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 */
sched_clock(void)53 unsigned long long sched_clock(void)
54 {
55 return paravirt_sched_clock();
56 }
57 #endif
58
59 #ifdef CONFIG_PARAVIRT
60 static void
paravirt_clocksource_resume(struct clocksource * cs)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
vtime_account_user(struct task_struct * tsk)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 */
arch_vtime_task_switch(struct task_struct * prev)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 */
vtime_delta(struct task_struct * tsk)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
vtime_account_system(struct task_struct * tsk)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
vtime_account_idle(struct task_struct * tsk)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
timer_interrupt(int irq,void * dev_id)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
ia64_cpu_local_tick(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
nojitter_setup(char * str)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
ia64_init_itm(void)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
itc_get_cycles(struct clocksource * cs)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
read_persistent_clock(struct timespec * ts)387 void read_persistent_clock(struct timespec *ts)
388 {
389 efi_gettimeofday(ts);
390 }
391
392 void __init
time_init(void)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
ia64_itc_udelay(unsigned long usecs)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
udelay(unsigned long usecs)417 udelay (unsigned long usecs)
418 {
419 (*ia64_udelay)(usecs);
420 }
421 EXPORT_SYMBOL(udelay);
422
423 /* IA64 doesn't cache the timezone */
update_vsyscall_tz(void)424 void update_vsyscall_tz(void)
425 {
426 }
427
update_vsyscall_old(struct timespec * wall,struct timespec * wtm,struct clocksource * c,u32 mult,cycle_t cycle_last)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