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 36static cycle_t itc_get_cycles(struct clocksource *cs); 37 38struct fsyscall_gtod_data_t fsyscall_gtod_data = { 39 .lock = SEQLOCK_UNLOCKED, 40}; 41 42struct itc_jitter_data_t itc_jitter_data; 43 44volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */ 45 46#ifdef CONFIG_IA64_DEBUG_IRQ 47 48unsigned long last_cli_ip; 49EXPORT_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 */ 56unsigned long long sched_clock(void) 57{ 58 return paravirt_sched_clock(); 59} 60#endif 61 62#ifdef CONFIG_PARAVIRT 63static void 64paravirt_clocksource_resume(struct clocksource *cs) 65{ 66 if (pv_time_ops.clocksource_resume) 67 pv_time_ops.clocksource_resume(); 68} 69#endif 70 71static struct clocksource clocksource_itc = { 72 .name = "itc", 73 .rating = 350, 74 .read = itc_get_cycles, 75 .mask = CLOCKSOURCE_MASK(64), 76 .mult = 0, /*to be calculated*/ 77 .shift = 16, 78 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 79#ifdef CONFIG_PARAVIRT 80 .resume = paravirt_clocksource_resume, 81#endif 82}; 83static struct clocksource *itc_clocksource; 84 85#ifdef CONFIG_VIRT_CPU_ACCOUNTING 86 87#include <linux/kernel_stat.h> 88 89extern cputime_t cycle_to_cputime(u64 cyc); 90 91/* 92 * Called from the context switch with interrupts disabled, to charge all 93 * accumulated times to the current process, and to prepare accounting on 94 * the next process. 95 */ 96void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next) 97{ 98 struct thread_info *pi = task_thread_info(prev); 99 struct thread_info *ni = task_thread_info(next); 100 cputime_t delta_stime, delta_utime; 101 __u64 now; 102 103 now = ia64_get_itc(); 104 105 delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp)); 106 if (idle_task(smp_processor_id()) != prev) 107 account_system_time(prev, 0, delta_stime, delta_stime); 108 else 109 account_idle_time(delta_stime); 110 111 if (pi->ac_utime) { 112 delta_utime = cycle_to_cputime(pi->ac_utime); 113 account_user_time(prev, delta_utime, delta_utime); 114 } 115 116 pi->ac_stamp = ni->ac_stamp = now; 117 ni->ac_stime = ni->ac_utime = 0; 118} 119 120/* 121 * Account time for a transition between system, hard irq or soft irq state. 122 * Note that this function is called with interrupts enabled. 123 */ 124void account_system_vtime(struct task_struct *tsk) 125{ 126 struct thread_info *ti = task_thread_info(tsk); 127 unsigned long flags; 128 cputime_t delta_stime; 129 __u64 now; 130 131 local_irq_save(flags); 132 133 now = ia64_get_itc(); 134 135 delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp)); 136 if (irq_count() || idle_task(smp_processor_id()) != tsk) 137 account_system_time(tsk, 0, delta_stime, delta_stime); 138 else 139 account_idle_time(delta_stime); 140 ti->ac_stime = 0; 141 142 ti->ac_stamp = now; 143 144 local_irq_restore(flags); 145} 146EXPORT_SYMBOL_GPL(account_system_vtime); 147 148/* 149 * Called from the timer interrupt handler to charge accumulated user time 150 * to the current process. Must be called with interrupts disabled. 151 */ 152void account_process_tick(struct task_struct *p, int user_tick) 153{ 154 struct thread_info *ti = task_thread_info(p); 155 cputime_t delta_utime; 156 157 if (ti->ac_utime) { 158 delta_utime = cycle_to_cputime(ti->ac_utime); 159 account_user_time(p, delta_utime, delta_utime); 160 ti->ac_utime = 0; 161 } 162} 163 164#endif /* CONFIG_VIRT_CPU_ACCOUNTING */ 165 166static irqreturn_t 167timer_interrupt (int irq, void *dev_id) 168{ 169 unsigned long new_itm; 170 171 if (unlikely(cpu_is_offline(smp_processor_id()))) { 172 return IRQ_HANDLED; 173 } 174 175 platform_timer_interrupt(irq, dev_id); 176 177 new_itm = local_cpu_data->itm_next; 178 179 if (!time_after(ia64_get_itc(), new_itm)) 180 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n", 181 ia64_get_itc(), new_itm); 182 183 profile_tick(CPU_PROFILING); 184 185 if (paravirt_do_steal_accounting(&new_itm)) 186 goto skip_process_time_accounting; 187 188 while (1) { 189 update_process_times(user_mode(get_irq_regs())); 190 191 new_itm += local_cpu_data->itm_delta; 192 193 if (smp_processor_id() == time_keeper_id) { 194 /* 195 * Here we are in the timer irq handler. We have irqs locally 196 * disabled, but we don't know if the timer_bh is running on 197 * another CPU. We need to avoid to SMP race by acquiring the 198 * xtime_lock. 199 */ 200 write_seqlock(&xtime_lock); 201 do_timer(1); 202 local_cpu_data->itm_next = new_itm; 203 write_sequnlock(&xtime_lock); 204 } else 205 local_cpu_data->itm_next = new_itm; 206 207 if (time_after(new_itm, ia64_get_itc())) 208 break; 209 210 /* 211 * Allow IPIs to interrupt the timer loop. 212 */ 213 local_irq_enable(); 214 local_irq_disable(); 215 } 216 217skip_process_time_accounting: 218 219 do { 220 /* 221 * If we're too close to the next clock tick for 222 * comfort, we increase the safety margin by 223 * intentionally dropping the next tick(s). We do NOT 224 * update itm.next because that would force us to call 225 * do_timer() which in turn would let our clock run 226 * too fast (with the potentially devastating effect 227 * of losing monotony of time). 228 */ 229 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2)) 230 new_itm += local_cpu_data->itm_delta; 231 ia64_set_itm(new_itm); 232 /* double check, in case we got hit by a (slow) PMI: */ 233 } while (time_after_eq(ia64_get_itc(), new_itm)); 234 return IRQ_HANDLED; 235} 236 237/* 238 * Encapsulate access to the itm structure for SMP. 239 */ 240void 241ia64_cpu_local_tick (void) 242{ 243 int cpu = smp_processor_id(); 244 unsigned long shift = 0, delta; 245 246 /* arrange for the cycle counter to generate a timer interrupt: */ 247 ia64_set_itv(IA64_TIMER_VECTOR); 248 249 delta = local_cpu_data->itm_delta; 250 /* 251 * Stagger the timer tick for each CPU so they don't occur all at (almost) the 252 * same time: 253 */ 254 if (cpu) { 255 unsigned long hi = 1UL << ia64_fls(cpu); 256 shift = (2*(cpu - hi) + 1) * delta/hi/2; 257 } 258 local_cpu_data->itm_next = ia64_get_itc() + delta + shift; 259 ia64_set_itm(local_cpu_data->itm_next); 260} 261 262static int nojitter; 263 264static int __init nojitter_setup(char *str) 265{ 266 nojitter = 1; 267 printk("Jitter checking for ITC timers disabled\n"); 268 return 1; 269} 270 271__setup("nojitter", nojitter_setup); 272 273 274void __devinit 275ia64_init_itm (void) 276{ 277 unsigned long platform_base_freq, itc_freq; 278 struct pal_freq_ratio itc_ratio, proc_ratio; 279 long status, platform_base_drift, itc_drift; 280 281 /* 282 * According to SAL v2.6, we need to use a SAL call to determine the platform base 283 * frequency and then a PAL call to determine the frequency ratio between the ITC 284 * and the base frequency. 285 */ 286 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM, 287 &platform_base_freq, &platform_base_drift); 288 if (status != 0) { 289 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status)); 290 } else { 291 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio); 292 if (status != 0) 293 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status); 294 } 295 if (status != 0) { 296 /* invent "random" values */ 297 printk(KERN_ERR 298 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n"); 299 platform_base_freq = 100000000; 300 platform_base_drift = -1; /* no drift info */ 301 itc_ratio.num = 3; 302 itc_ratio.den = 1; 303 } 304 if (platform_base_freq < 40000000) { 305 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n", 306 platform_base_freq); 307 platform_base_freq = 75000000; 308 platform_base_drift = -1; 309 } 310 if (!proc_ratio.den) 311 proc_ratio.den = 1; /* avoid division by zero */ 312 if (!itc_ratio.den) 313 itc_ratio.den = 1; /* avoid division by zero */ 314 315 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den; 316 317 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ; 318 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, " 319 "ITC freq=%lu.%03luMHz", smp_processor_id(), 320 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000, 321 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000); 322 323 if (platform_base_drift != -1) { 324 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den; 325 printk("+/-%ldppm\n", itc_drift); 326 } else { 327 itc_drift = -1; 328 printk("\n"); 329 } 330 331 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den; 332 local_cpu_data->itc_freq = itc_freq; 333 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC; 334 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT) 335 + itc_freq/2)/itc_freq; 336 337 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) { 338#ifdef CONFIG_SMP 339 /* On IA64 in an SMP configuration ITCs are never accurately synchronized. 340 * Jitter compensation requires a cmpxchg which may limit 341 * the scalability of the syscalls for retrieving time. 342 * The ITC synchronization is usually successful to within a few 343 * ITC ticks but this is not a sure thing. If you need to improve 344 * timer performance in SMP situations then boot the kernel with the 345 * "nojitter" option. However, doing so may result in time fluctuating (maybe 346 * even going backward) if the ITC offsets between the individual CPUs 347 * are too large. 348 */ 349 if (!nojitter) 350 itc_jitter_data.itc_jitter = 1; 351#endif 352 } else 353 /* 354 * ITC is drifty and we have not synchronized the ITCs in smpboot.c. 355 * ITC values may fluctuate significantly between processors. 356 * Clock should not be used for hrtimers. Mark itc as only 357 * useful for boot and testing. 358 * 359 * Note that jitter compensation is off! There is no point of 360 * synchronizing ITCs since they may be large differentials 361 * that change over time. 362 * 363 * The only way to fix this would be to repeatedly sync the 364 * ITCs. Until that time we have to avoid ITC. 365 */ 366 clocksource_itc.rating = 50; 367 368 paravirt_init_missing_ticks_accounting(smp_processor_id()); 369 370 /* avoid softlock up message when cpu is unplug and plugged again. */ 371 touch_softlockup_watchdog(); 372 373 /* Setup the CPU local timer tick */ 374 ia64_cpu_local_tick(); 375 376 if (!itc_clocksource) { 377 /* Sort out mult/shift values: */ 378 clocksource_itc.mult = 379 clocksource_hz2mult(local_cpu_data->itc_freq, 380 clocksource_itc.shift); 381 clocksource_register(&clocksource_itc); 382 itc_clocksource = &clocksource_itc; 383 } 384} 385 386static cycle_t itc_get_cycles(struct clocksource *cs) 387{ 388 unsigned long lcycle, now, ret; 389 390 if (!itc_jitter_data.itc_jitter) 391 return get_cycles(); 392 393 lcycle = itc_jitter_data.itc_lastcycle; 394 now = get_cycles(); 395 if (lcycle && time_after(lcycle, now)) 396 return lcycle; 397 398 /* 399 * Keep track of the last timer value returned. 400 * In an SMP environment, you could lose out in contention of 401 * cmpxchg. If so, your cmpxchg returns new value which the 402 * winner of contention updated to. Use the new value instead. 403 */ 404 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now); 405 if (unlikely(ret != lcycle)) 406 return ret; 407 408 return now; 409} 410 411 412static struct irqaction timer_irqaction = { 413 .handler = timer_interrupt, 414 .flags = IRQF_DISABLED | IRQF_IRQPOLL, 415 .name = "timer" 416}; 417 418static struct platform_device rtc_efi_dev = { 419 .name = "rtc-efi", 420 .id = -1, 421}; 422 423static int __init rtc_init(void) 424{ 425 if (platform_device_register(&rtc_efi_dev) < 0) 426 printk(KERN_ERR "unable to register rtc device...\n"); 427 428 /* not necessarily an error */ 429 return 0; 430} 431module_init(rtc_init); 432 433void read_persistent_clock(struct timespec *ts) 434{ 435 efi_gettimeofday(ts); 436} 437 438void __init 439time_init (void) 440{ 441 register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction); 442 ia64_init_itm(); 443} 444 445/* 446 * Generic udelay assumes that if preemption is allowed and the thread 447 * migrates to another CPU, that the ITC values are synchronized across 448 * all CPUs. 449 */ 450static void 451ia64_itc_udelay (unsigned long usecs) 452{ 453 unsigned long start = ia64_get_itc(); 454 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec; 455 456 while (time_before(ia64_get_itc(), end)) 457 cpu_relax(); 458} 459 460void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay; 461 462void 463udelay (unsigned long usecs) 464{ 465 (*ia64_udelay)(usecs); 466} 467EXPORT_SYMBOL(udelay); 468 469/* IA64 doesn't cache the timezone */ 470void update_vsyscall_tz(void) 471{ 472} 473 474void update_vsyscall(struct timespec *wall, struct timespec *wtm, 475 struct clocksource *c, u32 mult) 476{ 477 unsigned long flags; 478 479 write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags); 480 481 /* copy fsyscall clock data */ 482 fsyscall_gtod_data.clk_mask = c->mask; 483 fsyscall_gtod_data.clk_mult = mult; 484 fsyscall_gtod_data.clk_shift = c->shift; 485 fsyscall_gtod_data.clk_fsys_mmio = c->fsys_mmio; 486 fsyscall_gtod_data.clk_cycle_last = c->cycle_last; 487 488 /* copy kernel time structures */ 489 fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec; 490 fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec; 491 fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec 492 + wall->tv_sec; 493 fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec 494 + wall->tv_nsec; 495 496 /* normalize */ 497 while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) { 498 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC; 499 fsyscall_gtod_data.monotonic_time.tv_sec++; 500 } 501 502 write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags); 503} 504