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