1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Common time routines among all ppc machines.
4 *
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)
9 *
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).
15 *
16 * Speeded up do_gettimeofday by getting rid of references to
17 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
18 *
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.
25 *
26 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
27 * "A Kernel Model for Precision Timekeeping" by Dave Mills
28 */
29
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>
37 #include <linux/mm.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>
58
59 #include <asm/io.h>
60 #include <asm/nvram.h>
61 #include <asm/cache.h>
62 #include <asm/machdep.h>
63 #include <linux/uaccess.h>
64 #include <asm/time.h>
65 #include <asm/prom.h>
66 #include <asm/irq.h>
67 #include <asm/div64.h>
68 #include <asm/smp.h>
69 #include <asm/vdso_datapage.h>
70 #include <asm/firmware.h>
71 #include <asm/asm-prototypes.h>
72
73 /* powerpc clocksource/clockevent code */
74
75 #include <linux/clockchips.h>
76 #include <linux/timekeeper_internal.h>
77
78 static u64 rtc_read(struct clocksource *);
79 static struct clocksource clocksource_rtc = {
80 .name = "rtc",
81 .rating = 400,
82 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
83 .mask = CLOCKSOURCE_MASK(64),
84 .read = rtc_read,
85 };
86
87 static u64 timebase_read(struct clocksource *);
88 static struct clocksource clocksource_timebase = {
89 .name = "timebase",
90 .rating = 400,
91 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
92 .mask = CLOCKSOURCE_MASK(64),
93 .read = timebase_read,
94 };
95
96 #define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
97 u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
98
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);
102
103 struct clock_event_device decrementer_clockevent = {
104 .name = "decrementer",
105 .rating = 200,
106 .irq = 0,
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,
113 };
114 EXPORT_SYMBOL(decrementer_clockevent);
115
116 DEFINE_PER_CPU(u64, decrementers_next_tb);
117 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
118
119 #define XSEC_PER_SEC (1024*1024)
120
121 #ifdef CONFIG_PPC64
122 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
123 #else
124 /* compute ((xsec << 12) * max) >> 32 */
125 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
126 #endif
127
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 */
133
134 DEFINE_SPINLOCK(rtc_lock);
135 EXPORT_SYMBOL_GPL(rtc_lock);
136
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;
140
141 extern struct timezone sys_tz;
142 static long timezone_offset;
143
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);
148
149 bool tb_invalid;
150
151 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
152 /*
153 * Factor for converting from cputime_t (timebase ticks) to
154 * microseconds. This is stored as 0.64 fixed-point binary fraction.
155 */
156 u64 __cputime_usec_factor;
157 EXPORT_SYMBOL(__cputime_usec_factor);
158
159 #ifdef CONFIG_PPC_SPLPAR
160 void (*dtl_consumer)(struct dtl_entry *, u64);
161 #endif
162
calc_cputime_factors(void)163 static void calc_cputime_factors(void)
164 {
165 struct div_result res;
166
167 div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
168 __cputime_usec_factor = res.result_low;
169 }
170
171 /*
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.
174 */
read_spurr(unsigned long tb)175 static inline unsigned long read_spurr(unsigned long tb)
176 {
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);
181 return tb;
182 }
183
184 #ifdef CONFIG_PPC_SPLPAR
185
186 /*
187 * Scan the dispatch trace log and count up the stolen time.
188 * Should be called with interrupts disabled.
189 */
scan_dispatch_log(u64 stop_tb)190 static u64 scan_dispatch_log(u64 stop_tb)
191 {
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;
196 u64 tb_delta;
197 u64 stolen = 0;
198 u64 dtb;
199
200 if (!dtl)
201 return 0;
202
203 if (i == be64_to_cpu(vpa->dtl_idx))
204 return 0;
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);
209 barrier();
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);
214 continue;
215 }
216 if (dtb > stop_tb)
217 break;
218 if (dtl_consumer)
219 dtl_consumer(dtl, i);
220 stolen += tb_delta;
221 ++i;
222 ++dtl;
223 if (dtl == dtl_end)
224 dtl = local_paca->dispatch_log;
225 }
226 local_paca->dtl_ridx = i;
227 local_paca->dtl_curr = dtl;
228 return stolen;
229 }
230
231 /*
232 * Accumulate stolen time by scanning the dispatch trace log.
233 * Called on entry from user mode.
234 */
accumulate_stolen_time(void)235 void notrace accumulate_stolen_time(void)
236 {
237 u64 sst, ust;
238 unsigned long save_irq_soft_mask = irq_soft_mask_return();
239 struct cpu_accounting_data *acct = &local_paca->accounting;
240
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
245 * complain
246 */
247 irq_soft_mask_set(IRQS_DISABLED);
248
249 sst = scan_dispatch_log(acct->starttime_user);
250 ust = scan_dispatch_log(acct->starttime);
251 acct->stime -= sst;
252 acct->utime -= ust;
253 acct->steal_time += ust + sst;
254
255 irq_soft_mask_set(save_irq_soft_mask);
256 }
257
calculate_stolen_time(u64 stop_tb)258 static inline u64 calculate_stolen_time(u64 stop_tb)
259 {
260 if (!firmware_has_feature(FW_FEATURE_SPLPAR))
261 return 0;
262
263 if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
264 return scan_dispatch_log(stop_tb);
265
266 return 0;
267 }
268
269 #else /* CONFIG_PPC_SPLPAR */
calculate_stolen_time(u64 stop_tb)270 static inline u64 calculate_stolen_time(u64 stop_tb)
271 {
272 return 0;
273 }
274
275 #endif /* CONFIG_PPC_SPLPAR */
276
277 /*
278 * Account time for a transition between system, hard irq
279 * or soft irq state.
280 */
vtime_delta_scaled(struct cpu_accounting_data * acct,unsigned long now,unsigned long stime)281 static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct,
282 unsigned long now, unsigned long stime)
283 {
284 unsigned long stime_scaled = 0;
285 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
286 unsigned long nowscaled, deltascaled;
287 unsigned long utime, utime_scaled;
288
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;
294
295 /*
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.
304 */
305 stime_scaled = stime;
306 utime_scaled = utime;
307 if (deltascaled != stime + utime) {
308 if (utime) {
309 stime_scaled = deltascaled * stime / (stime + utime);
310 utime_scaled = deltascaled - stime_scaled;
311 } else {
312 stime_scaled = deltascaled;
313 }
314 }
315 acct->utime_scaled += utime_scaled;
316 #endif
317
318 return stime_scaled;
319 }
320
vtime_delta(struct task_struct * tsk,unsigned long * stime_scaled,unsigned long * steal_time)321 static unsigned long vtime_delta(struct task_struct *tsk,
322 unsigned long *stime_scaled,
323 unsigned long *steal_time)
324 {
325 unsigned long now, stime;
326 struct cpu_accounting_data *acct = get_accounting(tsk);
327
328 WARN_ON_ONCE(!irqs_disabled());
329
330 now = mftb();
331 stime = now - acct->starttime;
332 acct->starttime = now;
333
334 *stime_scaled = vtime_delta_scaled(acct, now, stime);
335
336 *steal_time = calculate_stolen_time(now);
337
338 return stime;
339 }
340
vtime_account_system(struct task_struct * tsk)341 void vtime_account_system(struct task_struct *tsk)
342 {
343 unsigned long stime, stime_scaled, steal_time;
344 struct cpu_accounting_data *acct = get_accounting(tsk);
345
346 stime = vtime_delta(tsk, &stime_scaled, &steal_time);
347
348 stime -= min(stime, steal_time);
349 acct->steal_time += steal_time;
350
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;
355 #endif
356 } else {
357 if (hardirq_count())
358 acct->hardirq_time += stime;
359 else if (in_serving_softirq())
360 acct->softirq_time += stime;
361 else
362 acct->stime += stime;
363
364 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
365 acct->stime_scaled += stime_scaled;
366 #endif
367 }
368 }
369 EXPORT_SYMBOL_GPL(vtime_account_system);
370
vtime_account_idle(struct task_struct * tsk)371 void vtime_account_idle(struct task_struct *tsk)
372 {
373 unsigned long stime, stime_scaled, steal_time;
374 struct cpu_accounting_data *acct = get_accounting(tsk);
375
376 stime = vtime_delta(tsk, &stime_scaled, &steal_time);
377 acct->idle_time += stime + steal_time;
378 }
379
vtime_flush_scaled(struct task_struct * tsk,struct cpu_accounting_data * acct)380 static void vtime_flush_scaled(struct task_struct *tsk,
381 struct cpu_accounting_data *acct)
382 {
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);
388
389 acct->utime_scaled = 0;
390 acct->utime_sspurr = 0;
391 acct->stime_scaled = 0;
392 #endif
393 }
394
395 /*
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.
401 */
vtime_flush(struct task_struct * tsk)402 void vtime_flush(struct task_struct *tsk)
403 {
404 struct cpu_accounting_data *acct = get_accounting(tsk);
405
406 if (acct->utime)
407 account_user_time(tsk, cputime_to_nsecs(acct->utime));
408
409 if (acct->gtime)
410 account_guest_time(tsk, cputime_to_nsecs(acct->gtime));
411
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;
415 }
416
417 if (acct->idle_time)
418 account_idle_time(cputime_to_nsecs(acct->idle_time));
419
420 if (acct->stime)
421 account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
422 CPUTIME_SYSTEM);
423
424 if (acct->hardirq_time)
425 account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
426 CPUTIME_IRQ);
427 if (acct->softirq_time)
428 account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
429 CPUTIME_SOFTIRQ);
430
431 vtime_flush_scaled(tsk, acct);
432
433 acct->utime = 0;
434 acct->gtime = 0;
435 acct->idle_time = 0;
436 acct->stime = 0;
437 acct->hardirq_time = 0;
438 acct->softirq_time = 0;
439 }
440
441 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
442 #define calc_cputime_factors()
443 #endif
444
__delay(unsigned long loops)445 void __delay(unsigned long loops)
446 {
447 unsigned long start;
448 int diff;
449
450 spin_begin();
451 if (__USE_RTC()) {
452 start = get_rtcl();
453 do {
454 /* the RTCL register wraps at 1000000000 */
455 diff = get_rtcl() - start;
456 if (diff < 0)
457 diff += 1000000000;
458 spin_cpu_relax();
459 } while (diff < loops);
460 } else if (tb_invalid) {
461 /*
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.
465 */
466 spin_cpu_relax();
467 } else {
468 start = get_tbl();
469 while (get_tbl() - start < loops)
470 spin_cpu_relax();
471 }
472 spin_end();
473 }
474 EXPORT_SYMBOL(__delay);
475
udelay(unsigned long usecs)476 void udelay(unsigned long usecs)
477 {
478 __delay(tb_ticks_per_usec * usecs);
479 }
480 EXPORT_SYMBOL(udelay);
481
482 #ifdef CONFIG_SMP
profile_pc(struct pt_regs * regs)483 unsigned long profile_pc(struct pt_regs *regs)
484 {
485 unsigned long pc = instruction_pointer(regs);
486
487 if (in_lock_functions(pc))
488 return regs->link;
489
490 return pc;
491 }
492 EXPORT_SYMBOL(profile_pc);
493 #endif
494
495 #ifdef CONFIG_IRQ_WORK
496
497 /*
498 * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
499 */
500 #ifdef CONFIG_PPC64
test_irq_work_pending(void)501 static inline unsigned long test_irq_work_pending(void)
502 {
503 unsigned long x;
504
505 asm volatile("lbz %0,%1(13)"
506 : "=r" (x)
507 : "i" (offsetof(struct paca_struct, irq_work_pending)));
508 return x;
509 }
510
set_irq_work_pending_flag(void)511 static inline void set_irq_work_pending_flag(void)
512 {
513 asm volatile("stb %0,%1(13)" : :
514 "r" (1),
515 "i" (offsetof(struct paca_struct, irq_work_pending)));
516 }
517
clear_irq_work_pending(void)518 static inline void clear_irq_work_pending(void)
519 {
520 asm volatile("stb %0,%1(13)" : :
521 "r" (0),
522 "i" (offsetof(struct paca_struct, irq_work_pending)));
523 }
524
arch_irq_work_raise(void)525 void arch_irq_work_raise(void)
526 {
527 preempt_disable();
528 set_irq_work_pending_flag();
529 /*
530 * Non-nmi code running with interrupts disabled will replay
531 * irq_happened before it re-enables interrupts, so setthe
532 * decrementer there instead of causing a hardware exception
533 * which would immediately hit the masked interrupt handler
534 * and have the net effect of setting the decrementer in
535 * irq_happened.
536 *
537 * NMI interrupts can not check this when they return, so the
538 * decrementer hardware exception is raised, which will fire
539 * when interrupts are next enabled.
540 *
541 * BookE does not support this yet, it must audit all NMI
542 * interrupt handlers to ensure they call nmi_enter() so this
543 * check would be correct.
544 */
545 if (IS_ENABLED(CONFIG_BOOKE) || !irqs_disabled() || in_nmi()) {
546 set_dec(1);
547 } else {
548 hard_irq_disable();
549 local_paca->irq_happened |= PACA_IRQ_DEC;
550 }
551 preempt_enable();
552 }
553
554 #else /* 32-bit */
555
556 DEFINE_PER_CPU(u8, irq_work_pending);
557
558 #define set_irq_work_pending_flag() __this_cpu_write(irq_work_pending, 1)
559 #define test_irq_work_pending() __this_cpu_read(irq_work_pending)
560 #define clear_irq_work_pending() __this_cpu_write(irq_work_pending, 0)
561
arch_irq_work_raise(void)562 void arch_irq_work_raise(void)
563 {
564 preempt_disable();
565 set_irq_work_pending_flag();
566 set_dec(1);
567 preempt_enable();
568 }
569
570 #endif /* 32 vs 64 bit */
571
572 #else /* CONFIG_IRQ_WORK */
573
574 #define test_irq_work_pending() 0
575 #define clear_irq_work_pending()
576
577 #endif /* CONFIG_IRQ_WORK */
578
579 /*
580 * timer_interrupt - gets called when the decrementer overflows,
581 * with interrupts disabled.
582 */
timer_interrupt(struct pt_regs * regs)583 void timer_interrupt(struct pt_regs *regs)
584 {
585 struct clock_event_device *evt = this_cpu_ptr(&decrementers);
586 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
587 struct pt_regs *old_regs;
588 u64 now;
589
590 /* Some implementations of hotplug will get timer interrupts while
591 * offline, just ignore these and we also need to set
592 * decrementers_next_tb as MAX to make sure __check_irq_replay
593 * don't replay timer interrupt when return, otherwise we'll trap
594 * here infinitely :(
595 */
596 if (unlikely(!cpu_online(smp_processor_id()))) {
597 *next_tb = ~(u64)0;
598 set_dec(decrementer_max);
599 return;
600 }
601
602 /* Ensure a positive value is written to the decrementer, or else
603 * some CPUs will continue to take decrementer exceptions. When the
604 * PPC_WATCHDOG (decrementer based) is configured, keep this at most
605 * 31 bits, which is about 4 seconds on most systems, which gives
606 * the watchdog a chance of catching timer interrupt hard lockups.
607 */
608 if (IS_ENABLED(CONFIG_PPC_WATCHDOG))
609 set_dec(0x7fffffff);
610 else
611 set_dec(decrementer_max);
612
613 /* Conditionally hard-enable interrupts now that the DEC has been
614 * bumped to its maximum value
615 */
616 may_hard_irq_enable();
617
618
619 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
620 if (atomic_read(&ppc_n_lost_interrupts) != 0)
621 do_IRQ(regs);
622 #endif
623
624 old_regs = set_irq_regs(regs);
625 irq_enter();
626 trace_timer_interrupt_entry(regs);
627
628 if (test_irq_work_pending()) {
629 clear_irq_work_pending();
630 irq_work_run();
631 }
632
633 now = get_tb_or_rtc();
634 if (now >= *next_tb) {
635 *next_tb = ~(u64)0;
636 if (evt->event_handler)
637 evt->event_handler(evt);
638 __this_cpu_inc(irq_stat.timer_irqs_event);
639 } else {
640 now = *next_tb - now;
641 if (now <= decrementer_max)
642 set_dec(now);
643 /* We may have raced with new irq work */
644 if (test_irq_work_pending())
645 set_dec(1);
646 __this_cpu_inc(irq_stat.timer_irqs_others);
647 }
648
649 trace_timer_interrupt_exit(regs);
650 irq_exit();
651 set_irq_regs(old_regs);
652 }
653 EXPORT_SYMBOL(timer_interrupt);
654
655 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
timer_broadcast_interrupt(void)656 void timer_broadcast_interrupt(void)
657 {
658 u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
659
660 *next_tb = ~(u64)0;
661 tick_receive_broadcast();
662 __this_cpu_inc(irq_stat.broadcast_irqs_event);
663 }
664 #endif
665
666 /*
667 * Hypervisor decrementer interrupts shouldn't occur but are sometimes
668 * left pending on exit from a KVM guest. We don't need to do anything
669 * to clear them, as they are edge-triggered.
670 */
hdec_interrupt(struct pt_regs * regs)671 void hdec_interrupt(struct pt_regs *regs)
672 {
673 }
674
675 #ifdef CONFIG_SUSPEND
generic_suspend_disable_irqs(void)676 static void generic_suspend_disable_irqs(void)
677 {
678 /* Disable the decrementer, so that it doesn't interfere
679 * with suspending.
680 */
681
682 set_dec(decrementer_max);
683 local_irq_disable();
684 set_dec(decrementer_max);
685 }
686
generic_suspend_enable_irqs(void)687 static void generic_suspend_enable_irqs(void)
688 {
689 local_irq_enable();
690 }
691
692 /* Overrides the weak version in kernel/power/main.c */
arch_suspend_disable_irqs(void)693 void arch_suspend_disable_irqs(void)
694 {
695 if (ppc_md.suspend_disable_irqs)
696 ppc_md.suspend_disable_irqs();
697 generic_suspend_disable_irqs();
698 }
699
700 /* Overrides the weak version in kernel/power/main.c */
arch_suspend_enable_irqs(void)701 void arch_suspend_enable_irqs(void)
702 {
703 generic_suspend_enable_irqs();
704 if (ppc_md.suspend_enable_irqs)
705 ppc_md.suspend_enable_irqs();
706 }
707 #endif
708
tb_to_ns(unsigned long long ticks)709 unsigned long long tb_to_ns(unsigned long long ticks)
710 {
711 return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
712 }
713 EXPORT_SYMBOL_GPL(tb_to_ns);
714
715 /*
716 * Scheduler clock - returns current time in nanosec units.
717 *
718 * Note: mulhdu(a, b) (multiply high double unsigned) returns
719 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
720 * are 64-bit unsigned numbers.
721 */
sched_clock(void)722 notrace unsigned long long sched_clock(void)
723 {
724 if (__USE_RTC())
725 return get_rtc();
726 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
727 }
728
729
730 #ifdef CONFIG_PPC_PSERIES
731
732 /*
733 * Running clock - attempts to give a view of time passing for a virtualised
734 * kernels.
735 * Uses the VTB register if available otherwise a next best guess.
736 */
running_clock(void)737 unsigned long long running_clock(void)
738 {
739 /*
740 * Don't read the VTB as a host since KVM does not switch in host
741 * timebase into the VTB when it takes a guest off the CPU, reading the
742 * VTB would result in reading 'last switched out' guest VTB.
743 *
744 * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
745 * would be unsafe to rely only on the #ifdef above.
746 */
747 if (firmware_has_feature(FW_FEATURE_LPAR) &&
748 cpu_has_feature(CPU_FTR_ARCH_207S))
749 return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
750
751 /*
752 * This is a next best approximation without a VTB.
753 * On a host which is running bare metal there should never be any stolen
754 * time and on a host which doesn't do any virtualisation TB *should* equal
755 * VTB so it makes no difference anyway.
756 */
757 return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
758 }
759 #endif
760
get_freq(char * name,int cells,unsigned long * val)761 static int __init get_freq(char *name, int cells, unsigned long *val)
762 {
763 struct device_node *cpu;
764 const __be32 *fp;
765 int found = 0;
766
767 /* The cpu node should have timebase and clock frequency properties */
768 cpu = of_find_node_by_type(NULL, "cpu");
769
770 if (cpu) {
771 fp = of_get_property(cpu, name, NULL);
772 if (fp) {
773 found = 1;
774 *val = of_read_ulong(fp, cells);
775 }
776
777 of_node_put(cpu);
778 }
779
780 return found;
781 }
782
start_cpu_decrementer(void)783 static void start_cpu_decrementer(void)
784 {
785 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
786 unsigned int tcr;
787
788 /* Clear any pending timer interrupts */
789 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
790
791 tcr = mfspr(SPRN_TCR);
792 /*
793 * The watchdog may have already been enabled by u-boot. So leave
794 * TRC[WP] (Watchdog Period) alone.
795 */
796 tcr &= TCR_WP_MASK; /* Clear all bits except for TCR[WP] */
797 tcr |= TCR_DIE; /* Enable decrementer */
798 mtspr(SPRN_TCR, tcr);
799 #endif
800 }
801
generic_calibrate_decr(void)802 void __init generic_calibrate_decr(void)
803 {
804 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
805
806 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
807 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
808
809 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
810 "(not found)\n");
811 }
812
813 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
814
815 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
816 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
817
818 printk(KERN_ERR "WARNING: Estimating processor frequency "
819 "(not found)\n");
820 }
821 }
822
update_persistent_clock64(struct timespec64 now)823 int update_persistent_clock64(struct timespec64 now)
824 {
825 struct rtc_time tm;
826
827 if (!ppc_md.set_rtc_time)
828 return -ENODEV;
829
830 rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);
831
832 return ppc_md.set_rtc_time(&tm);
833 }
834
__read_persistent_clock(struct timespec64 * ts)835 static void __read_persistent_clock(struct timespec64 *ts)
836 {
837 struct rtc_time tm;
838 static int first = 1;
839
840 ts->tv_nsec = 0;
841 /* XXX this is a litle fragile but will work okay in the short term */
842 if (first) {
843 first = 0;
844 if (ppc_md.time_init)
845 timezone_offset = ppc_md.time_init();
846
847 /* get_boot_time() isn't guaranteed to be safe to call late */
848 if (ppc_md.get_boot_time) {
849 ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
850 return;
851 }
852 }
853 if (!ppc_md.get_rtc_time) {
854 ts->tv_sec = 0;
855 return;
856 }
857 ppc_md.get_rtc_time(&tm);
858
859 ts->tv_sec = rtc_tm_to_time64(&tm);
860 }
861
read_persistent_clock64(struct timespec64 * ts)862 void read_persistent_clock64(struct timespec64 *ts)
863 {
864 __read_persistent_clock(ts);
865
866 /* Sanitize it in case real time clock is set below EPOCH */
867 if (ts->tv_sec < 0) {
868 ts->tv_sec = 0;
869 ts->tv_nsec = 0;
870 }
871
872 }
873
874 /* clocksource code */
rtc_read(struct clocksource * cs)875 static notrace u64 rtc_read(struct clocksource *cs)
876 {
877 return (u64)get_rtc();
878 }
879
timebase_read(struct clocksource * cs)880 static notrace u64 timebase_read(struct clocksource *cs)
881 {
882 return (u64)get_tb();
883 }
884
885
update_vsyscall(struct timekeeper * tk)886 void update_vsyscall(struct timekeeper *tk)
887 {
888 struct timespec xt;
889 struct clocksource *clock = tk->tkr_mono.clock;
890 u32 mult = tk->tkr_mono.mult;
891 u32 shift = tk->tkr_mono.shift;
892 u64 cycle_last = tk->tkr_mono.cycle_last;
893 u64 new_tb_to_xs, new_stamp_xsec;
894 u64 frac_sec;
895
896 if (clock != &clocksource_timebase)
897 return;
898
899 xt.tv_sec = tk->xtime_sec;
900 xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
901
902 /* Make userspace gettimeofday spin until we're done. */
903 ++vdso_data->tb_update_count;
904 smp_mb();
905
906 /*
907 * This computes ((2^20 / 1e9) * mult) >> shift as a
908 * 0.64 fixed-point fraction.
909 * The computation in the else clause below won't overflow
910 * (as long as the timebase frequency is >= 1.049 MHz)
911 * but loses precision because we lose the low bits of the constant
912 * in the shift. Note that 19342813113834067 ~= 2^(20+64) / 1e9.
913 * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
914 * over a second. (Shift values are usually 22, 23 or 24.)
915 * For high frequency clocks such as the 512MHz timebase clock
916 * on POWER[6789], the mult value is small (e.g. 32768000)
917 * and so we can shift the constant by 16 initially
918 * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
919 * remaining shifts after the multiplication, which gives a
920 * more accurate result (e.g. with mult = 32768000, shift = 24,
921 * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
922 */
923 if (mult <= 62500000 && clock->shift >= 16)
924 new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
925 else
926 new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
927
928 /*
929 * Compute the fractional second in units of 2^-32 seconds.
930 * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
931 * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
932 * it in units of 2^-32 seconds.
933 * We assume shift <= 32 because clocks_calc_mult_shift()
934 * generates shift values in the range 0 - 32.
935 */
936 frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
937 do_div(frac_sec, NSEC_PER_SEC);
938
939 /*
940 * Work out new stamp_xsec value for any legacy users of systemcfg.
941 * stamp_xsec is in units of 2^-20 seconds.
942 */
943 new_stamp_xsec = frac_sec >> 12;
944 new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
945
946 /*
947 * tb_update_count is used to allow the userspace gettimeofday code
948 * to assure itself that it sees a consistent view of the tb_to_xs and
949 * stamp_xsec variables. It reads the tb_update_count, then reads
950 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
951 * the two values of tb_update_count match and are even then the
952 * tb_to_xs and stamp_xsec values are consistent. If not, then it
953 * loops back and reads them again until this criteria is met.
954 */
955 vdso_data->tb_orig_stamp = cycle_last;
956 vdso_data->stamp_xsec = new_stamp_xsec;
957 vdso_data->tb_to_xs = new_tb_to_xs;
958 vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
959 vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
960 vdso_data->stamp_xtime = xt;
961 vdso_data->stamp_sec_fraction = frac_sec;
962 vdso_data->hrtimer_res = hrtimer_resolution;
963 smp_wmb();
964 ++(vdso_data->tb_update_count);
965 }
966
update_vsyscall_tz(void)967 void update_vsyscall_tz(void)
968 {
969 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
970 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
971 }
972
clocksource_init(void)973 static void __init clocksource_init(void)
974 {
975 struct clocksource *clock;
976
977 if (__USE_RTC())
978 clock = &clocksource_rtc;
979 else
980 clock = &clocksource_timebase;
981
982 if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
983 printk(KERN_ERR "clocksource: %s is already registered\n",
984 clock->name);
985 return;
986 }
987
988 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
989 clock->name, clock->mult, clock->shift);
990 }
991
decrementer_set_next_event(unsigned long evt,struct clock_event_device * dev)992 static int decrementer_set_next_event(unsigned long evt,
993 struct clock_event_device *dev)
994 {
995 __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
996 set_dec(evt);
997
998 /* We may have raced with new irq work */
999 if (test_irq_work_pending())
1000 set_dec(1);
1001
1002 return 0;
1003 }
1004
decrementer_shutdown(struct clock_event_device * dev)1005 static int decrementer_shutdown(struct clock_event_device *dev)
1006 {
1007 decrementer_set_next_event(decrementer_max, dev);
1008 return 0;
1009 }
1010
register_decrementer_clockevent(int cpu)1011 static void register_decrementer_clockevent(int cpu)
1012 {
1013 struct clock_event_device *dec = &per_cpu(decrementers, cpu);
1014
1015 *dec = decrementer_clockevent;
1016 dec->cpumask = cpumask_of(cpu);
1017
1018 clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
1019
1020 printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
1021 dec->name, dec->mult, dec->shift, cpu);
1022
1023 /* Set values for KVM, see kvm_emulate_dec() */
1024 decrementer_clockevent.mult = dec->mult;
1025 decrementer_clockevent.shift = dec->shift;
1026 }
1027
enable_large_decrementer(void)1028 static void enable_large_decrementer(void)
1029 {
1030 if (!cpu_has_feature(CPU_FTR_ARCH_300))
1031 return;
1032
1033 if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
1034 return;
1035
1036 /*
1037 * If we're running as the hypervisor we need to enable the LD manually
1038 * otherwise firmware should have done it for us.
1039 */
1040 if (cpu_has_feature(CPU_FTR_HVMODE))
1041 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
1042 }
1043
set_decrementer_max(void)1044 static void __init set_decrementer_max(void)
1045 {
1046 struct device_node *cpu;
1047 u32 bits = 32;
1048
1049 /* Prior to ISAv3 the decrementer is always 32 bit */
1050 if (!cpu_has_feature(CPU_FTR_ARCH_300))
1051 return;
1052
1053 cpu = of_find_node_by_type(NULL, "cpu");
1054
1055 if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
1056 if (bits > 64 || bits < 32) {
1057 pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
1058 bits = 32;
1059 }
1060
1061 /* calculate the signed maximum given this many bits */
1062 decrementer_max = (1ul << (bits - 1)) - 1;
1063 }
1064
1065 of_node_put(cpu);
1066
1067 pr_info("time_init: %u bit decrementer (max: %llx)\n",
1068 bits, decrementer_max);
1069 }
1070
init_decrementer_clockevent(void)1071 static void __init init_decrementer_clockevent(void)
1072 {
1073 register_decrementer_clockevent(smp_processor_id());
1074 }
1075
secondary_cpu_time_init(void)1076 void secondary_cpu_time_init(void)
1077 {
1078 /* Enable and test the large decrementer for this cpu */
1079 enable_large_decrementer();
1080
1081 /* Start the decrementer on CPUs that have manual control
1082 * such as BookE
1083 */
1084 start_cpu_decrementer();
1085
1086 /* FIME: Should make unrelatred change to move snapshot_timebase
1087 * call here ! */
1088 register_decrementer_clockevent(smp_processor_id());
1089 }
1090
1091 /* This function is only called on the boot processor */
time_init(void)1092 void __init time_init(void)
1093 {
1094 struct div_result res;
1095 u64 scale;
1096 unsigned shift;
1097
1098 if (__USE_RTC()) {
1099 /* 601 processor: dec counts down by 128 every 128ns */
1100 ppc_tb_freq = 1000000000;
1101 } else {
1102 /* Normal PowerPC with timebase register */
1103 ppc_md.calibrate_decr();
1104 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
1105 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
1106 printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
1107 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
1108 }
1109
1110 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
1111 tb_ticks_per_sec = ppc_tb_freq;
1112 tb_ticks_per_usec = ppc_tb_freq / 1000000;
1113 calc_cputime_factors();
1114
1115 /*
1116 * Compute scale factor for sched_clock.
1117 * The calibrate_decr() function has set tb_ticks_per_sec,
1118 * which is the timebase frequency.
1119 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
1120 * the 128-bit result as a 64.64 fixed-point number.
1121 * We then shift that number right until it is less than 1.0,
1122 * giving us the scale factor and shift count to use in
1123 * sched_clock().
1124 */
1125 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
1126 scale = res.result_low;
1127 for (shift = 0; res.result_high != 0; ++shift) {
1128 scale = (scale >> 1) | (res.result_high << 63);
1129 res.result_high >>= 1;
1130 }
1131 tb_to_ns_scale = scale;
1132 tb_to_ns_shift = shift;
1133 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
1134 boot_tb = get_tb_or_rtc();
1135
1136 /* If platform provided a timezone (pmac), we correct the time */
1137 if (timezone_offset) {
1138 sys_tz.tz_minuteswest = -timezone_offset / 60;
1139 sys_tz.tz_dsttime = 0;
1140 }
1141
1142 vdso_data->tb_update_count = 0;
1143 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1144
1145 /* initialise and enable the large decrementer (if we have one) */
1146 set_decrementer_max();
1147 enable_large_decrementer();
1148
1149 /* Start the decrementer on CPUs that have manual control
1150 * such as BookE
1151 */
1152 start_cpu_decrementer();
1153
1154 /* Register the clocksource */
1155 clocksource_init();
1156
1157 init_decrementer_clockevent();
1158 tick_setup_hrtimer_broadcast();
1159
1160 #ifdef CONFIG_COMMON_CLK
1161 of_clk_init(NULL);
1162 #endif
1163 }
1164
1165 /*
1166 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1167 * result.
1168 */
div128_by_32(u64 dividend_high,u64 dividend_low,unsigned divisor,struct div_result * dr)1169 void div128_by_32(u64 dividend_high, u64 dividend_low,
1170 unsigned divisor, struct div_result *dr)
1171 {
1172 unsigned long a, b, c, d;
1173 unsigned long w, x, y, z;
1174 u64 ra, rb, rc;
1175
1176 a = dividend_high >> 32;
1177 b = dividend_high & 0xffffffff;
1178 c = dividend_low >> 32;
1179 d = dividend_low & 0xffffffff;
1180
1181 w = a / divisor;
1182 ra = ((u64)(a - (w * divisor)) << 32) + b;
1183
1184 rb = ((u64) do_div(ra, divisor) << 32) + c;
1185 x = ra;
1186
1187 rc = ((u64) do_div(rb, divisor) << 32) + d;
1188 y = rb;
1189
1190 do_div(rc, divisor);
1191 z = rc;
1192
1193 dr->result_high = ((u64)w << 32) + x;
1194 dr->result_low = ((u64)y << 32) + z;
1195
1196 }
1197
1198 /* We don't need to calibrate delay, we use the CPU timebase for that */
calibrate_delay(void)1199 void calibrate_delay(void)
1200 {
1201 /* Some generic code (such as spinlock debug) use loops_per_jiffy
1202 * as the number of __delay(1) in a jiffy, so make it so
1203 */
1204 loops_per_jiffy = tb_ticks_per_jiffy;
1205 }
1206
1207 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
rtc_generic_get_time(struct device * dev,struct rtc_time * tm)1208 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
1209 {
1210 ppc_md.get_rtc_time(tm);
1211 return 0;
1212 }
1213
rtc_generic_set_time(struct device * dev,struct rtc_time * tm)1214 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1215 {
1216 if (!ppc_md.set_rtc_time)
1217 return -EOPNOTSUPP;
1218
1219 if (ppc_md.set_rtc_time(tm) < 0)
1220 return -EOPNOTSUPP;
1221
1222 return 0;
1223 }
1224
1225 static const struct rtc_class_ops rtc_generic_ops = {
1226 .read_time = rtc_generic_get_time,
1227 .set_time = rtc_generic_set_time,
1228 };
1229
rtc_init(void)1230 static int __init rtc_init(void)
1231 {
1232 struct platform_device *pdev;
1233
1234 if (!ppc_md.get_rtc_time)
1235 return -ENODEV;
1236
1237 pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1238 &rtc_generic_ops,
1239 sizeof(rtc_generic_ops));
1240
1241 return PTR_ERR_OR_ZERO(pdev);
1242 }
1243
1244 device_initcall(rtc_init);
1245 #endif
1246