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/ptrace.h> 29 #include <asm/sal.h> 30 #include <asm/sections.h> 31 32 #include "fsyscall_gtod_data.h" 33 34 static cycle_t itc_get_cycles(struct clocksource *cs); 35 36 struct fsyscall_gtod_data_t fsyscall_gtod_data; 37 38 struct itc_jitter_data_t itc_jitter_data; 39 40 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */ 41 42 #ifdef CONFIG_IA64_DEBUG_IRQ 43 44 unsigned long last_cli_ip; 45 EXPORT_SYMBOL(last_cli_ip); 46 47 #endif 48 49 static struct clocksource clocksource_itc = { 50 .name = "itc", 51 .rating = 350, 52 .read = itc_get_cycles, 53 .mask = CLOCKSOURCE_MASK(64), 54 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 55 }; 56 static struct clocksource *itc_clocksource; 57 58 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE 59 60 #include <linux/kernel_stat.h> 61 62 extern cputime_t cycle_to_cputime(u64 cyc); 63 64 void vtime_account_user(struct task_struct *tsk) 65 { 66 cputime_t delta_utime; 67 struct thread_info *ti = task_thread_info(tsk); 68 69 if (ti->ac_utime) { 70 delta_utime = cycle_to_cputime(ti->ac_utime); 71 account_user_time(tsk, delta_utime, delta_utime); 72 ti->ac_utime = 0; 73 } 74 } 75 76 /* 77 * Called from the context switch with interrupts disabled, to charge all 78 * accumulated times to the current process, and to prepare accounting on 79 * the next process. 80 */ 81 void arch_vtime_task_switch(struct task_struct *prev) 82 { 83 struct thread_info *pi = task_thread_info(prev); 84 struct thread_info *ni = task_thread_info(current); 85 86 pi->ac_stamp = ni->ac_stamp; 87 ni->ac_stime = ni->ac_utime = 0; 88 } 89 90 /* 91 * Account time for a transition between system, hard irq or soft irq state. 92 * Note that this function is called with interrupts enabled. 93 */ 94 static cputime_t vtime_delta(struct task_struct *tsk) 95 { 96 struct thread_info *ti = task_thread_info(tsk); 97 cputime_t delta_stime; 98 __u64 now; 99 100 WARN_ON_ONCE(!irqs_disabled()); 101 102 now = ia64_get_itc(); 103 104 delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp)); 105 ti->ac_stime = 0; 106 ti->ac_stamp = now; 107 108 return delta_stime; 109 } 110 111 void vtime_account_system(struct task_struct *tsk) 112 { 113 cputime_t delta = vtime_delta(tsk); 114 115 account_system_time(tsk, 0, delta, delta); 116 } 117 EXPORT_SYMBOL_GPL(vtime_account_system); 118 119 void vtime_account_idle(struct task_struct *tsk) 120 { 121 account_idle_time(vtime_delta(tsk)); 122 } 123 124 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */ 125 126 static irqreturn_t 127 timer_interrupt (int irq, void *dev_id) 128 { 129 unsigned long new_itm; 130 131 if (cpu_is_offline(smp_processor_id())) { 132 return IRQ_HANDLED; 133 } 134 135 platform_timer_interrupt(irq, dev_id); 136 137 new_itm = local_cpu_data->itm_next; 138 139 if (!time_after(ia64_get_itc(), new_itm)) 140 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n", 141 ia64_get_itc(), new_itm); 142 143 profile_tick(CPU_PROFILING); 144 145 while (1) { 146 update_process_times(user_mode(get_irq_regs())); 147 148 new_itm += local_cpu_data->itm_delta; 149 150 if (smp_processor_id() == time_keeper_id) 151 xtime_update(1); 152 153 local_cpu_data->itm_next = new_itm; 154 155 if (time_after(new_itm, ia64_get_itc())) 156 break; 157 158 /* 159 * Allow IPIs to interrupt the timer loop. 160 */ 161 local_irq_enable(); 162 local_irq_disable(); 163 } 164 165 do { 166 /* 167 * If we're too close to the next clock tick for 168 * comfort, we increase the safety margin by 169 * intentionally dropping the next tick(s). We do NOT 170 * update itm.next because that would force us to call 171 * xtime_update() which in turn would let our clock run 172 * too fast (with the potentially devastating effect 173 * of losing monotony of time). 174 */ 175 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2)) 176 new_itm += local_cpu_data->itm_delta; 177 ia64_set_itm(new_itm); 178 /* double check, in case we got hit by a (slow) PMI: */ 179 } while (time_after_eq(ia64_get_itc(), new_itm)); 180 return IRQ_HANDLED; 181 } 182 183 /* 184 * Encapsulate access to the itm structure for SMP. 185 */ 186 void 187 ia64_cpu_local_tick (void) 188 { 189 int cpu = smp_processor_id(); 190 unsigned long shift = 0, delta; 191 192 /* arrange for the cycle counter to generate a timer interrupt: */ 193 ia64_set_itv(IA64_TIMER_VECTOR); 194 195 delta = local_cpu_data->itm_delta; 196 /* 197 * Stagger the timer tick for each CPU so they don't occur all at (almost) the 198 * same time: 199 */ 200 if (cpu) { 201 unsigned long hi = 1UL << ia64_fls(cpu); 202 shift = (2*(cpu - hi) + 1) * delta/hi/2; 203 } 204 local_cpu_data->itm_next = ia64_get_itc() + delta + shift; 205 ia64_set_itm(local_cpu_data->itm_next); 206 } 207 208 static int nojitter; 209 210 static int __init nojitter_setup(char *str) 211 { 212 nojitter = 1; 213 printk("Jitter checking for ITC timers disabled\n"); 214 return 1; 215 } 216 217 __setup("nojitter", nojitter_setup); 218 219 220 void ia64_init_itm(void) 221 { 222 unsigned long platform_base_freq, itc_freq; 223 struct pal_freq_ratio itc_ratio, proc_ratio; 224 long status, platform_base_drift, itc_drift; 225 226 /* 227 * According to SAL v2.6, we need to use a SAL call to determine the platform base 228 * frequency and then a PAL call to determine the frequency ratio between the ITC 229 * and the base frequency. 230 */ 231 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM, 232 &platform_base_freq, &platform_base_drift); 233 if (status != 0) { 234 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status)); 235 } else { 236 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio); 237 if (status != 0) 238 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status); 239 } 240 if (status != 0) { 241 /* invent "random" values */ 242 printk(KERN_ERR 243 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n"); 244 platform_base_freq = 100000000; 245 platform_base_drift = -1; /* no drift info */ 246 itc_ratio.num = 3; 247 itc_ratio.den = 1; 248 } 249 if (platform_base_freq < 40000000) { 250 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n", 251 platform_base_freq); 252 platform_base_freq = 75000000; 253 platform_base_drift = -1; 254 } 255 if (!proc_ratio.den) 256 proc_ratio.den = 1; /* avoid division by zero */ 257 if (!itc_ratio.den) 258 itc_ratio.den = 1; /* avoid division by zero */ 259 260 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den; 261 262 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ; 263 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, " 264 "ITC freq=%lu.%03luMHz", smp_processor_id(), 265 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000, 266 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000); 267 268 if (platform_base_drift != -1) { 269 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den; 270 printk("+/-%ldppm\n", itc_drift); 271 } else { 272 itc_drift = -1; 273 printk("\n"); 274 } 275 276 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den; 277 local_cpu_data->itc_freq = itc_freq; 278 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC; 279 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT) 280 + itc_freq/2)/itc_freq; 281 282 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) { 283 #ifdef CONFIG_SMP 284 /* On IA64 in an SMP configuration ITCs are never accurately synchronized. 285 * Jitter compensation requires a cmpxchg which may limit 286 * the scalability of the syscalls for retrieving time. 287 * The ITC synchronization is usually successful to within a few 288 * ITC ticks but this is not a sure thing. If you need to improve 289 * timer performance in SMP situations then boot the kernel with the 290 * "nojitter" option. However, doing so may result in time fluctuating (maybe 291 * even going backward) if the ITC offsets between the individual CPUs 292 * are too large. 293 */ 294 if (!nojitter) 295 itc_jitter_data.itc_jitter = 1; 296 #endif 297 } else 298 /* 299 * ITC is drifty and we have not synchronized the ITCs in smpboot.c. 300 * ITC values may fluctuate significantly between processors. 301 * Clock should not be used for hrtimers. Mark itc as only 302 * useful for boot and testing. 303 * 304 * Note that jitter compensation is off! There is no point of 305 * synchronizing ITCs since they may be large differentials 306 * that change over time. 307 * 308 * The only way to fix this would be to repeatedly sync the 309 * ITCs. Until that time we have to avoid ITC. 310 */ 311 clocksource_itc.rating = 50; 312 313 /* avoid softlock up message when cpu is unplug and plugged again. */ 314 touch_softlockup_watchdog(); 315 316 /* Setup the CPU local timer tick */ 317 ia64_cpu_local_tick(); 318 319 if (!itc_clocksource) { 320 clocksource_register_hz(&clocksource_itc, 321 local_cpu_data->itc_freq); 322 itc_clocksource = &clocksource_itc; 323 } 324 } 325 326 static cycle_t itc_get_cycles(struct clocksource *cs) 327 { 328 unsigned long lcycle, now, ret; 329 330 if (!itc_jitter_data.itc_jitter) 331 return get_cycles(); 332 333 lcycle = itc_jitter_data.itc_lastcycle; 334 now = get_cycles(); 335 if (lcycle && time_after(lcycle, now)) 336 return lcycle; 337 338 /* 339 * Keep track of the last timer value returned. 340 * In an SMP environment, you could lose out in contention of 341 * cmpxchg. If so, your cmpxchg returns new value which the 342 * winner of contention updated to. Use the new value instead. 343 */ 344 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now); 345 if (unlikely(ret != lcycle)) 346 return ret; 347 348 return now; 349 } 350 351 352 static struct irqaction timer_irqaction = { 353 .handler = timer_interrupt, 354 .flags = IRQF_IRQPOLL, 355 .name = "timer" 356 }; 357 358 void read_persistent_clock(struct timespec *ts) 359 { 360 efi_gettimeofday(ts); 361 } 362 363 void __init 364 time_init (void) 365 { 366 register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction); 367 ia64_init_itm(); 368 } 369 370 /* 371 * Generic udelay assumes that if preemption is allowed and the thread 372 * migrates to another CPU, that the ITC values are synchronized across 373 * all CPUs. 374 */ 375 static void 376 ia64_itc_udelay (unsigned long usecs) 377 { 378 unsigned long start = ia64_get_itc(); 379 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec; 380 381 while (time_before(ia64_get_itc(), end)) 382 cpu_relax(); 383 } 384 385 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay; 386 387 void 388 udelay (unsigned long usecs) 389 { 390 (*ia64_udelay)(usecs); 391 } 392 EXPORT_SYMBOL(udelay); 393 394 /* IA64 doesn't cache the timezone */ 395 void update_vsyscall_tz(void) 396 { 397 } 398 399 void update_vsyscall_old(struct timespec *wall, struct timespec *wtm, 400 struct clocksource *c, u32 mult, cycle_t cycle_last) 401 { 402 write_seqcount_begin(&fsyscall_gtod_data.seq); 403 404 /* copy fsyscall clock data */ 405 fsyscall_gtod_data.clk_mask = c->mask; 406 fsyscall_gtod_data.clk_mult = mult; 407 fsyscall_gtod_data.clk_shift = c->shift; 408 fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio; 409 fsyscall_gtod_data.clk_cycle_last = cycle_last; 410 411 /* copy kernel time structures */ 412 fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec; 413 fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec; 414 fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec 415 + wall->tv_sec; 416 fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec 417 + wall->tv_nsec; 418 419 /* normalize */ 420 while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) { 421 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC; 422 fsyscall_gtod_data.monotonic_time.tv_sec++; 423 } 424 425 write_seqcount_end(&fsyscall_gtod_data.seq); 426 } 427 428