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