1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Common time routines among all ppc machines.
5 * Written by Cort Dougan (cort@cs.nmt.edu) to merge
6 * Paul Mackerras' version and mine for PReP and Pmac.
7 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
8 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
10 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
11 * to make clock more stable (2.4.0-test5). The only thing
12 * that this code assumes is that the timebases have been synchronized
13 * by firmware on SMP and are never stopped (never do sleep
14 * on SMP then, nap and doze are OK).
16 * Speeded up do_gettimeofday by getting rid of references to
17 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
19 * TODO (not necessarily in this file):
20 * - improve precision and reproducibility of timebase frequency
21 * measurement at boot time.
22 * - for astronomical applications: add a new function to get
23 * non ambiguous timestamps even around leap seconds. This needs
24 * a new timestamp format and a good name.
26 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
27 * "A Kernel Model for Precision Timekeeping" by Dave Mills
30 #include <linux/errno.h>
31 #include <linux/export.h>
32 #include <linux/sched.h>
33 #include <linux/sched/clock.h>
34 #include <linux/kernel.h>
35 #include <linux/param.h>
36 #include <linux/string.h>
38 #include <linux/interrupt.h>
39 #include <linux/timex.h>
40 #include <linux/kernel_stat.h>
41 #include <linux/time.h>
42 #include <linux/init.h>
43 #include <linux/profile.h>
44 #include <linux/cpu.h>
45 #include <linux/security.h>
46 #include <linux/percpu.h>
47 #include <linux/rtc.h>
48 #include <linux/jiffies.h>
49 #include <linux/posix-timers.h>
50 #include <linux/irq.h>
51 #include <linux/delay.h>
52 #include <linux/irq_work.h>
53 #include <linux/clk-provider.h>
54 #include <linux/suspend.h>
55 #include <linux/sched/cputime.h>
56 #include <linux/processor.h>
57 #include <asm/trace.h>
60 #include <asm/nvram.h>
61 #include <asm/cache.h>
62 #include <asm/machdep.h>
63 #include <linux/uaccess.h>
67 #include <asm/div64.h>
69 #include <asm/vdso_datapage.h>
70 #include <asm/firmware.h>
71 #include <asm/asm-prototypes.h>
73 /* powerpc clocksource/clockevent code */
75 #include <linux/clockchips.h>
76 #include <linux/timekeeper_internal.h>
78 static u64 rtc_read(struct clocksource *);
79 static struct clocksource clocksource_rtc = {
82 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
83 .mask = CLOCKSOURCE_MASK(64),
87 static u64 timebase_read(struct clocksource *);
88 static struct clocksource clocksource_timebase = {
91 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
92 .mask = CLOCKSOURCE_MASK(64),
93 .read = timebase_read,
96 #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
97 u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
99 static int decrementer_set_next_event(unsigned long evt,
100 struct clock_event_device *dev);
101 static int decrementer_shutdown(struct clock_event_device *evt);
103 struct clock_event_device decrementer_clockevent = {
104 .name = "decrementer",
107 .set_next_event = decrementer_set_next_event,
108 .set_state_oneshot_stopped = decrementer_shutdown,
109 .set_state_shutdown = decrementer_shutdown,
110 .tick_resume = decrementer_shutdown,
111 .features = CLOCK_EVT_FEAT_ONESHOT |
112 CLOCK_EVT_FEAT_C3STOP,
114 EXPORT_SYMBOL(decrementer_clockevent);
116 DEFINE_PER_CPU(u64, decrementers_next_tb);
117 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
119 #define XSEC_PER_SEC (1024*1024)
122 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
124 /* compute ((xsec << 12) * max) >> 32 */
125 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
128 unsigned long tb_ticks_per_jiffy;
129 unsigned long tb_ticks_per_usec = 100; /* sane default */
130 EXPORT_SYMBOL(tb_ticks_per_usec);
131 unsigned long tb_ticks_per_sec;
132 EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
134 DEFINE_SPINLOCK(rtc_lock);
135 EXPORT_SYMBOL_GPL(rtc_lock);
137 static u64 tb_to_ns_scale __read_mostly;
138 static unsigned tb_to_ns_shift __read_mostly;
139 static u64 boot_tb __read_mostly;
141 extern struct timezone sys_tz;
142 static long timezone_offset;
144 unsigned long ppc_proc_freq;
145 EXPORT_SYMBOL_GPL(ppc_proc_freq);
146 unsigned long ppc_tb_freq;
147 EXPORT_SYMBOL_GPL(ppc_tb_freq);
151 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
153 * Factor for converting from cputime_t (timebase ticks) to
154 * microseconds. This is stored as 0.64 fixed-point binary fraction.
156 u64 __cputime_usec_factor;
157 EXPORT_SYMBOL(__cputime_usec_factor);
159 #ifdef CONFIG_PPC_SPLPAR
160 void (*dtl_consumer)(struct dtl_entry *, u64);
163 static void calc_cputime_factors(void)
165 struct div_result res;
167 div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
168 __cputime_usec_factor = res.result_low;
172 * Read the SPURR on systems that have it, otherwise the PURR,
173 * or if that doesn't exist return the timebase value passed in.
175 static inline unsigned long read_spurr(unsigned long tb)
177 if (cpu_has_feature(CPU_FTR_SPURR))
178 return mfspr(SPRN_SPURR);
179 if (cpu_has_feature(CPU_FTR_PURR))
180 return mfspr(SPRN_PURR);
184 #ifdef CONFIG_PPC_SPLPAR
187 * Scan the dispatch trace log and count up the stolen time.
188 * Should be called with interrupts disabled.
190 static u64 scan_dispatch_log(u64 stop_tb)
192 u64 i = local_paca->dtl_ridx;
193 struct dtl_entry *dtl = local_paca->dtl_curr;
194 struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
195 struct lppaca *vpa = local_paca->lppaca_ptr;
203 if (i == be64_to_cpu(vpa->dtl_idx))
205 while (i < be64_to_cpu(vpa->dtl_idx)) {
206 dtb = be64_to_cpu(dtl->timebase);
207 tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
208 be32_to_cpu(dtl->ready_to_enqueue_time);
210 if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
211 /* buffer has overflowed */
212 i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
213 dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
219 dtl_consumer(dtl, i);
224 dtl = local_paca->dispatch_log;
226 local_paca->dtl_ridx = i;
227 local_paca->dtl_curr = dtl;
232 * Accumulate stolen time by scanning the dispatch trace log.
233 * Called on entry from user mode.
235 void notrace accumulate_stolen_time(void)
238 unsigned long save_irq_soft_mask = irq_soft_mask_return();
239 struct cpu_accounting_data *acct = &local_paca->accounting;
241 /* We are called early in the exception entry, before
242 * soft/hard_enabled are sync'ed to the expected state
243 * for the exception. We are hard disabled but the PACA
244 * needs to reflect that so various debug stuff doesn't
247 irq_soft_mask_set(IRQS_DISABLED);
249 sst = scan_dispatch_log(acct->starttime_user);
250 ust = scan_dispatch_log(acct->starttime);
253 acct->steal_time += ust + sst;
255 irq_soft_mask_set(save_irq_soft_mask);
258 static inline u64 calculate_stolen_time(u64 stop_tb)
260 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
263 if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
264 return scan_dispatch_log(stop_tb);
269 #else /* CONFIG_PPC_SPLPAR */
270 static inline u64 calculate_stolen_time(u64 stop_tb)
275 #endif /* CONFIG_PPC_SPLPAR */
278 * Account time for a transition between system, hard irq
281 static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct,
282 unsigned long now, unsigned long stime)
284 unsigned long stime_scaled = 0;
285 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
286 unsigned long nowscaled, deltascaled;
287 unsigned long utime, utime_scaled;
289 nowscaled = read_spurr(now);
290 deltascaled = nowscaled - acct->startspurr;
291 acct->startspurr = nowscaled;
292 utime = acct->utime - acct->utime_sspurr;
293 acct->utime_sspurr = acct->utime;
296 * Because we don't read the SPURR on every kernel entry/exit,
297 * deltascaled includes both user and system SPURR ticks.
298 * Apportion these ticks to system SPURR ticks and user
299 * SPURR ticks in the same ratio as the system time (delta)
300 * and user time (udelta) values obtained from the timebase
301 * over the same interval. The system ticks get accounted here;
302 * the user ticks get saved up in paca->user_time_scaled to be
303 * used by account_process_tick.
305 stime_scaled = stime;
306 utime_scaled = utime;
307 if (deltascaled != stime + utime) {
309 stime_scaled = deltascaled * stime / (stime + utime);
310 utime_scaled = deltascaled - stime_scaled;
312 stime_scaled = deltascaled;
315 acct->utime_scaled += utime_scaled;
321 static unsigned long vtime_delta(struct task_struct *tsk,
322 unsigned long *stime_scaled,
323 unsigned long *steal_time)
325 unsigned long now, stime;
326 struct cpu_accounting_data *acct = get_accounting(tsk);
328 WARN_ON_ONCE(!irqs_disabled());
331 stime = now - acct->starttime;
332 acct->starttime = now;
334 *stime_scaled = vtime_delta_scaled(acct, now, stime);
336 *steal_time = calculate_stolen_time(now);
341 void vtime_account_system(struct task_struct *tsk)
343 unsigned long stime, stime_scaled, steal_time;
344 struct cpu_accounting_data *acct = get_accounting(tsk);
346 stime = vtime_delta(tsk, &stime_scaled, &steal_time);
348 stime -= min(stime, steal_time);
349 acct->steal_time += steal_time;
351 if ((tsk->flags & PF_VCPU) && !irq_count()) {
352 acct->gtime += stime;
353 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
354 acct->utime_scaled += stime_scaled;
358 acct->hardirq_time += stime;
359 else if (in_serving_softirq())
360 acct->softirq_time += stime;
362 acct->stime += stime;
364 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
365 acct->stime_scaled += stime_scaled;
369 EXPORT_SYMBOL_GPL(vtime_account_system);
371 void vtime_account_idle(struct task_struct *tsk)
373 unsigned long stime, stime_scaled, steal_time;
374 struct cpu_accounting_data *acct = get_accounting(tsk);
376 stime = vtime_delta(tsk, &stime_scaled, &steal_time);
377 acct->idle_time += stime + steal_time;
380 static void vtime_flush_scaled(struct task_struct *tsk,
381 struct cpu_accounting_data *acct)
383 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
384 if (acct->utime_scaled)
385 tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
386 if (acct->stime_scaled)
387 tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);
389 acct->utime_scaled = 0;
390 acct->utime_sspurr = 0;
391 acct->stime_scaled = 0;
396 * Account the whole cputime accumulated in the paca
397 * Must be called with interrupts disabled.
398 * Assumes that vtime_account_system/idle() has been called
399 * recently (i.e. since the last entry from usermode) so that
400 * get_paca()->user_time_scaled is up to date.
402 void vtime_flush(struct task_struct *tsk)
404 struct cpu_accounting_data *acct = get_accounting(tsk);
407 account_user_time(tsk, cputime_to_nsecs(acct->utime));
410 account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
412 if (IS_ENABLED(CONFIG_PPC_SPLPAR) && acct->steal_time) {
413 account_steal_time(cputime_to_nsecs(acct->steal_time));
414 acct->steal_time = 0;
418 account_idle_time(cputime_to_nsecs(acct->idle_time));
421 account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
424 if (acct->hardirq_time)
425 account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
427 if (acct->softirq_time)
428 account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
431 vtime_flush_scaled(tsk, acct);
437 acct->hardirq_time = 0;
438 acct->softirq_time = 0;
441 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
442 #define calc_cputime_factors()
445 void __delay(unsigned long loops)
454 /* the RTCL register wraps at 1000000000 */
455 diff = get_rtcl() - start;
459 } while (diff < loops);
460 } else if (tb_invalid) {
462 * TB is in error state and isn't ticking anymore.
463 * HMI handler was unable to recover from TB error.
464 * Return immediately, so that kernel won't get stuck here.
469 while (get_tbl() - start < loops)
474 EXPORT_SYMBOL(__delay);
476 void udelay(unsigned long usecs)
478 __delay(tb_ticks_per_usec * usecs);
480 EXPORT_SYMBOL(udelay);
483 unsigned long profile_pc(struct pt_regs *regs)
485 unsigned long pc = instruction_pointer(regs);
487 if (in_lock_functions(pc))
492 EXPORT_SYMBOL(profile_pc);
495 #ifdef CONFIG_IRQ_WORK
498 * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
501 static inline unsigned long test_irq_work_pending(void)
505 asm volatile("lbz %0,%1(13)"
507 : "i" (offsetof(struct paca_struct, irq_work_pending)));
511 static inline void set_irq_work_pending_flag(void)
513 asm volatile("stb %0,%1(13)" : :
515 "i" (offsetof(struct paca_struct, irq_work_pending)));
518 static inline void clear_irq_work_pending(void)
520 asm volatile("stb %0,%1(13)" : :
522 "i" (offsetof(struct paca_struct, irq_work_pending)));
527 DEFINE_PER_CPU(u8, irq_work_pending);
529 #define set_irq_work_pending_flag() __this_cpu_write(irq_work_pending, 1)
530 #define test_irq_work_pending() __this_cpu_read(irq_work_pending)
531 #define clear_irq_work_pending() __this_cpu_write(irq_work_pending, 0)
533 #endif /* 32 vs 64 bit */
535 void arch_irq_work_raise(void)
538 * 64-bit code that uses irq soft-mask can just cause an immediate
539 * interrupt here that gets soft masked, if this is called under
540 * local_irq_disable(). It might be possible to prevent that happening
541 * by noticing interrupts are disabled and setting decrementer pending
542 * to be replayed when irqs are enabled. The problem there is that
543 * tracing can call irq_work_raise, including in code that does low
544 * level manipulations of irq soft-mask state (e.g., trace_hardirqs_on)
545 * which could get tangled up if we're messing with the same state
549 set_irq_work_pending_flag();
554 #else /* CONFIG_IRQ_WORK */
556 #define test_irq_work_pending() 0
557 #define clear_irq_work_pending()
559 #endif /* CONFIG_IRQ_WORK */
562 * timer_interrupt - gets called when the decrementer overflows,
563 * with interrupts disabled.
565 void timer_interrupt(struct pt_regs *regs)
567 struct clock_event_device *evt = this_cpu_ptr(&decrementers);
568 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
569 struct pt_regs *old_regs;
572 /* Some implementations of hotplug will get timer interrupts while
573 * offline, just ignore these and we also need to set
574 * decrementers_next_tb as MAX to make sure __check_irq_replay
575 * don't replay timer interrupt when return, otherwise we'll trap
578 if (unlikely(!cpu_online(smp_processor_id()))) {
580 set_dec(decrementer_max);
584 /* Ensure a positive value is written to the decrementer, or else
585 * some CPUs will continue to take decrementer exceptions. When the
586 * PPC_WATCHDOG (decrementer based) is configured, keep this at most
587 * 31 bits, which is about 4 seconds on most systems, which gives
588 * the watchdog a chance of catching timer interrupt hard lockups.
590 if (IS_ENABLED(CONFIG_PPC_WATCHDOG))
593 set_dec(decrementer_max);
595 /* Conditionally hard-enable interrupts now that the DEC has been
596 * bumped to its maximum value
598 may_hard_irq_enable();
601 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
602 if (atomic_read(&ppc_n_lost_interrupts) != 0)
606 old_regs = set_irq_regs(regs);
608 trace_timer_interrupt_entry(regs);
610 if (test_irq_work_pending()) {
611 clear_irq_work_pending();
615 now = get_tb_or_rtc();
616 if (now >= *next_tb) {
618 if (evt->event_handler)
619 evt->event_handler(evt);
620 __this_cpu_inc(irq_stat.timer_irqs_event);
622 now = *next_tb - now;
623 if (now <= decrementer_max)
625 /* We may have raced with new irq work */
626 if (test_irq_work_pending())
628 __this_cpu_inc(irq_stat.timer_irqs_others);
631 trace_timer_interrupt_exit(regs);
633 set_irq_regs(old_regs);
635 EXPORT_SYMBOL(timer_interrupt);
637 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
638 void timer_broadcast_interrupt(void)
640 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
643 tick_receive_broadcast();
644 __this_cpu_inc(irq_stat.broadcast_irqs_event);
649 * Hypervisor decrementer interrupts shouldn't occur but are sometimes
650 * left pending on exit from a KVM guest. We don't need to do anything
651 * to clear them, as they are edge-triggered.
653 void hdec_interrupt(struct pt_regs *regs)
657 #ifdef CONFIG_SUSPEND
658 static void generic_suspend_disable_irqs(void)
660 /* Disable the decrementer, so that it doesn't interfere
664 set_dec(decrementer_max);
666 set_dec(decrementer_max);
669 static void generic_suspend_enable_irqs(void)
674 /* Overrides the weak version in kernel/power/main.c */
675 void arch_suspend_disable_irqs(void)
677 if (ppc_md.suspend_disable_irqs)
678 ppc_md.suspend_disable_irqs();
679 generic_suspend_disable_irqs();
682 /* Overrides the weak version in kernel/power/main.c */
683 void arch_suspend_enable_irqs(void)
685 generic_suspend_enable_irqs();
686 if (ppc_md.suspend_enable_irqs)
687 ppc_md.suspend_enable_irqs();
691 unsigned long long tb_to_ns(unsigned long long ticks)
693 return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
695 EXPORT_SYMBOL_GPL(tb_to_ns);
698 * Scheduler clock - returns current time in nanosec units.
700 * Note: mulhdu(a, b) (multiply high double unsigned) returns
701 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
702 * are 64-bit unsigned numbers.
704 notrace unsigned long long sched_clock(void)
708 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
712 #ifdef CONFIG_PPC_PSERIES
715 * Running clock - attempts to give a view of time passing for a virtualised
717 * Uses the VTB register if available otherwise a next best guess.
719 unsigned long long running_clock(void)
722 * Don't read the VTB as a host since KVM does not switch in host
723 * timebase into the VTB when it takes a guest off the CPU, reading the
724 * VTB would result in reading 'last switched out' guest VTB.
726 * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
727 * would be unsafe to rely only on the #ifdef above.
729 if (firmware_has_feature(FW_FEATURE_LPAR) &&
730 cpu_has_feature(CPU_FTR_ARCH_207S))
731 return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
734 * This is a next best approximation without a VTB.
735 * On a host which is running bare metal there should never be any stolen
736 * time and on a host which doesn't do any virtualisation TB *should* equal
737 * VTB so it makes no difference anyway.
739 return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
743 static int __init get_freq(char *name, int cells, unsigned long *val)
745 struct device_node *cpu;
749 /* The cpu node should have timebase and clock frequency properties */
750 cpu = of_find_node_by_type(NULL, "cpu");
753 fp = of_get_property(cpu, name, NULL);
756 *val = of_read_ulong(fp, cells);
765 static void start_cpu_decrementer(void)
767 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
770 /* Clear any pending timer interrupts */
771 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
773 tcr = mfspr(SPRN_TCR);
775 * The watchdog may have already been enabled by u-boot. So leave
776 * TRC[WP] (Watchdog Period) alone.
778 tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */
779 tcr |= TCR_DIE; /* Enable decrementer */
780 mtspr(SPRN_TCR, tcr);
784 void __init generic_calibrate_decr(void)
786 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
788 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
789 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
791 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
795 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
797 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
798 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
800 printk(KERN_ERR "WARNING: Estimating processor frequency "
805 int update_persistent_clock64(struct timespec64 now)
809 if (!ppc_md.set_rtc_time)
812 rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);
814 return ppc_md.set_rtc_time(&tm);
817 static void __read_persistent_clock(struct timespec64 *ts)
820 static int first = 1;
823 /* XXX this is a litle fragile but will work okay in the short term */
826 if (ppc_md.time_init)
827 timezone_offset = ppc_md.time_init();
829 /* get_boot_time() isn't guaranteed to be safe to call late */
830 if (ppc_md.get_boot_time) {
831 ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
835 if (!ppc_md.get_rtc_time) {
839 ppc_md.get_rtc_time(&tm);
841 ts->tv_sec = rtc_tm_to_time64(&tm);
844 void read_persistent_clock64(struct timespec64 *ts)
846 __read_persistent_clock(ts);
848 /* Sanitize it in case real time clock is set below EPOCH */
849 if (ts->tv_sec < 0) {
856 /* clocksource code */
857 static notrace u64 rtc_read(struct clocksource *cs)
859 return (u64)get_rtc();
862 static notrace u64 timebase_read(struct clocksource *cs)
864 return (u64)get_tb();
868 void update_vsyscall(struct timekeeper *tk)
871 struct clocksource *clock = tk->tkr_mono.clock;
872 u32 mult = tk->tkr_mono.mult;
873 u32 shift = tk->tkr_mono.shift;
874 u64 cycle_last = tk->tkr_mono.cycle_last;
875 u64 new_tb_to_xs, new_stamp_xsec;
878 if (clock != &clocksource_timebase)
881 xt.tv_sec = tk->xtime_sec;
882 xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
884 /* Make userspace gettimeofday spin until we're done. */
885 ++vdso_data->tb_update_count;
889 * This computes ((2^20 / 1e9) * mult) >> shift as a
890 * 0.64 fixed-point fraction.
891 * The computation in the else clause below won't overflow
892 * (as long as the timebase frequency is >= 1.049 MHz)
893 * but loses precision because we lose the low bits of the constant
894 * in the shift. Note that 19342813113834067 ~= 2^(20+64) / 1e9.
895 * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
896 * over a second. (Shift values are usually 22, 23 or 24.)
897 * For high frequency clocks such as the 512MHz timebase clock
898 * on POWER[6789], the mult value is small (e.g. 32768000)
899 * and so we can shift the constant by 16 initially
900 * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
901 * remaining shifts after the multiplication, which gives a
902 * more accurate result (e.g. with mult = 32768000, shift = 24,
903 * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
905 if (mult <= 62500000 && clock->shift >= 16)
906 new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
908 new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
911 * Compute the fractional second in units of 2^-32 seconds.
912 * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
913 * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
914 * it in units of 2^-32 seconds.
915 * We assume shift <= 32 because clocks_calc_mult_shift()
916 * generates shift values in the range 0 - 32.
918 frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
919 do_div(frac_sec, NSEC_PER_SEC);
922 * Work out new stamp_xsec value for any legacy users of systemcfg.
923 * stamp_xsec is in units of 2^-20 seconds.
925 new_stamp_xsec = frac_sec >> 12;
926 new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
929 * tb_update_count is used to allow the userspace gettimeofday code
930 * to assure itself that it sees a consistent view of the tb_to_xs and
931 * stamp_xsec variables. It reads the tb_update_count, then reads
932 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
933 * the two values of tb_update_count match and are even then the
934 * tb_to_xs and stamp_xsec values are consistent. If not, then it
935 * loops back and reads them again until this criteria is met.
937 vdso_data->tb_orig_stamp = cycle_last;
938 vdso_data->stamp_xsec = new_stamp_xsec;
939 vdso_data->tb_to_xs = new_tb_to_xs;
940 vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
941 vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
942 vdso_data->stamp_xtime = xt;
943 vdso_data->stamp_sec_fraction = frac_sec;
944 vdso_data->hrtimer_res = hrtimer_resolution;
946 ++(vdso_data->tb_update_count);
949 void update_vsyscall_tz(void)
951 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
952 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
955 static void __init clocksource_init(void)
957 struct clocksource *clock;
960 clock = &clocksource_rtc;
962 clock = &clocksource_timebase;
964 if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
965 printk(KERN_ERR "clocksource: %s is already registered\n",
970 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
971 clock->name, clock->mult, clock->shift);
974 static int decrementer_set_next_event(unsigned long evt,
975 struct clock_event_device *dev)
977 __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
980 /* We may have raced with new irq work */
981 if (test_irq_work_pending())
987 static int decrementer_shutdown(struct clock_event_device *dev)
989 decrementer_set_next_event(decrementer_max, dev);
993 static void register_decrementer_clockevent(int cpu)
995 struct clock_event_device *dec = &per_cpu(decrementers, cpu);
997 *dec = decrementer_clockevent;
998 dec->cpumask = cpumask_of(cpu);
1000 clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
1002 printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
1003 dec->name, dec->mult, dec->shift, cpu);
1005 /* Set values for KVM, see kvm_emulate_dec() */
1006 decrementer_clockevent.mult = dec->mult;
1007 decrementer_clockevent.shift = dec->shift;
1010 static void enable_large_decrementer(void)
1012 if (!cpu_has_feature(CPU_FTR_ARCH_300))
1015 if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
1019 * If we're running as the hypervisor we need to enable the LD manually
1020 * otherwise firmware should have done it for us.
1022 if (cpu_has_feature(CPU_FTR_HVMODE))
1023 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
1026 static void __init set_decrementer_max(void)
1028 struct device_node *cpu;
1031 /* Prior to ISAv3 the decrementer is always 32 bit */
1032 if (!cpu_has_feature(CPU_FTR_ARCH_300))
1035 cpu = of_find_node_by_type(NULL, "cpu");
1037 if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
1038 if (bits > 64 || bits < 32) {
1039 pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
1043 /* calculate the signed maximum given this many bits */
1044 decrementer_max = (1ul << (bits - 1)) - 1;
1049 pr_info("time_init: %u bit decrementer (max: %llx)\n",
1050 bits, decrementer_max);
1053 static void __init init_decrementer_clockevent(void)
1055 register_decrementer_clockevent(smp_processor_id());
1058 void secondary_cpu_time_init(void)
1060 /* Enable and test the large decrementer for this cpu */
1061 enable_large_decrementer();
1063 /* Start the decrementer on CPUs that have manual control
1066 start_cpu_decrementer();
1068 /* FIME: Should make unrelatred change to move snapshot_timebase
1070 register_decrementer_clockevent(smp_processor_id());
1073 /* This function is only called on the boot processor */
1074 void __init time_init(void)
1076 struct div_result res;
1081 /* 601 processor: dec counts down by 128 every 128ns */
1082 ppc_tb_freq = 1000000000;
1084 /* Normal PowerPC with timebase register */
1085 ppc_md.calibrate_decr();
1086 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
1087 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
1088 printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
1089 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
1092 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
1093 tb_ticks_per_sec = ppc_tb_freq;
1094 tb_ticks_per_usec = ppc_tb_freq / 1000000;
1095 calc_cputime_factors();
1098 * Compute scale factor for sched_clock.
1099 * The calibrate_decr() function has set tb_ticks_per_sec,
1100 * which is the timebase frequency.
1101 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
1102 * the 128-bit result as a 64.64 fixed-point number.
1103 * We then shift that number right until it is less than 1.0,
1104 * giving us the scale factor and shift count to use in
1107 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
1108 scale = res.result_low;
1109 for (shift = 0; res.result_high != 0; ++shift) {
1110 scale = (scale >> 1) | (res.result_high << 63);
1111 res.result_high >>= 1;
1113 tb_to_ns_scale = scale;
1114 tb_to_ns_shift = shift;
1115 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
1116 boot_tb = get_tb_or_rtc();
1118 /* If platform provided a timezone (pmac), we correct the time */
1119 if (timezone_offset) {
1120 sys_tz.tz_minuteswest = -timezone_offset / 60;
1121 sys_tz.tz_dsttime = 0;
1124 vdso_data->tb_update_count = 0;
1125 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1127 /* initialise and enable the large decrementer (if we have one) */
1128 set_decrementer_max();
1129 enable_large_decrementer();
1131 /* Start the decrementer on CPUs that have manual control
1134 start_cpu_decrementer();
1136 /* Register the clocksource */
1139 init_decrementer_clockevent();
1140 tick_setup_hrtimer_broadcast();
1142 #ifdef CONFIG_COMMON_CLK
1148 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1151 void div128_by_32(u64 dividend_high, u64 dividend_low,
1152 unsigned divisor, struct div_result *dr)
1154 unsigned long a, b, c, d;
1155 unsigned long w, x, y, z;
1158 a = dividend_high >> 32;
1159 b = dividend_high & 0xffffffff;
1160 c = dividend_low >> 32;
1161 d = dividend_low & 0xffffffff;
1164 ra = ((u64)(a - (w * divisor)) << 32) + b;
1166 rb = ((u64) do_div(ra, divisor) << 32) + c;
1169 rc = ((u64) do_div(rb, divisor) << 32) + d;
1172 do_div(rc, divisor);
1175 dr->result_high = ((u64)w << 32) + x;
1176 dr->result_low = ((u64)y << 32) + z;
1180 /* We don't need to calibrate delay, we use the CPU timebase for that */
1181 void calibrate_delay(void)
1183 /* Some generic code (such as spinlock debug) use loops_per_jiffy
1184 * as the number of __delay(1) in a jiffy, so make it so
1186 loops_per_jiffy = tb_ticks_per_jiffy;
1189 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
1190 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
1192 ppc_md.get_rtc_time(tm);
1196 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1198 if (!ppc_md.set_rtc_time)
1201 if (ppc_md.set_rtc_time(tm) < 0)
1207 static const struct rtc_class_ops rtc_generic_ops = {
1208 .read_time = rtc_generic_get_time,
1209 .set_time = rtc_generic_set_time,
1212 static int __init rtc_init(void)
1214 struct platform_device *pdev;
1216 if (!ppc_md.get_rtc_time)
1219 pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1221 sizeof(rtc_generic_ops));
1223 return PTR_ERR_OR_ZERO(pdev);
1226 device_initcall(rtc_init);