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 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(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 } 485 486