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