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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/ia64/kernel/time.c
4 *
5 * Copyright (C) 1998-2003 Hewlett-Packard Co
6 * Stephane Eranian <eranian@hpl.hp.com>
7 * David Mosberger <davidm@hpl.hp.com>
8 * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
9 * Copyright (C) 1999-2000 VA Linux Systems
10 * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
11 */
12
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>
27
28#include <asm/delay.h>
29#include <asm/efi.h>
30#include <asm/hw_irq.h>
31#include <asm/ptrace.h>
32#include <asm/sal.h>
33#include <asm/sections.h>
34
35#include "fsyscall_gtod_data.h"
36#include "irq.h"
37
38static u64 itc_get_cycles(struct clocksource *cs);
39
40struct fsyscall_gtod_data_t fsyscall_gtod_data;
41
42struct itc_jitter_data_t itc_jitter_data;
43
44volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
45
46#ifdef CONFIG_IA64_DEBUG_IRQ
47
48unsigned long last_cli_ip;
49EXPORT_SYMBOL(last_cli_ip);
50
51#endif
52
53static struct clocksource clocksource_itc = {
54 .name = "itc",
55 .rating = 350,
56 .read = itc_get_cycles,
57 .mask = CLOCKSOURCE_MASK(64),
58 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
59};
60static struct clocksource *itc_clocksource;
61
62#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
63
64#include <linux/kernel_stat.h>
65
66extern u64 cycle_to_nsec(u64 cyc);
67
68void vtime_flush(struct task_struct *tsk)
69{
70 struct thread_info *ti = task_thread_info(tsk);
71 u64 delta;
72
73 if (ti->utime)
74 account_user_time(tsk, cycle_to_nsec(ti->utime));
75
76 if (ti->gtime)
77 account_guest_time(tsk, cycle_to_nsec(ti->gtime));
78
79 if (ti->idle_time)
80 account_idle_time(cycle_to_nsec(ti->idle_time));
81
82 if (ti->stime) {
83 delta = cycle_to_nsec(ti->stime);
84 account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
85 }
86
87 if (ti->hardirq_time) {
88 delta = cycle_to_nsec(ti->hardirq_time);
89 account_system_index_time(tsk, delta, CPUTIME_IRQ);
90 }
91
92 if (ti->softirq_time) {
93 delta = cycle_to_nsec(ti->softirq_time);
94 account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
95 }
96
97 ti->utime = 0;
98 ti->gtime = 0;
99 ti->idle_time = 0;
100 ti->stime = 0;
101 ti->hardirq_time = 0;
102 ti->softirq_time = 0;
103}
104
105/*
106 * Called from the context switch with interrupts disabled, to charge all
107 * accumulated times to the current process, and to prepare accounting on
108 * the next process.
109 */
110void arch_vtime_task_switch(struct task_struct *prev)
111{
112 struct thread_info *pi = task_thread_info(prev);
113 struct thread_info *ni = task_thread_info(current);
114
115 ni->ac_stamp = pi->ac_stamp;
116 ni->ac_stime = ni->ac_utime = 0;
117}
118
119/*
120 * Account time for a transition between system, hard irq or soft irq state.
121 * Note that this function is called with interrupts enabled.
122 */
123static __u64 vtime_delta(struct task_struct *tsk)
124{
125 struct thread_info *ti = task_thread_info(tsk);
126 __u64 now, delta_stime;
127
128 WARN_ON_ONCE(!irqs_disabled());
129
130 now = ia64_get_itc();
131 delta_stime = now - ti->ac_stamp;
132 ti->ac_stamp = now;
133
134 return delta_stime;
135}
136
137void vtime_account_kernel(struct task_struct *tsk)
138{
139 struct thread_info *ti = task_thread_info(tsk);
140 __u64 stime = vtime_delta(tsk);
141
142 if (tsk->flags & PF_VCPU)
143 ti->gtime += stime;
144 else
145 ti->stime += stime;
146}
147EXPORT_SYMBOL_GPL(vtime_account_kernel);
148
149void vtime_account_idle(struct task_struct *tsk)
150{
151 struct thread_info *ti = task_thread_info(tsk);
152
153 ti->idle_time += vtime_delta(tsk);
154}
155
156void vtime_account_softirq(struct task_struct *tsk)
157{
158 struct thread_info *ti = task_thread_info(tsk);
159
160 ti->softirq_time += vtime_delta(tsk);
161}
162
163void vtime_account_hardirq(struct task_struct *tsk)
164{
165 struct thread_info *ti = task_thread_info(tsk);
166
167 ti->hardirq_time += vtime_delta(tsk);
168}
169
170#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
171
172static irqreturn_t
173timer_interrupt (int irq, void *dev_id)
174{
175 unsigned long new_itm;
176
177 if (cpu_is_offline(smp_processor_id())) {
178 return IRQ_HANDLED;
179 }
180
181 new_itm = local_cpu_data->itm_next;
182
183 if (!time_after(ia64_get_itc(), new_itm))
184 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
185 ia64_get_itc(), new_itm);
186
187 while (1) {
188 new_itm += local_cpu_data->itm_delta;
189
190 legacy_timer_tick(smp_processor_id() == time_keeper_id);
191
192 local_cpu_data->itm_next = new_itm;
193
194 if (time_after(new_itm, ia64_get_itc()))
195 break;
196
197 /*
198 * Allow IPIs to interrupt the timer loop.
199 */
200 local_irq_enable();
201 local_irq_disable();
202 }
203
204 do {
205 /*
206 * If we're too close to the next clock tick for
207 * comfort, we increase the safety margin by
208 * intentionally dropping the next tick(s). We do NOT
209 * update itm.next because that would force us to call
210 * xtime_update() which in turn would let our clock run
211 * too fast (with the potentially devastating effect
212 * of losing monotony of time).
213 */
214 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
215 new_itm += local_cpu_data->itm_delta;
216 ia64_set_itm(new_itm);
217 /* double check, in case we got hit by a (slow) PMI: */
218 } while (time_after_eq(ia64_get_itc(), new_itm));
219 return IRQ_HANDLED;
220}
221
222/*
223 * Encapsulate access to the itm structure for SMP.
224 */
225void
226ia64_cpu_local_tick (void)
227{
228 int cpu = smp_processor_id();
229 unsigned long shift = 0, delta;
230
231 /* arrange for the cycle counter to generate a timer interrupt: */
232 ia64_set_itv(IA64_TIMER_VECTOR);
233
234 delta = local_cpu_data->itm_delta;
235 /*
236 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
237 * same time:
238 */
239 if (cpu) {
240 unsigned long hi = 1UL << ia64_fls(cpu);
241 shift = (2*(cpu - hi) + 1) * delta/hi/2;
242 }
243 local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
244 ia64_set_itm(local_cpu_data->itm_next);
245}
246
247static int nojitter;
248
249static int __init nojitter_setup(char *str)
250{
251 nojitter = 1;
252 printk("Jitter checking for ITC timers disabled\n");
253 return 1;
254}
255
256__setup("nojitter", nojitter_setup);
257
258
259void ia64_init_itm(void)
260{
261 unsigned long platform_base_freq, itc_freq;
262 struct pal_freq_ratio itc_ratio, proc_ratio;
263 long status, platform_base_drift, itc_drift;
264
265 /*
266 * According to SAL v2.6, we need to use a SAL call to determine the platform base
267 * frequency and then a PAL call to determine the frequency ratio between the ITC
268 * and the base frequency.
269 */
270 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
271 &platform_base_freq, &platform_base_drift);
272 if (status != 0) {
273 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
274 } else {
275 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
276 if (status != 0)
277 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
278 }
279 if (status != 0) {
280 /* invent "random" values */
281 printk(KERN_ERR
282 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
283 platform_base_freq = 100000000;
284 platform_base_drift = -1; /* no drift info */
285 itc_ratio.num = 3;
286 itc_ratio.den = 1;
287 }
288 if (platform_base_freq < 40000000) {
289 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
290 platform_base_freq);
291 platform_base_freq = 75000000;
292 platform_base_drift = -1;
293 }
294 if (!proc_ratio.den)
295 proc_ratio.den = 1; /* avoid division by zero */
296 if (!itc_ratio.den)
297 itc_ratio.den = 1; /* avoid division by zero */
298
299 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
300
301 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
302 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
303 "ITC freq=%lu.%03luMHz", smp_processor_id(),
304 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
305 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
306
307 if (platform_base_drift != -1) {
308 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
309 printk("+/-%ldppm\n", itc_drift);
310 } else {
311 itc_drift = -1;
312 printk("\n");
313 }
314
315 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
316 local_cpu_data->itc_freq = itc_freq;
317 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
318 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
319 + itc_freq/2)/itc_freq;
320
321 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
322#ifdef CONFIG_SMP
323 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
324 * Jitter compensation requires a cmpxchg which may limit
325 * the scalability of the syscalls for retrieving time.
326 * The ITC synchronization is usually successful to within a few
327 * ITC ticks but this is not a sure thing. If you need to improve
328 * timer performance in SMP situations then boot the kernel with the
329 * "nojitter" option. However, doing so may result in time fluctuating (maybe
330 * even going backward) if the ITC offsets between the individual CPUs
331 * are too large.
332 */
333 if (!nojitter)
334 itc_jitter_data.itc_jitter = 1;
335#endif
336 } else
337 /*
338 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
339 * ITC values may fluctuate significantly between processors.
340 * Clock should not be used for hrtimers. Mark itc as only
341 * useful for boot and testing.
342 *
343 * Note that jitter compensation is off! There is no point of
344 * synchronizing ITCs since they may be large differentials
345 * that change over time.
346 *
347 * The only way to fix this would be to repeatedly sync the
348 * ITCs. Until that time we have to avoid ITC.
349 */
350 clocksource_itc.rating = 50;
351
352 /* avoid softlock up message when cpu is unplug and plugged again. */
353 touch_softlockup_watchdog();
354
355 /* Setup the CPU local timer tick */
356 ia64_cpu_local_tick();
357
358 if (!itc_clocksource) {
359 clocksource_register_hz(&clocksource_itc,
360 local_cpu_data->itc_freq);
361 itc_clocksource = &clocksource_itc;
362 }
363}
364
365static u64 itc_get_cycles(struct clocksource *cs)
366{
367 unsigned long lcycle, now, ret;
368
369 if (!itc_jitter_data.itc_jitter)
370 return get_cycles();
371
372 lcycle = itc_jitter_data.itc_lastcycle;
373 now = get_cycles();
374 if (lcycle && time_after(lcycle, now))
375 return lcycle;
376
377 /*
378 * Keep track of the last timer value returned.
379 * In an SMP environment, you could lose out in contention of
380 * cmpxchg. If so, your cmpxchg returns new value which the
381 * winner of contention updated to. Use the new value instead.
382 */
383 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
384 if (unlikely(ret != lcycle))
385 return ret;
386
387 return now;
388}
389
390void read_persistent_clock64(struct timespec64 *ts)
391{
392 efi_gettimeofday(ts);
393}
394
395void __init
396time_init (void)
397{
398 register_percpu_irq(IA64_TIMER_VECTOR, timer_interrupt, IRQF_IRQPOLL,
399 "timer");
400 ia64_init_itm();
401}
402
403/*
404 * Generic udelay assumes that if preemption is allowed and the thread
405 * migrates to another CPU, that the ITC values are synchronized across
406 * all CPUs.
407 */
408static void
409ia64_itc_udelay (unsigned long usecs)
410{
411 unsigned long start = ia64_get_itc();
412 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
413
414 while (time_before(ia64_get_itc(), end))
415 cpu_relax();
416}
417
418void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
419
420void
421udelay (unsigned long usecs)
422{
423 (*ia64_udelay)(usecs);
424}
425EXPORT_SYMBOL(udelay);
426
427/* IA64 doesn't cache the timezone */
428void update_vsyscall_tz(void)
429{
430}
431
432void update_vsyscall(struct timekeeper *tk)
433{
434 write_seqcount_begin(&fsyscall_gtod_data.seq);
435
436 /* copy vsyscall data */
437 fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask;
438 fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult;
439 fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift;
440 fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio;
441 fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last;
442
443 fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
444 fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
445
446 fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec
447 + tk->wall_to_monotonic.tv_sec;
448 fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec
449 + ((u64)tk->wall_to_monotonic.tv_nsec
450 << tk->tkr_mono.shift);
451
452 /* normalize */
453 while (fsyscall_gtod_data.monotonic_time.snsec >=
454 (((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
455 fsyscall_gtod_data.monotonic_time.snsec -=
456 ((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
457 fsyscall_gtod_data.monotonic_time.sec++;
458 }
459
460 write_seqcount_end(&fsyscall_gtod_data.seq);
461}
462