arch/ia64/kernel/time.c

   1 /*
   2  * linux/arch/ia64/kernel/time.c
   3  *
   4  * Copyright (C) 1998-2003 Hewlett-Packard Co
   5  *      Stephane Eranian <eranian@hpl.hp.com>
   6  *      David Mosberger <davidm@hpl.hp.com>
   7  * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
   8  * Copyright (C) 1999-2000 VA Linux Systems
   9  * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
  10  */
  11
  12 #include <linux/cpu.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/profile.h>
  17 #include <linux/sched.h>
  18 #include <linux/time.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/efi.h>
  21 #include <linux/timex.h>
  22 #include <linux/clocksource.h>
  23 #include <linux/platform_device.h>
  24
  25 #include <asm/machvec.h>
  26 #include <asm/delay.h>
  27 #include <asm/hw_irq.h>
  28 #include <asm/paravirt.h>
  29 #include <asm/ptrace.h>
  30 #include <asm/sal.h>
  31 #include <asm/sections.h>
  32 #include <asm/system.h>
  33
  34 #include "fsyscall_gtod_data.h"
  35
  36 static cycle_t itc_get_cycles(void);
  37
  38 struct fsyscall_gtod_data_t fsyscall_gtod_data = {
  39         .lock = SEQLOCK_UNLOCKED,
  40 };
  41
  42 struct itc_jitter_data_t itc_jitter_data;
  43
  44 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
  45
  46 #ifdef CONFIG_IA64_DEBUG_IRQ
  47
  48 unsigned long last_cli_ip;
  49 EXPORT_SYMBOL(last_cli_ip);
  50
  51 #endif
  52
  53 #ifdef CONFIG_PARAVIRT
  54 /* We need to define a real function for sched_clock, to override the
  55    weak default version */
  56 unsigned long long sched_clock(void)
  57 {
  58         return paravirt_sched_clock();
  59 }
  60 #endif
  61
  62 #ifdef CONFIG_PARAVIRT
  63 static void
  64 paravirt_clocksource_resume(void)
  65 {
  66         if (pv_time_ops.clocksource_resume)
  67                 pv_time_ops.clocksource_resume();
  68 }
  69 #endif
  70
  71 static struct clocksource clocksource_itc = {
  72         .name           = "itc",
  73         .rating         = 350,
  74         .read           = itc_get_cycles,
  75         .mask           = CLOCKSOURCE_MASK(64),
  76         .mult           = 0, /*to be calculated*/
  77         .shift          = 16,
  78         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  79 #ifdef CONFIG_PARAVIRT
  80         .resume         = paravirt_clocksource_resume,
  81 #endif
  82 };
  83 static struct clocksource *itc_clocksource;
  84
  85 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
  86
  87 #include <linux/kernel_stat.h>
  88
  89 extern cputime_t cycle_to_cputime(u64 cyc);
  90
  91 /*
  92  * Called from the context switch with interrupts disabled, to charge all
  93  * accumulated times to the current process, and to prepare accounting on
  94  * the next process.
  95  */
  96 void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next)
  97 {
  98         struct thread_info *pi = task_thread_info(prev);
  99         struct thread_info *ni = task_thread_info(next);
 100         cputime_t delta_stime, delta_utime;
 101         __u64 now;
 102
 103         now = ia64_get_itc();
 104
 105         delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp));
 106         if (idle_task(smp_processor_id()) != prev)
 107                 account_system_time(prev, 0, delta_stime, delta_stime);
 108         else
 109                 account_idle_time(delta_stime);
 110
 111         if (pi->ac_utime) {
 112                 delta_utime = cycle_to_cputime(pi->ac_utime);
 113                 account_user_time(prev, delta_utime, delta_utime);
 114         }
 115
 116         pi->ac_stamp = ni->ac_stamp = now;
 117         ni->ac_stime = ni->ac_utime = 0;
 118 }
 119
 120 /*
 121  * Account time for a transition between system, hard irq or soft irq state.
 122  * Note that this function is called with interrupts enabled.
 123  */
 124 void account_system_vtime(struct task_struct *tsk)
 125 {
 126         struct thread_info *ti = task_thread_info(tsk);
 127         unsigned long flags;
 128         cputime_t delta_stime;
 129         __u64 now;
 130
 131         local_irq_save(flags);
 132
 133         now = ia64_get_itc();
 134
 135         delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
 136         if (irq_count() || idle_task(smp_processor_id()) != tsk)
 137                 account_system_time(tsk, 0, delta_stime, delta_stime);
 138         else
 139                 account_idle_time(delta_stime);
 140         ti->ac_stime = 0;
 141
 142         ti->ac_stamp = now;
 143
 144         local_irq_restore(flags);
 145 }
 146 EXPORT_SYMBOL_GPL(account_system_vtime);
 147
 148 /*
 149  * Called from the timer interrupt handler to charge accumulated user time
 150  * to the current process.  Must be called with interrupts disabled.
 151  */
 152 void account_process_tick(struct task_struct *p, int user_tick)
 153 {
 154         struct thread_info *ti = task_thread_info(p);
 155         cputime_t delta_utime;
 156
 157         if (ti->ac_utime) {
 158                 delta_utime = cycle_to_cputime(ti->ac_utime);
 159                 account_user_time(p, delta_utime, delta_utime);
 160                 ti->ac_utime = 0;
 161         }
 162 }
 163
 164 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 165
 166 static irqreturn_t
 167 timer_interrupt (int irq, void *dev_id)
 168 {
 169         unsigned long new_itm;
 170
 171         if (unlikely(cpu_is_offline(smp_processor_id()))) {
 172                 return IRQ_HANDLED;
 173         }
 174
 175         platform_timer_interrupt(irq, dev_id);
 176
 177         new_itm = local_cpu_data->itm_next;
 178
 179         if (!time_after(ia64_get_itc(), new_itm))
 180                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
 181                        ia64_get_itc(), new_itm);
 182
 183         profile_tick(CPU_PROFILING);
 184
 185         if (paravirt_do_steal_accounting(&new_itm))
 186                 goto skip_process_time_accounting;
 187
 188         while (1) {
 189                 update_process_times(user_mode(get_irq_regs()));
 190
 191                 new_itm += local_cpu_data->itm_delta;
 192
 193                 if (smp_processor_id() == time_keeper_id) {
 194                         /*
 195                          * Here we are in the timer irq handler. We have irqs locally
 196                          * disabled, but we don't know if the timer_bh is running on
 197                          * another CPU. We need to avoid to SMP race by acquiring the
 198                          * xtime_lock.
 199                          */
 200                         write_seqlock(&xtime_lock);
 201                         do_timer(1);
 202                         local_cpu_data->itm_next = new_itm;
 203                         write_sequnlock(&xtime_lock);
 204                 } else
 205                         local_cpu_data->itm_next = new_itm;
 206
 207                 if (time_after(new_itm, ia64_get_itc()))
 208                         break;
 209
 210                 /*
 211                  * Allow IPIs to interrupt the timer loop.
 212                  */
 213                 local_irq_enable();
 214                 local_irq_disable();
 215         }
 216
 217 skip_process_time_accounting:
 218
 219         do {
 220                 /*
 221                  * If we're too close to the next clock tick for
 222                  * comfort, we increase the safety margin by
 223                  * intentionally dropping the next tick(s).  We do NOT
 224                  * update itm.next because that would force us to call
 225                  * do_timer() which in turn would let our clock run
 226                  * too fast (with the potentially devastating effect
 227                  * of losing monotony of time).
 228                  */
 229                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
 230                         new_itm += local_cpu_data->itm_delta;
 231                 ia64_set_itm(new_itm);
 232                 /* double check, in case we got hit by a (slow) PMI: */
 233         } while (time_after_eq(ia64_get_itc(), new_itm));
 234         return IRQ_HANDLED;
 235 }
 236
 237 /*
 238  * Encapsulate access to the itm structure for SMP.
 239  */
 240 void
 241 ia64_cpu_local_tick (void)
 242 {
 243         int cpu = smp_processor_id();
 244         unsigned long shift = 0, delta;
 245
 246         /* arrange for the cycle counter to generate a timer interrupt: */
 247         ia64_set_itv(IA64_TIMER_VECTOR);
 248
 249         delta = local_cpu_data->itm_delta;
 250         /*
 251          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
 252          * same time:
 253          */
 254         if (cpu) {
 255                 unsigned long hi = 1UL << ia64_fls(cpu);
 256                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
 257         }
 258         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
 259         ia64_set_itm(local_cpu_data->itm_next);
 260 }
 261
 262 static int nojitter;
 263
 264 static int __init nojitter_setup(char *str)
 265 {
 266         nojitter = 1;
 267         printk("Jitter checking for ITC timers disabled\n");
 268         return 1;
 269 }
 270
 271 __setup("nojitter", nojitter_setup);
 272
 273
 274 void __devinit
 275 ia64_init_itm (void)
 276 {
 277         unsigned long platform_base_freq, itc_freq;
 278         struct pal_freq_ratio itc_ratio, proc_ratio;
 279         long status, platform_base_drift, itc_drift;
 280
 281         /*
 282          * According to SAL v2.6, we need to use a SAL call to determine the platform base
 283          * frequency and then a PAL call to determine the frequency ratio between the ITC
 284          * and the base frequency.
 285          */
 286         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
 287                                     &platform_base_freq, &platform_base_drift);
 288         if (status != 0) {
 289                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
 290         } else {
 291                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
 292                 if (status != 0)
 293                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
 294         }
 295         if (status != 0) {
 296                 /* invent "random" values */
 297                 printk(KERN_ERR
 298                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
 299                 platform_base_freq = 100000000;
 300                 platform_base_drift = -1;       /* no drift info */
 301                 itc_ratio.num = 3;
 302                 itc_ratio.den = 1;
 303         }
 304         if (platform_base_freq < 40000000) {
 305                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
 306                        platform_base_freq);
 307                 platform_base_freq = 75000000;
 308                 platform_base_drift = -1;
 309         }
 310         if (!proc_ratio.den)
 311                 proc_ratio.den = 1;     /* avoid division by zero */
 312         if (!itc_ratio.den)
 313                 itc_ratio.den = 1;      /* avoid division by zero */
 314
 315         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
 316
 317         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
 318         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
 319                "ITC freq=%lu.%03luMHz", smp_processor_id(),
 320                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
 321                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
 322
 323         if (platform_base_drift != -1) {
 324                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
 325                 printk("+/-%ldppm\n", itc_drift);
 326         } else {
 327                 itc_drift = -1;
 328                 printk("\n");
 329         }
 330
 331         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
 332         local_cpu_data->itc_freq = itc_freq;
 333         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
 334         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
 335                                         + itc_freq/2)/itc_freq;
 336
 337         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
 338 #ifdef CONFIG_SMP
 339                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
 340                  * Jitter compensation requires a cmpxchg which may limit
 341                  * the scalability of the syscalls for retrieving time.
 342                  * The ITC synchronization is usually successful to within a few
 343                  * ITC ticks but this is not a sure thing. If you need to improve
 344                  * timer performance in SMP situations then boot the kernel with the
 345                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
 346                  * even going backward) if the ITC offsets between the individual CPUs
 347                  * are too large.
 348                  */
 349                 if (!nojitter)
 350                         itc_jitter_data.itc_jitter = 1;
 351 #endif
 352         } else
 353                 /*
 354                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
 355                  * ITC values may fluctuate significantly between processors.
 356                  * Clock should not be used for hrtimers. Mark itc as only
 357                  * useful for boot and testing.
 358                  *
 359                  * Note that jitter compensation is off! There is no point of
 360                  * synchronizing ITCs since they may be large differentials
 361                  * that change over time.
 362                  *
 363                  * The only way to fix this would be to repeatedly sync the
 364                  * ITCs. Until that time we have to avoid ITC.
 365                  */
 366                 clocksource_itc.rating = 50;
 367
 368         paravirt_init_missing_ticks_accounting(smp_processor_id());
 369
 370         /* avoid softlock up message when cpu is unplug and plugged again. */
 371         touch_softlockup_watchdog();
 372
 373         /* Setup the CPU local timer tick */
 374         ia64_cpu_local_tick();
 375
 376         if (!itc_clocksource) {
 377                 /* Sort out mult/shift values: */
 378                 clocksource_itc.mult =
 379                         clocksource_hz2mult(local_cpu_data->itc_freq,
 380                                                 clocksource_itc.shift);
 381                 clocksource_register(&clocksource_itc);
 382                 itc_clocksource = &clocksource_itc;
 383         }
 384 }
 385
 386 static cycle_t itc_get_cycles(void)
 387 {
 388         u64 lcycle, now, ret;
 389
 390         if (!itc_jitter_data.itc_jitter)
 391                 return get_cycles();
 392
 393         lcycle = itc_jitter_data.itc_lastcycle;
 394         now = get_cycles();
 395         if (lcycle && time_after(lcycle, now))
 396                 return lcycle;
 397
 398         /*
 399          * Keep track of the last timer value returned.
 400          * In an SMP environment, you could lose out in contention of
 401          * cmpxchg. If so, your cmpxchg returns new value which the
 402          * winner of contention updated to. Use the new value instead.
 403          */
 404         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
 405         if (unlikely(ret != lcycle))
 406                 return ret;
 407
 408         return now;
 409 }
 410
 411
 412 static struct irqaction timer_irqaction = {
 413         .handler =      timer_interrupt,
 414         .flags =        IRQF_DISABLED | IRQF_IRQPOLL,
 415         .name =         "timer"
 416 };
 417
 418 static struct platform_device rtc_efi_dev = {
 419         .name = "rtc-efi",
 420         .id = -1,
 421 };
 422
 423 static int __init rtc_init(void)
 424 {
 425         if (platform_device_register(&rtc_efi_dev) < 0)
 426                 printk(KERN_ERR "unable to register rtc device...\n");
 427
 428         /* not necessarily an error */
 429         return 0;
 430 }
 431 module_init(rtc_init);
 432
 433 void __init
 434 time_init (void)
 435 {
 436         register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
 437         efi_gettimeofday(&xtime);
 438         ia64_init_itm();
 439
 440         /*
 441          * Initialize wall_to_monotonic such that adding it to xtime will yield zero, the
 442          * tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC).
 443          */
 444         set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
 445 }
 446
 447 /*
 448  * Generic udelay assumes that if preemption is allowed and the thread
 449  * migrates to another CPU, that the ITC values are synchronized across
 450  * all CPUs.
 451  */
 452 static void
 453 ia64_itc_udelay (unsigned long usecs)
 454 {
 455         unsigned long start = ia64_get_itc();
 456         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
 457
 458         while (time_before(ia64_get_itc(), end))
 459                 cpu_relax();
 460 }
 461
 462 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
 463
 464 void
 465 udelay (unsigned long usecs)
 466 {
 467         (*ia64_udelay)(usecs);
 468 }
 469 EXPORT_SYMBOL(udelay);
 470
 471 /* IA64 doesn't cache the timezone */
 472 void update_vsyscall_tz(void)
 473 {
 474 }
 475
 476 void update_vsyscall(struct timespec *wall, struct clocksource *c)
 477 {
 478         unsigned long flags;
 479
 480         write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags);
 481
 482         /* copy fsyscall clock data */
 483         fsyscall_gtod_data.clk_mask = c->mask;
 484         fsyscall_gtod_data.clk_mult = c->mult;
 485         fsyscall_gtod_data.clk_shift = c->shift;
 486         fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio;
 487         fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
 488
 489         /* copy kernel time structures */
 490         fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
 491         fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
 492         fsyscall_gtod_data.monotonic_time.tv_sec = wall_to_monotonic.tv_sec
 493                                                         + wall->tv_sec;
 494         fsyscall_gtod_data.monotonic_time.tv_nsec = wall_to_monotonic.tv_nsec
 495                                                         + wall->tv_nsec;
 496
 497         /* normalize */
 498         while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
 499                 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
 500                 fsyscall_gtod_data.monotonic_time.tv_sec++;
 501         }
 502
 503         write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
 504 }
 505