linux/arch/powerpc/kernel/time.c
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   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
  78static u64 rtc_read(struct clocksource *);
  79static 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
  87static u64 timebase_read(struct clocksource *);
  88static 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
  97u64 decrementer_max = DECREMENTER_DEFAULT_MAX;
  98
  99static int decrementer_set_next_event(unsigned long evt,
 100                                      struct clock_event_device *dev);
 101static int decrementer_shutdown(struct clock_event_device *evt);
 102
 103struct 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};
 114EXPORT_SYMBOL(decrementer_clockevent);
 115
 116DEFINE_PER_CPU(u64, decrementers_next_tb);
 117static 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
 128unsigned long tb_ticks_per_jiffy;
 129unsigned long tb_ticks_per_usec = 100; /* sane default */
 130EXPORT_SYMBOL(tb_ticks_per_usec);
 131unsigned long tb_ticks_per_sec;
 132EXPORT_SYMBOL(tb_ticks_per_sec);        /* for cputime_t conversions */
 133
 134DEFINE_SPINLOCK(rtc_lock);
 135EXPORT_SYMBOL_GPL(rtc_lock);
 136
 137static u64 tb_to_ns_scale __read_mostly;
 138static unsigned tb_to_ns_shift __read_mostly;
 139static u64 boot_tb __read_mostly;
 140
 141extern struct timezone sys_tz;
 142static long timezone_offset;
 143
 144unsigned long ppc_proc_freq;
 145EXPORT_SYMBOL_GPL(ppc_proc_freq);
 146unsigned long ppc_tb_freq;
 147EXPORT_SYMBOL_GPL(ppc_tb_freq);
 148
 149bool 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 */
 156u64 __cputime_usec_factor;
 157EXPORT_SYMBOL(__cputime_usec_factor);
 158
 159#ifdef CONFIG_PPC_SPLPAR
 160void (*dtl_consumer)(struct dtl_entry *, u64);
 161#endif
 162
 163static 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 */
 175static 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 */
 190static 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 */
 235void 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
 258static 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 */
 270static 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 */
 281static 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
 321static 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
 341void 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}
 369EXPORT_SYMBOL_GPL(vtime_account_system);
 370
 371void 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
 380static 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 */
 402void 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
 445void __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}
 474EXPORT_SYMBOL(__delay);
 475
 476void udelay(unsigned long usecs)
 477{
 478        __delay(tb_ticks_per_usec * usecs);
 479}
 480EXPORT_SYMBOL(udelay);
 481
 482#ifdef CONFIG_SMP
 483unsigned 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}
 492EXPORT_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
 501static 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
 511static 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
 518static 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
 525void 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
 556DEFINE_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
 562void 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 */
 583void 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}
 653EXPORT_SYMBOL(timer_interrupt);
 654
 655#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 656void 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 */
 671void hdec_interrupt(struct pt_regs *regs)
 672{
 673}
 674
 675#ifdef CONFIG_SUSPEND
 676static 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
 687static void generic_suspend_enable_irqs(void)
 688{
 689        local_irq_enable();
 690}
 691
 692/* Overrides the weak version in kernel/power/main.c */
 693void 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 */
 701void 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
 709unsigned long long tb_to_ns(unsigned long long ticks)
 710{
 711        return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
 712}
 713EXPORT_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 */
 722notrace 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 */
 737unsigned 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
 761static 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
 783static 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
 802void __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
 823int 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
 835static 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
 862void 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 */
 875static notrace u64 rtc_read(struct clocksource *cs)
 876{
 877        return (u64)get_rtc();
 878}
 879
 880static notrace u64 timebase_read(struct clocksource *cs)
 881{
 882        return (u64)get_tb();
 883}
 884
 885
 886void 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        smp_wmb();
 963        ++(vdso_data->tb_update_count);
 964}
 965
 966void update_vsyscall_tz(void)
 967{
 968        vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
 969        vdso_data->tz_dsttime = sys_tz.tz_dsttime;
 970}
 971
 972static void __init clocksource_init(void)
 973{
 974        struct clocksource *clock;
 975
 976        if (__USE_RTC())
 977                clock = &clocksource_rtc;
 978        else
 979                clock = &clocksource_timebase;
 980
 981        if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
 982                printk(KERN_ERR "clocksource: %s is already registered\n",
 983                       clock->name);
 984                return;
 985        }
 986
 987        printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
 988               clock->name, clock->mult, clock->shift);
 989}
 990
 991static int decrementer_set_next_event(unsigned long evt,
 992                                      struct clock_event_device *dev)
 993{
 994        __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
 995        set_dec(evt);
 996
 997        /* We may have raced with new irq work */
 998        if (test_irq_work_pending())
 999                set_dec(1);
1000
1001        return 0;
1002}
1003
1004static int decrementer_shutdown(struct clock_event_device *dev)
1005{
1006        decrementer_set_next_event(decrementer_max, dev);
1007        return 0;
1008}
1009
1010static void register_decrementer_clockevent(int cpu)
1011{
1012        struct clock_event_device *dec = &per_cpu(decrementers, cpu);
1013
1014        *dec = decrementer_clockevent;
1015        dec->cpumask = cpumask_of(cpu);
1016
1017        clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
1018
1019        printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
1020                    dec->name, dec->mult, dec->shift, cpu);
1021
1022        /* Set values for KVM, see kvm_emulate_dec() */
1023        decrementer_clockevent.mult = dec->mult;
1024        decrementer_clockevent.shift = dec->shift;
1025}
1026
1027static void enable_large_decrementer(void)
1028{
1029        if (!cpu_has_feature(CPU_FTR_ARCH_300))
1030                return;
1031
1032        if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
1033                return;
1034
1035        /*
1036         * If we're running as the hypervisor we need to enable the LD manually
1037         * otherwise firmware should have done it for us.
1038         */
1039        if (cpu_has_feature(CPU_FTR_HVMODE))
1040                mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
1041}
1042
1043static void __init set_decrementer_max(void)
1044{
1045        struct device_node *cpu;
1046        u32 bits = 32;
1047
1048        /* Prior to ISAv3 the decrementer is always 32 bit */
1049        if (!cpu_has_feature(CPU_FTR_ARCH_300))
1050                return;
1051
1052        cpu = of_find_node_by_type(NULL, "cpu");
1053
1054        if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
1055                if (bits > 64 || bits < 32) {
1056                        pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
1057                        bits = 32;
1058                }
1059
1060                /* calculate the signed maximum given this many bits */
1061                decrementer_max = (1ul << (bits - 1)) - 1;
1062        }
1063
1064        of_node_put(cpu);
1065
1066        pr_info("time_init: %u bit decrementer (max: %llx)\n",
1067                bits, decrementer_max);
1068}
1069
1070static void __init init_decrementer_clockevent(void)
1071{
1072        register_decrementer_clockevent(smp_processor_id());
1073}
1074
1075void secondary_cpu_time_init(void)
1076{
1077        /* Enable and test the large decrementer for this cpu */
1078        enable_large_decrementer();
1079
1080        /* Start the decrementer on CPUs that have manual control
1081         * such as BookE
1082         */
1083        start_cpu_decrementer();
1084
1085        /* FIME: Should make unrelatred change to move snapshot_timebase
1086         * call here ! */
1087        register_decrementer_clockevent(smp_processor_id());
1088}
1089
1090/* This function is only called on the boot processor */
1091void __init time_init(void)
1092{
1093        struct div_result res;
1094        u64 scale;
1095        unsigned shift;
1096
1097        if (__USE_RTC()) {
1098                /* 601 processor: dec counts down by 128 every 128ns */
1099                ppc_tb_freq = 1000000000;
1100        } else {
1101                /* Normal PowerPC with timebase register */
1102                ppc_md.calibrate_decr();
1103                printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
1104                       ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
1105                printk(KERN_DEBUG "time_init: processor frequency   = %lu.%.6lu MHz\n",
1106                       ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
1107        }
1108
1109        tb_ticks_per_jiffy = ppc_tb_freq / HZ;
1110        tb_ticks_per_sec = ppc_tb_freq;
1111        tb_ticks_per_usec = ppc_tb_freq / 1000000;
1112        calc_cputime_factors();
1113
1114        /*
1115         * Compute scale factor for sched_clock.
1116         * The calibrate_decr() function has set tb_ticks_per_sec,
1117         * which is the timebase frequency.
1118         * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
1119         * the 128-bit result as a 64.64 fixed-point number.
1120         * We then shift that number right until it is less than 1.0,
1121         * giving us the scale factor and shift count to use in
1122         * sched_clock().
1123         */
1124        div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
1125        scale = res.result_low;
1126        for (shift = 0; res.result_high != 0; ++shift) {
1127                scale = (scale >> 1) | (res.result_high << 63);
1128                res.result_high >>= 1;
1129        }
1130        tb_to_ns_scale = scale;
1131        tb_to_ns_shift = shift;
1132        /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
1133        boot_tb = get_tb_or_rtc();
1134
1135        /* If platform provided a timezone (pmac), we correct the time */
1136        if (timezone_offset) {
1137                sys_tz.tz_minuteswest = -timezone_offset / 60;
1138                sys_tz.tz_dsttime = 0;
1139        }
1140
1141        vdso_data->tb_update_count = 0;
1142        vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1143
1144        /* initialise and enable the large decrementer (if we have one) */
1145        set_decrementer_max();
1146        enable_large_decrementer();
1147
1148        /* Start the decrementer on CPUs that have manual control
1149         * such as BookE
1150         */
1151        start_cpu_decrementer();
1152
1153        /* Register the clocksource */
1154        clocksource_init();
1155
1156        init_decrementer_clockevent();
1157        tick_setup_hrtimer_broadcast();
1158
1159#ifdef CONFIG_COMMON_CLK
1160        of_clk_init(NULL);
1161#endif
1162}
1163
1164/*
1165 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1166 * result.
1167 */
1168void div128_by_32(u64 dividend_high, u64 dividend_low,
1169                  unsigned divisor, struct div_result *dr)
1170{
1171        unsigned long a, b, c, d;
1172        unsigned long w, x, y, z;
1173        u64 ra, rb, rc;
1174
1175        a = dividend_high >> 32;
1176        b = dividend_high & 0xffffffff;
1177        c = dividend_low >> 32;
1178        d = dividend_low & 0xffffffff;
1179
1180        w = a / divisor;
1181        ra = ((u64)(a - (w * divisor)) << 32) + b;
1182
1183        rb = ((u64) do_div(ra, divisor) << 32) + c;
1184        x = ra;
1185
1186        rc = ((u64) do_div(rb, divisor) << 32) + d;
1187        y = rb;
1188
1189        do_div(rc, divisor);
1190        z = rc;
1191
1192        dr->result_high = ((u64)w << 32) + x;
1193        dr->result_low  = ((u64)y << 32) + z;
1194
1195}
1196
1197/* We don't need to calibrate delay, we use the CPU timebase for that */
1198void calibrate_delay(void)
1199{
1200        /* Some generic code (such as spinlock debug) use loops_per_jiffy
1201         * as the number of __delay(1) in a jiffy, so make it so
1202         */
1203        loops_per_jiffy = tb_ticks_per_jiffy;
1204}
1205
1206#if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
1207static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
1208{
1209        ppc_md.get_rtc_time(tm);
1210        return 0;
1211}
1212
1213static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1214{
1215        if (!ppc_md.set_rtc_time)
1216                return -EOPNOTSUPP;
1217
1218        if (ppc_md.set_rtc_time(tm) < 0)
1219                return -EOPNOTSUPP;
1220
1221        return 0;
1222}
1223
1224static const struct rtc_class_ops rtc_generic_ops = {
1225        .read_time = rtc_generic_get_time,
1226        .set_time = rtc_generic_set_time,
1227};
1228
1229static int __init rtc_init(void)
1230{
1231        struct platform_device *pdev;
1232
1233        if (!ppc_md.get_rtc_time)
1234                return -ENODEV;
1235
1236        pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1237                                             &rtc_generic_ops,
1238                                             sizeof(rtc_generic_ops));
1239
1240        return PTR_ERR_OR_ZERO(pdev);
1241}
1242
1243device_initcall(rtc_init);
1244#endif
1245