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Linux/arch/powerpc/kernel/time.c

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  1 /*
  2  * Common time routines among all ppc machines.
  3  *
  4  * Written by Cort Dougan (cort@cs.nmt.edu) to merge
  5  * Paul Mackerras' version and mine for PReP and Pmac.
  6  * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
  7  * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
  8  *
  9  * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
 10  * to make clock more stable (2.4.0-test5). The only thing
 11  * that this code assumes is that the timebases have been synchronized
 12  * by firmware on SMP and are never stopped (never do sleep
 13  * on SMP then, nap and doze are OK).
 14  * 
 15  * Speeded up do_gettimeofday by getting rid of references to
 16  * xtime (which required locks for consistency). (mikejc@us.ibm.com)
 17  *
 18  * TODO (not necessarily in this file):
 19  * - improve precision and reproducibility of timebase frequency
 20  * measurement at boot time.
 21  * - for astronomical applications: add a new function to get
 22  * non ambiguous timestamps even around leap seconds. This needs
 23  * a new timestamp format and a good name.
 24  *
 25  * 1997-09-10  Updated NTP code according to technical memorandum Jan '96
 26  *             "A Kernel Model for Precision Timekeeping" by Dave Mills
 27  *
 28  *      This program is free software; you can redistribute it and/or
 29  *      modify it under the terms of the GNU General Public License
 30  *      as published by the Free Software Foundation; either version
 31  *      2 of the License, or (at your option) any later version.
 32  */
 33 
 34 #include <linux/errno.h>
 35 #include <linux/export.h>
 36 #include <linux/sched.h>
 37 #include <linux/sched/clock.h>
 38 #include <linux/kernel.h>
 39 #include <linux/param.h>
 40 #include <linux/string.h>
 41 #include <linux/mm.h>
 42 #include <linux/interrupt.h>
 43 #include <linux/timex.h>
 44 #include <linux/kernel_stat.h>
 45 #include <linux/time.h>
 46 #include <linux/clockchips.h>
 47 #include <linux/init.h>
 48 #include <linux/profile.h>
 49 #include <linux/cpu.h>
 50 #include <linux/security.h>
 51 #include <linux/percpu.h>
 52 #include <linux/rtc.h>
 53 #include <linux/jiffies.h>
 54 #include <linux/posix-timers.h>
 55 #include <linux/irq.h>
 56 #include <linux/delay.h>
 57 #include <linux/irq_work.h>
 58 #include <linux/clk-provider.h>
 59 #include <linux/suspend.h>
 60 #include <linux/rtc.h>
 61 #include <linux/sched/cputime.h>
 62 #include <linux/processor.h>
 63 #include <asm/trace.h>
 64 
 65 #include <asm/io.h>
 66 #include <asm/nvram.h>
 67 #include <asm/cache.h>
 68 #include <asm/machdep.h>
 69 #include <linux/uaccess.h>
 70 #include <asm/time.h>
 71 #include <asm/prom.h>
 72 #include <asm/irq.h>
 73 #include <asm/div64.h>
 74 #include <asm/smp.h>
 75 #include <asm/vdso_datapage.h>
 76 #include <asm/firmware.h>
 77 #include <asm/asm-prototypes.h>
 78 
 79 /* powerpc clocksource/clockevent code */
 80 
 81 #include <linux/clockchips.h>
 82 #include <linux/timekeeper_internal.h>
 83 
 84 static u64 rtc_read(struct clocksource *);
 85 static struct clocksource clocksource_rtc = {
 86         .name         = "rtc",
 87         .rating       = 400,
 88         .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
 89         .mask         = CLOCKSOURCE_MASK(64),
 90         .read         = rtc_read,
 91 };
 92 
 93 static u64 timebase_read(struct clocksource *);
 94 static struct clocksource clocksource_timebase = {
 95         .name         = "timebase",
 96         .rating       = 400,
 97         .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
 98         .mask         = CLOCKSOURCE_MASK(64),
 99         .read         = timebase_read,
100 };
101 
102 #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
103 u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
104 
105 static int decrementer_set_next_event(unsigned long evt,
106                                       struct clock_event_device *dev);
107 static int decrementer_shutdown(struct clock_event_device *evt);
108 
109 struct clock_event_device decrementer_clockevent = {
110         .name                   = "decrementer",
111         .rating                 = 200,
112         .irq                    = 0,
113         .set_next_event         = decrementer_set_next_event,
114         .set_state_shutdown     = decrementer_shutdown,
115         .tick_resume            = decrementer_shutdown,
116         .features               = CLOCK_EVT_FEAT_ONESHOT |
117                                   CLOCK_EVT_FEAT_C3STOP,
118 };
119 EXPORT_SYMBOL(decrementer_clockevent);
120 
121 DEFINE_PER_CPU(u64, decrementers_next_tb);
122 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
123 
124 #define XSEC_PER_SEC (1024*1024)
125 
126 #ifdef CONFIG_PPC64
127 #define SCALE_XSEC(xsec, max)   (((xsec) * max) / XSEC_PER_SEC)
128 #else
129 /* compute ((xsec << 12) * max) >> 32 */
130 #define SCALE_XSEC(xsec, max)   mulhwu((xsec) << 12, max)
131 #endif
132 
133 unsigned long tb_ticks_per_jiffy;
134 unsigned long tb_ticks_per_usec = 100; /* sane default */
135 EXPORT_SYMBOL(tb_ticks_per_usec);
136 unsigned long tb_ticks_per_sec;
137 EXPORT_SYMBOL(tb_ticks_per_sec);        /* for cputime_t conversions */
138 
139 DEFINE_SPINLOCK(rtc_lock);
140 EXPORT_SYMBOL_GPL(rtc_lock);
141 
142 static u64 tb_to_ns_scale __read_mostly;
143 static unsigned tb_to_ns_shift __read_mostly;
144 static u64 boot_tb __read_mostly;
145 
146 extern struct timezone sys_tz;
147 static long timezone_offset;
148 
149 unsigned long ppc_proc_freq;
150 EXPORT_SYMBOL_GPL(ppc_proc_freq);
151 unsigned long ppc_tb_freq;
152 EXPORT_SYMBOL_GPL(ppc_tb_freq);
153 
154 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
155 /*
156  * Factor for converting from cputime_t (timebase ticks) to
157  * microseconds. This is stored as 0.64 fixed-point binary fraction.
158  */
159 u64 __cputime_usec_factor;
160 EXPORT_SYMBOL(__cputime_usec_factor);
161 
162 #ifdef CONFIG_PPC_SPLPAR
163 void (*dtl_consumer)(struct dtl_entry *, u64);
164 #endif
165 
166 #ifdef CONFIG_PPC64
167 #define get_accounting(tsk)     (&get_paca()->accounting)
168 #else
169 #define get_accounting(tsk)     (&task_thread_info(tsk)->accounting)
170 #endif
171 
172 static void calc_cputime_factors(void)
173 {
174         struct div_result res;
175 
176         div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
177         __cputime_usec_factor = res.result_low;
178 }
179 
180 /*
181  * Read the SPURR on systems that have it, otherwise the PURR,
182  * or if that doesn't exist return the timebase value passed in.
183  */
184 static unsigned long read_spurr(unsigned long tb)
185 {
186         if (cpu_has_feature(CPU_FTR_SPURR))
187                 return mfspr(SPRN_SPURR);
188         if (cpu_has_feature(CPU_FTR_PURR))
189                 return mfspr(SPRN_PURR);
190         return tb;
191 }
192 
193 #ifdef CONFIG_PPC_SPLPAR
194 
195 /*
196  * Scan the dispatch trace log and count up the stolen time.
197  * Should be called with interrupts disabled.
198  */
199 static u64 scan_dispatch_log(u64 stop_tb)
200 {
201         u64 i = local_paca->dtl_ridx;
202         struct dtl_entry *dtl = local_paca->dtl_curr;
203         struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
204         struct lppaca *vpa = local_paca->lppaca_ptr;
205         u64 tb_delta;
206         u64 stolen = 0;
207         u64 dtb;
208 
209         if (!dtl)
210                 return 0;
211 
212         if (i == be64_to_cpu(vpa->dtl_idx))
213                 return 0;
214         while (i < be64_to_cpu(vpa->dtl_idx)) {
215                 dtb = be64_to_cpu(dtl->timebase);
216                 tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
217                         be32_to_cpu(dtl->ready_to_enqueue_time);
218                 barrier();
219                 if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
220                         /* buffer has overflowed */
221                         i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
222                         dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
223                         continue;
224                 }
225                 if (dtb > stop_tb)
226                         break;
227                 if (dtl_consumer)
228                         dtl_consumer(dtl, i);
229                 stolen += tb_delta;
230                 ++i;
231                 ++dtl;
232                 if (dtl == dtl_end)
233                         dtl = local_paca->dispatch_log;
234         }
235         local_paca->dtl_ridx = i;
236         local_paca->dtl_curr = dtl;
237         return stolen;
238 }
239 
240 /*
241  * Accumulate stolen time by scanning the dispatch trace log.
242  * Called on entry from user mode.
243  */
244 void accumulate_stolen_time(void)
245 {
246         u64 sst, ust;
247         unsigned long save_irq_soft_mask = irq_soft_mask_return();
248         struct cpu_accounting_data *acct = &local_paca->accounting;
249 
250         /* We are called early in the exception entry, before
251          * soft/hard_enabled are sync'ed to the expected state
252          * for the exception. We are hard disabled but the PACA
253          * needs to reflect that so various debug stuff doesn't
254          * complain
255          */
256         irq_soft_mask_set(IRQS_DISABLED);
257 
258         sst = scan_dispatch_log(acct->starttime_user);
259         ust = scan_dispatch_log(acct->starttime);
260         acct->stime -= sst;
261         acct->utime -= ust;
262         acct->steal_time += ust + sst;
263 
264         irq_soft_mask_set(save_irq_soft_mask);
265 }
266 
267 static inline u64 calculate_stolen_time(u64 stop_tb)
268 {
269         if (!firmware_has_feature(FW_FEATURE_SPLPAR))
270                 return 0;
271 
272         if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
273                 return scan_dispatch_log(stop_tb);
274 
275         return 0;
276 }
277 
278 #else /* CONFIG_PPC_SPLPAR */
279 static inline u64 calculate_stolen_time(u64 stop_tb)
280 {
281         return 0;
282 }
283 
284 #endif /* CONFIG_PPC_SPLPAR */
285 
286 /*
287  * Account time for a transition between system, hard irq
288  * or soft irq state.
289  */
290 static unsigned long vtime_delta(struct task_struct *tsk,
291                                  unsigned long *stime_scaled,
292                                  unsigned long *steal_time)
293 {
294         unsigned long now, nowscaled, deltascaled;
295         unsigned long stime;
296         unsigned long utime, utime_scaled;
297         struct cpu_accounting_data *acct = get_accounting(tsk);
298 
299         WARN_ON_ONCE(!irqs_disabled());
300 
301         now = mftb();
302         nowscaled = read_spurr(now);
303         stime = now - acct->starttime;
304         acct->starttime = now;
305         deltascaled = nowscaled - acct->startspurr;
306         acct->startspurr = nowscaled;
307 
308         *steal_time = calculate_stolen_time(now);
309 
310         utime = acct->utime - acct->utime_sspurr;
311         acct->utime_sspurr = acct->utime;
312 
313         /*
314          * Because we don't read the SPURR on every kernel entry/exit,
315          * deltascaled includes both user and system SPURR ticks.
316          * Apportion these ticks to system SPURR ticks and user
317          * SPURR ticks in the same ratio as the system time (delta)
318          * and user time (udelta) values obtained from the timebase
319          * over the same interval.  The system ticks get accounted here;
320          * the user ticks get saved up in paca->user_time_scaled to be
321          * used by account_process_tick.
322          */
323         *stime_scaled = stime;
324         utime_scaled = utime;
325         if (deltascaled != stime + utime) {
326                 if (utime) {
327                         *stime_scaled = deltascaled * stime / (stime + utime);
328                         utime_scaled = deltascaled - *stime_scaled;
329                 } else {
330                         *stime_scaled = deltascaled;
331                 }
332         }
333         acct->utime_scaled += utime_scaled;
334 
335         return stime;
336 }
337 
338 void vtime_account_system(struct task_struct *tsk)
339 {
340         unsigned long stime, stime_scaled, steal_time;
341         struct cpu_accounting_data *acct = get_accounting(tsk);
342 
343         stime = vtime_delta(tsk, &stime_scaled, &steal_time);
344 
345         stime -= min(stime, steal_time);
346         acct->steal_time += steal_time;
347 
348         if ((tsk->flags & PF_VCPU) && !irq_count()) {
349                 acct->gtime += stime;
350                 acct->utime_scaled += stime_scaled;
351         } else {
352                 if (hardirq_count())
353                         acct->hardirq_time += stime;
354                 else if (in_serving_softirq())
355                         acct->softirq_time += stime;
356                 else
357                         acct->stime += stime;
358 
359                 acct->stime_scaled += stime_scaled;
360         }
361 }
362 EXPORT_SYMBOL_GPL(vtime_account_system);
363 
364 void vtime_account_idle(struct task_struct *tsk)
365 {
366         unsigned long stime, stime_scaled, steal_time;
367         struct cpu_accounting_data *acct = get_accounting(tsk);
368 
369         stime = vtime_delta(tsk, &stime_scaled, &steal_time);
370         acct->idle_time += stime + steal_time;
371 }
372 
373 /*
374  * Account the whole cputime accumulated in the paca
375  * Must be called with interrupts disabled.
376  * Assumes that vtime_account_system/idle() has been called
377  * recently (i.e. since the last entry from usermode) so that
378  * get_paca()->user_time_scaled is up to date.
379  */
380 void vtime_flush(struct task_struct *tsk)
381 {
382         struct cpu_accounting_data *acct = get_accounting(tsk);
383 
384         if (acct->utime)
385                 account_user_time(tsk, cputime_to_nsecs(acct->utime));
386 
387         if (acct->utime_scaled)
388                 tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
389 
390         if (acct->gtime)
391                 account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
392 
393         if (acct->steal_time)
394                 account_steal_time(cputime_to_nsecs(acct->steal_time));
395 
396         if (acct->idle_time)
397                 account_idle_time(cputime_to_nsecs(acct->idle_time));
398 
399         if (acct->stime)
400                 account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
401                                           CPUTIME_SYSTEM);
402         if (acct->stime_scaled)
403                 tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);
404 
405         if (acct->hardirq_time)
406                 account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
407                                           CPUTIME_IRQ);
408         if (acct->softirq_time)
409                 account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
410                                           CPUTIME_SOFTIRQ);
411 
412         acct->utime = 0;
413         acct->utime_scaled = 0;
414         acct->utime_sspurr = 0;
415         acct->gtime = 0;
416         acct->steal_time = 0;
417         acct->idle_time = 0;
418         acct->stime = 0;
419         acct->stime_scaled = 0;
420         acct->hardirq_time = 0;
421         acct->softirq_time = 0;
422 }
423 
424 #ifdef CONFIG_PPC32
425 /*
426  * Called from the context switch with interrupts disabled, to charge all
427  * accumulated times to the current process, and to prepare accounting on
428  * the next process.
429  */
430 void arch_vtime_task_switch(struct task_struct *prev)
431 {
432         struct cpu_accounting_data *acct = get_accounting(current);
433 
434         acct->starttime = get_accounting(prev)->starttime;
435         acct->startspurr = get_accounting(prev)->startspurr;
436 }
437 #endif /* CONFIG_PPC32 */
438 
439 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
440 #define calc_cputime_factors()
441 #endif
442 
443 void __delay(unsigned long loops)
444 {
445         unsigned long start;
446         int diff;
447 
448         spin_begin();
449         if (__USE_RTC()) {
450                 start = get_rtcl();
451                 do {
452                         /* the RTCL register wraps at 1000000000 */
453                         diff = get_rtcl() - start;
454                         if (diff < 0)
455                                 diff += 1000000000;
456                         spin_cpu_relax();
457                 } while (diff < loops);
458         } else {
459                 start = get_tbl();
460                 while (get_tbl() - start < loops)
461                         spin_cpu_relax();
462         }
463         spin_end();
464 }
465 EXPORT_SYMBOL(__delay);
466 
467 void udelay(unsigned long usecs)
468 {
469         __delay(tb_ticks_per_usec * usecs);
470 }
471 EXPORT_SYMBOL(udelay);
472 
473 #ifdef CONFIG_SMP
474 unsigned long profile_pc(struct pt_regs *regs)
475 {
476         unsigned long pc = instruction_pointer(regs);
477 
478         if (in_lock_functions(pc))
479                 return regs->link;
480 
481         return pc;
482 }
483 EXPORT_SYMBOL(profile_pc);
484 #endif
485 
486 #ifdef CONFIG_IRQ_WORK
487 
488 /*
489  * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
490  */
491 #ifdef CONFIG_PPC64
492 static inline unsigned long test_irq_work_pending(void)
493 {
494         unsigned long x;
495 
496         asm volatile("lbz %0,%1(13)"
497                 : "=r" (x)
498                 : "i" (offsetof(struct paca_struct, irq_work_pending)));
499         return x;
500 }
501 
502 static inline void set_irq_work_pending_flag(void)
503 {
504         asm volatile("stb %0,%1(13)" : :
505                 "r" (1),
506                 "i" (offsetof(struct paca_struct, irq_work_pending)));
507 }
508 
509 static inline void clear_irq_work_pending(void)
510 {
511         asm volatile("stb %0,%1(13)" : :
512                 "r" (0),
513                 "i" (offsetof(struct paca_struct, irq_work_pending)));
514 }
515 
516 #else /* 32-bit */
517 
518 DEFINE_PER_CPU(u8, irq_work_pending);
519 
520 #define set_irq_work_pending_flag()     __this_cpu_write(irq_work_pending, 1)
521 #define test_irq_work_pending()         __this_cpu_read(irq_work_pending)
522 #define clear_irq_work_pending()        __this_cpu_write(irq_work_pending, 0)
523 
524 #endif /* 32 vs 64 bit */
525 
526 void arch_irq_work_raise(void)
527 {
528         preempt_disable();
529         set_irq_work_pending_flag();
530         set_dec(1);
531         preempt_enable();
532 }
533 
534 #else  /* CONFIG_IRQ_WORK */
535 
536 #define test_irq_work_pending() 0
537 #define clear_irq_work_pending()
538 
539 #endif /* CONFIG_IRQ_WORK */
540 
541 static void __timer_interrupt(void)
542 {
543         struct pt_regs *regs = get_irq_regs();
544         u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
545         struct clock_event_device *evt = this_cpu_ptr(&decrementers);
546         u64 now;
547 
548         trace_timer_interrupt_entry(regs);
549 
550         if (test_irq_work_pending()) {
551                 clear_irq_work_pending();
552                 irq_work_run();
553         }
554 
555         now = get_tb_or_rtc();
556         if (now >= *next_tb) {
557                 *next_tb = ~(u64)0;
558                 if (evt->event_handler)
559                         evt->event_handler(evt);
560                 __this_cpu_inc(irq_stat.timer_irqs_event);
561         } else {
562                 now = *next_tb - now;
563                 if (now <= decrementer_max)
564                         set_dec(now);
565                 /* We may have raced with new irq work */
566                 if (test_irq_work_pending())
567                         set_dec(1);
568                 __this_cpu_inc(irq_stat.timer_irqs_others);
569         }
570 
571 #ifdef CONFIG_PPC64
572         /* collect purr register values often, for accurate calculations */
573         if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
574                 struct cpu_usage *cu = this_cpu_ptr(&cpu_usage_array);
575                 cu->current_tb = mfspr(SPRN_PURR);
576         }
577 #endif
578 
579         trace_timer_interrupt_exit(regs);
580 }
581 
582 /*
583  * timer_interrupt - gets called when the decrementer overflows,
584  * with interrupts disabled.
585  */
586 void timer_interrupt(struct pt_regs * regs)
587 {
588         struct pt_regs *old_regs;
589         u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
590 
591         /* Ensure a positive value is written to the decrementer, or else
592          * some CPUs will continue to take decrementer exceptions.
593          */
594         set_dec(decrementer_max);
595 
596         /* Some implementations of hotplug will get timer interrupts while
597          * offline, just ignore these and we also need to set
598          * decrementers_next_tb as MAX to make sure __check_irq_replay
599          * don't replay timer interrupt when return, otherwise we'll trap
600          * here infinitely :(
601          */
602         if (!cpu_online(smp_processor_id())) {
603                 *next_tb = ~(u64)0;
604                 return;
605         }
606 
607         /* Conditionally hard-enable interrupts now that the DEC has been
608          * bumped to its maximum value
609          */
610         may_hard_irq_enable();
611 
612 
613 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
614         if (atomic_read(&ppc_n_lost_interrupts) != 0)
615                 do_IRQ(regs);
616 #endif
617 
618         old_regs = set_irq_regs(regs);
619         irq_enter();
620 
621         __timer_interrupt();
622         irq_exit();
623         set_irq_regs(old_regs);
624 }
625 EXPORT_SYMBOL(timer_interrupt);
626 
627 /*
628  * Hypervisor decrementer interrupts shouldn't occur but are sometimes
629  * left pending on exit from a KVM guest.  We don't need to do anything
630  * to clear them, as they are edge-triggered.
631  */
632 void hdec_interrupt(struct pt_regs *regs)
633 {
634 }
635 
636 #ifdef CONFIG_SUSPEND
637 static void generic_suspend_disable_irqs(void)
638 {
639         /* Disable the decrementer, so that it doesn't interfere
640          * with suspending.
641          */
642 
643         set_dec(decrementer_max);
644         local_irq_disable();
645         set_dec(decrementer_max);
646 }
647 
648 static void generic_suspend_enable_irqs(void)
649 {
650         local_irq_enable();
651 }
652 
653 /* Overrides the weak version in kernel/power/main.c */
654 void arch_suspend_disable_irqs(void)
655 {
656         if (ppc_md.suspend_disable_irqs)
657                 ppc_md.suspend_disable_irqs();
658         generic_suspend_disable_irqs();
659 }
660 
661 /* Overrides the weak version in kernel/power/main.c */
662 void arch_suspend_enable_irqs(void)
663 {
664         generic_suspend_enable_irqs();
665         if (ppc_md.suspend_enable_irqs)
666                 ppc_md.suspend_enable_irqs();
667 }
668 #endif
669 
670 unsigned long long tb_to_ns(unsigned long long ticks)
671 {
672         return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
673 }
674 EXPORT_SYMBOL_GPL(tb_to_ns);
675 
676 /*
677  * Scheduler clock - returns current time in nanosec units.
678  *
679  * Note: mulhdu(a, b) (multiply high double unsigned) returns
680  * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
681  * are 64-bit unsigned numbers.
682  */
683 notrace unsigned long long sched_clock(void)
684 {
685         if (__USE_RTC())
686                 return get_rtc();
687         return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
688 }
689 
690 
691 #ifdef CONFIG_PPC_PSERIES
692 
693 /*
694  * Running clock - attempts to give a view of time passing for a virtualised
695  * kernels.
696  * Uses the VTB register if available otherwise a next best guess.
697  */
698 unsigned long long running_clock(void)
699 {
700         /*
701          * Don't read the VTB as a host since KVM does not switch in host
702          * timebase into the VTB when it takes a guest off the CPU, reading the
703          * VTB would result in reading 'last switched out' guest VTB.
704          *
705          * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
706          * would be unsafe to rely only on the #ifdef above.
707          */
708         if (firmware_has_feature(FW_FEATURE_LPAR) &&
709             cpu_has_feature(CPU_FTR_ARCH_207S))
710                 return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
711 
712         /*
713          * This is a next best approximation without a VTB.
714          * On a host which is running bare metal there should never be any stolen
715          * time and on a host which doesn't do any virtualisation TB *should* equal
716          * VTB so it makes no difference anyway.
717          */
718         return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
719 }
720 #endif
721 
722 static int __init get_freq(char *name, int cells, unsigned long *val)
723 {
724         struct device_node *cpu;
725         const __be32 *fp;
726         int found = 0;
727 
728         /* The cpu node should have timebase and clock frequency properties */
729         cpu = of_find_node_by_type(NULL, "cpu");
730 
731         if (cpu) {
732                 fp = of_get_property(cpu, name, NULL);
733                 if (fp) {
734                         found = 1;
735                         *val = of_read_ulong(fp, cells);
736                 }
737 
738                 of_node_put(cpu);
739         }
740 
741         return found;
742 }
743 
744 static void start_cpu_decrementer(void)
745 {
746 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
747         unsigned int tcr;
748 
749         /* Clear any pending timer interrupts */
750         mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
751 
752         tcr = mfspr(SPRN_TCR);
753         /*
754          * The watchdog may have already been enabled by u-boot. So leave
755          * TRC[WP] (Watchdog Period) alone.
756          */
757         tcr &= TCR_WP_MASK;     /* Clear all bits except for TCR[WP] */
758         tcr |= TCR_DIE;         /* Enable decrementer */
759         mtspr(SPRN_TCR, tcr);
760 #endif
761 }
762 
763 void __init generic_calibrate_decr(void)
764 {
765         ppc_tb_freq = DEFAULT_TB_FREQ;          /* hardcoded default */
766 
767         if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
768             !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
769 
770                 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
771                                 "(not found)\n");
772         }
773 
774         ppc_proc_freq = DEFAULT_PROC_FREQ;      /* hardcoded default */
775 
776         if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
777             !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
778 
779                 printk(KERN_ERR "WARNING: Estimating processor frequency "
780                                 "(not found)\n");
781         }
782 }
783 
784 int update_persistent_clock(struct timespec now)
785 {
786         struct rtc_time tm;
787 
788         if (!ppc_md.set_rtc_time)
789                 return -ENODEV;
790 
791         to_tm(now.tv_sec + 1 + timezone_offset, &tm);
792         tm.tm_year -= 1900;
793         tm.tm_mon -= 1;
794 
795         return ppc_md.set_rtc_time(&tm);
796 }
797 
798 static void __read_persistent_clock(struct timespec *ts)
799 {
800         struct rtc_time tm;
801         static int first = 1;
802 
803         ts->tv_nsec = 0;
804         /* XXX this is a litle fragile but will work okay in the short term */
805         if (first) {
806                 first = 0;
807                 if (ppc_md.time_init)
808                         timezone_offset = ppc_md.time_init();
809 
810                 /* get_boot_time() isn't guaranteed to be safe to call late */
811                 if (ppc_md.get_boot_time) {
812                         ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
813                         return;
814                 }
815         }
816         if (!ppc_md.get_rtc_time) {
817                 ts->tv_sec = 0;
818                 return;
819         }
820         ppc_md.get_rtc_time(&tm);
821 
822         ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
823                             tm.tm_hour, tm.tm_min, tm.tm_sec);
824 }
825 
826 void read_persistent_clock(struct timespec *ts)
827 {
828         __read_persistent_clock(ts);
829 
830         /* Sanitize it in case real time clock is set below EPOCH */
831         if (ts->tv_sec < 0) {
832                 ts->tv_sec = 0;
833                 ts->tv_nsec = 0;
834         }
835                 
836 }
837 
838 /* clocksource code */
839 static notrace u64 rtc_read(struct clocksource *cs)
840 {
841         return (u64)get_rtc();
842 }
843 
844 static notrace u64 timebase_read(struct clocksource *cs)
845 {
846         return (u64)get_tb();
847 }
848 
849 
850 void update_vsyscall(struct timekeeper *tk)
851 {
852         struct timespec xt;
853         struct clocksource *clock = tk->tkr_mono.clock;
854         u32 mult = tk->tkr_mono.mult;
855         u32 shift = tk->tkr_mono.shift;
856         u64 cycle_last = tk->tkr_mono.cycle_last;
857         u64 new_tb_to_xs, new_stamp_xsec;
858         u64 frac_sec;
859 
860         if (clock != &clocksource_timebase)
861                 return;
862 
863         xt.tv_sec = tk->xtime_sec;
864         xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
865 
866         /* Make userspace gettimeofday spin until we're done. */
867         ++vdso_data->tb_update_count;
868         smp_mb();
869 
870         /*
871          * This computes ((2^20 / 1e9) * mult) >> shift as a
872          * 0.64 fixed-point fraction.
873          * The computation in the else clause below won't overflow
874          * (as long as the timebase frequency is >= 1.049 MHz)
875          * but loses precision because we lose the low bits of the constant
876          * in the shift.  Note that 19342813113834067 ~= 2^(20+64) / 1e9.
877          * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
878          * over a second.  (Shift values are usually 22, 23 or 24.)
879          * For high frequency clocks such as the 512MHz timebase clock
880          * on POWER[6789], the mult value is small (e.g. 32768000)
881          * and so we can shift the constant by 16 initially
882          * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
883          * remaining shifts after the multiplication, which gives a
884          * more accurate result (e.g. with mult = 32768000, shift = 24,
885          * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
886          */
887         if (mult <= 62500000 && clock->shift >= 16)
888                 new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
889         else
890                 new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
891 
892         /*
893          * Compute the fractional second in units of 2^-32 seconds.
894          * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
895          * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
896          * it in units of 2^-32 seconds.
897          * We assume shift <= 32 because clocks_calc_mult_shift()
898          * generates shift values in the range 0 - 32.
899          */
900         frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
901         do_div(frac_sec, NSEC_PER_SEC);
902 
903         /*
904          * Work out new stamp_xsec value for any legacy users of systemcfg.
905          * stamp_xsec is in units of 2^-20 seconds.
906          */
907         new_stamp_xsec = frac_sec >> 12;
908         new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
909 
910         /*
911          * tb_update_count is used to allow the userspace gettimeofday code
912          * to assure itself that it sees a consistent view of the tb_to_xs and
913          * stamp_xsec variables.  It reads the tb_update_count, then reads
914          * tb_to_xs and stamp_xsec and then reads tb_update_count again.  If
915          * the two values of tb_update_count match and are even then the
916          * tb_to_xs and stamp_xsec values are consistent.  If not, then it
917          * loops back and reads them again until this criteria is met.
918          */
919         vdso_data->tb_orig_stamp = cycle_last;
920         vdso_data->stamp_xsec = new_stamp_xsec;
921         vdso_data->tb_to_xs = new_tb_to_xs;
922         vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
923         vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
924         vdso_data->stamp_xtime = xt;
925         vdso_data->stamp_sec_fraction = frac_sec;
926         smp_wmb();
927         ++(vdso_data->tb_update_count);
928 }
929 
930 void update_vsyscall_tz(void)
931 {
932         vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
933         vdso_data->tz_dsttime = sys_tz.tz_dsttime;
934 }
935 
936 static void __init clocksource_init(void)
937 {
938         struct clocksource *clock;
939 
940         if (__USE_RTC())
941                 clock = &clocksource_rtc;
942         else
943                 clock = &clocksource_timebase;
944 
945         if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
946                 printk(KERN_ERR "clocksource: %s is already registered\n",
947                        clock->name);
948                 return;
949         }
950 
951         printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
952                clock->name, clock->mult, clock->shift);
953 }
954 
955 static int decrementer_set_next_event(unsigned long evt,
956                                       struct clock_event_device *dev)
957 {
958         __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
959         set_dec(evt);
960 
961         /* We may have raced with new irq work */
962         if (test_irq_work_pending())
963                 set_dec(1);
964 
965         return 0;
966 }
967 
968 static int decrementer_shutdown(struct clock_event_device *dev)
969 {
970         decrementer_set_next_event(decrementer_max, dev);
971         return 0;
972 }
973 
974 /* Interrupt handler for the timer broadcast IPI */
975 void tick_broadcast_ipi_handler(void)
976 {
977         u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
978 
979         *next_tb = get_tb_or_rtc();
980         __timer_interrupt();
981 }
982 
983 static void register_decrementer_clockevent(int cpu)
984 {
985         struct clock_event_device *dec = &per_cpu(decrementers, cpu);
986 
987         *dec = decrementer_clockevent;
988         dec->cpumask = cpumask_of(cpu);
989 
990         printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
991                     dec->name, dec->mult, dec->shift, cpu);
992 
993         clockevents_register_device(dec);
994 }
995 
996 static void enable_large_decrementer(void)
997 {
998         if (!cpu_has_feature(CPU_FTR_ARCH_300))
999                 return;
1000 
1001         if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
1002                 return;
1003 
1004         /*
1005          * If we're running as the hypervisor we need to enable the LD manually
1006          * otherwise firmware should have done it for us.
1007          */
1008         if (cpu_has_feature(CPU_FTR_HVMODE))
1009                 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
1010 }
1011 
1012 static void __init set_decrementer_max(void)
1013 {
1014         struct device_node *cpu;
1015         u32 bits = 32;
1016 
1017         /* Prior to ISAv3 the decrementer is always 32 bit */
1018         if (!cpu_has_feature(CPU_FTR_ARCH_300))
1019                 return;
1020 
1021         cpu = of_find_node_by_type(NULL, "cpu");
1022 
1023         if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
1024                 if (bits > 64 || bits < 32) {
1025                         pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
1026                         bits = 32;
1027                 }
1028 
1029                 /* calculate the signed maximum given this many bits */
1030                 decrementer_max = (1ul << (bits - 1)) - 1;
1031         }
1032 
1033         of_node_put(cpu);
1034 
1035         pr_info("time_init: %u bit decrementer (max: %llx)\n",
1036                 bits, decrementer_max);
1037 }
1038 
1039 static void __init init_decrementer_clockevent(void)
1040 {
1041         int cpu = smp_processor_id();
1042 
1043         clockevents_calc_mult_shift(&decrementer_clockevent, ppc_tb_freq, 4);
1044 
1045         decrementer_clockevent.max_delta_ns =
1046                 clockevent_delta2ns(decrementer_max, &decrementer_clockevent);
1047         decrementer_clockevent.max_delta_ticks = decrementer_max;
1048         decrementer_clockevent.min_delta_ns =
1049                 clockevent_delta2ns(2, &decrementer_clockevent);
1050         decrementer_clockevent.min_delta_ticks = 2;
1051 
1052         register_decrementer_clockevent(cpu);
1053 }
1054 
1055 void secondary_cpu_time_init(void)
1056 {
1057         /* Enable and test the large decrementer for this cpu */
1058         enable_large_decrementer();
1059 
1060         /* Start the decrementer on CPUs that have manual control
1061          * such as BookE
1062          */
1063         start_cpu_decrementer();
1064 
1065         /* FIME: Should make unrelatred change to move snapshot_timebase
1066          * call here ! */
1067         register_decrementer_clockevent(smp_processor_id());
1068 }
1069 
1070 /* This function is only called on the boot processor */
1071 void __init time_init(void)
1072 {
1073         struct div_result res;
1074         u64 scale;
1075         unsigned shift;
1076 
1077         if (__USE_RTC()) {
1078                 /* 601 processor: dec counts down by 128 every 128ns */
1079                 ppc_tb_freq = 1000000000;
1080         } else {
1081                 /* Normal PowerPC with timebase register */
1082                 ppc_md.calibrate_decr();
1083                 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
1084                        ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
1085                 printk(KERN_DEBUG "time_init: processor frequency   = %lu.%.6lu MHz\n",
1086                        ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
1087         }
1088 
1089         tb_ticks_per_jiffy = ppc_tb_freq / HZ;
1090         tb_ticks_per_sec = ppc_tb_freq;
1091         tb_ticks_per_usec = ppc_tb_freq / 1000000;
1092         calc_cputime_factors();
1093 
1094         /*
1095          * Compute scale factor for sched_clock.
1096          * The calibrate_decr() function has set tb_ticks_per_sec,
1097          * which is the timebase frequency.
1098          * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
1099          * the 128-bit result as a 64.64 fixed-point number.
1100          * We then shift that number right until it is less than 1.0,
1101          * giving us the scale factor and shift count to use in
1102          * sched_clock().
1103          */
1104         div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
1105         scale = res.result_low;
1106         for (shift = 0; res.result_high != 0; ++shift) {
1107                 scale = (scale >> 1) | (res.result_high << 63);
1108                 res.result_high >>= 1;
1109         }
1110         tb_to_ns_scale = scale;
1111         tb_to_ns_shift = shift;
1112         /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
1113         boot_tb = get_tb_or_rtc();
1114 
1115         /* If platform provided a timezone (pmac), we correct the time */
1116         if (timezone_offset) {
1117                 sys_tz.tz_minuteswest = -timezone_offset / 60;
1118                 sys_tz.tz_dsttime = 0;
1119         }
1120 
1121         vdso_data->tb_update_count = 0;
1122         vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1123 
1124         /* initialise and enable the large decrementer (if we have one) */
1125         set_decrementer_max();
1126         enable_large_decrementer();
1127 
1128         /* Start the decrementer on CPUs that have manual control
1129          * such as BookE
1130          */
1131         start_cpu_decrementer();
1132 
1133         /* Register the clocksource */
1134         clocksource_init();
1135 
1136         init_decrementer_clockevent();
1137         tick_setup_hrtimer_broadcast();
1138 
1139 #ifdef CONFIG_COMMON_CLK
1140         of_clk_init(NULL);
1141 #endif
1142 }
1143 
1144 
1145 #define FEBRUARY        2
1146 #define STARTOFTIME     1970
1147 #define SECDAY          86400L
1148 #define SECYR           (SECDAY * 365)
1149 #define leapyear(year)          ((year) % 4 == 0 && \
1150                                  ((year) % 100 != 0 || (year) % 400 == 0))
1151 #define days_in_year(a)         (leapyear(a) ? 366 : 365)
1152 #define days_in_month(a)        (month_days[(a) - 1])
1153 
1154 static int month_days[12] = {
1155         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
1156 };
1157 
1158 void to_tm(int tim, struct rtc_time * tm)
1159 {
1160         register int    i;
1161         register long   hms, day;
1162 
1163         day = tim / SECDAY;
1164         hms = tim % SECDAY;
1165 
1166         /* Hours, minutes, seconds are easy */
1167         tm->tm_hour = hms / 3600;
1168         tm->tm_min = (hms % 3600) / 60;
1169         tm->tm_sec = (hms % 3600) % 60;
1170 
1171         /* Number of years in days */
1172         for (i = STARTOFTIME; day >= days_in_year(i); i++)
1173                 day -= days_in_year(i);
1174         tm->tm_year = i;
1175 
1176         /* Number of months in days left */
1177         if (leapyear(tm->tm_year))
1178                 days_in_month(FEBRUARY) = 29;
1179         for (i = 1; day >= days_in_month(i); i++)
1180                 day -= days_in_month(i);
1181         days_in_month(FEBRUARY) = 28;
1182         tm->tm_mon = i;
1183 
1184         /* Days are what is left over (+1) from all that. */
1185         tm->tm_mday = day + 1;
1186 
1187         /*
1188          * No-one uses the day of the week.
1189          */
1190         tm->tm_wday = -1;
1191 }
1192 EXPORT_SYMBOL(to_tm);
1193 
1194 /*
1195  * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1196  * result.
1197  */
1198 void div128_by_32(u64 dividend_high, u64 dividend_low,
1199                   unsigned divisor, struct div_result *dr)
1200 {
1201         unsigned long a, b, c, d;
1202         unsigned long w, x, y, z;
1203         u64 ra, rb, rc;
1204 
1205         a = dividend_high >> 32;
1206         b = dividend_high & 0xffffffff;
1207         c = dividend_low >> 32;
1208         d = dividend_low & 0xffffffff;
1209 
1210         w = a / divisor;
1211         ra = ((u64)(a - (w * divisor)) << 32) + b;
1212 
1213         rb = ((u64) do_div(ra, divisor) << 32) + c;
1214         x = ra;
1215 
1216         rc = ((u64) do_div(rb, divisor) << 32) + d;
1217         y = rb;
1218 
1219         do_div(rc, divisor);
1220         z = rc;
1221 
1222         dr->result_high = ((u64)w << 32) + x;
1223         dr->result_low  = ((u64)y << 32) + z;
1224 
1225 }
1226 
1227 /* We don't need to calibrate delay, we use the CPU timebase for that */
1228 void calibrate_delay(void)
1229 {
1230         /* Some generic code (such as spinlock debug) use loops_per_jiffy
1231          * as the number of __delay(1) in a jiffy, so make it so
1232          */
1233         loops_per_jiffy = tb_ticks_per_jiffy;
1234 }
1235 
1236 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
1237 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
1238 {
1239         ppc_md.get_rtc_time(tm);
1240         return 0;
1241 }
1242 
1243 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1244 {
1245         if (!ppc_md.set_rtc_time)
1246                 return -EOPNOTSUPP;
1247 
1248         if (ppc_md.set_rtc_time(tm) < 0)
1249                 return -EOPNOTSUPP;
1250 
1251         return 0;
1252 }
1253 
1254 static const struct rtc_class_ops rtc_generic_ops = {
1255         .read_time = rtc_generic_get_time,
1256         .set_time = rtc_generic_set_time,
1257 };
1258 
1259 static int __init rtc_init(void)
1260 {
1261         struct platform_device *pdev;
1262 
1263         if (!ppc_md.get_rtc_time)
1264                 return -ENODEV;
1265 
1266         pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1267                                              &rtc_generic_ops,
1268                                              sizeof(rtc_generic_ops));
1269 
1270         return PTR_ERR_OR_ZERO(pdev);
1271 }
1272 
1273 device_initcall(rtc_init);
1274 #endif
1275 

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