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/sched/cputime.h>
35 #include <linux/kernel.h>
36 #include <linux/param.h>
37 #include <linux/string.h>
39 #include <linux/interrupt.h>
40 #include <linux/timex.h>
41 #include <linux/kernel_stat.h>
42 #include <linux/time.h>
43 #include <linux/init.h>
44 #include <linux/profile.h>
45 #include <linux/cpu.h>
46 #include <linux/security.h>
47 #include <linux/percpu.h>
48 #include <linux/rtc.h>
49 #include <linux/jiffies.h>
50 #include <linux/posix-timers.h>
51 #include <linux/irq.h>
52 #include <linux/delay.h>
53 #include <linux/irq_work.h>
54 #include <linux/of_clk.h>
55 #include <linux/suspend.h>
56 #include <linux/processor.h>
57 #include <linux/mc146818rtc.h>
58 #include <linux/platform_device.h>
60 #include <asm/trace.h>
61 #include <asm/interrupt.h>
63 #include <asm/nvram.h>
64 #include <asm/cache.h>
65 #include <asm/machdep.h>
66 #include <linux/uaccess.h>
69 #include <asm/div64.h>
71 #include <asm/vdso_datapage.h>
72 #include <asm/firmware.h>
75 /* powerpc clocksource/clockevent code */
77 #include <linux/clockchips.h>
78 #include <linux/timekeeper_internal.h>
80 static u64 timebase_read(struct clocksource *);
81 static struct clocksource clocksource_timebase = {
84 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
85 .mask = CLOCKSOURCE_MASK(64),
86 .read = timebase_read,
87 .vdso_clock_mode = VDSO_CLOCKMODE_ARCHTIMER,
90 #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
91 u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
92 EXPORT_SYMBOL_GPL(decrementer_max); /* for KVM HDEC */
94 static int decrementer_set_next_event(unsigned long evt,
95 struct clock_event_device *dev);
96 static int decrementer_shutdown(struct clock_event_device *evt);
98 struct clock_event_device decrementer_clockevent = {
99 .name = "decrementer",
102 .set_next_event = decrementer_set_next_event,
103 .set_state_oneshot_stopped = decrementer_shutdown,
104 .set_state_shutdown = decrementer_shutdown,
105 .tick_resume = decrementer_shutdown,
106 .features = CLOCK_EVT_FEAT_ONESHOT |
107 CLOCK_EVT_FEAT_C3STOP,
109 EXPORT_SYMBOL(decrementer_clockevent);
112 * This always puts next_tb beyond now, so the clock event will never fire
113 * with the usual comparison, no need for a separate test for stopped.
115 #define DEC_CLOCKEVENT_STOPPED ~0ULL
116 DEFINE_PER_CPU(u64, decrementers_next_tb) = DEC_CLOCKEVENT_STOPPED;
117 EXPORT_SYMBOL_GPL(decrementers_next_tb);
118 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
120 #define XSEC_PER_SEC (1024*1024)
123 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
125 /* compute ((xsec << 12) * max) >> 32 */
126 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
129 unsigned long tb_ticks_per_jiffy;
130 unsigned long tb_ticks_per_usec = 100; /* sane default */
131 EXPORT_SYMBOL(tb_ticks_per_usec);
132 unsigned long tb_ticks_per_sec;
133 EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime conversions */
135 DEFINE_SPINLOCK(rtc_lock);
136 EXPORT_SYMBOL_GPL(rtc_lock);
138 static u64 tb_to_ns_scale __read_mostly;
139 static unsigned tb_to_ns_shift __read_mostly;
140 static u64 boot_tb __read_mostly;
142 extern struct timezone sys_tz;
143 static long timezone_offset;
145 unsigned long ppc_proc_freq;
146 EXPORT_SYMBOL_GPL(ppc_proc_freq);
147 unsigned long ppc_tb_freq;
148 EXPORT_SYMBOL_GPL(ppc_tb_freq);
152 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
154 * Read the SPURR on systems that have it, otherwise the PURR,
155 * or if that doesn't exist return the timebase value passed in.
157 static inline unsigned long read_spurr(unsigned long tb)
159 if (cpu_has_feature(CPU_FTR_SPURR))
160 return mfspr(SPRN_SPURR);
161 if (cpu_has_feature(CPU_FTR_PURR))
162 return mfspr(SPRN_PURR);
167 * Account time for a transition between system, hard irq
170 static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct,
171 unsigned long now, unsigned long stime)
173 unsigned long stime_scaled = 0;
174 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
175 unsigned long nowscaled, deltascaled;
176 unsigned long utime, utime_scaled;
178 nowscaled = read_spurr(now);
179 deltascaled = nowscaled - acct->startspurr;
180 acct->startspurr = nowscaled;
181 utime = acct->utime - acct->utime_sspurr;
182 acct->utime_sspurr = acct->utime;
185 * Because we don't read the SPURR on every kernel entry/exit,
186 * deltascaled includes both user and system SPURR ticks.
187 * Apportion these ticks to system SPURR ticks and user
188 * SPURR ticks in the same ratio as the system time (delta)
189 * and user time (udelta) values obtained from the timebase
190 * over the same interval. The system ticks get accounted here;
191 * the user ticks get saved up in paca->user_time_scaled to be
192 * used by account_process_tick.
194 stime_scaled = stime;
195 utime_scaled = utime;
196 if (deltascaled != stime + utime) {
198 stime_scaled = deltascaled * stime / (stime + utime);
199 utime_scaled = deltascaled - stime_scaled;
201 stime_scaled = deltascaled;
204 acct->utime_scaled += utime_scaled;
210 static unsigned long vtime_delta(struct cpu_accounting_data *acct,
211 unsigned long *stime_scaled,
212 unsigned long *steal_time)
214 unsigned long now, stime;
216 WARN_ON_ONCE(!irqs_disabled());
219 stime = now - acct->starttime;
220 acct->starttime = now;
222 *stime_scaled = vtime_delta_scaled(acct, now, stime);
224 if (IS_ENABLED(CONFIG_PPC_SPLPAR) &&
225 firmware_has_feature(FW_FEATURE_SPLPAR))
226 *steal_time = pseries_calculate_stolen_time(now);
233 static void vtime_delta_kernel(struct cpu_accounting_data *acct,
234 unsigned long *stime, unsigned long *stime_scaled)
236 unsigned long steal_time;
238 *stime = vtime_delta(acct, stime_scaled, &steal_time);
239 *stime -= min(*stime, steal_time);
240 acct->steal_time += steal_time;
243 void vtime_account_kernel(struct task_struct *tsk)
245 struct cpu_accounting_data *acct = get_accounting(tsk);
246 unsigned long stime, stime_scaled;
248 vtime_delta_kernel(acct, &stime, &stime_scaled);
250 if (tsk->flags & PF_VCPU) {
251 acct->gtime += stime;
252 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
253 acct->utime_scaled += stime_scaled;
256 acct->stime += stime;
257 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
258 acct->stime_scaled += stime_scaled;
262 EXPORT_SYMBOL_GPL(vtime_account_kernel);
264 void vtime_account_idle(struct task_struct *tsk)
266 unsigned long stime, stime_scaled, steal_time;
267 struct cpu_accounting_data *acct = get_accounting(tsk);
269 stime = vtime_delta(acct, &stime_scaled, &steal_time);
270 acct->idle_time += stime + steal_time;
273 static void vtime_account_irq_field(struct cpu_accounting_data *acct,
274 unsigned long *field)
276 unsigned long stime, stime_scaled;
278 vtime_delta_kernel(acct, &stime, &stime_scaled);
280 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
281 acct->stime_scaled += stime_scaled;
285 void vtime_account_softirq(struct task_struct *tsk)
287 struct cpu_accounting_data *acct = get_accounting(tsk);
288 vtime_account_irq_field(acct, &acct->softirq_time);
291 void vtime_account_hardirq(struct task_struct *tsk)
293 struct cpu_accounting_data *acct = get_accounting(tsk);
294 vtime_account_irq_field(acct, &acct->hardirq_time);
297 static void vtime_flush_scaled(struct task_struct *tsk,
298 struct cpu_accounting_data *acct)
300 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
301 if (acct->utime_scaled)
302 tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
303 if (acct->stime_scaled)
304 tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);
306 acct->utime_scaled = 0;
307 acct->utime_sspurr = 0;
308 acct->stime_scaled = 0;
313 * Account the whole cputime accumulated in the paca
314 * Must be called with interrupts disabled.
315 * Assumes that vtime_account_kernel/idle() has been called
316 * recently (i.e. since the last entry from usermode) so that
317 * get_paca()->user_time_scaled is up to date.
319 void vtime_flush(struct task_struct *tsk)
321 struct cpu_accounting_data *acct = get_accounting(tsk);
324 account_user_time(tsk, cputime_to_nsecs(acct->utime));
327 account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
329 if (IS_ENABLED(CONFIG_PPC_SPLPAR) && acct->steal_time) {
330 account_steal_time(cputime_to_nsecs(acct->steal_time));
331 acct->steal_time = 0;
335 account_idle_time(cputime_to_nsecs(acct->idle_time));
338 account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
341 if (acct->hardirq_time)
342 account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
344 if (acct->softirq_time)
345 account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
348 vtime_flush_scaled(tsk, acct);
354 acct->hardirq_time = 0;
355 acct->softirq_time = 0;
357 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
359 void __no_kcsan __delay(unsigned long loops)
366 * TB is in error state and isn't ticking anymore.
367 * HMI handler was unable to recover from TB error.
368 * Return immediately, so that kernel won't get stuck here.
373 while (mftb() - start < loops)
378 EXPORT_SYMBOL(__delay);
380 void __no_kcsan udelay(unsigned long usecs)
382 __delay(tb_ticks_per_usec * usecs);
384 EXPORT_SYMBOL(udelay);
387 unsigned long profile_pc(struct pt_regs *regs)
389 unsigned long pc = instruction_pointer(regs);
391 if (in_lock_functions(pc))
396 EXPORT_SYMBOL(profile_pc);
399 #ifdef CONFIG_IRQ_WORK
402 * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
405 static inline unsigned long test_irq_work_pending(void)
409 asm volatile("lbz %0,%1(13)"
411 : "i" (offsetof(struct paca_struct, irq_work_pending)));
415 static inline void set_irq_work_pending_flag(void)
417 asm volatile("stb %0,%1(13)" : :
419 "i" (offsetof(struct paca_struct, irq_work_pending)));
422 static inline void clear_irq_work_pending(void)
424 asm volatile("stb %0,%1(13)" : :
426 "i" (offsetof(struct paca_struct, irq_work_pending)));
431 DEFINE_PER_CPU(u8, irq_work_pending);
433 #define set_irq_work_pending_flag() __this_cpu_write(irq_work_pending, 1)
434 #define test_irq_work_pending() __this_cpu_read(irq_work_pending)
435 #define clear_irq_work_pending() __this_cpu_write(irq_work_pending, 0)
437 #endif /* 32 vs 64 bit */
439 void arch_irq_work_raise(void)
442 * 64-bit code that uses irq soft-mask can just cause an immediate
443 * interrupt here that gets soft masked, if this is called under
444 * local_irq_disable(). It might be possible to prevent that happening
445 * by noticing interrupts are disabled and setting decrementer pending
446 * to be replayed when irqs are enabled. The problem there is that
447 * tracing can call irq_work_raise, including in code that does low
448 * level manipulations of irq soft-mask state (e.g., trace_hardirqs_on)
449 * which could get tangled up if we're messing with the same state
453 set_irq_work_pending_flag();
458 static void set_dec_or_work(u64 val)
461 /* We may have raced with new irq work */
462 if (unlikely(test_irq_work_pending()))
466 #else /* CONFIG_IRQ_WORK */
468 #define test_irq_work_pending() 0
469 #define clear_irq_work_pending()
471 static void set_dec_or_work(u64 val)
475 #endif /* CONFIG_IRQ_WORK */
477 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
478 void timer_rearm_host_dec(u64 now)
480 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
482 WARN_ON_ONCE(!arch_irqs_disabled());
483 WARN_ON_ONCE(mfmsr() & MSR_EE);
485 if (now >= *next_tb) {
486 local_paca->irq_happened |= PACA_IRQ_DEC;
488 now = *next_tb - now;
489 if (now > decrementer_max)
490 now = decrementer_max;
491 set_dec_or_work(now);
494 EXPORT_SYMBOL_GPL(timer_rearm_host_dec);
498 * timer_interrupt - gets called when the decrementer overflows,
499 * with interrupts disabled.
501 DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt)
503 struct clock_event_device *evt = this_cpu_ptr(&decrementers);
504 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
505 struct pt_regs *old_regs;
509 * Some implementations of hotplug will get timer interrupts while
510 * offline, just ignore these.
512 if (unlikely(!cpu_online(smp_processor_id()))) {
513 set_dec(decrementer_max);
517 /* Conditionally hard-enable interrupts. */
518 if (should_hard_irq_enable(regs)) {
520 * Ensure a positive value is written to the decrementer, or
521 * else some CPUs will continue to take decrementer exceptions.
522 * When the PPC_WATCHDOG (decrementer based) is configured,
523 * keep this at most 31 bits, which is about 4 seconds on most
524 * systems, which gives the watchdog a chance of catching timer
525 * interrupt hard lockups.
527 if (IS_ENABLED(CONFIG_PPC_WATCHDOG))
530 set_dec(decrementer_max);
532 do_hard_irq_enable();
535 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
536 if (atomic_read(&ppc_n_lost_interrupts) != 0)
540 old_regs = set_irq_regs(regs);
542 trace_timer_interrupt_entry(regs);
544 if (test_irq_work_pending()) {
545 clear_irq_work_pending();
546 mce_run_irq_context_handlers();
551 if (now >= *next_tb) {
552 evt->event_handler(evt);
553 __this_cpu_inc(irq_stat.timer_irqs_event);
555 now = *next_tb - now;
556 if (now > decrementer_max)
557 now = decrementer_max;
558 set_dec_or_work(now);
559 __this_cpu_inc(irq_stat.timer_irqs_others);
562 trace_timer_interrupt_exit(regs);
564 set_irq_regs(old_regs);
566 EXPORT_SYMBOL(timer_interrupt);
568 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
569 void timer_broadcast_interrupt(void)
571 tick_receive_broadcast();
572 __this_cpu_inc(irq_stat.broadcast_irqs_event);
576 #ifdef CONFIG_SUSPEND
577 /* Overrides the weak version in kernel/power/main.c */
578 void arch_suspend_disable_irqs(void)
580 if (ppc_md.suspend_disable_irqs)
581 ppc_md.suspend_disable_irqs();
583 /* Disable the decrementer, so that it doesn't interfere
587 set_dec(decrementer_max);
589 set_dec(decrementer_max);
592 /* Overrides the weak version in kernel/power/main.c */
593 void arch_suspend_enable_irqs(void)
597 if (ppc_md.suspend_enable_irqs)
598 ppc_md.suspend_enable_irqs();
602 unsigned long long tb_to_ns(unsigned long long ticks)
604 return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
606 EXPORT_SYMBOL_GPL(tb_to_ns);
609 * Scheduler clock - returns current time in nanosec units.
611 * Note: mulhdu(a, b) (multiply high double unsigned) returns
612 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
613 * are 64-bit unsigned numbers.
615 notrace unsigned long long sched_clock(void)
617 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
621 #ifdef CONFIG_PPC_PSERIES
624 * Running clock - attempts to give a view of time passing for a virtualised
626 * Uses the VTB register if available otherwise a next best guess.
628 unsigned long long running_clock(void)
631 * Don't read the VTB as a host since KVM does not switch in host
632 * timebase into the VTB when it takes a guest off the CPU, reading the
633 * VTB would result in reading 'last switched out' guest VTB.
635 * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
636 * would be unsafe to rely only on the #ifdef above.
638 if (firmware_has_feature(FW_FEATURE_LPAR) &&
639 cpu_has_feature(CPU_FTR_ARCH_207S))
640 return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
643 * This is a next best approximation without a VTB.
644 * On a host which is running bare metal there should never be any stolen
645 * time and on a host which doesn't do any virtualisation TB *should* equal
646 * VTB so it makes no difference anyway.
648 return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
652 static int __init get_freq(char *name, int cells, unsigned long *val)
654 struct device_node *cpu;
658 /* The cpu node should have timebase and clock frequency properties */
659 cpu = of_find_node_by_type(NULL, "cpu");
662 fp = of_get_property(cpu, name, NULL);
665 *val = of_read_ulong(fp, cells);
674 static void start_cpu_decrementer(void)
676 #ifdef CONFIG_BOOKE_OR_40x
679 /* Clear any pending timer interrupts */
680 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
682 tcr = mfspr(SPRN_TCR);
684 * The watchdog may have already been enabled by u-boot. So leave
685 * TRC[WP] (Watchdog Period) alone.
687 tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */
688 tcr |= TCR_DIE; /* Enable decrementer */
689 mtspr(SPRN_TCR, tcr);
693 void __init generic_calibrate_decr(void)
695 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
697 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
698 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
700 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
704 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
706 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
707 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
709 printk(KERN_ERR "WARNING: Estimating processor frequency "
714 int update_persistent_clock64(struct timespec64 now)
718 if (!ppc_md.set_rtc_time)
721 rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);
723 return ppc_md.set_rtc_time(&tm);
726 static void __read_persistent_clock(struct timespec64 *ts)
729 static int first = 1;
732 /* XXX this is a little fragile but will work okay in the short term */
735 if (ppc_md.time_init)
736 timezone_offset = ppc_md.time_init();
738 /* get_boot_time() isn't guaranteed to be safe to call late */
739 if (ppc_md.get_boot_time) {
740 ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
744 if (!ppc_md.get_rtc_time) {
748 ppc_md.get_rtc_time(&tm);
750 ts->tv_sec = rtc_tm_to_time64(&tm);
753 void read_persistent_clock64(struct timespec64 *ts)
755 __read_persistent_clock(ts);
757 /* Sanitize it in case real time clock is set below EPOCH */
758 if (ts->tv_sec < 0) {
765 /* clocksource code */
766 static notrace u64 timebase_read(struct clocksource *cs)
768 return (u64)get_tb();
771 static void __init clocksource_init(void)
773 struct clocksource *clock = &clocksource_timebase;
775 if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
776 printk(KERN_ERR "clocksource: %s is already registered\n",
781 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
782 clock->name, clock->mult, clock->shift);
785 static int decrementer_set_next_event(unsigned long evt,
786 struct clock_event_device *dev)
788 __this_cpu_write(decrementers_next_tb, get_tb() + evt);
789 set_dec_or_work(evt);
794 static int decrementer_shutdown(struct clock_event_device *dev)
796 __this_cpu_write(decrementers_next_tb, DEC_CLOCKEVENT_STOPPED);
797 set_dec_or_work(decrementer_max);
802 static void register_decrementer_clockevent(int cpu)
804 struct clock_event_device *dec = &per_cpu(decrementers, cpu);
806 *dec = decrementer_clockevent;
807 dec->cpumask = cpumask_of(cpu);
809 clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
811 printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
812 dec->name, dec->mult, dec->shift, cpu);
814 /* Set values for KVM, see kvm_emulate_dec() */
815 decrementer_clockevent.mult = dec->mult;
816 decrementer_clockevent.shift = dec->shift;
819 static void enable_large_decrementer(void)
821 if (!cpu_has_feature(CPU_FTR_ARCH_300))
824 if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
828 * If we're running as the hypervisor we need to enable the LD manually
829 * otherwise firmware should have done it for us.
831 if (cpu_has_feature(CPU_FTR_HVMODE))
832 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
835 static void __init set_decrementer_max(void)
837 struct device_node *cpu;
840 /* Prior to ISAv3 the decrementer is always 32 bit */
841 if (!cpu_has_feature(CPU_FTR_ARCH_300))
844 cpu = of_find_node_by_type(NULL, "cpu");
846 if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
847 if (bits > 64 || bits < 32) {
848 pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
852 /* calculate the signed maximum given this many bits */
853 decrementer_max = (1ul << (bits - 1)) - 1;
858 pr_info("time_init: %u bit decrementer (max: %llx)\n",
859 bits, decrementer_max);
862 static void __init init_decrementer_clockevent(void)
864 register_decrementer_clockevent(smp_processor_id());
867 void secondary_cpu_time_init(void)
869 /* Enable and test the large decrementer for this cpu */
870 enable_large_decrementer();
872 /* Start the decrementer on CPUs that have manual control
875 start_cpu_decrementer();
877 /* FIME: Should make unrelated change to move snapshot_timebase
879 register_decrementer_clockevent(smp_processor_id());
882 /* This function is only called on the boot processor */
883 void __init time_init(void)
885 struct div_result res;
889 /* Normal PowerPC with timebase register */
890 if (ppc_md.calibrate_decr)
891 ppc_md.calibrate_decr();
893 generic_calibrate_decr();
895 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
896 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
897 printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
898 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
900 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
901 tb_ticks_per_sec = ppc_tb_freq;
902 tb_ticks_per_usec = ppc_tb_freq / 1000000;
905 * Compute scale factor for sched_clock.
906 * The calibrate_decr() function has set tb_ticks_per_sec,
907 * which is the timebase frequency.
908 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
909 * the 128-bit result as a 64.64 fixed-point number.
910 * We then shift that number right until it is less than 1.0,
911 * giving us the scale factor and shift count to use in
914 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
915 scale = res.result_low;
916 for (shift = 0; res.result_high != 0; ++shift) {
917 scale = (scale >> 1) | (res.result_high << 63);
918 res.result_high >>= 1;
920 tb_to_ns_scale = scale;
921 tb_to_ns_shift = shift;
922 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
925 /* If platform provided a timezone (pmac), we correct the time */
926 if (timezone_offset) {
927 sys_tz.tz_minuteswest = -timezone_offset / 60;
928 sys_tz.tz_dsttime = 0;
931 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
933 /* initialise and enable the large decrementer (if we have one) */
934 set_decrementer_max();
935 enable_large_decrementer();
937 /* Start the decrementer on CPUs that have manual control
940 start_cpu_decrementer();
942 /* Register the clocksource */
945 init_decrementer_clockevent();
946 tick_setup_hrtimer_broadcast();
949 enable_sched_clock_irqtime();
953 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
956 void div128_by_32(u64 dividend_high, u64 dividend_low,
957 unsigned divisor, struct div_result *dr)
959 unsigned long a, b, c, d;
960 unsigned long w, x, y, z;
963 a = dividend_high >> 32;
964 b = dividend_high & 0xffffffff;
965 c = dividend_low >> 32;
966 d = dividend_low & 0xffffffff;
969 ra = ((u64)(a - (w * divisor)) << 32) + b;
971 rb = ((u64) do_div(ra, divisor) << 32) + c;
974 rc = ((u64) do_div(rb, divisor) << 32) + d;
980 dr->result_high = ((u64)w << 32) + x;
981 dr->result_low = ((u64)y << 32) + z;
985 /* We don't need to calibrate delay, we use the CPU timebase for that */
986 void calibrate_delay(void)
988 /* Some generic code (such as spinlock debug) use loops_per_jiffy
989 * as the number of __delay(1) in a jiffy, so make it so
991 loops_per_jiffy = tb_ticks_per_jiffy;
994 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
995 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
997 ppc_md.get_rtc_time(tm);
1001 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1003 if (!ppc_md.set_rtc_time)
1006 if (ppc_md.set_rtc_time(tm) < 0)
1012 static const struct rtc_class_ops rtc_generic_ops = {
1013 .read_time = rtc_generic_get_time,
1014 .set_time = rtc_generic_set_time,
1017 static int __init rtc_init(void)
1019 struct platform_device *pdev;
1021 if (!ppc_md.get_rtc_time)
1024 pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1026 sizeof(rtc_generic_ops));
1028 return PTR_ERR_OR_ZERO(pdev);
1031 device_initcall(rtc_init);