arch/powerpc/kernel/time.c

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This source file includes following definitions.
calc_cputime_factors
read_spurr
scan_dispatch_log
accumulate_stolen_time
calculate_stolen_time
calculate_stolen_time
vtime_delta_scaled
vtime_delta
vtime_account_system
vtime_account_idle
vtime_flush_scaled
vtime_flush
__delay
udelay
profile_pc
test_irq_work_pending
set_irq_work_pending_flag
clear_irq_work_pending
arch_irq_work_raise
timer_interrupt
timer_broadcast_interrupt
hdec_interrupt
generic_suspend_disable_irqs
generic_suspend_enable_irqs
arch_suspend_disable_irqs
arch_suspend_enable_irqs
tb_to_ns
sched_clock
running_clock
get_freq
start_cpu_decrementer
generic_calibrate_decr
update_persistent_clock64
__read_persistent_clock
read_persistent_clock64
rtc_read
timebase_read
update_vsyscall
update_vsyscall_tz
clocksource_init
decrementer_set_next_event
decrementer_shutdown
register_decrementer_clockevent
enable_large_decrementer
set_decrementer_max
init_decrementer_clockevent
secondary_cpu_time_init
time_init
div128_by_32
calibrate_delay
rtc_generic_get_time
rtc_generic_set_time
rtc_init
   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 
 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  */
 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  */
 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  */
 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 
 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 */
 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  */
 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 
 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 
 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 
 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 
 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  */
 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 
 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 
 476 void udelay(unsigned long usecs)
 477 {
 478         __delay(tb_ticks_per_usec * usecs);
 479 }
 480 EXPORT_SYMBOL(udelay);
 481 
 482 #ifdef CONFIG_SMP
 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
 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 
 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 
 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 
 525 #else /* 32-bit */
 526 
 527 DEFINE_PER_CPU(u8, irq_work_pending);
 528 
 529 #define set_irq_work_pending_flag()     __this_cpu_write(irq_work_pending, 1)
 530 #define test_irq_work_pending()         __this_cpu_read(irq_work_pending)
 531 #define clear_irq_work_pending()        __this_cpu_write(irq_work_pending, 0)
 532 
 533 #endif /* 32 vs 64 bit */
 534 
 535 void arch_irq_work_raise(void)
 536 {
 537         /*
 538          * 64-bit code that uses irq soft-mask can just cause an immediate
 539          * interrupt here that gets soft masked, if this is called under
 540          * local_irq_disable(). It might be possible to prevent that happening
 541          * by noticing interrupts are disabled and setting decrementer pending
 542          * to be replayed when irqs are enabled. The problem there is that
 543          * tracing can call irq_work_raise, including in code that does low
 544          * level manipulations of irq soft-mask state (e.g., trace_hardirqs_on)
 545          * which could get tangled up if we're messing with the same state
 546          * here.
 547          */
 548         preempt_disable();
 549         set_irq_work_pending_flag();
 550         set_dec(1);
 551         preempt_enable();
 552 }
 553 
 554 #else  /* CONFIG_IRQ_WORK */
 555 
 556 #define test_irq_work_pending() 0
 557 #define clear_irq_work_pending()
 558 
 559 #endif /* CONFIG_IRQ_WORK */
 560 
 561 /*
 562  * timer_interrupt - gets called when the decrementer overflows,
 563  * with interrupts disabled.
 564  */
 565 void timer_interrupt(struct pt_regs *regs)
 566 {
 567         struct clock_event_device *evt = this_cpu_ptr(&decrementers);
 568         u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
 569         struct pt_regs *old_regs;
 570         u64 now;
 571 
 572         /* Some implementations of hotplug will get timer interrupts while
 573          * offline, just ignore these and we also need to set
 574          * decrementers_next_tb as MAX to make sure __check_irq_replay
 575          * don't replay timer interrupt when return, otherwise we'll trap
 576          * here infinitely :(
 577          */
 578         if (unlikely(!cpu_online(smp_processor_id()))) {
 579                 *next_tb = ~(u64)0;
 580                 set_dec(decrementer_max);
 581                 return;
 582         }
 583 
 584         /* Ensure a positive value is written to the decrementer, or else
 585          * some CPUs will continue to take decrementer exceptions. When the
 586          * PPC_WATCHDOG (decrementer based) is configured, keep this at most
 587          * 31 bits, which is about 4 seconds on most systems, which gives
 588          * the watchdog a chance of catching timer interrupt hard lockups.
 589          */
 590         if (IS_ENABLED(CONFIG_PPC_WATCHDOG))
 591                 set_dec(0x7fffffff);
 592         else
 593                 set_dec(decrementer_max);
 594 
 595         /* Conditionally hard-enable interrupts now that the DEC has been
 596          * bumped to its maximum value
 597          */
 598         may_hard_irq_enable();
 599 
 600 
 601 #if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
 602         if (atomic_read(&ppc_n_lost_interrupts) != 0)
 603                 do_IRQ(regs);
 604 #endif
 605 
 606         old_regs = set_irq_regs(regs);
 607         irq_enter();
 608         trace_timer_interrupt_entry(regs);
 609 
 610         if (test_irq_work_pending()) {
 611                 clear_irq_work_pending();
 612                 irq_work_run();
 613         }
 614 
 615         now = get_tb_or_rtc();
 616         if (now >= *next_tb) {
 617                 *next_tb = ~(u64)0;
 618                 if (evt->event_handler)
 619                         evt->event_handler(evt);
 620                 __this_cpu_inc(irq_stat.timer_irqs_event);
 621         } else {
 622                 now = *next_tb - now;
 623                 if (now <= decrementer_max)
 624                         set_dec(now);
 625                 /* We may have raced with new irq work */
 626                 if (test_irq_work_pending())
 627                         set_dec(1);
 628                 __this_cpu_inc(irq_stat.timer_irqs_others);
 629         }
 630 
 631         trace_timer_interrupt_exit(regs);
 632         irq_exit();
 633         set_irq_regs(old_regs);
 634 }
 635 EXPORT_SYMBOL(timer_interrupt);
 636 
 637 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 638 void timer_broadcast_interrupt(void)
 639 {
 640         u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
 641 
 642         *next_tb = ~(u64)0;
 643         tick_receive_broadcast();
 644         __this_cpu_inc(irq_stat.broadcast_irqs_event);
 645 }
 646 #endif
 647 
 648 /*
 649  * Hypervisor decrementer interrupts shouldn't occur but are sometimes
 650  * left pending on exit from a KVM guest.  We don't need to do anything
 651  * to clear them, as they are edge-triggered.
 652  */
 653 void hdec_interrupt(struct pt_regs *regs)
 654 {
 655 }
 656 
 657 #ifdef CONFIG_SUSPEND
 658 static void generic_suspend_disable_irqs(void)
 659 {
 660         /* Disable the decrementer, so that it doesn't interfere
 661          * with suspending.
 662          */
 663 
 664         set_dec(decrementer_max);
 665         local_irq_disable();
 666         set_dec(decrementer_max);
 667 }
 668 
 669 static void generic_suspend_enable_irqs(void)
 670 {
 671         local_irq_enable();
 672 }
 673 
 674 /* Overrides the weak version in kernel/power/main.c */
 675 void arch_suspend_disable_irqs(void)
 676 {
 677         if (ppc_md.suspend_disable_irqs)
 678                 ppc_md.suspend_disable_irqs();
 679         generic_suspend_disable_irqs();
 680 }
 681 
 682 /* Overrides the weak version in kernel/power/main.c */
 683 void arch_suspend_enable_irqs(void)
 684 {
 685         generic_suspend_enable_irqs();
 686         if (ppc_md.suspend_enable_irqs)
 687                 ppc_md.suspend_enable_irqs();
 688 }
 689 #endif
 690 
 691 unsigned long long tb_to_ns(unsigned long long ticks)
 692 {
 693         return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
 694 }
 695 EXPORT_SYMBOL_GPL(tb_to_ns);
 696 
 697 /*
 698  * Scheduler clock - returns current time in nanosec units.
 699  *
 700  * Note: mulhdu(a, b) (multiply high double unsigned) returns
 701  * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
 702  * are 64-bit unsigned numbers.
 703  */
 704 notrace unsigned long long sched_clock(void)
 705 {
 706         if (__USE_RTC())
 707                 return get_rtc();
 708         return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
 709 }
 710 
 711 
 712 #ifdef CONFIG_PPC_PSERIES
 713 
 714 /*
 715  * Running clock - attempts to give a view of time passing for a virtualised
 716  * kernels.
 717  * Uses the VTB register if available otherwise a next best guess.
 718  */
 719 unsigned long long running_clock(void)
 720 {
 721         /*
 722          * Don't read the VTB as a host since KVM does not switch in host
 723          * timebase into the VTB when it takes a guest off the CPU, reading the
 724          * VTB would result in reading 'last switched out' guest VTB.
 725          *
 726          * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
 727          * would be unsafe to rely only on the #ifdef above.
 728          */
 729         if (firmware_has_feature(FW_FEATURE_LPAR) &&
 730             cpu_has_feature(CPU_FTR_ARCH_207S))
 731                 return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
 732 
 733         /*
 734          * This is a next best approximation without a VTB.
 735          * On a host which is running bare metal there should never be any stolen
 736          * time and on a host which doesn't do any virtualisation TB *should* equal
 737          * VTB so it makes no difference anyway.
 738          */
 739         return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
 740 }
 741 #endif
 742 
 743 static int __init get_freq(char *name, int cells, unsigned long *val)
 744 {
 745         struct device_node *cpu;
 746         const __be32 *fp;
 747         int found = 0;
 748 
 749         /* The cpu node should have timebase and clock frequency properties */
 750         cpu = of_find_node_by_type(NULL, "cpu");
 751 
 752         if (cpu) {
 753                 fp = of_get_property(cpu, name, NULL);
 754                 if (fp) {
 755                         found = 1;
 756                         *val = of_read_ulong(fp, cells);
 757                 }
 758 
 759                 of_node_put(cpu);
 760         }
 761 
 762         return found;
 763 }
 764 
 765 static void start_cpu_decrementer(void)
 766 {
 767 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
 768         unsigned int tcr;
 769 
 770         /* Clear any pending timer interrupts */
 771         mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
 772 
 773         tcr = mfspr(SPRN_TCR);
 774         /*
 775          * The watchdog may have already been enabled by u-boot. So leave
 776          * TRC[WP] (Watchdog Period) alone.
 777          */
 778         tcr &= TCR_WP_MASK;     /* Clear all bits except for TCR[WP] */
 779         tcr |= TCR_DIE;         /* Enable decrementer */
 780         mtspr(SPRN_TCR, tcr);
 781 #endif
 782 }
 783 
 784 void __init generic_calibrate_decr(void)
 785 {
 786         ppc_tb_freq = DEFAULT_TB_FREQ;          /* hardcoded default */
 787 
 788         if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
 789             !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
 790 
 791                 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
 792                                 "(not found)\n");
 793         }
 794 
 795         ppc_proc_freq = DEFAULT_PROC_FREQ;      /* hardcoded default */
 796 
 797         if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
 798             !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
 799 
 800                 printk(KERN_ERR "WARNING: Estimating processor frequency "
 801                                 "(not found)\n");
 802         }
 803 }
 804 
 805 int update_persistent_clock64(struct timespec64 now)
 806 {
 807         struct rtc_time tm;
 808 
 809         if (!ppc_md.set_rtc_time)
 810                 return -ENODEV;
 811 
 812         rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);
 813 
 814         return ppc_md.set_rtc_time(&tm);
 815 }
 816 
 817 static void __read_persistent_clock(struct timespec64 *ts)
 818 {
 819         struct rtc_time tm;
 820         static int first = 1;
 821 
 822         ts->tv_nsec = 0;
 823         /* XXX this is a litle fragile but will work okay in the short term */
 824         if (first) {
 825                 first = 0;
 826                 if (ppc_md.time_init)
 827                         timezone_offset = ppc_md.time_init();
 828 
 829                 /* get_boot_time() isn't guaranteed to be safe to call late */
 830                 if (ppc_md.get_boot_time) {
 831                         ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
 832                         return;
 833                 }
 834         }
 835         if (!ppc_md.get_rtc_time) {
 836                 ts->tv_sec = 0;
 837                 return;
 838         }
 839         ppc_md.get_rtc_time(&tm);
 840 
 841         ts->tv_sec = rtc_tm_to_time64(&tm);
 842 }
 843 
 844 void read_persistent_clock64(struct timespec64 *ts)
 845 {
 846         __read_persistent_clock(ts);
 847 
 848         /* Sanitize it in case real time clock is set below EPOCH */
 849         if (ts->tv_sec < 0) {
 850                 ts->tv_sec = 0;
 851                 ts->tv_nsec = 0;
 852         }
 853                 
 854 }
 855 
 856 /* clocksource code */
 857 static notrace u64 rtc_read(struct clocksource *cs)
 858 {
 859         return (u64)get_rtc();
 860 }
 861 
 862 static notrace u64 timebase_read(struct clocksource *cs)
 863 {
 864         return (u64)get_tb();
 865 }
 866 
 867 
 868 void update_vsyscall(struct timekeeper *tk)
 869 {
 870         struct timespec xt;
 871         struct clocksource *clock = tk->tkr_mono.clock;
 872         u32 mult = tk->tkr_mono.mult;
 873         u32 shift = tk->tkr_mono.shift;
 874         u64 cycle_last = tk->tkr_mono.cycle_last;
 875         u64 new_tb_to_xs, new_stamp_xsec;
 876         u64 frac_sec;
 877 
 878         if (clock != &clocksource_timebase)
 879                 return;
 880 
 881         xt.tv_sec = tk->xtime_sec;
 882         xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 883 
 884         /* Make userspace gettimeofday spin until we're done. */
 885         ++vdso_data->tb_update_count;
 886         smp_mb();
 887 
 888         /*
 889          * This computes ((2^20 / 1e9) * mult) >> shift as a
 890          * 0.64 fixed-point fraction.
 891          * The computation in the else clause below won't overflow
 892          * (as long as the timebase frequency is >= 1.049 MHz)
 893          * but loses precision because we lose the low bits of the constant
 894          * in the shift.  Note that 19342813113834067 ~= 2^(20+64) / 1e9.
 895          * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
 896          * over a second.  (Shift values are usually 22, 23 or 24.)
 897          * For high frequency clocks such as the 512MHz timebase clock
 898          * on POWER[6789], the mult value is small (e.g. 32768000)
 899          * and so we can shift the constant by 16 initially
 900          * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
 901          * remaining shifts after the multiplication, which gives a
 902          * more accurate result (e.g. with mult = 32768000, shift = 24,
 903          * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
 904          */
 905         if (mult <= 62500000 && clock->shift >= 16)
 906                 new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
 907         else
 908                 new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
 909 
 910         /*
 911          * Compute the fractional second in units of 2^-32 seconds.
 912          * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
 913          * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
 914          * it in units of 2^-32 seconds.
 915          * We assume shift <= 32 because clocks_calc_mult_shift()
 916          * generates shift values in the range 0 - 32.
 917          */
 918         frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
 919         do_div(frac_sec, NSEC_PER_SEC);
 920 
 921         /*
 922          * Work out new stamp_xsec value for any legacy users of systemcfg.
 923          * stamp_xsec is in units of 2^-20 seconds.
 924          */
 925         new_stamp_xsec = frac_sec >> 12;
 926         new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
 927 
 928         /*
 929          * tb_update_count is used to allow the userspace gettimeofday code
 930          * to assure itself that it sees a consistent view of the tb_to_xs and
 931          * stamp_xsec variables.  It reads the tb_update_count, then reads
 932          * tb_to_xs and stamp_xsec and then reads tb_update_count again.  If
 933          * the two values of tb_update_count match and are even then the
 934          * tb_to_xs and stamp_xsec values are consistent.  If not, then it
 935          * loops back and reads them again until this criteria is met.
 936          */
 937         vdso_data->tb_orig_stamp = cycle_last;
 938         vdso_data->stamp_xsec = new_stamp_xsec;
 939         vdso_data->tb_to_xs = new_tb_to_xs;
 940         vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
 941         vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
 942         vdso_data->stamp_xtime = xt;
 943         vdso_data->stamp_sec_fraction = frac_sec;
 944         vdso_data->hrtimer_res = hrtimer_resolution;
 945         smp_wmb();
 946         ++(vdso_data->tb_update_count);
 947 }
 948 
 949 void update_vsyscall_tz(void)
 950 {
 951         vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
 952         vdso_data->tz_dsttime = sys_tz.tz_dsttime;
 953 }
 954 
 955 static void __init clocksource_init(void)
 956 {
 957         struct clocksource *clock;
 958 
 959         if (__USE_RTC())
 960                 clock = &clocksource_rtc;
 961         else
 962                 clock = &clocksource_timebase;
 963 
 964         if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
 965                 printk(KERN_ERR "clocksource: %s is already registered\n",
 966                        clock->name);
 967                 return;
 968         }
 969 
 970         printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
 971                clock->name, clock->mult, clock->shift);
 972 }
 973 
 974 static int decrementer_set_next_event(unsigned long evt,
 975                                       struct clock_event_device *dev)
 976 {
 977         __this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
 978         set_dec(evt);
 979 
 980         /* We may have raced with new irq work */
 981         if (test_irq_work_pending())
 982                 set_dec(1);
 983 
 984         return 0;
 985 }
 986 
 987 static int decrementer_shutdown(struct clock_event_device *dev)
 988 {
 989         decrementer_set_next_event(decrementer_max, dev);
 990         return 0;
 991 }
 992 
 993 static void register_decrementer_clockevent(int cpu)
 994 {
 995         struct clock_event_device *dec = &per_cpu(decrementers, cpu);
 996 
 997         *dec = decrementer_clockevent;
 998         dec->cpumask = cpumask_of(cpu);
 999 
1000         clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);
1001 
1002         printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
1003                     dec->name, dec->mult, dec->shift, cpu);
1004 
1005         /* Set values for KVM, see kvm_emulate_dec() */
1006         decrementer_clockevent.mult = dec->mult;
1007         decrementer_clockevent.shift = dec->shift;
1008 }
1009 
1010 static void enable_large_decrementer(void)
1011 {
1012         if (!cpu_has_feature(CPU_FTR_ARCH_300))
1013                 return;
1014 
1015         if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
1016                 return;
1017 
1018         /*
1019          * If we're running as the hypervisor we need to enable the LD manually
1020          * otherwise firmware should have done it for us.
1021          */
1022         if (cpu_has_feature(CPU_FTR_HVMODE))
1023                 mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
1024 }
1025 
1026 static void __init set_decrementer_max(void)
1027 {
1028         struct device_node *cpu;
1029         u32 bits = 32;
1030 
1031         /* Prior to ISAv3 the decrementer is always 32 bit */
1032         if (!cpu_has_feature(CPU_FTR_ARCH_300))
1033                 return;
1034 
1035         cpu = of_find_node_by_type(NULL, "cpu");
1036 
1037         if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
1038                 if (bits > 64 || bits < 32) {
1039                         pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
1040                         bits = 32;
1041                 }
1042 
1043                 /* calculate the signed maximum given this many bits */
1044                 decrementer_max = (1ul << (bits - 1)) - 1;
1045         }
1046 
1047         of_node_put(cpu);
1048 
1049         pr_info("time_init: %u bit decrementer (max: %llx)\n",
1050                 bits, decrementer_max);
1051 }
1052 
1053 static void __init init_decrementer_clockevent(void)
1054 {
1055         register_decrementer_clockevent(smp_processor_id());
1056 }
1057 
1058 void secondary_cpu_time_init(void)
1059 {
1060         /* Enable and test the large decrementer for this cpu */
1061         enable_large_decrementer();
1062 
1063         /* Start the decrementer on CPUs that have manual control
1064          * such as BookE
1065          */
1066         start_cpu_decrementer();
1067 
1068         /* FIME: Should make unrelatred change to move snapshot_timebase
1069          * call here ! */
1070         register_decrementer_clockevent(smp_processor_id());
1071 }
1072 
1073 /* This function is only called on the boot processor */
1074 void __init time_init(void)
1075 {
1076         struct div_result res;
1077         u64 scale;
1078         unsigned shift;
1079 
1080         if (__USE_RTC()) {
1081                 /* 601 processor: dec counts down by 128 every 128ns */
1082                 ppc_tb_freq = 1000000000;
1083         } else {
1084                 /* Normal PowerPC with timebase register */
1085                 ppc_md.calibrate_decr();
1086                 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
1087                        ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
1088                 printk(KERN_DEBUG "time_init: processor frequency   = %lu.%.6lu MHz\n",
1089                        ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
1090         }
1091 
1092         tb_ticks_per_jiffy = ppc_tb_freq / HZ;
1093         tb_ticks_per_sec = ppc_tb_freq;
1094         tb_ticks_per_usec = ppc_tb_freq / 1000000;
1095         calc_cputime_factors();
1096 
1097         /*
1098          * Compute scale factor for sched_clock.
1099          * The calibrate_decr() function has set tb_ticks_per_sec,
1100          * which is the timebase frequency.
1101          * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
1102          * the 128-bit result as a 64.64 fixed-point number.
1103          * We then shift that number right until it is less than 1.0,
1104          * giving us the scale factor and shift count to use in
1105          * sched_clock().
1106          */
1107         div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
1108         scale = res.result_low;
1109         for (shift = 0; res.result_high != 0; ++shift) {
1110                 scale = (scale >> 1) | (res.result_high << 63);
1111                 res.result_high >>= 1;
1112         }
1113         tb_to_ns_scale = scale;
1114         tb_to_ns_shift = shift;
1115         /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
1116         boot_tb = get_tb_or_rtc();
1117 
1118         /* If platform provided a timezone (pmac), we correct the time */
1119         if (timezone_offset) {
1120                 sys_tz.tz_minuteswest = -timezone_offset / 60;
1121                 sys_tz.tz_dsttime = 0;
1122         }
1123 
1124         vdso_data->tb_update_count = 0;
1125         vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1126 
1127         /* initialise and enable the large decrementer (if we have one) */
1128         set_decrementer_max();
1129         enable_large_decrementer();
1130 
1131         /* Start the decrementer on CPUs that have manual control
1132          * such as BookE
1133          */
1134         start_cpu_decrementer();
1135 
1136         /* Register the clocksource */
1137         clocksource_init();
1138 
1139         init_decrementer_clockevent();
1140         tick_setup_hrtimer_broadcast();
1141 
1142 #ifdef CONFIG_COMMON_CLK
1143         of_clk_init(NULL);
1144 #endif
1145 }
1146 
1147 /*
1148  * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1149  * result.
1150  */
1151 void div128_by_32(u64 dividend_high, u64 dividend_low,
1152                   unsigned divisor, struct div_result *dr)
1153 {
1154         unsigned long a, b, c, d;
1155         unsigned long w, x, y, z;
1156         u64 ra, rb, rc;
1157 
1158         a = dividend_high >> 32;
1159         b = dividend_high & 0xffffffff;
1160         c = dividend_low >> 32;
1161         d = dividend_low & 0xffffffff;
1162 
1163         w = a / divisor;
1164         ra = ((u64)(a - (w * divisor)) << 32) + b;
1165 
1166         rb = ((u64) do_div(ra, divisor) << 32) + c;
1167         x = ra;
1168 
1169         rc = ((u64) do_div(rb, divisor) << 32) + d;
1170         y = rb;
1171 
1172         do_div(rc, divisor);
1173         z = rc;
1174 
1175         dr->result_high = ((u64)w << 32) + x;
1176         dr->result_low  = ((u64)y << 32) + z;
1177 
1178 }
1179 
1180 /* We don't need to calibrate delay, we use the CPU timebase for that */
1181 void calibrate_delay(void)
1182 {
1183         /* Some generic code (such as spinlock debug) use loops_per_jiffy
1184          * as the number of __delay(1) in a jiffy, so make it so
1185          */
1186         loops_per_jiffy = tb_ticks_per_jiffy;
1187 }
1188 
1189 #if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
1190 static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
1191 {
1192         ppc_md.get_rtc_time(tm);
1193         return 0;
1194 }
1195 
1196 static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
1197 {
1198         if (!ppc_md.set_rtc_time)
1199                 return -EOPNOTSUPP;
1200 
1201         if (ppc_md.set_rtc_time(tm) < 0)
1202                 return -EOPNOTSUPP;
1203 
1204         return 0;
1205 }
1206 
1207 static const struct rtc_class_ops rtc_generic_ops = {
1208         .read_time = rtc_generic_get_time,
1209         .set_time = rtc_generic_set_time,
1210 };
1211 
1212 static int __init rtc_init(void)
1213 {
1214         struct platform_device *pdev;
1215 
1216         if (!ppc_md.get_rtc_time)
1217                 return -ENODEV;
1218 
1219         pdev = platform_device_register_data(NULL, "rtc-generic", -1,
1220                                              &rtc_generic_ops,
1221                                              sizeof(rtc_generic_ops));
1222 
1223         return PTR_ERR_OR_ZERO(pdev);
1224 }
1225 
1226 device_initcall(rtc_init);
1227 #endif
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root/arch/powerpc/kernel/time.c

DEFINITIONS
