2 * Common time routines among all ppc machines.
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)
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).
15 * Speeded up do_gettimeofday by getting rid of references to
16 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
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.
25 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
26 * "A Kernel Model for Precision Timekeeping" by Dave Mills
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.
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>
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>
66 #include <asm/nvram.h>
67 #include <asm/cache.h>
68 #include <asm/machdep.h>
69 #include <linux/uaccess.h>
73 #include <asm/div64.h>
75 #include <asm/vdso_datapage.h>
76 #include <asm/firmware.h>
77 #include <asm/asm-prototypes.h>
79 /* powerpc clocksource/clockevent code */
81 #include <linux/clockchips.h>
82 #include <linux/timekeeper_internal.h>
84 static u64 rtc_read(struct clocksource *);
85 static struct clocksource clocksource_rtc = {
88 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
89 .mask = CLOCKSOURCE_MASK(64),
93 static u64 timebase_read(struct clocksource *);
94 static struct clocksource clocksource_timebase = {
97 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
98 .mask = CLOCKSOURCE_MASK(64),
99 .read = timebase_read,
102 #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
103 u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
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);
109 struct clock_event_device decrementer_clockevent = {
110 .name = "decrementer",
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,
119 EXPORT_SYMBOL(decrementer_clockevent);
121 DEFINE_PER_CPU(u64, decrementers_next_tb);
122 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
124 #define XSEC_PER_SEC (1024*1024)
127 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
129 /* compute ((xsec << 12) * max) >> 32 */
130 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
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 */
139 DEFINE_SPINLOCK(rtc_lock);
140 EXPORT_SYMBOL_GPL(rtc_lock);
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;
146 extern struct timezone sys_tz;
147 static long timezone_offset;
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);
154 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
156 * Factor for converting from cputime_t (timebase ticks) to
157 * microseconds. This is stored as 0.64 fixed-point binary fraction.
159 u64 __cputime_usec_factor;
160 EXPORT_SYMBOL(__cputime_usec_factor);
162 #ifdef CONFIG_PPC_SPLPAR
163 void (*dtl_consumer)(struct dtl_entry *, u64);
167 #define get_accounting(tsk) (&get_paca()->accounting)
169 #define get_accounting(tsk) (&task_thread_info(tsk)->accounting)
172 static void calc_cputime_factors(void)
174 struct div_result res;
176 div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
177 __cputime_usec_factor = res.result_low;
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.
184 static unsigned long read_spurr(unsigned long tb)
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);
193 #ifdef CONFIG_PPC_SPLPAR
196 * Scan the dispatch trace log and count up the stolen time.
197 * Should be called with interrupts disabled.
199 static u64 scan_dispatch_log(u64 stop_tb)
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;
212 if (i == be64_to_cpu(vpa->dtl_idx))
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);
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);
228 dtl_consumer(dtl, i);
233 dtl = local_paca->dispatch_log;
235 local_paca->dtl_ridx = i;
236 local_paca->dtl_curr = dtl;
241 * Accumulate stolen time by scanning the dispatch trace log.
242 * Called on entry from user mode.
244 void accumulate_stolen_time(void)
247 unsigned long save_irq_soft_mask = irq_soft_mask_return();
248 struct cpu_accounting_data *acct = &local_paca->accounting;
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
256 irq_soft_mask_set(IRQS_DISABLED);
258 sst = scan_dispatch_log(acct->starttime_user);
259 ust = scan_dispatch_log(acct->starttime);
262 acct->steal_time += ust + sst;
264 irq_soft_mask_set(save_irq_soft_mask);
267 static inline u64 calculate_stolen_time(u64 stop_tb)
269 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
272 if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
273 return scan_dispatch_log(stop_tb);
278 #else /* CONFIG_PPC_SPLPAR */
279 static inline u64 calculate_stolen_time(u64 stop_tb)
284 #endif /* CONFIG_PPC_SPLPAR */
287 * Account time for a transition between system, hard irq
290 static unsigned long vtime_delta(struct task_struct *tsk,
291 unsigned long *stime_scaled,
292 unsigned long *steal_time)
294 unsigned long now, nowscaled, deltascaled;
296 unsigned long utime, utime_scaled;
297 struct cpu_accounting_data *acct = get_accounting(tsk);
299 WARN_ON_ONCE(!irqs_disabled());
302 nowscaled = read_spurr(now);
303 stime = now - acct->starttime;
304 acct->starttime = now;
305 deltascaled = nowscaled - acct->startspurr;
306 acct->startspurr = nowscaled;
308 *steal_time = calculate_stolen_time(now);
310 utime = acct->utime - acct->utime_sspurr;
311 acct->utime_sspurr = acct->utime;
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.
323 *stime_scaled = stime;
324 utime_scaled = utime;
325 if (deltascaled != stime + utime) {
327 *stime_scaled = deltascaled * stime / (stime + utime);
328 utime_scaled = deltascaled - *stime_scaled;
330 *stime_scaled = deltascaled;
333 acct->utime_scaled += utime_scaled;
338 void vtime_account_system(struct task_struct *tsk)
340 unsigned long stime, stime_scaled, steal_time;
341 struct cpu_accounting_data *acct = get_accounting(tsk);
343 stime = vtime_delta(tsk, &stime_scaled, &steal_time);
345 stime -= min(stime, steal_time);
346 acct->steal_time += steal_time;
348 if ((tsk->flags & PF_VCPU) && !irq_count()) {
349 acct->gtime += stime;
350 acct->utime_scaled += stime_scaled;
353 acct->hardirq_time += stime;
354 else if (in_serving_softirq())
355 acct->softirq_time += stime;
357 acct->stime += stime;
359 acct->stime_scaled += stime_scaled;
362 EXPORT_SYMBOL_GPL(vtime_account_system);
364 void vtime_account_idle(struct task_struct *tsk)
366 unsigned long stime, stime_scaled, steal_time;
367 struct cpu_accounting_data *acct = get_accounting(tsk);
369 stime = vtime_delta(tsk, &stime_scaled, &steal_time);
370 acct->idle_time += stime + steal_time;
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.
380 void vtime_flush(struct task_struct *tsk)
382 struct cpu_accounting_data *acct = get_accounting(tsk);
385 account_user_time(tsk, cputime_to_nsecs(acct->utime));
387 if (acct->utime_scaled)
388 tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
391 account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
393 if (acct->steal_time)
394 account_steal_time(cputime_to_nsecs(acct->steal_time));
397 account_idle_time(cputime_to_nsecs(acct->idle_time));
400 account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
402 if (acct->stime_scaled)
403 tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);
405 if (acct->hardirq_time)
406 account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
408 if (acct->softirq_time)
409 account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
413 acct->utime_scaled = 0;
414 acct->utime_sspurr = 0;
416 acct->steal_time = 0;
419 acct->stime_scaled = 0;
420 acct->hardirq_time = 0;
421 acct->softirq_time = 0;
426 * Called from the context switch with interrupts disabled, to charge all
427 * accumulated times to the current process, and to prepare accounting on
430 void arch_vtime_task_switch(struct task_struct *prev)
432 struct cpu_accounting_data *acct = get_accounting(current);
434 acct->starttime = get_accounting(prev)->starttime;
435 acct->startspurr = get_accounting(prev)->startspurr;
437 #endif /* CONFIG_PPC32 */
439 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
440 #define calc_cputime_factors()
443 void __delay(unsigned long loops)
452 /* the RTCL register wraps at 1000000000 */
453 diff = get_rtcl() - start;
457 } while (diff < loops);
460 while (get_tbl() - start < loops)
465 EXPORT_SYMBOL(__delay);
467 void udelay(unsigned long usecs)
469 __delay(tb_ticks_per_usec * usecs);
471 EXPORT_SYMBOL(udelay);
474 unsigned long profile_pc(struct pt_regs *regs)
476 unsigned long pc = instruction_pointer(regs);
478 if (in_lock_functions(pc))
483 EXPORT_SYMBOL(profile_pc);
486 #ifdef CONFIG_IRQ_WORK
489 * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
492 static inline unsigned long test_irq_work_pending(void)
496 asm volatile("lbz %0,%1(13)"
498 : "i" (offsetof(struct paca_struct, irq_work_pending)));
502 static inline void set_irq_work_pending_flag(void)
504 asm volatile("stb %0,%1(13)" : :
506 "i" (offsetof(struct paca_struct, irq_work_pending)));
509 static inline void clear_irq_work_pending(void)
511 asm volatile("stb %0,%1(13)" : :
513 "i" (offsetof(struct paca_struct, irq_work_pending)));
518 DEFINE_PER_CPU(u8, irq_work_pending);
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)
524 #endif /* 32 vs 64 bit */
526 void arch_irq_work_raise(void)
529 set_irq_work_pending_flag();
534 #else /* CONFIG_IRQ_WORK */
536 #define test_irq_work_pending() 0
537 #define clear_irq_work_pending()
539 #endif /* CONFIG_IRQ_WORK */
541 static void __timer_interrupt(void)
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);
548 trace_timer_interrupt_entry(regs);
550 if (test_irq_work_pending()) {
551 clear_irq_work_pending();
555 now = get_tb_or_rtc();
556 if (now >= *next_tb) {
558 if (evt->event_handler)
559 evt->event_handler(evt);
560 __this_cpu_inc(irq_stat.timer_irqs_event);
562 now = *next_tb - now;
563 if (now <= decrementer_max)
565 /* We may have raced with new irq work */
566 if (test_irq_work_pending())
568 __this_cpu_inc(irq_stat.timer_irqs_others);
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);
579 trace_timer_interrupt_exit(regs);
583 * timer_interrupt - gets called when the decrementer overflows,
584 * with interrupts disabled.
586 void timer_interrupt(struct pt_regs * regs)
588 struct pt_regs *old_regs;
589 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
591 /* Ensure a positive value is written to the decrementer, or else
592 * some CPUs will continue to take decrementer exceptions.
594 set_dec(decrementer_max);
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
602 if (!cpu_online(smp_processor_id())) {
607 /* Conditionally hard-enable interrupts now that the DEC has been
608 * bumped to its maximum value
610 may_hard_irq_enable();
613 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
614 if (atomic_read(&ppc_n_lost_interrupts) != 0)
618 old_regs = set_irq_regs(regs);
623 set_irq_regs(old_regs);
625 EXPORT_SYMBOL(timer_interrupt);
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.
632 void hdec_interrupt(struct pt_regs *regs)
636 #ifdef CONFIG_SUSPEND
637 static void generic_suspend_disable_irqs(void)
639 /* Disable the decrementer, so that it doesn't interfere
643 set_dec(decrementer_max);
645 set_dec(decrementer_max);
648 static void generic_suspend_enable_irqs(void)
653 /* Overrides the weak version in kernel/power/main.c */
654 void arch_suspend_disable_irqs(void)
656 if (ppc_md.suspend_disable_irqs)
657 ppc_md.suspend_disable_irqs();
658 generic_suspend_disable_irqs();
661 /* Overrides the weak version in kernel/power/main.c */
662 void arch_suspend_enable_irqs(void)
664 generic_suspend_enable_irqs();
665 if (ppc_md.suspend_enable_irqs)
666 ppc_md.suspend_enable_irqs();
670 unsigned long long tb_to_ns(unsigned long long ticks)
672 return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
674 EXPORT_SYMBOL_GPL(tb_to_ns);
677 * Scheduler clock - returns current time in nanosec units.
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.
683 notrace unsigned long long sched_clock(void)
687 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
691 #ifdef CONFIG_PPC_PSERIES
694 * Running clock - attempts to give a view of time passing for a virtualised
696 * Uses the VTB register if available otherwise a next best guess.
698 unsigned long long running_clock(void)
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.
705 * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
706 * would be unsafe to rely only on the #ifdef above.
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;
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.
718 return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
722 static int __init get_freq(char *name, int cells, unsigned long *val)
724 struct device_node *cpu;
728 /* The cpu node should have timebase and clock frequency properties */
729 cpu = of_find_node_by_type(NULL, "cpu");
732 fp = of_get_property(cpu, name, NULL);
735 *val = of_read_ulong(fp, cells);
744 static void start_cpu_decrementer(void)
746 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
749 /* Clear any pending timer interrupts */
750 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
752 tcr = mfspr(SPRN_TCR);
754 * The watchdog may have already been enabled by u-boot. So leave
755 * TRC[WP] (Watchdog Period) alone.
757 tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */
758 tcr |= TCR_DIE; /* Enable decrementer */
759 mtspr(SPRN_TCR, tcr);
763 void __init generic_calibrate_decr(void)
765 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
767 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
768 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
770 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
774 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
776 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
777 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
779 printk(KERN_ERR "WARNING: Estimating processor frequency "
784 int update_persistent_clock(struct timespec now)
788 if (!ppc_md.set_rtc_time)
791 to_tm(now.tv_sec + 1 + timezone_offset, &tm);
795 return ppc_md.set_rtc_time(&tm);
798 static void __read_persistent_clock(struct timespec *ts)
801 static int first = 1;
804 /* XXX this is a litle fragile but will work okay in the short term */
807 if (ppc_md.time_init)
808 timezone_offset = ppc_md.time_init();
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;
816 if (!ppc_md.get_rtc_time) {
820 ppc_md.get_rtc_time(&tm);
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);
826 void read_persistent_clock(struct timespec *ts)
828 __read_persistent_clock(ts);
830 /* Sanitize it in case real time clock is set below EPOCH */
831 if (ts->tv_sec < 0) {
838 /* clocksource code */
839 static notrace u64 rtc_read(struct clocksource *cs)
841 return (u64)get_rtc();
844 static notrace u64 timebase_read(struct clocksource *cs)
846 return (u64)get_tb();
850 void update_vsyscall(struct timekeeper *tk)
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;
860 if (clock != &clocksource_timebase)
863 xt.tv_sec = tk->xtime_sec;
864 xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
866 /* Make userspace gettimeofday spin until we're done. */
867 ++vdso_data->tb_update_count;
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).
887 if (mult <= 62500000 && clock->shift >= 16)
888 new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
890 new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
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.
900 frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
901 do_div(frac_sec, NSEC_PER_SEC);
904 * Work out new stamp_xsec value for any legacy users of systemcfg.
905 * stamp_xsec is in units of 2^-20 seconds.
907 new_stamp_xsec = frac_sec >> 12;
908 new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
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.
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;
927 ++(vdso_data->tb_update_count);
930 void update_vsyscall_tz(void)
932 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
933 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
936 static void __init clocksource_init(void)
938 struct clocksource *clock;
941 clock = &clocksource_rtc;
943 clock = &clocksource_timebase;
945 if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
946 printk(KERN_ERR "clocksource: %s is already registered\n",
951 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
952 clock->name, clock->mult, clock->shift);
955 static int decrementer_set_next_event(unsigned long evt,
956 struct clock_event_device *dev)
958 __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
961 /* We may have raced with new irq work */
962 if (test_irq_work_pending())
968 static int decrementer_shutdown(struct clock_event_device *dev)
970 decrementer_set_next_event(decrementer_max, dev);
974 /* Interrupt handler for the timer broadcast IPI */
975 void tick_broadcast_ipi_handler(void)
977 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
979 *next_tb = get_tb_or_rtc();
983 static void register_decrementer_clockevent(int cpu)
985 struct clock_event_device *dec = &per_cpu(decrementers, cpu);
987 *dec = decrementer_clockevent;
988 dec->cpumask = cpumask_of(cpu);
990 printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
991 dec->name, dec->mult, dec->shift, cpu);
993 clockevents_register_device(dec);
996 static void enable_large_decrementer(void)
998 if (!cpu_has_feature(CPU_FTR_ARCH_300))
1001 if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
1005 * If we're running as the hypervisor we need to enable the LD manually
1006 * otherwise firmware should have done it for us.
1008 if (cpu_has_feature(CPU_FTR_HVMODE))
1009 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
1012 static void __init set_decrementer_max(void)
1014 struct device_node *cpu;
1017 /* Prior to ISAv3 the decrementer is always 32 bit */
1018 if (!cpu_has_feature(CPU_FTR_ARCH_300))
1021 cpu = of_find_node_by_type(NULL, "cpu");
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");
1029 /* calculate the signed maximum given this many bits */
1030 decrementer_max = (1ul << (bits - 1)) - 1;
1035 pr_info("time_init: %u bit decrementer (max: %llx)\n",
1036 bits, decrementer_max);
1039 static void __init init_decrementer_clockevent(void)
1041 int cpu = smp_processor_id();
1043 clockevents_calc_mult_shift(&decrementer_clockevent, ppc_tb_freq, 4);
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;
1052 register_decrementer_clockevent(cpu);
1055 void secondary_cpu_time_init(void)
1057 /* Enable and test the large decrementer for this cpu */
1058 enable_large_decrementer();
1060 /* Start the decrementer on CPUs that have manual control
1063 start_cpu_decrementer();
1065 /* FIME: Should make unrelatred change to move snapshot_timebase
1067 register_decrementer_clockevent(smp_processor_id());
1070 /* This function is only called on the boot processor */
1071 void __init time_init(void)
1073 struct div_result res;
1078 /* 601 processor: dec counts down by 128 every 128ns */
1079 ppc_tb_freq = 1000000000;
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);
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();
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
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;
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();
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;
1121 vdso_data->tb_update_count = 0;
1122 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1124 /* initialise and enable the large decrementer (if we have one) */
1125 set_decrementer_max();
1126 enable_large_decrementer();
1128 /* Start the decrementer on CPUs that have manual control
1131 start_cpu_decrementer();
1133 /* Register the clocksource */
1136 init_decrementer_clockevent();
1137 tick_setup_hrtimer_broadcast();
1139 #ifdef CONFIG_COMMON_CLK
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])
1154 static int month_days[12] = {
1155 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
1158 void to_tm(int tim, struct rtc_time * tm)
1161 register long hms, day;
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;
1171 /* Number of years in days */
1172 for (i = STARTOFTIME; day >= days_in_year(i); i++)
1173 day -= days_in_year(i);
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;
1184 /* Days are what is left over (+1) from all that. */
1185 tm->tm_mday = day + 1;
1188 * No-one uses the day of the week.
1192 EXPORT_SYMBOL(to_tm);
1195 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1198 void div128_by_32(u64 dividend_high, u64 dividend_low,
1199 unsigned divisor, struct div_result *dr)
1201 unsigned long a, b, c, d;
1202 unsigned long w, x, y, z;
1205 a = dividend_high >> 32;
1206 b = dividend_high & 0xffffffff;
1207 c = dividend_low >> 32;
1208 d = dividend_low & 0xffffffff;
1211 ra = ((u64)(a - (w * divisor)) << 32) + b;
1213 rb = ((u64) do_div(ra, divisor) << 32) + c;
1216 rc = ((u64) do_div(rb, divisor) << 32) + d;
1219 do_div(rc, divisor);
1222 dr->result_high = ((u64)w << 32) + x;
1223 dr->result_low = ((u64)y << 32) + z;
1227 /* We don't need to calibrate delay, we use the CPU timebase for that */
1228 void calibrate_delay(void)
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
1233 loops_per_jiffy = tb_ticks_per_jiffy;
1236 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
1237 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
1239 ppc_md.get_rtc_time(tm);
1243 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1245 if (!ppc_md.set_rtc_time)
1248 if (ppc_md.set_rtc_time(tm) < 0)
1254 static const struct rtc_class_ops rtc_generic_ops = {
1255 .read_time = rtc_generic_get_time,
1256 .set_time = rtc_generic_set_time,
1259 static int __init rtc_init(void)
1261 struct platform_device *pdev;
1263 if (!ppc_md.get_rtc_time)
1266 pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1268 sizeof(rtc_generic_ops));
1270 return PTR_ERR_OR_ZERO(pdev);
1273 device_initcall(rtc_init);