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1 /*
2 * linux/arch/ia64/kernel/time.c
3 *
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>
10 */
11
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/clocksource.h>
23 #include <linux/platform_device.h>
24
25 #include <asm/machvec.h>
26 #include <asm/delay.h>
27 #include <asm/hw_irq.h>
28 #include <asm/paravirt.h>
29 #include <asm/ptrace.h>
30 #include <asm/sal.h>
31 #include <asm/sections.h>
32 #include <asm/system.h>
33
34 #include "fsyscall_gtod_data.h"
35
36 static cycle_t itc_get_cycles(struct clocksource *cs);
37
38 struct fsyscall_gtod_data_t fsyscall_gtod_data = {
39 .lock = SEQLOCK_UNLOCKED,
40 };
41
42 struct itc_jitter_data_t itc_jitter_data;
43
44 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
45
46 #ifdef CONFIG_IA64_DEBUG_IRQ
47
48 unsigned long last_cli_ip;
49 EXPORT_SYMBOL(last_cli_ip);
50
51 #endif
52
53 #ifdef CONFIG_PARAVIRT
54 /* We need to define a real function for sched_clock, to override the
55 weak default version */
56 unsigned long long sched_clock(void)
57 {
58 return paravirt_sched_clock();
59 }
60 #endif
61
62 #ifdef CONFIG_PARAVIRT
63 static void
64 paravirt_clocksource_resume(struct clocksource *cs)
65 {
66 if (pv_time_ops.clocksource_resume)
67 pv_time_ops.clocksource_resume();
68 }
69 #endif
70
71 static struct clocksource clocksource_itc = {
72 .name = "itc",
73 .rating = 350,
74 .read = itc_get_cycles,
75 .mask = CLOCKSOURCE_MASK(64),
76 .mult = 0, /*to be calculated*/
77 .shift = 16,
78 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
79 #ifdef CONFIG_PARAVIRT
80 .resume = paravirt_clocksource_resume,
81 #endif
82 };
83 static struct clocksource *itc_clocksource;
84
85 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
86
87 #include <linux/kernel_stat.h>
88
89 extern cputime_t cycle_to_cputime(u64 cyc);
90
91 /*
92 * Called from the context switch with interrupts disabled, to charge all
93 * accumulated times to the current process, and to prepare accounting on
94 * the next process.
95 */
96 void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next)
97 {
98 struct thread_info *pi = task_thread_info(prev);
99 struct thread_info *ni = task_thread_info(next);
100 cputime_t delta_stime, delta_utime;
101 __u64 now;
102
103 now = ia64_get_itc();
104
105 delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp));
106 if (idle_task(smp_processor_id()) != prev)
107 account_system_time(prev, 0, delta_stime, delta_stime);
108 else
109 account_idle_time(delta_stime);
110
111 if (pi->ac_utime) {
112 delta_utime = cycle_to_cputime(pi->ac_utime);
113 account_user_time(prev, delta_utime, delta_utime);
114 }
115
116 pi->ac_stamp = ni->ac_stamp = now;
117 ni->ac_stime = ni->ac_utime = 0;
118 }
119
120 /*
121 * Account time for a transition between system, hard irq or soft irq state.
122 * Note that this function is called with interrupts enabled.
123 */
124 void account_system_vtime(struct task_struct *tsk)
125 {
126 struct thread_info *ti = task_thread_info(tsk);
127 unsigned long flags;
128 cputime_t delta_stime;
129 __u64 now;
130
131 local_irq_save(flags);
132
133 now = ia64_get_itc();
134
135 delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
136 if (irq_count() || idle_task(smp_processor_id()) != tsk)
137 account_system_time(tsk, 0, delta_stime, delta_stime);
138 else
139 account_idle_time(delta_stime);
140 ti->ac_stime = 0;
141
142 ti->ac_stamp = now;
143
144 local_irq_restore(flags);
145 }
146 EXPORT_SYMBOL_GPL(account_system_vtime);
147
148 /*
149 * Called from the timer interrupt handler to charge accumulated user time
150 * to the current process. Must be called with interrupts disabled.
151 */
152 void account_process_tick(struct task_struct *p, int user_tick)
153 {
154 struct thread_info *ti = task_thread_info(p);
155 cputime_t delta_utime;
156
157 if (ti->ac_utime) {
158 delta_utime = cycle_to_cputime(ti->ac_utime);
159 account_user_time(p, delta_utime, delta_utime);
160 ti->ac_utime = 0;
161 }
162 }
163
164 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
165
166 static irqreturn_t
167 timer_interrupt (int irq, void *dev_id)
168 {
169 unsigned long new_itm;
170
171 if (cpu_is_offline(smp_processor_id())) {
172 return IRQ_HANDLED;
173 }
174
175 platform_timer_interrupt(irq, dev_id);
176
177 new_itm = local_cpu_data->itm_next;
178
179 if (!time_after(ia64_get_itc(), new_itm))
180 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
181 ia64_get_itc(), new_itm);
182
183 profile_tick(CPU_PROFILING);
184
185 if (paravirt_do_steal_accounting(&new_itm))
186 goto skip_process_time_accounting;
187
188 while (1) {
189 update_process_times(user_mode(get_irq_regs()));
190
191 new_itm += local_cpu_data->itm_delta;
192
193 if (smp_processor_id() == time_keeper_id) {
194 /*
195 * Here we are in the timer irq handler. We have irqs locally
196 * disabled, but we don't know if the timer_bh is running on
197 * another CPU. We need to avoid to SMP race by acquiring the
198 * xtime_lock.
199 */
200 write_seqlock(&xtime_lock);
201 do_timer(1);
202 local_cpu_data->itm_next = new_itm;
203 write_sequnlock(&xtime_lock);
204 } else
205 local_cpu_data->itm_next = new_itm;
206
207 if (time_after(new_itm, ia64_get_itc()))
208 break;
209
210 /*
211 * Allow IPIs to interrupt the timer loop.
212 */
213 local_irq_enable();
214 local_irq_disable();
215 }
216
217 skip_process_time_accounting:
218
219 do {
220 /*
221 * If we're too close to the next clock tick for
222 * comfort, we increase the safety margin by
223 * intentionally dropping the next tick(s). We do NOT
224 * update itm.next because that would force us to call
225 * do_timer() which in turn would let our clock run
226 * too fast (with the potentially devastating effect
227 * of losing monotony of time).
228 */
229 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
230 new_itm += local_cpu_data->itm_delta;
231 ia64_set_itm(new_itm);
232 /* double check, in case we got hit by a (slow) PMI: */
233 } while (time_after_eq(ia64_get_itc(), new_itm));
234 return IRQ_HANDLED;
235 }
236
237 /*
238 * Encapsulate access to the itm structure for SMP.
239 */
240 void
241 ia64_cpu_local_tick (void)
242 {
243 int cpu = smp_processor_id();
244 unsigned long shift = 0, delta;
245
246 /* arrange for the cycle counter to generate a timer interrupt: */
247 ia64_set_itv(IA64_TIMER_VECTOR);
248
249 delta = local_cpu_data->itm_delta;
250 /*
251 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
252 * same time:
253 */
254 if (cpu) {
255 unsigned long hi = 1UL << ia64_fls(cpu);
256 shift = (2*(cpu - hi) + 1) * delta/hi/2;
257 }
258 local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
259 ia64_set_itm(local_cpu_data->itm_next);
260 }
261
262 static int nojitter;
263
264 static int __init nojitter_setup(char *str)
265 {
266 nojitter = 1;
267 printk("Jitter checking for ITC timers disabled\n");
268 return 1;
269 }
270
271 __setup("nojitter", nojitter_setup);
272
273
274 void __devinit
275 ia64_init_itm (void)
276 {
277 unsigned long platform_base_freq, itc_freq;
278 struct pal_freq_ratio itc_ratio, proc_ratio;
279 long status, platform_base_drift, itc_drift;
280
281 /*
282 * According to SAL v2.6, we need to use a SAL call to determine the platform base
283 * frequency and then a PAL call to determine the frequency ratio between the ITC
284 * and the base frequency.
285 */
286 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
287 &platform_base_freq, &platform_base_drift);
288 if (status != 0) {
289 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
290 } else {
291 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
292 if (status != 0)
293 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
294 }
295 if (status != 0) {
296 /* invent "random" values */
297 printk(KERN_ERR
298 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
299 platform_base_freq = 100000000;
300 platform_base_drift = -1; /* no drift info */
301 itc_ratio.num = 3;
302 itc_ratio.den = 1;
303 }
304 if (platform_base_freq < 40000000) {
305 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
306 platform_base_freq);
307 platform_base_freq = 75000000;
308 platform_base_drift = -1;
309 }
310 if (!proc_ratio.den)
311 proc_ratio.den = 1; /* avoid division by zero */
312 if (!itc_ratio.den)
313 itc_ratio.den = 1; /* avoid division by zero */
314
315 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
316
317 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
318 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
319 "ITC freq=%lu.%03luMHz", smp_processor_id(),
320 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
321 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
322
323 if (platform_base_drift != -1) {
324 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
325 printk("+/-%ldppm\n", itc_drift);
326 } else {
327 itc_drift = -1;
328 printk("\n");
329 }
330
331 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
332 local_cpu_data->itc_freq = itc_freq;
333 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
334 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
335 + itc_freq/2)/itc_freq;
336
337 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
338 #ifdef CONFIG_SMP
339 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
340 * Jitter compensation requires a cmpxchg which may limit
341 * the scalability of the syscalls for retrieving time.
342 * The ITC synchronization is usually successful to within a few
343 * ITC ticks but this is not a sure thing. If you need to improve
344 * timer performance in SMP situations then boot the kernel with the
345 * "nojitter" option. However, doing so may result in time fluctuating (maybe
346 * even going backward) if the ITC offsets between the individual CPUs
347 * are too large.
348 */
349 if (!nojitter)
350 itc_jitter_data.itc_jitter = 1;
351 #endif
352 } else
353 /*
354 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
355 * ITC values may fluctuate significantly between processors.
356 * Clock should not be used for hrtimers. Mark itc as only
357 * useful for boot and testing.
358 *
359 * Note that jitter compensation is off! There is no point of
360 * synchronizing ITCs since they may be large differentials
361 * that change over time.
362 *
363 * The only way to fix this would be to repeatedly sync the
364 * ITCs. Until that time we have to avoid ITC.
365 */
366 clocksource_itc.rating = 50;
367
368 paravirt_init_missing_ticks_accounting(smp_processor_id());
369
370 /* avoid softlock up message when cpu is unplug and plugged again. */
371 touch_softlockup_watchdog();
372
373 /* Setup the CPU local timer tick */
374 ia64_cpu_local_tick();
375
376 if (!itc_clocksource) {
377 /* Sort out mult/shift values: */
378 clocksource_itc.mult =
379 clocksource_hz2mult(local_cpu_data->itc_freq,
380 clocksource_itc.shift);
381 clocksource_register(&clocksource_itc);
382 itc_clocksource = &clocksource_itc;
383 }
384 }
385
386 static cycle_t itc_get_cycles(struct clocksource *cs)
387 {
388 unsigned long lcycle, now, ret;
389
390 if (!itc_jitter_data.itc_jitter)
391 return get_cycles();
392
393 lcycle = itc_jitter_data.itc_lastcycle;
394 now = get_cycles();
395 if (lcycle && time_after(lcycle, now))
396 return lcycle;
397
398 /*
399 * Keep track of the last timer value returned.
400 * In an SMP environment, you could lose out in contention of
401 * cmpxchg. If so, your cmpxchg returns new value which the
402 * winner of contention updated to. Use the new value instead.
403 */
404 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
405 if (unlikely(ret != lcycle))
406 return ret;
407
408 return now;
409 }
410
411
412 static struct irqaction timer_irqaction = {
413 .handler = timer_interrupt,
414 .flags = IRQF_DISABLED | IRQF_IRQPOLL,
415 .name = "timer"
416 };
417
418 static struct platform_device rtc_efi_dev = {
419 .name = "rtc-efi",
420 .id = -1,
421 };
422
423 static int __init rtc_init(void)
424 {
425 if (platform_device_register(&rtc_efi_dev) < 0)
426 printk(KERN_ERR "unable to register rtc device...\n");
427
428 /* not necessarily an error */
429 return 0;
430 }
431 module_init(rtc_init);
432
433 void read_persistent_clock(struct timespec *ts)
434 {
435 efi_gettimeofday(ts);
436 }
437
438 void __init
439 time_init (void)
440 {
441 register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
442 ia64_init_itm();
443 }
444
445 /*
446 * Generic udelay assumes that if preemption is allowed and the thread
447 * migrates to another CPU, that the ITC values are synchronized across
448 * all CPUs.
449 */
450 static void
451 ia64_itc_udelay (unsigned long usecs)
452 {
453 unsigned long start = ia64_get_itc();
454 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
455
456 while (time_before(ia64_get_itc(), end))
457 cpu_relax();
458 }
459
460 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
461
462 void
463 udelay (unsigned long usecs)
464 {
465 (*ia64_udelay)(usecs);
466 }
467 EXPORT_SYMBOL(udelay);
468
469 /* IA64 doesn't cache the timezone */
470 void update_vsyscall_tz(void)
471 {
472 }
473
474 void update_vsyscall(struct timespec *wall, struct timespec *wtm,
475 struct clocksource *c, u32 mult)
476 {
477 unsigned long flags;
478
479 write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags);
480
481 /* copy fsyscall clock data */
482 fsyscall_gtod_data.clk_mask = c->mask;
483 fsyscall_gtod_data.clk_mult = mult;
484 fsyscall_gtod_data.clk_shift = c->shift;
485 fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio;
486 fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
487
488 /* copy kernel time structures */
489 fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
490 fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
491 fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
492 + wall->tv_sec;
493 fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
494 + wall->tv_nsec;
495
496 /* normalize */
497 while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
498 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
499 fsyscall_gtod_data.monotonic_time.tv_sec++;
500 }
501
502 write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
503 }
504