1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/arch/ia64/kernel/time.c
5 * Copyright (C) 1998-2003 Hewlett-Packard Co
9 * Copyright (C) 1999-2000 VA Linux Systems
13 #include <linux/cpu.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/profile.h>
18 #include <linux/sched.h>
19 #include <linux/time.h>
20 #include <linux/nmi.h>
21 #include <linux/interrupt.h>
22 #include <linux/efi.h>
23 #include <linux/timex.h>
24 #include <linux/timekeeper_internal.h>
25 #include <linux/platform_device.h>
26 #include <linux/sched/cputime.h>
28 #include <asm/cputime.h>
29 #include <asm/delay.h>
31 #include <asm/hw_irq.h>
32 #include <asm/ptrace.h>
34 #include <asm/sections.h>
36 #include "fsyscall_gtod_data.h"
39 static u64 itc_get_cycles(struct clocksource *cs);
41 struct fsyscall_gtod_data_t fsyscall_gtod_data;
43 struct itc_jitter_data_t itc_jitter_data;
45 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
47 #ifdef CONFIG_IA64_DEBUG_IRQ
49 unsigned long last_cli_ip;
50 EXPORT_SYMBOL(last_cli_ip);
54 static struct clocksource clocksource_itc = {
57 .read = itc_get_cycles,
58 .mask = CLOCKSOURCE_MASK(64),
59 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
61 static struct clocksource *itc_clocksource;
63 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
65 #include <linux/kernel_stat.h>
67 extern u64 cycle_to_nsec(u64 cyc);
69 void vtime_flush(struct task_struct *tsk)
71 struct thread_info *ti = task_thread_info(tsk);
75 account_user_time(tsk, cycle_to_nsec(ti->utime));
78 account_guest_time(tsk, cycle_to_nsec(ti->gtime));
81 account_idle_time(cycle_to_nsec(ti->idle_time));
84 delta = cycle_to_nsec(ti->stime);
85 account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
88 if (ti->hardirq_time) {
89 delta = cycle_to_nsec(ti->hardirq_time);
90 account_system_index_time(tsk, delta, CPUTIME_IRQ);
93 if (ti->softirq_time) {
94 delta = cycle_to_nsec(ti->softirq_time);
95 account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
102 ti->hardirq_time = 0;
103 ti->softirq_time = 0;
107 * Called from the context switch with interrupts disabled, to charge all
108 * accumulated times to the current process, and to prepare accounting on
111 void arch_vtime_task_switch(struct task_struct *prev)
113 struct thread_info *pi = task_thread_info(prev);
114 struct thread_info *ni = task_thread_info(current);
116 ni->ac_stamp = pi->ac_stamp;
117 ni->ac_stime = ni->ac_utime = 0;
121 * Account time for a transition between system, hard irq or soft irq state.
122 * Note that this function is called with interrupts enabled.
124 static __u64 vtime_delta(struct task_struct *tsk)
126 struct thread_info *ti = task_thread_info(tsk);
127 __u64 now, delta_stime;
129 WARN_ON_ONCE(!irqs_disabled());
131 now = ia64_get_itc();
132 delta_stime = now - ti->ac_stamp;
138 void vtime_account_kernel(struct task_struct *tsk)
140 struct thread_info *ti = task_thread_info(tsk);
141 __u64 stime = vtime_delta(tsk);
143 if (tsk->flags & PF_VCPU)
148 EXPORT_SYMBOL_GPL(vtime_account_kernel);
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 void vtime_account_softirq(struct task_struct *tsk)
159 struct thread_info *ti = task_thread_info(tsk);
161 ti->softirq_time += vtime_delta(tsk);
164 void vtime_account_hardirq(struct task_struct *tsk)
166 struct thread_info *ti = task_thread_info(tsk);
168 ti->hardirq_time += vtime_delta(tsk);
171 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
174 timer_interrupt (int irq, void *dev_id)
176 unsigned long new_itm;
178 if (cpu_is_offline(smp_processor_id())) {
182 new_itm = local_cpu_data->itm_next;
184 if (!time_after(ia64_get_itc(), new_itm))
185 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
186 ia64_get_itc(), new_itm);
189 new_itm += local_cpu_data->itm_delta;
191 legacy_timer_tick(smp_processor_id() == time_keeper_id);
193 local_cpu_data->itm_next = new_itm;
195 if (time_after(new_itm, ia64_get_itc()))
199 * Allow IPIs to interrupt the timer loop.
207 * If we're too close to the next clock tick for
208 * comfort, we increase the safety margin by
209 * intentionally dropping the next tick(s). We do NOT
210 * update itm.next because that would force us to call
211 * xtime_update() which in turn would let our clock run
212 * too fast (with the potentially devastating effect
213 * of losing monotony of time).
215 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
216 new_itm += local_cpu_data->itm_delta;
217 ia64_set_itm(new_itm);
218 /* double check, in case we got hit by a (slow) PMI: */
219 } while (time_after_eq(ia64_get_itc(), new_itm));
224 * Encapsulate access to the itm structure for SMP.
227 ia64_cpu_local_tick (void)
229 int cpu = smp_processor_id();
230 unsigned long shift = 0, delta;
232 /* arrange for the cycle counter to generate a timer interrupt: */
233 ia64_set_itv(IA64_TIMER_VECTOR);
235 delta = local_cpu_data->itm_delta;
237 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
241 unsigned long hi = 1UL << ia64_fls(cpu);
242 shift = (2*(cpu - hi) + 1) * delta/hi/2;
244 local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
245 ia64_set_itm(local_cpu_data->itm_next);
250 static int __init nojitter_setup(char *str)
253 printk("Jitter checking for ITC timers disabled\n");
257 __setup("nojitter", nojitter_setup);
260 void ia64_init_itm(void)
262 unsigned long platform_base_freq, itc_freq;
263 struct pal_freq_ratio itc_ratio, proc_ratio;
264 long status, platform_base_drift, itc_drift;
267 * According to SAL v2.6, we need to use a SAL call to determine the platform base
268 * frequency and then a PAL call to determine the frequency ratio between the ITC
269 * and the base frequency.
271 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
272 &platform_base_freq, &platform_base_drift);
274 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
276 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
278 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
281 /* invent "random" values */
283 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
284 platform_base_freq = 100000000;
285 platform_base_drift = -1; /* no drift info */
289 if (platform_base_freq < 40000000) {
290 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
292 platform_base_freq = 75000000;
293 platform_base_drift = -1;
296 proc_ratio.den = 1; /* avoid division by zero */
298 itc_ratio.den = 1; /* avoid division by zero */
300 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
302 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
303 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
304 "ITC freq=%lu.%03luMHz", smp_processor_id(),
305 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
306 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
308 if (platform_base_drift != -1) {
309 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
310 printk("+/-%ldppm\n", itc_drift);
316 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
317 local_cpu_data->itc_freq = itc_freq;
318 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
319 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
320 + itc_freq/2)/itc_freq;
322 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
324 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
325 * Jitter compensation requires a cmpxchg which may limit
326 * the scalability of the syscalls for retrieving time.
327 * The ITC synchronization is usually successful to within a few
328 * ITC ticks but this is not a sure thing. If you need to improve
329 * timer performance in SMP situations then boot the kernel with the
330 * "nojitter" option. However, doing so may result in time fluctuating (maybe
331 * even going backward) if the ITC offsets between the individual CPUs
335 itc_jitter_data.itc_jitter = 1;
339 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
340 * ITC values may fluctuate significantly between processors.
341 * Clock should not be used for hrtimers. Mark itc as only
342 * useful for boot and testing.
344 * Note that jitter compensation is off! There is no point of
345 * synchronizing ITCs since they may be large differentials
346 * that change over time.
348 * The only way to fix this would be to repeatedly sync the
349 * ITCs. Until that time we have to avoid ITC.
351 clocksource_itc.rating = 50;
353 /* avoid softlock up message when cpu is unplug and plugged again. */
354 touch_softlockup_watchdog();
356 /* Setup the CPU local timer tick */
357 ia64_cpu_local_tick();
359 if (!itc_clocksource) {
360 clocksource_register_hz(&clocksource_itc,
361 local_cpu_data->itc_freq);
362 itc_clocksource = &clocksource_itc;
366 static u64 itc_get_cycles(struct clocksource *cs)
368 unsigned long lcycle, now, ret;
370 if (!itc_jitter_data.itc_jitter)
373 lcycle = itc_jitter_data.itc_lastcycle;
375 if (lcycle && time_after(lcycle, now))
379 * Keep track of the last timer value returned.
380 * In an SMP environment, you could lose out in contention of
381 * cmpxchg. If so, your cmpxchg returns new value which the
382 * winner of contention updated to. Use the new value instead.
384 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
385 if (unlikely(ret != lcycle))
391 void read_persistent_clock64(struct timespec64 *ts)
393 efi_gettimeofday(ts);
399 register_percpu_irq(IA64_TIMER_VECTOR, timer_interrupt, IRQF_IRQPOLL,
405 * Generic udelay assumes that if preemption is allowed and the thread
406 * migrates to another CPU, that the ITC values are synchronized across
410 ia64_itc_udelay (unsigned long usecs)
412 unsigned long start = ia64_get_itc();
413 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
415 while (time_before(ia64_get_itc(), end))
419 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
422 udelay (unsigned long usecs)
424 (*ia64_udelay)(usecs);
426 EXPORT_SYMBOL(udelay);
428 /* IA64 doesn't cache the timezone */
429 void update_vsyscall_tz(void)
433 void update_vsyscall(struct timekeeper *tk)
435 write_seqcount_begin(&fsyscall_gtod_data.seq);
437 /* copy vsyscall data */
438 fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask;
439 fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult;
440 fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift;
441 fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio;
442 fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last;
444 fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
445 fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
447 fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec
448 + tk->wall_to_monotonic.tv_sec;
449 fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec
450 + ((u64)tk->wall_to_monotonic.tv_nsec
451 << tk->tkr_mono.shift);
454 while (fsyscall_gtod_data.monotonic_time.snsec >=
455 (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
456 fsyscall_gtod_data.monotonic_time.snsec -=
457 ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
458 fsyscall_gtod_data.monotonic_time.sec++;
461 write_seqcount_end(&fsyscall_gtod_data.seq);