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