_set_itm(local_cpu_data->itm_next);
243 static int __init nojitter_setup(char *str)
246 printk("Jitter checking for ITC timers disabled\n");
250 __setup("nojitter", nojitter_setup);
253 void ia64_init_itm(void)
255 unsigned long platform_base_freq, itc_freq;
256 struct pal_freq_ratio itc_ratio, proc_ratio;
257 long status, platform_base_drift, itc_drift;
260 * According to SAL v2.6, we need to use a SAL call to determine the platform base
261 * frequency and then a PAL call to determine the frequency ratio between the ITC
262 * and the base frequency.
264 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
265 &platform_base_freq, &platform_base_drift);
267 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
269 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
271 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
274 /* invent "random" values */
276 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
277 platform_base_freq = 100000000;
278 platform_base_drift = -1; /* no drift info */
282 if (platform_base_freq < 40000000) {
283 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
285 platform_base_freq = 75000000;
286 platform_base_drift = -1;
289 proc_ratio.den = 1; /* avoid division by zero */
291 itc_ratio.den = 1; /* avoid division by zero */
293 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
295 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
296 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
297 "ITC freq=%lu.%03luMHz", smp_processor_id(),
298 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
299 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
301 if (platform_base_drift != -1) {
302 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
303 printk("+/-%ldppm\n", itc_drift);
309 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
310 local_cpu_data->itc_freq = itc_freq;
311 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
312 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
313 + itc_freq/2)/itc_freq;
315 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
317 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
318 * Jitter compensation requires a cmpxchg which may limit
319 * the scalability of the syscalls for retrieving time.
320 * The ITC synchronization is usually successful to within a few
321 * ITC ticks but this is not a sure thing. If you need to improve
322 * timer performance in SMP situations then boot the kernel with the
323 * "nojitter" option. However, doing so may result in time fluctuating (maybe
324 * even going backward) if the ITC offsets between the individual CPUs
328 itc_jitter_data.itc_jitter = 1;
332 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
333 * ITC values may fluctuate significantly between processors.
334 * Clock should not be used for hrtimers. Mark itc as only
335 * useful for boot and testing.
337 * Note that jitter compensation is off! There is no point of
338 * synchronizing ITCs since they may be large differentials
339 * that change over time.
341 * The only way to fix this would be to repeatedly sync the
342 * ITCs. Until that time we have to avoid ITC.
344 clocksource_itc.rating = 50;
346 /* avoid softlock up message when cpu is unplug and plugged again. */
347 touch_softlockup_watchdog();
349 /* Setup the CPU local timer tick */
350 ia64_cpu_local_tick();
352 if (!itc_clocksource) {
353 clocksource_register_hz(&clocksource_itc,
354 local_cpu_data->itc_freq);
355 itc_clocksource = &clocksource_itc;
359 static u64 itc_get_cycles(struct clocksource *cs)
361 unsigned long lcycle, now, ret;
363 if (!itc_jitter_data.itc_jitter)
366 lcycle = itc_jitter_data.itc_lastcycle;
368 if (lcycle && time_after(lcycle, now))
372 * Keep track of the last timer value returned.
373 * In an SMP environment, you could lose out in contention of
374 * cmpxchg. If so, your cmpxchg returns new value which the
375 * winner of contention updated to. Use the new value instead.
377 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
378 if (unlikely(ret != lcycle))
385 static struct irqaction timer_irqaction = {
386 .handler = timer_interrupt,
387 .flags = IRQF_IRQPOLL,
391 void read_persistent_clock64(struct timespec64 *ts)
393 efi_gettimeofday(ts);
399 register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
404 * Generic udelay assumes that if preemption is allowed and the thread
405 * migrates to another CPU, that the ITC values are synchronized across
409 ia64_itc_udelay (unsigned long usecs)
411 unsigned long start = ia64_get_itc();
412 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
414 while (time_before(ia64_get_itc(), end))
418 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
421 udelay (unsigned long usecs)
423 (*ia64_udelay)(usecs);
425 EXPORT_SYMBOL(udelay);
427 /* IA64 doesn't cache the timezone */
428 void update_vsyscall_tz(void)
432 void update_vsyscall_old(struct timespec *wall, struct timespec *wtm,
433 struct clocksource *c, u32 mult, u64 cycle_last)
435 write_seqcount_begin(&fsyscall_gtod_data.seq);
437 /* copy fsyscall clock data */
438 fsyscall_gtod_data.clk_mask = c->mask;
439 fsyscall_gtod_data.clk_mult = mult;
440 fsyscall_gtod_data.clk_shift = c->shift;
441 fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio;
442 fsyscall_gtod_data.clk_cycle_last = cycle_last;
444 /* copy kernel time structures */
445 fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
446 fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
447 fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
449 fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
453 while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
454 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
455 fsyscall_gtod_data.monotonic_time.tv_sec++;
458 write_seqcount_end(&fsyscall_gtod_data.seq);