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(struct clocksource *cs);
  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(struct clocksource *cs)
  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         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  77 #ifdef CONFIG_PARAVIRT
  78         .resume         = paravirt_clocksource_resume,
  79 #endif
  80 };
  81 static struct clocksource *itc_clocksource;
  82
  83 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
  84
  85 #include <linux/kernel_stat.h>
  86
  87 extern cputime_t cycle_to_cputime(u64 cyc);
  88
  89 /*
  90  * Called from the context switch with interrupts disabled, to charge all
  91  * accumulated times to the current process, and to prepare accounting on
  92  * the next process.
  93  */
  94 void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next)
  95 {
  96         struct thread_info *pi = task_thread_info(prev);
  97         struct thread_info *ni = task_thread_info(next);
  98         cputime_t delta_stime, delta_utime;
  99         __u64 now;
 100
 101         now = ia64_get_itc();
 102
 103         delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp));
 104         if (idle_task(smp_processor_id()) != prev)
 105                 account_system_time(prev, 0, delta_stime, delta_stime);
 106         else
 107                 account_idle_time(delta_stime);
 108
 109         if (pi->ac_utime) {
 110                 delta_utime = cycle_to_cputime(pi->ac_utime);
 111                 account_user_time(prev, delta_utime, delta_utime);
 112         }
 113
 114         pi->ac_stamp = ni->ac_stamp = now;
 115         ni->ac_stime = ni->ac_utime = 0;
 116 }
 117
 118 /*
 119  * Account time for a transition between system, hard irq or soft irq state.
 120  * Note that this function is called with interrupts enabled.
 121  */
 122 void account_system_vtime(struct task_struct *tsk)
 123 {
 124         struct thread_info *ti = task_thread_info(tsk);
 125         unsigned long flags;
 126         cputime_t delta_stime;
 127         __u64 now;
 128
 129         local_irq_save(flags);
 130
 131         now = ia64_get_itc();
 132
 133         delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
 134         if (irq_count() || idle_task(smp_processor_id()) != tsk)
 135                 account_system_time(tsk, 0, delta_stime, delta_stime);
 136         else
 137                 account_idle_time(delta_stime);
 138         ti->ac_stime = 0;
 139
 140         ti->ac_stamp = now;
 141
 142         local_irq_restore(flags);
 143 }
 144 EXPORT_SYMBOL_GPL(account_system_vtime);
 145
 146 /*
 147  * Called from the timer interrupt handler to charge accumulated user time
 148  * to the current process.  Must be called with interrupts disabled.
 149  */
 150 void account_process_tick(struct task_struct *p, int user_tick)
 151 {
 152         struct thread_info *ti = task_thread_info(p);
 153         cputime_t delta_utime;
 154
 155         if (ti->ac_utime) {
 156                 delta_utime = cycle_to_cputime(ti->ac_utime);
 157                 account_user_time(p, delta_utime, delta_utime);
 158                 ti->ac_utime = 0;
 159         }
 160 }
 161
 162 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 163
 164 static irqreturn_t
 165 timer_interrupt (int irq, void *dev_id)
 166 {
 167         unsigned long new_itm;
 168
 169         if (cpu_is_offline(smp_processor_id())) {
 170                 return IRQ_HANDLED;
 171         }
 172
 173         platform_timer_interrupt(irq, dev_id);
 174
 175         new_itm = local_cpu_data->itm_next;
 176
 177         if (!time_after(ia64_get_itc(), new_itm))
 178                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
 179                        ia64_get_itc(), new_itm);
 180
 181         profile_tick(CPU_PROFILING);
 182
 183         if (paravirt_do_steal_accounting(&new_itm))
 184                 goto skip_process_time_accounting;
 185
 186         while (1) {
 187                 update_process_times(user_mode(get_irq_regs()));
 188
 189                 new_itm += local_cpu_data->itm_delta;
 190
 191                 if (smp_processor_id() == time_keeper_id)
 192                         xtime_update(1);
 193
 194                 local_cpu_data->itm_next = new_itm;
 195
 196                 if (time_after(new_itm, ia64_get_itc()))
 197                         break;
 198
 199                 /*
 200                  * Allow IPIs to interrupt the timer loop.
 201                  */
 202                 local_irq_enable();
 203                 local_irq_disable();
 204         }
 205
 206 skip_process_time_accounting:
 207
 208         do {
 209                 /*
 210                  * If we're too close to the next clock tick for
 211                  * comfort, we increase the safety margin by
 212                  * intentionally dropping the next tick(s).  We do NOT
 213                  * update itm.next because that would force us to call
 214                  * xtime_update() which in turn would let our clock run
 215                  * too fast (with the potentially devastating effect
 216                  * of losing monotony of time).
 217                  */
 218                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
 219                         new_itm += local_cpu_data->itm_delta;
 220                 ia64_set_itm(new_itm);
 221                 /* double check, in case we got hit by a (slow) PMI: */
 222         } while (time_after_eq(ia64_get_itc(), new_itm));
 223         return IRQ_HANDLED;
 224 }
 225
 226 /*
 227  * Encapsulate access to the itm structure for SMP.
 228  */
 229 void
 230 ia64_cpu_local_tick (void)
 231 {
 232         int cpu = smp_processor_id();
 233         unsigned long shift = 0, delta;
 234
 235         /* arrange for the cycle counter to generate a timer interrupt: */
 236         ia64_set_itv(IA64_TIMER_VECTOR);
 237
 238         delta = local_cpu_data->itm_delta;
 239         /*
 240          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
 241          * same time:
 242          */
 243         if (cpu) {
 244                 unsigned long hi = 1UL << ia64_fls(cpu);
 245                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
 246         }
 247         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
 248         ia64_set_itm(local_cpu_data->itm_next);
 249 }
 250
 251 static int nojitter;
 252
 253 static int __init nojitter_setup(char *str)
 254 {
 255         nojitter = 1;
 256         printk("Jitter checking for ITC timers disabled\n");
 257         return 1;
 258 }
 259
 260 __setup("nojitter", nojitter_setup);
 261
 262
 263 void __devinit
 264 ia64_init_itm (void)
 265 {
 266         unsigned long platform_base_freq, itc_freq;
 267         struct pal_freq_ratio itc_ratio, proc_ratio;
 268         long status, platform_base_drift, itc_drift;
 269
 270         /*
 271          * According to SAL v2.6, we need to use a SAL call to determine the platform base
 272          * frequency and then a PAL call to determine the frequency ratio between the ITC
 273          * and the base frequency.
 274          */
 275         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
 276                                     &platform_base_freq, &platform_base_drift);
 277         if (status != 0) {
 278                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
 279         } else {
 280                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
 281                 if (status != 0)
 282                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
 283         }
 284         if (status != 0) {
 285                 /* invent "random" values */
 286                 printk(KERN_ERR
 287                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
 288                 platform_base_freq = 100000000;
 289                 platform_base_drift = -1;       /* no drift info */
 290                 itc_ratio.num = 3;
 291                 itc_ratio.den = 1;
 292         }
 293         if (platform_base_freq < 40000000) {
 294                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
 295                        platform_base_freq);
 296                 platform_base_freq = 75000000;
 297                 platform_base_drift = -1;
 298         }
 299         if (!proc_ratio.den)
 300                 proc_ratio.den = 1;     /* avoid division by zero */
 301         if (!itc_ratio.den)
 302                 itc_ratio.den = 1;      /* avoid division by zero */
 303
 304         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
 305
 306         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
 307         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
 308                "ITC freq=%lu.%03luMHz", smp_processor_id(),
 309                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
 310                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
 311
 312         if (platform_base_drift != -1) {
 313                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
 314                 printk("+/-%ldppm\n", itc_drift);
 315         } else {
 316                 itc_drift = -1;
 317                 printk("\n");
 318         }
 319
 320         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
 321         local_cpu_data->itc_freq = itc_freq;
 322         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
 323         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
 324                                         + itc_freq/2)/itc_freq;
 325
 326         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
 327 #ifdef CONFIG_SMP
 328                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
 329                  * Jitter compensation requires a cmpxchg which may limit
 330                  * the scalability of the syscalls for retrieving time.
 331                  * The ITC synchronization is usually successful to within a few
 332                  * ITC ticks but this is not a sure thing. If you need to improve
 333                  * timer performance in SMP situations then boot the kernel with the
 334                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
 335                  * even going backward) if the ITC offsets between the individual CPUs
 336                  * are too large.
 337                  */
 338                 if (!nojitter)
 339                         itc_jitter_data.itc_jitter = 1;
 340 #endif
 341         } else
 342                 /*
 343                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
 344                  * ITC values may fluctuate significantly between processors.
 345                  * Clock should not be used for hrtimers. Mark itc as only
 346                  * useful for boot and testing.
 347                  *
 348                  * Note that jitter compensation is off! There is no point of
 349                  * synchronizing ITCs since they may be large differentials
 350                  * that change over time.
 351                  *
 352                  * The only way to fix this would be to repeatedly sync the
 353                  * ITCs. Until that time we have to avoid ITC.
 354                  */
 355                 clocksource_itc.rating = 50;
 356
 357         paravirt_init_missing_ticks_accounting(smp_processor_id());
 358
 359         /* avoid softlock up message when cpu is unplug and plugged again. */
 360         touch_softlockup_watchdog();
 361
 362         /* Setup the CPU local timer tick */
 363         ia64_cpu_local_tick();
 364
 365         if (!itc_clocksource) {
 366                 clocksource_register_hz(&clocksource_itc,
 367                                                 local_cpu_data->itc_freq);
 368                 itc_clocksource = &clocksource_itc;
 369         }
 370 }
 371
 372 static cycle_t itc_get_cycles(struct clocksource *cs)
 373 {
 374         unsigned long lcycle, now, ret;
 375
 376         if (!itc_jitter_data.itc_jitter)
 377                 return get_cycles();
 378
 379         lcycle = itc_jitter_data.itc_lastcycle;
 380         now = get_cycles();
 381         if (lcycle && time_after(lcycle, now))
 382                 return lcycle;
 383
 384         /*
 385          * Keep track of the last timer value returned.
 386          * In an SMP environment, you could lose out in contention of
 387          * cmpxchg. If so, your cmpxchg returns new value which the
 388          * winner of contention updated to. Use the new value instead.
 389          */
 390         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
 391         if (unlikely(ret != lcycle))
 392                 return ret;
 393
 394         return now;
 395 }
 396
 397
 398 static struct irqaction timer_irqaction = {
 399         .handler =      timer_interrupt,
 400         .flags =        IRQF_DISABLED | IRQF_IRQPOLL,
 401         .name =         "timer"
 402 };
 403
 404 static struct platform_device rtc_efi_dev = {
 405         .name = "rtc-efi",
 406         .id = -1,
 407 };
 408
 409 static int __init rtc_init(void)
 410 {
 411         if (platform_device_register(&rtc_efi_dev) < 0)
 412                 printk(KERN_ERR "unable to register rtc device...\n");
 413
 414         /* not necessarily an error */
 415         return 0;
 416 }
 417 module_init(rtc_init);
 418
 419 void read_persistent_clock(struct timespec *ts)
 420 {
 421         efi_gettimeofday(ts);
 422 }
 423
 424 void __init
 425 time_init (void)
 426 {
 427         register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
 428         ia64_init_itm();
 429 }
 430
 431 /*
 432  * Generic udelay assumes that if preemption is allowed and the thread
 433  * migrates to another CPU, that the ITC values are synchronized across
 434  * all CPUs.
 435  */
 436 static void
 437 ia64_itc_udelay (unsigned long usecs)
 438 {
 439         unsigned long start = ia64_get_itc();
 440         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
 441
 442         while (time_before(ia64_get_itc(), end))
 443                 cpu_relax();
 444 }
 445
 446 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
 447
 448 void
 449 udelay (unsigned long usecs)
 450 {
 451         (*ia64_udelay)(usecs);
 452 }
 453 EXPORT_SYMBOL(udelay);
 454
 455 /* IA64 doesn't cache the timezone */
 456 void update_vsyscall_tz(void)
 457 {
 458 }
 459
 460 void update_vsyscall(struct timespec *wall, struct timespec *wtm,
 461                         struct clocksource *c, u32 mult)
 462 {
 463         unsigned long flags;
 464
 465         write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags);
 466
 467         /* copy fsyscall clock data */
 468         fsyscall_gtod_data.clk_mask = c->mask;
 469         fsyscall_gtod_data.clk_mult = mult;
 470         fsyscall_gtod_data.clk_shift = c->shift;
 471         fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio;
 472         fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
 473
 474         /* copy kernel time structures */
 475         fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
 476         fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
 477         fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
 478                                                         + wall->tv_sec;
 479         fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
 480                                                         + wall->tv_nsec;
 481
 482         /* normalize */
 483         while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
 484                 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
 485                 fsyscall_gtod_data.monotonic_time.tv_sec++;
 486         }
 487
 488         write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
 489 }
 490