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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/kernel.h>
 38 #include <linux/param.h>
 39 #include <linux/string.h>
 40 #include <linux/mm.h>
 41 #include <linux/interrupt.h>
 42 #include <linux/timex.h>
 43 #include <linux/kernel_stat.h>
 44 #include <linux/time.h>
 45 #include <linux/clockchips.h>
 46 #include <linux/init.h>
 47 #include <linux/profile.h>
 48 #include <linux/cpu.h>
 49 #include <linux/security.h>
 50 #include <linux/percpu.h>
 51 #include <linux/rtc.h>
 52 #include <linux/jiffies.h>
 53 #include <linux/posix-timers.h>
 54 #include <linux/irq.h>
 55 #include <linux/delay.h>
 56 #include <linux/irq_work.h>
 57 #include <asm/trace.h>
 58 
 59 #include <asm/io.h>
 60 #include <asm/processor.h>
 61 #include <asm/nvram.h>
 62 #include <asm/cache.h>
 63 #include <asm/machdep.h>
 64 #include <asm/uaccess.h>
 65 #include <asm/time.h>
 66 #include <asm/prom.h>
 67 #include <asm/irq.h>
 68 #include <asm/div64.h>
 69 #include <asm/smp.h>
 70 #include <asm/vdso_datapage.h>
 71 #include <asm/firmware.h>
 72 #include <asm/cputime.h>
 73 
 74 /* powerpc clocksource/clockevent code */
 75 
 76 #include <linux/clockchips.h>
 77 #include <linux/timekeeper_internal.h>
 78 
 79 static cycle_t rtc_read(struct clocksource *);
 80 static struct clocksource clocksource_rtc = {
 81         .name         = "rtc",
 82         .rating       = 400,
 83         .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
 84         .mask         = CLOCKSOURCE_MASK(64),
 85         .read         = rtc_read,
 86 };
 87 
 88 static cycle_t timebase_read(struct clocksource *);
 89 static struct clocksource clocksource_timebase = {
 90         .name         = "timebase",
 91         .rating       = 400,
 92         .flags        = CLOCK_SOURCE_IS_CONTINUOUS,
 93         .mask         = CLOCKSOURCE_MASK(64),
 94         .read         = timebase_read,
 95 };
 96 
 97 #define DECREMENTER_MAX 0x7fffffff
 98 
 99 static int decrementer_set_next_event(unsigned long evt,
100                                       struct clock_event_device *dev);
101 static void decrementer_set_mode(enum clock_event_mode mode,
102                                  struct clock_event_device *dev);
103 
104 struct clock_event_device decrementer_clockevent = {
105         .name           = "decrementer",
106         .rating         = 200,
107         .irq            = 0,
108         .set_next_event = decrementer_set_next_event,
109         .set_mode       = decrementer_set_mode,
110         .features       = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP,
111 };
112 EXPORT_SYMBOL(decrementer_clockevent);
113 
114 DEFINE_PER_CPU(u64, decrementers_next_tb);
115 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
116 
117 #define XSEC_PER_SEC (1024*1024)
118 
119 #ifdef CONFIG_PPC64
120 #define SCALE_XSEC(xsec, max)   (((xsec) * max) / XSEC_PER_SEC)
121 #else
122 /* compute ((xsec << 12) * max) >> 32 */
123 #define SCALE_XSEC(xsec, max)   mulhwu((xsec) << 12, max)
124 #endif
125 
126 unsigned long tb_ticks_per_jiffy;
127 unsigned long tb_ticks_per_usec = 100; /* sane default */
128 EXPORT_SYMBOL(tb_ticks_per_usec);
129 unsigned long tb_ticks_per_sec;
130 EXPORT_SYMBOL(tb_ticks_per_sec);        /* for cputime_t conversions */
131 
132 DEFINE_SPINLOCK(rtc_lock);
133 EXPORT_SYMBOL_GPL(rtc_lock);
134 
135 static u64 tb_to_ns_scale __read_mostly;
136 static unsigned tb_to_ns_shift __read_mostly;
137 static u64 boot_tb __read_mostly;
138 
139 extern struct timezone sys_tz;
140 static long timezone_offset;
141 
142 unsigned long ppc_proc_freq;
143 EXPORT_SYMBOL_GPL(ppc_proc_freq);
144 unsigned long ppc_tb_freq;
145 EXPORT_SYMBOL_GPL(ppc_tb_freq);
146 
147 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
148 /*
149  * Factors for converting from cputime_t (timebase ticks) to
150  * jiffies, microseconds, seconds, and clock_t (1/USER_HZ seconds).
151  * These are all stored as 0.64 fixed-point binary fractions.
152  */
153 u64 __cputime_jiffies_factor;
154 EXPORT_SYMBOL(__cputime_jiffies_factor);
155 u64 __cputime_usec_factor;
156 EXPORT_SYMBOL(__cputime_usec_factor);
157 u64 __cputime_sec_factor;
158 EXPORT_SYMBOL(__cputime_sec_factor);
159 u64 __cputime_clockt_factor;
160 EXPORT_SYMBOL(__cputime_clockt_factor);
161 DEFINE_PER_CPU(unsigned long, cputime_last_delta);
162 DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
163 
164 cputime_t cputime_one_jiffy;
165 
166 void (*dtl_consumer)(struct dtl_entry *, u64);
167 
168 static void calc_cputime_factors(void)
169 {
170         struct div_result res;
171 
172         div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
173         __cputime_jiffies_factor = res.result_low;
174         div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
175         __cputime_usec_factor = res.result_low;
176         div128_by_32(1, 0, tb_ticks_per_sec, &res);
177         __cputime_sec_factor = res.result_low;
178         div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
179         __cputime_clockt_factor = res.result_low;
180 }
181 
182 /*
183  * Read the SPURR on systems that have it, otherwise the PURR,
184  * or if that doesn't exist return the timebase value passed in.
185  */
186 static u64 read_spurr(u64 tb)
187 {
188         if (cpu_has_feature(CPU_FTR_SPURR))
189                 return mfspr(SPRN_SPURR);
190         if (cpu_has_feature(CPU_FTR_PURR))
191                 return mfspr(SPRN_PURR);
192         return tb;
193 }
194 
195 #ifdef CONFIG_PPC_SPLPAR
196 
197 /*
198  * Scan the dispatch trace log and count up the stolen time.
199  * Should be called with interrupts disabled.
200  */
201 static u64 scan_dispatch_log(u64 stop_tb)
202 {
203         u64 i = local_paca->dtl_ridx;
204         struct dtl_entry *dtl = local_paca->dtl_curr;
205         struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
206         struct lppaca *vpa = local_paca->lppaca_ptr;
207         u64 tb_delta;
208         u64 stolen = 0;
209         u64 dtb;
210 
211         if (!dtl)
212                 return 0;
213 
214         if (i == be64_to_cpu(vpa->dtl_idx))
215                 return 0;
216         while (i < be64_to_cpu(vpa->dtl_idx)) {
217                 dtb = be64_to_cpu(dtl->timebase);
218                 tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
219                         be32_to_cpu(dtl->ready_to_enqueue_time);
220                 barrier();
221                 if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
222                         /* buffer has overflowed */
223                         i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
224                         dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
225                         continue;
226                 }
227                 if (dtb > stop_tb)
228                         break;
229                 if (dtl_consumer)
230                         dtl_consumer(dtl, i);
231                 stolen += tb_delta;
232                 ++i;
233                 ++dtl;
234                 if (dtl == dtl_end)
235                         dtl = local_paca->dispatch_log;
236         }
237         local_paca->dtl_ridx = i;
238         local_paca->dtl_curr = dtl;
239         return stolen;
240 }
241 
242 /*
243  * Accumulate stolen time by scanning the dispatch trace log.
244  * Called on entry from user mode.
245  */
246 void accumulate_stolen_time(void)
247 {
248         u64 sst, ust;
249 
250         u8 save_soft_enabled = local_paca->soft_enabled;
251 
252         /* We are called early in the exception entry, before
253          * soft/hard_enabled are sync'ed to the expected state
254          * for the exception. We are hard disabled but the PACA
255          * needs to reflect that so various debug stuff doesn't
256          * complain
257          */
258         local_paca->soft_enabled = 0;
259 
260         sst = scan_dispatch_log(local_paca->starttime_user);
261         ust = scan_dispatch_log(local_paca->starttime);
262         local_paca->system_time -= sst;
263         local_paca->user_time -= ust;
264         local_paca->stolen_time += ust + sst;
265 
266         local_paca->soft_enabled = save_soft_enabled;
267 }
268 
269 static inline u64 calculate_stolen_time(u64 stop_tb)
270 {
271         u64 stolen = 0;
272 
273         if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx)) {
274                 stolen = scan_dispatch_log(stop_tb);
275                 get_paca()->system_time -= stolen;
276         }
277 
278         stolen += get_paca()->stolen_time;
279         get_paca()->stolen_time = 0;
280         return stolen;
281 }
282 
283 #else /* CONFIG_PPC_SPLPAR */
284 static inline u64 calculate_stolen_time(u64 stop_tb)
285 {
286         return 0;
287 }
288 
289 #endif /* CONFIG_PPC_SPLPAR */
290 
291 /*
292  * Account time for a transition between system, hard irq
293  * or soft irq state.
294  */
295 static u64 vtime_delta(struct task_struct *tsk,
296                         u64 *sys_scaled, u64 *stolen)
297 {
298         u64 now, nowscaled, deltascaled;
299         u64 udelta, delta, user_scaled;
300 
301         WARN_ON_ONCE(!irqs_disabled());
302 
303         now = mftb();
304         nowscaled = read_spurr(now);
305         get_paca()->system_time += now - get_paca()->starttime;
306         get_paca()->starttime = now;
307         deltascaled = nowscaled - get_paca()->startspurr;
308         get_paca()->startspurr = nowscaled;
309 
310         *stolen = calculate_stolen_time(now);
311 
312         delta = get_paca()->system_time;
313         get_paca()->system_time = 0;
314         udelta = get_paca()->user_time - get_paca()->utime_sspurr;
315         get_paca()->utime_sspurr = get_paca()->user_time;
316 
317         /*
318          * Because we don't read the SPURR on every kernel entry/exit,
319          * deltascaled includes both user and system SPURR ticks.
320          * Apportion these ticks to system SPURR ticks and user
321          * SPURR ticks in the same ratio as the system time (delta)
322          * and user time (udelta) values obtained from the timebase
323          * over the same interval.  The system ticks get accounted here;
324          * the user ticks get saved up in paca->user_time_scaled to be
325          * used by account_process_tick.
326          */
327         *sys_scaled = delta;
328         user_scaled = udelta;
329         if (deltascaled != delta + udelta) {
330                 if (udelta) {
331                         *sys_scaled = deltascaled * delta / (delta + udelta);
332                         user_scaled = deltascaled - *sys_scaled;
333                 } else {
334                         *sys_scaled = deltascaled;
335                 }
336         }
337         get_paca()->user_time_scaled += user_scaled;
338 
339         return delta;
340 }
341 
342 void vtime_account_system(struct task_struct *tsk)
343 {
344         u64 delta, sys_scaled, stolen;
345 
346         delta = vtime_delta(tsk, &sys_scaled, &stolen);
347         account_system_time(tsk, 0, delta, sys_scaled);
348         if (stolen)
349                 account_steal_time(stolen);
350 }
351 EXPORT_SYMBOL_GPL(vtime_account_system);
352 
353 void vtime_account_idle(struct task_struct *tsk)
354 {
355         u64 delta, sys_scaled, stolen;
356 
357         delta = vtime_delta(tsk, &sys_scaled, &stolen);
358         account_idle_time(delta + stolen);
359 }
360 
361 /*
362  * Transfer the user time accumulated in the paca
363  * by the exception entry and exit code to the generic
364  * process user time records.
365  * Must be called with interrupts disabled.
366  * Assumes that vtime_account_system/idle() has been called
367  * recently (i.e. since the last entry from usermode) so that
368  * get_paca()->user_time_scaled is up to date.
369  */
370 void vtime_account_user(struct task_struct *tsk)
371 {
372         cputime_t utime, utimescaled;
373 
374         utime = get_paca()->user_time;
375         utimescaled = get_paca()->user_time_scaled;
376         get_paca()->user_time = 0;
377         get_paca()->user_time_scaled = 0;
378         get_paca()->utime_sspurr = 0;
379         account_user_time(tsk, utime, utimescaled);
380 }
381 
382 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
383 #define calc_cputime_factors()
384 #endif
385 
386 void __delay(unsigned long loops)
387 {
388         unsigned long start;
389         int diff;
390 
391         if (__USE_RTC()) {
392                 start = get_rtcl();
393                 do {
394                         /* the RTCL register wraps at 1000000000 */
395                         diff = get_rtcl() - start;
396                         if (diff < 0)
397                                 diff += 1000000000;
398                 } while (diff < loops);
399         } else {
400                 start = get_tbl();
401                 while (get_tbl() - start < loops)
402                         HMT_low();
403                 HMT_medium();
404         }
405 }
406 EXPORT_SYMBOL(__delay);
407 
408 void udelay(unsigned long usecs)
409 {
410         __delay(tb_ticks_per_usec * usecs);
411 }
412 EXPORT_SYMBOL(udelay);
413 
414 #ifdef CONFIG_SMP
415 unsigned long profile_pc(struct pt_regs *regs)
416 {
417         unsigned long pc = instruction_pointer(regs);
418 
419         if (in_lock_functions(pc))
420                 return regs->link;
421 
422         return pc;
423 }
424 EXPORT_SYMBOL(profile_pc);
425 #endif
426 
427 #ifdef CONFIG_IRQ_WORK
428 
429 /*
430  * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
431  */
432 #ifdef CONFIG_PPC64
433 static inline unsigned long test_irq_work_pending(void)
434 {
435         unsigned long x;
436 
437         asm volatile("lbz %0,%1(13)"
438                 : "=r" (x)
439                 : "i" (offsetof(struct paca_struct, irq_work_pending)));
440         return x;
441 }
442 
443 static inline void set_irq_work_pending_flag(void)
444 {
445         asm volatile("stb %0,%1(13)" : :
446                 "r" (1),
447                 "i" (offsetof(struct paca_struct, irq_work_pending)));
448 }
449 
450 static inline void clear_irq_work_pending(void)
451 {
452         asm volatile("stb %0,%1(13)" : :
453                 "r" (0),
454                 "i" (offsetof(struct paca_struct, irq_work_pending)));
455 }
456 
457 #else /* 32-bit */
458 
459 DEFINE_PER_CPU(u8, irq_work_pending);
460 
461 #define set_irq_work_pending_flag()     __get_cpu_var(irq_work_pending) = 1
462 #define test_irq_work_pending()         __get_cpu_var(irq_work_pending)
463 #define clear_irq_work_pending()        __get_cpu_var(irq_work_pending) = 0
464 
465 #endif /* 32 vs 64 bit */
466 
467 void arch_irq_work_raise(void)
468 {
469         preempt_disable();
470         set_irq_work_pending_flag();
471         set_dec(1);
472         preempt_enable();
473 }
474 
475 #else  /* CONFIG_IRQ_WORK */
476 
477 #define test_irq_work_pending() 0
478 #define clear_irq_work_pending()
479 
480 #endif /* CONFIG_IRQ_WORK */
481 
482 static void __timer_interrupt(void)
483 {
484         struct pt_regs *regs = get_irq_regs();
485         u64 *next_tb = &__get_cpu_var(decrementers_next_tb);
486         struct clock_event_device *evt = &__get_cpu_var(decrementers);
487         u64 now;
488 
489         trace_timer_interrupt_entry(regs);
490 
491         if (test_irq_work_pending()) {
492                 clear_irq_work_pending();
493                 irq_work_run();
494         }
495 
496         now = get_tb_or_rtc();
497         if (now >= *next_tb) {
498                 *next_tb = ~(u64)0;
499                 if (evt->event_handler)
500                         evt->event_handler(evt);
501                 __get_cpu_var(irq_stat).timer_irqs_event++;
502         } else {
503                 now = *next_tb - now;
504                 if (now <= DECREMENTER_MAX)
505                         set_dec((int)now);
506                 /* We may have raced with new irq work */
507                 if (test_irq_work_pending())
508                         set_dec(1);
509                 __get_cpu_var(irq_stat).timer_irqs_others++;
510         }
511 
512 #ifdef CONFIG_PPC64
513         /* collect purr register values often, for accurate calculations */
514         if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
515                 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
516                 cu->current_tb = mfspr(SPRN_PURR);
517         }
518 #endif
519 
520         trace_timer_interrupt_exit(regs);
521 }
522 
523 /*
524  * timer_interrupt - gets called when the decrementer overflows,
525  * with interrupts disabled.
526  */
527 void timer_interrupt(struct pt_regs * regs)
528 {
529         struct pt_regs *old_regs;
530         u64 *next_tb = &__get_cpu_var(decrementers_next_tb);
531 
532         /* Ensure a positive value is written to the decrementer, or else
533          * some CPUs will continue to take decrementer exceptions.
534          */
535         set_dec(DECREMENTER_MAX);
536 
537         /* Some implementations of hotplug will get timer interrupts while
538          * offline, just ignore these and we also need to set
539          * decrementers_next_tb as MAX to make sure __check_irq_replay
540          * don't replay timer interrupt when return, otherwise we'll trap
541          * here infinitely :(
542          */
543         if (!cpu_online(smp_processor_id())) {
544                 *next_tb = ~(u64)0;
545                 return;
546         }
547 
548         /* Conditionally hard-enable interrupts now that the DEC has been
549          * bumped to its maximum value
550          */
551         may_hard_irq_enable();
552 
553 
554 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
555         if (atomic_read(&ppc_n_lost_interrupts) != 0)
556                 do_IRQ(regs);
557 #endif
558 
559         old_regs = set_irq_regs(regs);
560         irq_enter();
561 
562         __timer_interrupt();
563         irq_exit();
564         set_irq_regs(old_regs);
565 }
566 
567 /*
568  * Hypervisor decrementer interrupts shouldn't occur but are sometimes
569  * left pending on exit from a KVM guest.  We don't need to do anything
570  * to clear them, as they are edge-triggered.
571  */
572 void hdec_interrupt(struct pt_regs *regs)
573 {
574 }
575 
576 #ifdef CONFIG_SUSPEND
577 static void generic_suspend_disable_irqs(void)
578 {
579         /* Disable the decrementer, so that it doesn't interfere
580          * with suspending.
581          */
582 
583         set_dec(DECREMENTER_MAX);
584         local_irq_disable();
585         set_dec(DECREMENTER_MAX);
586 }
587 
588 static void generic_suspend_enable_irqs(void)
589 {
590         local_irq_enable();
591 }
592 
593 /* Overrides the weak version in kernel/power/main.c */
594 void arch_suspend_disable_irqs(void)
595 {
596         if (ppc_md.suspend_disable_irqs)
597                 ppc_md.suspend_disable_irqs();
598         generic_suspend_disable_irqs();
599 }
600 
601 /* Overrides the weak version in kernel/power/main.c */
602 void arch_suspend_enable_irqs(void)
603 {
604         generic_suspend_enable_irqs();
605         if (ppc_md.suspend_enable_irqs)
606                 ppc_md.suspend_enable_irqs();
607 }
608 #endif
609 
610 /*
611  * Scheduler clock - returns current time in nanosec units.
612  *
613  * Note: mulhdu(a, b) (multiply high double unsigned) returns
614  * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
615  * are 64-bit unsigned numbers.
616  */
617 unsigned long long sched_clock(void)
618 {
619         if (__USE_RTC())
620                 return get_rtc();
621         return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
622 }
623 
624 static int __init get_freq(char *name, int cells, unsigned long *val)
625 {
626         struct device_node *cpu;
627         const __be32 *fp;
628         int found = 0;
629 
630         /* The cpu node should have timebase and clock frequency properties */
631         cpu = of_find_node_by_type(NULL, "cpu");
632 
633         if (cpu) {
634                 fp = of_get_property(cpu, name, NULL);
635                 if (fp) {
636                         found = 1;
637                         *val = of_read_ulong(fp, cells);
638                 }
639 
640                 of_node_put(cpu);
641         }
642 
643         return found;
644 }
645 
646 static void start_cpu_decrementer(void)
647 {
648 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
649         unsigned int tcr;
650 
651         /* Clear any pending timer interrupts */
652         mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
653 
654         tcr = mfspr(SPRN_TCR);
655         /*
656          * The watchdog may have already been enabled by u-boot. So leave
657          * TRC[WP] (Watchdog Period) alone.
658          */
659         tcr &= TCR_WP_MASK;     /* Clear all bits except for TCR[WP] */
660         tcr |= TCR_DIE;         /* Enable decrementer */
661         mtspr(SPRN_TCR, tcr);
662 #endif
663 }
664 
665 void __init generic_calibrate_decr(void)
666 {
667         ppc_tb_freq = DEFAULT_TB_FREQ;          /* hardcoded default */
668 
669         if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
670             !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
671 
672                 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
673                                 "(not found)\n");
674         }
675 
676         ppc_proc_freq = DEFAULT_PROC_FREQ;      /* hardcoded default */
677 
678         if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
679             !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
680 
681                 printk(KERN_ERR "WARNING: Estimating processor frequency "
682                                 "(not found)\n");
683         }
684 }
685 
686 int update_persistent_clock(struct timespec now)
687 {
688         struct rtc_time tm;
689 
690         if (!ppc_md.set_rtc_time)
691                 return -ENODEV;
692 
693         to_tm(now.tv_sec + 1 + timezone_offset, &tm);
694         tm.tm_year -= 1900;
695         tm.tm_mon -= 1;
696 
697         return ppc_md.set_rtc_time(&tm);
698 }
699 
700 static void __read_persistent_clock(struct timespec *ts)
701 {
702         struct rtc_time tm;
703         static int first = 1;
704 
705         ts->tv_nsec = 0;
706         /* XXX this is a litle fragile but will work okay in the short term */
707         if (first) {
708                 first = 0;
709                 if (ppc_md.time_init)
710                         timezone_offset = ppc_md.time_init();
711 
712                 /* get_boot_time() isn't guaranteed to be safe to call late */
713                 if (ppc_md.get_boot_time) {
714                         ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
715                         return;
716                 }
717         }
718         if (!ppc_md.get_rtc_time) {
719                 ts->tv_sec = 0;
720                 return;
721         }
722         ppc_md.get_rtc_time(&tm);
723 
724         ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
725                             tm.tm_hour, tm.tm_min, tm.tm_sec);
726 }
727 
728 void read_persistent_clock(struct timespec *ts)
729 {
730         __read_persistent_clock(ts);
731 
732         /* Sanitize it in case real time clock is set below EPOCH */
733         if (ts->tv_sec < 0) {
734                 ts->tv_sec = 0;
735                 ts->tv_nsec = 0;
736         }
737                 
738 }
739 
740 /* clocksource code */
741 static cycle_t rtc_read(struct clocksource *cs)
742 {
743         return (cycle_t)get_rtc();
744 }
745 
746 static cycle_t timebase_read(struct clocksource *cs)
747 {
748         return (cycle_t)get_tb();
749 }
750 
751 void update_vsyscall_old(struct timespec *wall_time, struct timespec *wtm,
752                          struct clocksource *clock, u32 mult, cycle_t cycle_last)
753 {
754         u64 new_tb_to_xs, new_stamp_xsec;
755         u32 frac_sec;
756 
757         if (clock != &clocksource_timebase)
758                 return;
759 
760         /* Make userspace gettimeofday spin until we're done. */
761         ++vdso_data->tb_update_count;
762         smp_mb();
763 
764         /* 19342813113834067 ~= 2^(20+64) / 1e9 */
765         new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
766         new_stamp_xsec = (u64) wall_time->tv_nsec * XSEC_PER_SEC;
767         do_div(new_stamp_xsec, 1000000000);
768         new_stamp_xsec += (u64) wall_time->tv_sec * XSEC_PER_SEC;
769 
770         BUG_ON(wall_time->tv_nsec >= NSEC_PER_SEC);
771         /* this is tv_nsec / 1e9 as a 0.32 fraction */
772         frac_sec = ((u64) wall_time->tv_nsec * 18446744073ULL) >> 32;
773 
774         /*
775          * tb_update_count is used to allow the userspace gettimeofday code
776          * to assure itself that it sees a consistent view of the tb_to_xs and
777          * stamp_xsec variables.  It reads the tb_update_count, then reads
778          * tb_to_xs and stamp_xsec and then reads tb_update_count again.  If
779          * the two values of tb_update_count match and are even then the
780          * tb_to_xs and stamp_xsec values are consistent.  If not, then it
781          * loops back and reads them again until this criteria is met.
782          * We expect the caller to have done the first increment of
783          * vdso_data->tb_update_count already.
784          */
785         vdso_data->tb_orig_stamp = cycle_last;
786         vdso_data->stamp_xsec = new_stamp_xsec;
787         vdso_data->tb_to_xs = new_tb_to_xs;
788         vdso_data->wtom_clock_sec = wtm->tv_sec;
789         vdso_data->wtom_clock_nsec = wtm->tv_nsec;
790         vdso_data->stamp_xtime = *wall_time;
791         vdso_data->stamp_sec_fraction = frac_sec;
792         smp_wmb();
793         ++(vdso_data->tb_update_count);
794 }
795 
796 void update_vsyscall_tz(void)
797 {
798         vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
799         vdso_data->tz_dsttime = sys_tz.tz_dsttime;
800 }
801 
802 static void __init clocksource_init(void)
803 {
804         struct clocksource *clock;
805 
806         if (__USE_RTC())
807                 clock = &clocksource_rtc;
808         else
809                 clock = &clocksource_timebase;
810 
811         if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
812                 printk(KERN_ERR "clocksource: %s is already registered\n",
813                        clock->name);
814                 return;
815         }
816 
817         printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
818                clock->name, clock->mult, clock->shift);
819 }
820 
821 static int decrementer_set_next_event(unsigned long evt,
822                                       struct clock_event_device *dev)
823 {
824         __get_cpu_var(decrementers_next_tb) = get_tb_or_rtc() + evt;
825         set_dec(evt);
826 
827         /* We may have raced with new irq work */
828         if (test_irq_work_pending())
829                 set_dec(1);
830 
831         return 0;
832 }
833 
834 static void decrementer_set_mode(enum clock_event_mode mode,
835                                  struct clock_event_device *dev)
836 {
837         if (mode != CLOCK_EVT_MODE_ONESHOT)
838                 decrementer_set_next_event(DECREMENTER_MAX, dev);
839 }
840 
841 /* Interrupt handler for the timer broadcast IPI */
842 void tick_broadcast_ipi_handler(void)
843 {
844         u64 *next_tb = &__get_cpu_var(decrementers_next_tb);
845 
846         *next_tb = get_tb_or_rtc();
847         __timer_interrupt();
848 }
849 
850 static void register_decrementer_clockevent(int cpu)
851 {
852         struct clock_event_device *dec = &per_cpu(decrementers, cpu);
853 
854         *dec = decrementer_clockevent;
855         dec->cpumask = cpumask_of(cpu);
856 
857         printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
858                     dec->name, dec->mult, dec->shift, cpu);
859 
860         clockevents_register_device(dec);
861 }
862 
863 static void __init init_decrementer_clockevent(void)
864 {
865         int cpu = smp_processor_id();
866 
867         clockevents_calc_mult_shift(&decrementer_clockevent, ppc_tb_freq, 4);
868 
869         decrementer_clockevent.max_delta_ns =
870                 clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
871         decrementer_clockevent.min_delta_ns =
872                 clockevent_delta2ns(2, &decrementer_clockevent);
873 
874         register_decrementer_clockevent(cpu);
875 }
876 
877 void secondary_cpu_time_init(void)
878 {
879         /* Start the decrementer on CPUs that have manual control
880          * such as BookE
881          */
882         start_cpu_decrementer();
883 
884         /* FIME: Should make unrelatred change to move snapshot_timebase
885          * call here ! */
886         register_decrementer_clockevent(smp_processor_id());
887 }
888 
889 /* This function is only called on the boot processor */
890 void __init time_init(void)
891 {
892         struct div_result res;
893         u64 scale;
894         unsigned shift;
895 
896         if (__USE_RTC()) {
897                 /* 601 processor: dec counts down by 128 every 128ns */
898                 ppc_tb_freq = 1000000000;
899         } else {
900                 /* Normal PowerPC with timebase register */
901                 ppc_md.calibrate_decr();
902                 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
903                        ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
904                 printk(KERN_DEBUG "time_init: processor frequency   = %lu.%.6lu MHz\n",
905                        ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
906         }
907 
908         tb_ticks_per_jiffy = ppc_tb_freq / HZ;
909         tb_ticks_per_sec = ppc_tb_freq;
910         tb_ticks_per_usec = ppc_tb_freq / 1000000;
911         calc_cputime_factors();
912         setup_cputime_one_jiffy();
913 
914         /*
915          * Compute scale factor for sched_clock.
916          * The calibrate_decr() function has set tb_ticks_per_sec,
917          * which is the timebase frequency.
918          * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
919          * the 128-bit result as a 64.64 fixed-point number.
920          * We then shift that number right until it is less than 1.0,
921          * giving us the scale factor and shift count to use in
922          * sched_clock().
923          */
924         div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
925         scale = res.result_low;
926         for (shift = 0; res.result_high != 0; ++shift) {
927                 scale = (scale >> 1) | (res.result_high << 63);
928                 res.result_high >>= 1;
929         }
930         tb_to_ns_scale = scale;
931         tb_to_ns_shift = shift;
932         /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
933         boot_tb = get_tb_or_rtc();
934 
935         /* If platform provided a timezone (pmac), we correct the time */
936         if (timezone_offset) {
937                 sys_tz.tz_minuteswest = -timezone_offset / 60;
938                 sys_tz.tz_dsttime = 0;
939         }
940 
941         vdso_data->tb_update_count = 0;
942         vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
943 
944         /* Start the decrementer on CPUs that have manual control
945          * such as BookE
946          */
947         start_cpu_decrementer();
948 
949         /* Register the clocksource */
950         clocksource_init();
951 
952         init_decrementer_clockevent();
953         tick_setup_hrtimer_broadcast();
954 }
955 
956 
957 #define FEBRUARY        2
958 #define STARTOFTIME     1970
959 #define SECDAY          86400L
960 #define SECYR           (SECDAY * 365)
961 #define leapyear(year)          ((year) % 4 == 0 && \
962                                  ((year) % 100 != 0 || (year) % 400 == 0))
963 #define days_in_year(a)         (leapyear(a) ? 366 : 365)
964 #define days_in_month(a)        (month_days[(a) - 1])
965 
966 static int month_days[12] = {
967         31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
968 };
969 
970 /*
971  * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
972  */
973 void GregorianDay(struct rtc_time * tm)
974 {
975         int leapsToDate;
976         int lastYear;
977         int day;
978         int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
979 
980         lastYear = tm->tm_year - 1;
981 
982         /*
983          * Number of leap corrections to apply up to end of last year
984          */
985         leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
986 
987         /*
988          * This year is a leap year if it is divisible by 4 except when it is
989          * divisible by 100 unless it is divisible by 400
990          *
991          * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
992          */
993         day = tm->tm_mon > 2 && leapyear(tm->tm_year);
994 
995         day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
996                    tm->tm_mday;
997 
998         tm->tm_wday = day % 7;
999 }
1000 
1001 void to_tm(int tim, struct rtc_time * tm)
1002 {
1003         register int    i;
1004         register long   hms, day;
1005 
1006         day = tim / SECDAY;
1007         hms = tim % SECDAY;
1008 
1009         /* Hours, minutes, seconds are easy */
1010         tm->tm_hour = hms / 3600;
1011         tm->tm_min = (hms % 3600) / 60;
1012         tm->tm_sec = (hms % 3600) % 60;
1013 
1014         /* Number of years in days */
1015         for (i = STARTOFTIME; day >= days_in_year(i); i++)
1016                 day -= days_in_year(i);
1017         tm->tm_year = i;
1018 
1019         /* Number of months in days left */
1020         if (leapyear(tm->tm_year))
1021                 days_in_month(FEBRUARY) = 29;
1022         for (i = 1; day >= days_in_month(i); i++)
1023                 day -= days_in_month(i);
1024         days_in_month(FEBRUARY) = 28;
1025         tm->tm_mon = i;
1026 
1027         /* Days are what is left over (+1) from all that. */
1028         tm->tm_mday = day + 1;
1029 
1030         /*
1031          * Determine the day of week
1032          */
1033         GregorianDay(tm);
1034 }
1035 EXPORT_SYMBOL(to_tm);
1036 
1037 /*
1038  * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1039  * result.
1040  */
1041 void div128_by_32(u64 dividend_high, u64 dividend_low,
1042                   unsigned divisor, struct div_result *dr)
1043 {
1044         unsigned long a, b, c, d;
1045         unsigned long w, x, y, z;
1046         u64 ra, rb, rc;
1047 
1048         a = dividend_high >> 32;
1049         b = dividend_high & 0xffffffff;
1050         c = dividend_low >> 32;
1051         d = dividend_low & 0xffffffff;
1052 
1053         w = a / divisor;
1054         ra = ((u64)(a - (w * divisor)) << 32) + b;
1055 
1056         rb = ((u64) do_div(ra, divisor) << 32) + c;
1057         x = ra;
1058 
1059         rc = ((u64) do_div(rb, divisor) << 32) + d;
1060         y = rb;
1061 
1062         do_div(rc, divisor);
1063         z = rc;
1064 
1065         dr->result_high = ((u64)w << 32) + x;
1066         dr->result_low  = ((u64)y << 32) + z;
1067 
1068 }
1069 
1070 /* We don't need to calibrate delay, we use the CPU timebase for that */
1071 void calibrate_delay(void)
1072 {
1073         /* Some generic code (such as spinlock debug) use loops_per_jiffy
1074          * as the number of __delay(1) in a jiffy, so make it so
1075          */
1076         loops_per_jiffy = tb_ticks_per_jiffy;
1077 }
1078 
1079 static int __init rtc_init(void)
1080 {
1081         struct platform_device *pdev;
1082 
1083         if (!ppc_md.get_rtc_time)
1084                 return -ENODEV;
1085 
1086         pdev = platform_device_register_simple("rtc-generic", -1, NULL, 0);
1087 
1088         return PTR_ERR_OR_ZERO(pdev);
1089 }
1090 
1091 module_init(rtc_init);
1092 

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