Loading...
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#include <asm/system.h>
33
34#include "fsyscall_gtod_data.h"
35
36static cycle_t itc_get_cycles(struct clocksource *cs);
37
38struct fsyscall_gtod_data_t fsyscall_gtod_data = {
39 .lock = __SEQLOCK_UNLOCKED(fsyscall_gtod_data.lock),
40};
41
42struct itc_jitter_data_t itc_jitter_data;
43
44volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
45
46#ifdef CONFIG_IA64_DEBUG_IRQ
47
48unsigned long last_cli_ip;
49EXPORT_SYMBOL(last_cli_ip);
50
51#endif
52
53#ifdef CONFIG_PARAVIRT
54/* We need to define a real function for sched_clock, to override the
55 weak default version */
56unsigned long long sched_clock(void)
57{
58 return paravirt_sched_clock();
59}
60#endif
61
62#ifdef CONFIG_PARAVIRT
63static void
64paravirt_clocksource_resume(struct clocksource *cs)
65{
66 if (pv_time_ops.clocksource_resume)
67 pv_time_ops.clocksource_resume();
68}
69#endif
70
71static struct clocksource clocksource_itc = {
72 .name = "itc",
73 .rating = 350,
74 .read = itc_get_cycles,
75 .mask = CLOCKSOURCE_MASK(64),
76 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
77#ifdef CONFIG_PARAVIRT
78 .resume = paravirt_clocksource_resume,
79#endif
80};
81static struct clocksource *itc_clocksource;
82
83#ifdef CONFIG_VIRT_CPU_ACCOUNTING
84
85#include <linux/kernel_stat.h>
86
87extern cputime_t cycle_to_cputime(u64 cyc);
88
89/*
90 * Called from the context switch with interrupts disabled, to charge all
91 * accumulated times to the current process, and to prepare accounting on
92 * the next process.
93 */
94void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next)
95{
96 struct thread_info *pi = task_thread_info(prev);
97 struct thread_info *ni = task_thread_info(next);
98 cputime_t delta_stime, delta_utime;
99 __u64 now;
100
101 now = ia64_get_itc();
102
103 delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp));
104 if (idle_task(smp_processor_id()) != prev)
105 account_system_time(prev, 0, delta_stime, delta_stime);
106 else
107 account_idle_time(delta_stime);
108
109 if (pi->ac_utime) {
110 delta_utime = cycle_to_cputime(pi->ac_utime);
111 account_user_time(prev, delta_utime, delta_utime);
112 }
113
114 pi->ac_stamp = ni->ac_stamp = now;
115 ni->ac_stime = ni->ac_utime = 0;
116}
117
118/*
119 * Account time for a transition between system, hard irq or soft irq state.
120 * Note that this function is called with interrupts enabled.
121 */
122void account_system_vtime(struct task_struct *tsk)
123{
124 struct thread_info *ti = task_thread_info(tsk);
125 unsigned long flags;
126 cputime_t delta_stime;
127 __u64 now;
128
129 local_irq_save(flags);
130
131 now = ia64_get_itc();
132
133 delta_stime = cycle_to_cputime(ti->ac_stime + (now - ti->ac_stamp));
134 if (irq_count() || idle_task(smp_processor_id()) != tsk)
135 account_system_time(tsk, 0, delta_stime, delta_stime);
136 else
137 account_idle_time(delta_stime);
138 ti->ac_stime = 0;
139
140 ti->ac_stamp = now;
141
142 local_irq_restore(flags);
143}
144EXPORT_SYMBOL_GPL(account_system_vtime);
145
146/*
147 * Called from the timer interrupt handler to charge accumulated user time
148 * to the current process. Must be called with interrupts disabled.
149 */
150void account_process_tick(struct task_struct *p, int user_tick)
151{
152 struct thread_info *ti = task_thread_info(p);
153 cputime_t delta_utime;
154
155 if (ti->ac_utime) {
156 delta_utime = cycle_to_cputime(ti->ac_utime);
157 account_user_time(p, delta_utime, delta_utime);
158 ti->ac_utime = 0;
159 }
160}
161
162#endif /* CONFIG_VIRT_CPU_ACCOUNTING */
163
164static irqreturn_t
165timer_interrupt (int irq, void *dev_id)
166{
167 unsigned long new_itm;
168
169 if (cpu_is_offline(smp_processor_id())) {
170 return IRQ_HANDLED;
171 }
172
173 platform_timer_interrupt(irq, dev_id);
174
175 new_itm = local_cpu_data->itm_next;
176
177 if (!time_after(ia64_get_itc(), new_itm))
178 printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
179 ia64_get_itc(), new_itm);
180
181 profile_tick(CPU_PROFILING);
182
183 if (paravirt_do_steal_accounting(&new_itm))
184 goto skip_process_time_accounting;
185
186 while (1) {
187 update_process_times(user_mode(get_irq_regs()));
188
189 new_itm += local_cpu_data->itm_delta;
190
191 if (smp_processor_id() == time_keeper_id)
192 xtime_update(1);
193
194 local_cpu_data->itm_next = new_itm;
195
196 if (time_after(new_itm, ia64_get_itc()))
197 break;
198
199 /*
200 * Allow IPIs to interrupt the timer loop.
201 */
202 local_irq_enable();
203 local_irq_disable();
204 }
205
206skip_process_time_accounting:
207
208 do {
209 /*
210 * If we're too close to the next clock tick for
211 * comfort, we increase the safety margin by
212 * intentionally dropping the next tick(s). We do NOT
213 * update itm.next because that would force us to call
214 * xtime_update() which in turn would let our clock run
215 * too fast (with the potentially devastating effect
216 * of losing monotony of time).
217 */
218 while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
219 new_itm += local_cpu_data->itm_delta;
220 ia64_set_itm(new_itm);
221 /* double check, in case we got hit by a (slow) PMI: */
222 } while (time_after_eq(ia64_get_itc(), new_itm));
223 return IRQ_HANDLED;
224}
225
226/*
227 * Encapsulate access to the itm structure for SMP.
228 */
229void
230ia64_cpu_local_tick (void)
231{
232 int cpu = smp_processor_id();
233 unsigned long shift = 0, delta;
234
235 /* arrange for the cycle counter to generate a timer interrupt: */
236 ia64_set_itv(IA64_TIMER_VECTOR);
237
238 delta = local_cpu_data->itm_delta;
239 /*
240 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
241 * same time:
242 */
243 if (cpu) {
244 unsigned long hi = 1UL << ia64_fls(cpu);
245 shift = (2*(cpu - hi) + 1) * delta/hi/2;
246 }
247 local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
248 ia64_set_itm(local_cpu_data->itm_next);
249}
250
251static int nojitter;
252
253static int __init nojitter_setup(char *str)
254{
255 nojitter = 1;
256 printk("Jitter checking for ITC timers disabled\n");
257 return 1;
258}
259
260__setup("nojitter", nojitter_setup);
261
262
263void __devinit
264ia64_init_itm (void)
265{
266 unsigned long platform_base_freq, itc_freq;
267 struct pal_freq_ratio itc_ratio, proc_ratio;
268 long status, platform_base_drift, itc_drift;
269
270 /*
271 * According to SAL v2.6, we need to use a SAL call to determine the platform base
272 * frequency and then a PAL call to determine the frequency ratio between the ITC
273 * and the base frequency.
274 */
275 status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
276 &platform_base_freq, &platform_base_drift);
277 if (status != 0) {
278 printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
279 } else {
280 status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
281 if (status != 0)
282 printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
283 }
284 if (status != 0) {
285 /* invent "random" values */
286 printk(KERN_ERR
287 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
288 platform_base_freq = 100000000;
289 platform_base_drift = -1; /* no drift info */
290 itc_ratio.num = 3;
291 itc_ratio.den = 1;
292 }
293 if (platform_base_freq < 40000000) {
294 printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
295 platform_base_freq);
296 platform_base_freq = 75000000;
297 platform_base_drift = -1;
298 }
299 if (!proc_ratio.den)
300 proc_ratio.den = 1; /* avoid division by zero */
301 if (!itc_ratio.den)
302 itc_ratio.den = 1; /* avoid division by zero */
303
304 itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
305
306 local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
307 printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
308 "ITC freq=%lu.%03luMHz", smp_processor_id(),
309 platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
310 itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
311
312 if (platform_base_drift != -1) {
313 itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
314 printk("+/-%ldppm\n", itc_drift);
315 } else {
316 itc_drift = -1;
317 printk("\n");
318 }
319
320 local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
321 local_cpu_data->itc_freq = itc_freq;
322 local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
323 local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
324 + itc_freq/2)/itc_freq;
325
326 if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
327#ifdef CONFIG_SMP
328 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
329 * Jitter compensation requires a cmpxchg which may limit
330 * the scalability of the syscalls for retrieving time.
331 * The ITC synchronization is usually successful to within a few
332 * ITC ticks but this is not a sure thing. If you need to improve
333 * timer performance in SMP situations then boot the kernel with the
334 * "nojitter" option. However, doing so may result in time fluctuating (maybe
335 * even going backward) if the ITC offsets between the individual CPUs
336 * are too large.
337 */
338 if (!nojitter)
339 itc_jitter_data.itc_jitter = 1;
340#endif
341 } else
342 /*
343 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
344 * ITC values may fluctuate significantly between processors.
345 * Clock should not be used for hrtimers. Mark itc as only
346 * useful for boot and testing.
347 *
348 * Note that jitter compensation is off! There is no point of
349 * synchronizing ITCs since they may be large differentials
350 * that change over time.
351 *
352 * The only way to fix this would be to repeatedly sync the
353 * ITCs. Until that time we have to avoid ITC.
354 */
355 clocksource_itc.rating = 50;
356
357 paravirt_init_missing_ticks_accounting(smp_processor_id());
358
359 /* avoid softlock up message when cpu is unplug and plugged again. */
360 touch_softlockup_watchdog();
361
362 /* Setup the CPU local timer tick */
363 ia64_cpu_local_tick();
364
365 if (!itc_clocksource) {
366 clocksource_register_hz(&clocksource_itc,
367 local_cpu_data->itc_freq);
368 itc_clocksource = &clocksource_itc;
369 }
370}
371
372static cycle_t itc_get_cycles(struct clocksource *cs)
373{
374 unsigned long lcycle, now, ret;
375
376 if (!itc_jitter_data.itc_jitter)
377 return get_cycles();
378
379 lcycle = itc_jitter_data.itc_lastcycle;
380 now = get_cycles();
381 if (lcycle && time_after(lcycle, now))
382 return lcycle;
383
384 /*
385 * Keep track of the last timer value returned.
386 * In an SMP environment, you could lose out in contention of
387 * cmpxchg. If so, your cmpxchg returns new value which the
388 * winner of contention updated to. Use the new value instead.
389 */
390 ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
391 if (unlikely(ret != lcycle))
392 return ret;
393
394 return now;
395}
396
397
398static struct irqaction timer_irqaction = {
399 .handler = timer_interrupt,
400 .flags = IRQF_DISABLED | IRQF_IRQPOLL,
401 .name = "timer"
402};
403
404static struct platform_device rtc_efi_dev = {
405 .name = "rtc-efi",
406 .id = -1,
407};
408
409static int __init rtc_init(void)
410{
411 if (platform_device_register(&rtc_efi_dev) < 0)
412 printk(KERN_ERR "unable to register rtc device...\n");
413
414 /* not necessarily an error */
415 return 0;
416}
417module_init(rtc_init);
418
419void read_persistent_clock(struct timespec *ts)
420{
421 efi_gettimeofday(ts);
422}
423
424void __init
425time_init (void)
426{
427 register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
428 ia64_init_itm();
429}
430
431/*
432 * Generic udelay assumes that if preemption is allowed and the thread
433 * migrates to another CPU, that the ITC values are synchronized across
434 * all CPUs.
435 */
436static void
437ia64_itc_udelay (unsigned long usecs)
438{
439 unsigned long start = ia64_get_itc();
440 unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
441
442 while (time_before(ia64_get_itc(), end))
443 cpu_relax();
444}
445
446void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
447
448void
449udelay (unsigned long usecs)
450{
451 (*ia64_udelay)(usecs);
452}
453EXPORT_SYMBOL(udelay);
454
455/* IA64 doesn't cache the timezone */
456void update_vsyscall_tz(void)
457{
458}
459
460void update_vsyscall(struct timespec *wall, struct timespec *wtm,
461 struct clocksource *c, u32 mult)
462{
463 unsigned long flags;
464
465 write_seqlock_irqsave(&fsyscall_gtod_data.lock, flags);
466
467 /* copy fsyscall clock data */
468 fsyscall_gtod_data.clk_mask = c->mask;
469 fsyscall_gtod_data.clk_mult = mult;
470 fsyscall_gtod_data.clk_shift = c->shift;
471 fsyscall_gtod_data.clk_fsys_mmio = c->archdata.fsys_mmio;
472 fsyscall_gtod_data.clk_cycle_last = c->cycle_last;
473
474 /* copy kernel time structures */
475 fsyscall_gtod_data.wall_time.tv_sec = wall->tv_sec;
476 fsyscall_gtod_data.wall_time.tv_nsec = wall->tv_nsec;
477 fsyscall_gtod_data.monotonic_time.tv_sec = wtm->tv_sec
478 + wall->tv_sec;
479 fsyscall_gtod_data.monotonic_time.tv_nsec = wtm->tv_nsec
480 + wall->tv_nsec;
481
482 /* normalize */
483 while (fsyscall_gtod_data.monotonic_time.tv_nsec >= NSEC_PER_SEC) {
484 fsyscall_gtod_data.monotonic_time.tv_nsec -= NSEC_PER_SEC;
485 fsyscall_gtod_data.monotonic_time.tv_sec++;
486 }
487
488 write_sequnlock_irqrestore(&fsyscall_gtod_data.lock, flags);
489}
490
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
35static cycle_t itc_get_cycles(struct clocksource *cs);
36
37struct fsyscall_gtod_data_t fsyscall_gtod_data;
38
39struct itc_jitter_data_t itc_jitter_data;
40
41volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
42
43#ifdef CONFIG_IA64_DEBUG_IRQ
44
45unsigned long last_cli_ip;
46EXPORT_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 */
53unsigned long long sched_clock(void)
54{
55 return paravirt_sched_clock();
56}
57#endif
58
59#ifdef CONFIG_PARAVIRT
60static void
61paravirt_clocksource_resume(struct clocksource *cs)
62{
63 if (pv_time_ops.clocksource_resume)
64 pv_time_ops.clocksource_resume();
65}
66#endif
67
68static 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};
78static struct clocksource *itc_clocksource;
79
80#ifdef CONFIG_VIRT_CPU_ACCOUNTING
81
82#include <linux/kernel_stat.h>
83
84extern 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 */
91void 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 */
119void 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}
141EXPORT_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 */
147void 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
161static irqreturn_t
162timer_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
203skip_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 */
226void
227ia64_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
248static int nojitter;
249
250static 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
260void __devinit
261ia64_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
369static 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
395static struct irqaction timer_irqaction = {
396 .handler = timer_interrupt,
397 .flags = IRQF_DISABLED | IRQF_IRQPOLL,
398 .name = "timer"
399};
400
401static struct platform_device rtc_efi_dev = {
402 .name = "rtc-efi",
403 .id = -1,
404};
405
406static 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}
414module_init(rtc_init);
415
416void read_persistent_clock(struct timespec *ts)
417{
418 efi_gettimeofday(ts);
419}
420
421void __init
422time_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 */
433static void
434ia64_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
443void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
444
445void
446udelay (unsigned long usecs)
447{
448 (*ia64_udelay)(usecs);
449}
450EXPORT_SYMBOL(udelay);
451
452/* IA64 doesn't cache the timezone */
453void update_vsyscall_tz(void)
454{
455}
456
457void 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