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
  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         .lock = __SEQLOCK_UNLOCKED(fsyscall_gtod_data.lock),
  39 };
  40
  41 struct itc_jitter_data_t itc_jitter_data;
  42
  43 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
  44
  45 #ifdef CONFIG_IA64_DEBUG_IRQ
  46
  47 unsigned long last_cli_ip;
  48 EXPORT_SYMBOL(last_cli_ip);
  49
  50 #endif
  51
  52 #ifdef CONFIG_PARAVIRT
  53 /* We need to define a real function for sched_clock, to override the
  54    weak default version */
  55 unsigned long long sched_clock(void)
  56 {
  57         return paravirt_sched_clock();
  58 }
  59 #endif
  60
  61 #ifdef CONFIG_PARAVIRT
  62 static void
  63 paravirt_clocksource_resume(struct clocksource *cs)
  64 {
  65         if (pv_time_ops.clocksource_resume)
  66                 pv_time_ops.clocksource_resume();
  67 }
  68 #endif
  69
  70 static struct clocksource clocksource_itc = {
  71         .name           = "itc",
  72         .rating         = 350,
  73         .read           = itc_get_cycles,
  74         .mask           = CLOCKSOURCE_MASK(64),
  75         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
  76 #ifdef CONFIG_PARAVIRT
  77         .resume         = paravirt_clocksource_resume,
  78 #endif
  79 };
  80 static struct clocksource *itc_clocksource;
  81
  82 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
  83
  84 #include <linux/kernel_stat.h>
  85
  86 extern cputime_t cycle_to_cputime(u64 cyc);
  87
  88 /*
  89  * Called from the context switch with interrupts disabled, to charge all
  90  * accumulated times to the current process, and to prepare accounting on
  91  * the next process.
  92  */
  93 void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next)
  94 {
  95         struct thread_info *pi = task_thread_info(prev);
  96         struct thread_info *ni = task_thread_info(next);
  97         cputime_t delta_stime, delta_utime;
  98         __u64 now;
  99
 100         now = ia64_get_itc();
 101
 102         delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp));
 103         if (idle_task(smp_processor_id()) != prev)
 104                 account_system_time(prev, 0, delta_stime, delta_stime);
 105         else
 106                 account_idle_time(delta_stime);
 107
 108         if (pi->ac_utime) {
 109                 delta_utime = cycle_to_cputime(pi->ac_utime);
 110                 account_user_time(prev, delta_utime, delta_utime);
 111         }
 112
 113         pi->ac_stamp = ni->ac_stamp = now;
 114         ni->ac_stime = ni->ac_utime = 0;
 115 }
 116
 117 /*
 118  * Account time for a transition between system, hard irq or soft irq state.
 119  * Note that this function is called with interrupts enabled.
 120  */
 121 void account_system_vtime(struct task_struct *tsk)
 122 {
 123         struct thread_info *ti = task_thread_info(tsk);
 124         unsigned long flags;
 125         cputime_t delta_stime;
 126         __u64 now;
 127
 128         local_irq_save(flags);
 129
 130         now = ia64_get_itc();
 131
 132         delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
 133         if (irq_count() || idle_task(smp_processor_id()) != tsk)
 134                 account_system_time(tsk, 0, delta_stime, delta_stime);
 135         else
 136                 account_idle_time(delta_stime);
 137         ti->ac_stime = 0;
 138
 139         ti->ac_stamp = now;
 140
 141         local_irq_restore(flags);
 142 }
 143 EXPORT_SYMBOL_GPL(account_system_vtime);
 144
 145 /*
 146  * Called from the timer interrupt handler to charge accumulated user time
 147  * to the current process.  Must be called with interrupts disabled.
 148  */
 149 void account_process_tick(struct task_struct *p, int user_tick)
 150 {
 151         struct thread_info *ti = task_thread_info(p);
 152         cputime_t delta_utime;
 153
 154         if (ti->ac_utime) {
 155                 delta_utime = cycle_to_cputime(ti->ac_utime);
 156                 account_user_time(p, delta_utime, delta_utime);
 157                 ti->ac_utime = 0;
 158         }
 159 }
 160
 161 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 162
 163 static irqreturn_t
 164 timer_interrupt (int irq, void *dev_id)
 165 {
 166         unsigned long new_itm;
 167
 168         if (cpu_is_offline(smp_processor_id())) {
 169                 return IRQ_HANDLED;
 170         }
 171
 172         platform_timer_interrupt(irq, dev_id);
 173
 174         new_itm = local_cpu_data->itm_next;
 175
 176         if (!time_after(ia64_get_itc(), new_itm))
 177                 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
 178                        ia64_get_itc(), new_itm);
 179
 180         profile_tick(CPU_PROFILING);
 181
 182         if (paravirt_do_steal_accounting(&new_itm))
 183                 goto skip_process_time_accounting;
 184
 185         while (1) {
 186                 update_process_times(user_mode(get_irq_regs()));
 187
 188                 new_itm += local_cpu_data->itm_delta;
 189
 190                 if (smp_processor_id() == time_keeper_id)
 191                         xtime_update(1);
 192
 193                 local_cpu_data->itm_next = new_itm;
 194
 195                 if (time_after(new_itm, ia64_get_itc()))
 196                         break;
 197
 198                 /*
 199                  * Allow IPIs to interrupt the timer loop.
 200                  */
 201                 local_irq_enable();
 202                 local_irq_disable();
 203         }
 204
 205 skip_process_time_accounting:
 206
 207         do {
 208                 /*
 209                  * If we're too close to the next clock tick for
 210                  * comfort, we increase the safety margin by
 211                  * intentionally dropping the next tick(s).  We do NOT
 212                  * update itm.next because that would force us to call
 213                  * xtime_update() which in turn would let our clock run
 214                  * too fast (with the potentially devastating effect
 215                  * of losing monotony of time).
 216                  */
 217                 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
 218                         new_itm += local_cpu_data->itm_delta;
 219                 ia64_set_itm(new_itm);
 220                 /* double check, in case we got hit by a (slow) PMI: */
 221         } while (time_after_eq(ia64_get_itc(), new_itm));
 222         return IRQ_HANDLED;
 223 }
 224
 225 /*
 226  * Encapsulate access to the itm structure for SMP.
 227  */
 228 void
 229 ia64_cpu_local_tick (void)
 230 {
 231         int cpu = smp_processor_id();
 232         unsigned long shift = 0, delta;
 233
 234         /* arrange for the cycle counter to generate a timer interrupt: */
 235         ia64_set_itv(IA64_TIMER_VECTOR);
 236
 237         delta = local_cpu_data->itm_delta;
 238         /*
 239          * Stagger the timer tick for each CPU so they don't occur all at (almost) the
 240          * same time:
 241          */
 242         if (cpu) {
 243                 unsigned long hi = 1UL << ia64_fls(cpu);
 244                 shift = (2*(cpu - hi) + 1) * delta/hi/2;
 245         }
 246         local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
 247         ia64_set_itm(local_cpu_data->itm_next);
 248 }
 249
 250 static int nojitter;
 251
 252 static int __init nojitter_setup(char *str)
 253 {
 254         nojitter = 1;
 255         printk("Jitter checking for ITC timers disabled\n");
 256         return 1;
 257 }
 258
 259 __setup("nojitter", nojitter_setup);
 260
 261
 262 void __devinit
 263 ia64_init_itm (void)
 264 {
 265         unsigned long platform_base_freq, itc_freq;
 266         struct pal_freq_ratio itc_ratio, proc_ratio;
 267         long status, platform_base_drift, itc_drift;
 268
 269         /*
 270          * According to SAL v2.6, we need to use a SAL call to determine the platform base
 271          * frequency and then a PAL call to determine the frequency ratio between the ITC
 272          * and the base frequency.
 273          */
 274         status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
 275                                     &platform_base_freq, &platform_base_drift);
 276         if (status != 0) {
 277                 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
 278         } else {
 279                 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
 280                 if (status != 0)
 281                         printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
 282         }
 283         if (status != 0) {
 284                 /* invent "random" values */
 285                 printk(KERN_ERR
 286                        "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
 287                 platform_base_freq = 100000000;
 288                 platform_base_drift = -1;       /* no drift info */
 289                 itc_ratio.num = 3;
 290                 itc_ratio.den = 1;
 291         }
 292         if (platform_base_freq < 40000000) {
 293                 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
 294                        platform_base_freq);
 295                 platform_base_freq = 75000000;
 296                 platform_base_drift = -1;
 297         }
 298         if (!proc_ratio.den)
 299                 proc_ratio.den = 1;     /* avoid division by zero */
 300         if (!itc_ratio.den)
 301                 itc_ratio.den = 1;      /* avoid division by zero */
 302
 303         itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
 304
 305         local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
 306         printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
 307                "ITC freq=%lu.%03luMHz", smp_processor_id(),
 308                platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
 309                itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
 310
 311         if (platform_base_drift != -1) {
 312                 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
 313                 printk("+/-%ldppm\n", itc_drift);
 314         } else {
 315                 itc_drift = -1;
 316                 printk("\n");
 317         }
 318
 319         local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
 320         local_cpu_data->itc_freq = itc_freq;
 321         local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
 322         local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
 323                                         + itc_freq/2)/itc_freq;
 324
 325         if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
 326 #ifdef CONFIG_SMP
 327                 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
 328                  * Jitter compensation requires a cmpxchg which may limit
 329                  * the scalability of the syscalls for retrieving time.
 330                  * The ITC synchronization is usually successful to within a few
 331                  * ITC ticks but this is not a sure thing. If you need to improve
 332                  * timer performance in SMP situations then boot the kernel with the
 333                  * "nojitter" option. However, doing so may result in time fluctuating (maybe
 334                  * even going backward) if the ITC offsets between the individual CPUs
 335                  * are too large.
 336                  */
 337                 if (!nojitter)
 338                         itc_jitter_data.itc_jitter = 1;
 339 #endif
 340         } else
 341                 /*
 342                  * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
 343                  * ITC values may fluctuate significantly between processors.
 344                  * Clock should not be used for hrtimers. Mark itc as only
 345                  * useful for boot and testing.
 346                  *
 347                  * Note that jitter compensation is off! There is no point of
 348                  * synchronizing ITCs since they may be large differentials
 349                  * that change over time.
 350                  *
 351                  * The only way to fix this would be to repeatedly sync the
 352                  * ITCs. Until that time we have to avoid ITC.
 353                  */
 354                 clocksource_itc.rating = 50;
 355
 356         paravirt_init_missing_ticks_accounting(smp_processor_id());
 357
 358         /* avoid softlock up message when cpu is unplug and plugged again. */
 359         touch_softlockup_watchdog();
 360
 361         /* Setup the CPU local timer tick */
 362         ia64_cpu_local_tick();
 363
 364         if (!itc_clocksource) {
 365                 clocksource_register_hz(&clocksource_itc,
 366                                                 local_cpu_data->itc_freq);
 367                 itc_clocksource = &clocksource_itc;
 368         }
 369 }
 370
 371 static cycle_t itc_get_cycles(struct clocksource *cs)
 372 {
 373         unsigned long lcycle, now, ret;
 374
 375         if (!itc_jitter_data.itc_jitter)
 376                 return get_cycles();
 377
 378         lcycle = itc_jitter_data.itc_lastcycle;
 379         now = get_cycles();
 380         if (lcycle && time_after(lcycle, now))
 381                 return lcycle;
 382
 383         /*
 384          * Keep track of the last timer value returned.
 385          * In an SMP environment, you could lose out in contention of
 386          * cmpxchg. If so, your cmpxchg returns new value which the
 387          * winner of contention updated to. Use the new value instead.
 388          */
 389         ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
 390         if (unlikely(ret != lcycle))
 391                 return ret;
 392
 393         return now;
 394 }
 395
 396
 397 static struct irqaction timer_irqaction = {
 398         .handler =      timer_interrupt,
 399         .flags =        IRQF_DISABLED | IRQF_IRQPOLL,
 400         .name =         "timer"
 401 };
 402
 403 static struct platform_device rtc_efi_dev = {
 404         .name = "rtc-efi",
 405         .id = -1,
 406 };
 407
 408 static int __init rtc_init(void)
 409 {
 410         if (platform_device_register(&rtc_efi_dev) < 0)
 411                 printk(KERN_ERR "unable to register rtc device...\n");
 412
 413         /* not necessarily an error */
 414         return 0;
 415 }
 416 module_init(rtc_init);
 417
 418 void read_persistent_clock(struct timespec *ts)
 419 {
 420         efi_gettimeofday(ts);
 421 }
 422
 423 void __init
 424 time_init (void)
 425 {
 426         register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
 427         ia64_init_itm();
 428 }
 429
 430 /*
 431  * Generic udelay assumes that if preemption is allowed and the thread
 432  * migrates to another CPU, that the ITC values are synchronized across
 433  * all CPUs.
 434  */
 435 static void
 436 ia64_itc_udelay (unsigned long usecs)
 437 {
 438         unsigned long start = ia64_get_itc();
 439         unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
 440
 441         while (time_before(ia64_get_itc(), end))
 442                 cpu_relax();
 443 }
 444
 445 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
 446
 447 void
 448 udelay (unsigned long usecs)
 449 {
 450         (*ia64_udelay)(usecs);
 451 }
 452 EXPORT_SYMBOL(udelay);
 453
 454 /* IA64 doesn't cache the timezone */
 455 void update_vsyscall_tz(void)
 456 {
 457 }
 458
 459 void update_vsyscall(struct timespec *wall, struct timespec *wtm,
 460                         struct clocksource *c, u32 mult)
 461 {
 462         unsigned long flags;
 463
 464         write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags);
 465
 466         /* copy fsyscall clock data */
 467         fsyscall_gtod_data.clk_mask = c->mask;
 468         fsyscall_gtod_data.clk_mult = mult;
 469         fsyscall_gtod_data.clk_shift = c->shift;
 470         fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio;
 471         fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
 472
 473         /* copy kernel time structures */
 474         fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
 475         fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
 476         fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
 477                                                         + wall->tv_sec;
 478         fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
 479                                                         + wall->tv_nsec;
 480
 481         /* normalize */
 482         while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
 483                 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
 484                 fsyscall_gtod_data.monotonic_time.tv_sec++;
 485         }
 486
 487         write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
 488 }
 489