kernel/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/timekeeper_internal.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
  33 #include "fsyscall_gtod_data.h"
  34
  35 static cycle_t itc_get_cycles(struct clocksource *cs);
  36
  37 struct fsyscall_gtod_data_t fsyscall_gtod_data;
  38
  39 struct itc_jitter_data_t itc_jitter_data;
  40
  41 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
  42
  43 #ifdef CONFIG_IA64_DEBUG_IRQ
  44
  45 unsigned long last_cli_ip;
  46 EXPORT_SYMBOL(last_cli_ip);
  47
  48 #endif
  49
  50 #ifdef CONFIG_PARAVIRT
  51 /* We need to define a real function for sched_clock, to override the
  52    weak default version */
  53 unsigned long long sched_clock(void)
  54 {
  55         return paravirt_sched_clock();
  56 }
  57 #endif
  58
  59 #ifdef CONFIG_PARAVIRT
  60 static void
  61 paravirt_clocksource_resume(struct clocksource *cs)
  62 {
  63         if (pv_time_ops.clocksource_resume)
  64                 pv_time_ops.clocksource_resume();
  65 }
  66 #endif
  67
  68 static struct clocksource clocksource_itc = {
  69         .name           = "itc",
  70         .rating         = 350,
  71         .read           = itc_get_cycles,
  72         .mask           = CLOCKSOURCE_MASK(64),
  73         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  74 #ifdef CONFIG_PARAVIRT
  75         .resume         = paravirt_clocksource_resume,
  76 #endif
  77 };
  78 static struct clocksource *itc_clocksource;
  79
  80 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
  81
  82 #include <linux/kernel_stat.h>
  83
  84 extern cputime_t cycle_to_cputime(u64 cyc);
  85
  86 void vtime_account_user(struct task_struct *tsk)
  87 {
  88         cputime_t delta_utime;
  89         struct thread_info *ti = task_thread_info(tsk);
  90
  91         if (ti->ac_utime) {
  92                 delta_utime = cycle_to_cputime(ti->ac_utime);
  93                 account_user_time(tsk, delta_utime, delta_utime);
  94                 ti->ac_utime = 0;
  95         }
  96 }
  97
  98 /*
  99  * Called from the context switch with interrupts disabled, to charge all
 100  * accumulated times to the current process, and to prepare accounting on
 101  * the next process.
 102  */
 103 void arch_vtime_task_switch(struct task_struct *prev)
 104 {
 105         struct thread_info *pi = task_thread_info(prev);
 106         struct thread_info *ni = task_thread_info(current);
 107
 108         pi->ac_stamp = ni->ac_stamp;
 109         ni->ac_stime = ni->ac_utime = 0;
 110 }
 111
 112 /*
 113  * Account time for a transition between system, hard irq or soft irq state.
 114  * Note that this function is called with interrupts enabled.
 115  */
 116 static cputime_t vtime_delta(struct task_struct *tsk)
 117 {
 118         struct thread_info *ti = task_thread_info(tsk);
 119         cputime_t delta_stime;
 120         __u64 now;
 121
 122         WARN_ON_ONCE(!irqs_disabled());
 123
 124         now = ia64_get_itc();
 125
 126         delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
 127         ti->ac_stime = 0;
 128         ti->ac_stamp = now;
 129
 130         return delta_stime;
 131 }
 132
 133 void vtime_account_system(struct task_struct *tsk)
 134 {
 135         cputime_t delta = vtime_delta(tsk);
 136
 137         account_system_time(tsk, 0, delta, delta);
 138 }
 139 EXPORT_SYMBOL_GPL(vtime_account_system);
 140
 141 void vtime_account_idle(struct task_struct *tsk)
 142 {
 143         account_idle_time(vtime_delta(tsk));
 144 }
 145
 146 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
 147
 148 static irqreturn_t
 149 timer_interrupt (int irq, void *dev_id)
 150 {
 151         unsigned long new_itm;
 152
 153         if (cpu_is_offline(smp_processor_id())) {
 154                 return IRQ_HANDLED;
 155         }
 156
 157         platform_timer_interrupt(irq, dev_id);
 158
 159         new_itm = local_cpu_data->itm_next;
 160
 161         if (!time_after(ia64_get_itc(), new_itm))
 162                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
 163                        ia64_get_itc(), new_itm);
 164
 165         profile_tick(CPU_PROFILING);
 166
 167         if (paravirt_do_steal_accounting(&new_itm))
 168                 goto skip_process_time_accounting;
 169
 170         while (1) {
 171                 update_process_times(user_mode(get_irq_regs()));
 172
 173                 new_itm += local_cpu_data->itm_delta;
 174
 175                 if (smp_processor_id() == time_keeper_id)
 176                         xtime_update(1);
 177
 178                 local_cpu_data->itm_next = new_itm;
 179
 180                 if (time_after(new_itm, ia64_get_itc()))
 181                         break;
 182
 183                 /*
 184                  * Allow IPIs to interrupt the timer loop.
 185                  */
 186                 local_irq_enable();
 187                 local_irq_disable();
 188         }
 189
 190 skip_process_time_accounting:
 191
 192         do {
 193                 /*
 194                  * If we're too close to the next clock tick for
 195                  * comfort, we increase the safety margin by
 196                  * intentionally dropping the next tick(s).  We do NOT
 197                  * update itm.next because that would force us to call
 198                  * xtime_update() which in turn would let our clock run
 199                  * too fast (with the potentially devastating effect
 200                  * of losing monotony of time).
 201                  */
 202                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
 203                         new_itm += local_cpu_data->itm_delta;
 204                 ia64_set_itm(new_itm);
 205                 /* double check, in case we got hit by a (slow) PMI: */
 206         } while (time_after_eq(ia64_get_itc(), new_itm));
 207         return IRQ_HANDLED;
 208 }
 209
 210 /*
 211  * Encapsulate access to the itm structure for SMP.
 212  */
 213 void
 214 ia64_cpu_local_tick (void)
 215 {
 216         int cpu = smp_processor_id();
 217         unsigned long shift = 0, delta;
 218
 219         /* arrange for the cycle counter to generate a timer interrupt: */
 220         ia64_set_itv(IA64_TIMER_VECTOR);
 221
 222         delta = local_cpu_data->itm_delta;
 223         /*
 224          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
 225          * same time:
 226          */
 227         if (cpu) {
 228                 unsigned long hi = 1UL << ia64_fls(cpu);
 229                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
 230         }
 231         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
 232         ia64_set_itm(local_cpu_data->itm_next);
 233 }
 234
 235 static int nojitter;
 236
 237 static int __init nojitter_setup(char *str)
 238 {
 239         nojitter = 1;
 240         printk("Jitter checking for ITC timers disabled\n");
 241         return 1;
 242 }
 243
 244 __setup("nojitter", nojitter_setup);
 245
 246
 247 void ia64_init_itm(void)
 248 {
 249         unsigned long platform_base_freq, itc_freq;
 250         struct pal_freq_ratio itc_ratio, proc_ratio;
 251         long status, platform_base_drift, itc_drift;
 252
 253         /*
 254          * According to SAL v2.6, we need to use a SAL call to determine the platform base
 255          * frequency and then a PAL call to determine the frequency ratio between the ITC
 256          * and the base frequency.
 257          */
 258         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
 259                                     &platform_base_freq, &platform_base_drift);
 260         if (status != 0) {
 261                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
 262         } else {
 263                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
 264                 if (status != 0)
 265                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
 266         }
 267         if (status != 0) {
 268                 /* invent "random" values */
 269                 printk(KERN_ERR
 270                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
 271                 platform_base_freq = 100000000;
 272                 platform_base_drift = -1;       /* no drift info */
 273                 itc_ratio.num = 3;
 274                 itc_ratio.den = 1;
 275         }
 276         if (platform_base_freq < 40000000) {
 277                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
 278                        platform_base_freq);
 279                 platform_base_freq = 75000000;
 280                 platform_base_drift = -1;
 281         }
 282         if (!proc_ratio.den)
 283                 proc_ratio.den = 1;     /* avoid division by zero */
 284         if (!itc_ratio.den)
 285                 itc_ratio.den = 1;      /* avoid division by zero */
 286
 287         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
 288
 289         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
 290         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
 291                "ITC freq=%lu.%03luMHz", smp_processor_id(),
 292                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
 293                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
 294
 295         if (platform_base_drift != -1) {
 296                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
 297                 printk("+/-%ldppm\n", itc_drift);
 298         } else {
 299                 itc_drift = -1;
 300                 printk("\n");
 301         }
 302
 303         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
 304         local_cpu_data->itc_freq = itc_freq;
 305         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
 306         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
 307                                         + itc_freq/2)/itc_freq;
 308
 309         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
 310 #ifdef CONFIG_SMP
 311                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
 312                  * Jitter compensation requires a cmpxchg which may limit
 313                  * the scalability of the syscalls for retrieving time.
 314                  * The ITC synchronization is usually successful to within a few
 315                  * ITC ticks but this is not a sure thing. If you need to improve
 316                  * timer performance in SMP situations then boot the kernel with the
 317                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
 318                  * even going backward) if the ITC offsets between the individual CPUs
 319                  * are too large.
 320                  */
 321                 if (!nojitter)
 322                         itc_jitter_data.itc_jitter = 1;
 323 #endif
 324         } else
 325                 /*
 326                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
 327                  * ITC values may fluctuate significantly between processors.
 328                  * Clock should not be used for hrtimers. Mark itc as only
 329                  * useful for boot and testing.
 330                  *
 331                  * Note that jitter compensation is off! There is no point of
 332                  * synchronizing ITCs since they may be large differentials
 333                  * that change over time.
 334                  *
 335                  * The only way to fix this would be to repeatedly sync the
 336                  * ITCs. Until that time we have to avoid ITC.
 337                  */
 338                 clocksource_itc.rating = 50;
 339
 340         paravirt_init_missing_ticks_accounting(smp_processor_id());
 341
 342         /* avoid softlock up message when cpu is unplug and plugged again. */
 343         touch_softlockup_watchdog();
 344
 345         /* Setup the CPU local timer tick */
 346         ia64_cpu_local_tick();
 347
 348         if (!itc_clocksource) {
 349                 clocksource_register_hz(&clocksource_itc,
 350                                                 local_cpu_data->itc_freq);
 351                 itc_clocksource = &clocksource_itc;
 352         }
 353 }
 354
 355 static cycle_t itc_get_cycles(struct clocksource *cs)
 356 {
 357         unsigned long lcycle, now, ret;
 358
 359         if (!itc_jitter_data.itc_jitter)
 360                 return get_cycles();
 361
 362         lcycle = itc_jitter_data.itc_lastcycle;
 363         now = get_cycles();
 364         if (lcycle && time_after(lcycle, now))
 365                 return lcycle;
 366
 367         /*
 368          * Keep track of the last timer value returned.
 369          * In an SMP environment, you could lose out in contention of
 370          * cmpxchg. If so, your cmpxchg returns new value which the
 371          * winner of contention updated to. Use the new value instead.
 372          */
 373         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
 374         if (unlikely(ret != lcycle))
 375                 return ret;
 376
 377         return now;
 378 }
 379
 380
 381 static struct irqaction timer_irqaction = {
 382         .handler =      timer_interrupt,
 383         .flags =        IRQF_IRQPOLL,
 384         .name =         "timer"
 385 };
 386
 387 void read_persistent_clock(struct timespec *ts)
 388 {
 389         efi_gettimeofday(ts);
 390 }
 391
 392 void __init
 393 time_init (void)
 394 {
 395         register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
 396         ia64_init_itm();
 397 }
 398
 399 /*
 400  * Generic udelay assumes that if preemption is allowed and the thread
 401  * migrates to another CPU, that the ITC values are synchronized across
 402  * all CPUs.
 403  */
 404 static void
 405 ia64_itc_udelay (unsigned long usecs)
 406 {
 407         unsigned long start = ia64_get_itc();
 408         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
 409
 410         while (time_before(ia64_get_itc(), end))
 411                 cpu_relax();
 412 }
 413
 414 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
 415
 416 void
 417 udelay (unsigned long usecs)
 418 {
 419         (*ia64_udelay)(usecs);
 420 }
 421 EXPORT_SYMBOL(udelay);
 422
 423 /* IA64 doesn't cache the timezone */
 424 void update_vsyscall_tz(void)
 425 {
 426 }
 427
 428 void update_vsyscall_old(struct timespec *wall, struct timespec *wtm,
 429                          struct clocksource *c, u32 mult, cycle_t cycle_last)
 430 {
 431         write_seqcount_begin(&fsyscall_gtod_data.seq);
 432
 433         /* copy fsyscall clock data */
 434         fsyscall_gtod_data.clk_mask = c->mask;
 435         fsyscall_gtod_data.clk_mult = mult;
 436         fsyscall_gtod_data.clk_shift = c->shift;
 437         fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio;
 438         fsyscall_gtod_data.clk_cycle_last = cycle_last;
 439
 440         /* copy kernel time structures */
 441         fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
 442         fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
 443         fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
 444                                                         + wall->tv_sec;
 445         fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
 446                                                         + wall->tv_nsec;
 447
 448         /* normalize */
 449         while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
 450                 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
 451                 fsyscall_gtod_data.monotonic_time.tv_sec++;
 452         }
 453
 454         write_seqcount_end(&fsyscall_gtod_data.seq);
 455 }
 456