2 * linux/arch/ia64/kernel/time.c
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>
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/nmi.h>
20 #include <linux/interrupt.h>
21 #include <linux/efi.h>
22 #include <linux/timex.h>
23 #include <linux/timekeeper_internal.h>
24 #include <linux/platform_device.h>
25 #include <linux/sched/cputime.h>
27 #include <asm/machvec.h>
28 #include <asm/delay.h>
29 #include <asm/hw_irq.h>
30 #include <asm/ptrace.h>
32 #include <asm/sections.h>
34 #include "fsyscall_gtod_data.h"
36 static u64
itc_get_cycles(struct clocksource
*cs
);
38 struct fsyscall_gtod_data_t fsyscall_gtod_data
;
40 struct itc_jitter_data_t itc_jitter_data
;
42 volatile int time_keeper_id
= 0; /* smp_processor_id() of time-keeper */
44 #ifdef CONFIG_IA64_DEBUG_IRQ
46 unsigned long last_cli_ip
;
47 EXPORT_SYMBOL(last_cli_ip
);
51 static struct clocksource clocksource_itc
= {
54 .read
= itc_get_cycles
,
55 .mask
= CLOCKSOURCE_MASK(64),
56 .flags
= CLOCK_SOURCE_IS_CONTINUOUS
,
58 static struct clocksource
*itc_clocksource
;
60 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
62 #include <linux/kernel_stat.h>
64 extern u64
cycle_to_nsec(u64 cyc
);
66 void vtime_flush(struct task_struct
*tsk
)
68 struct thread_info
*ti
= task_thread_info(tsk
);
72 account_user_time(tsk
, cycle_to_nsec(ti
->utime
));
75 account_guest_time(tsk
, cycle_to_nsec(ti
->gtime
));
78 account_idle_time(cycle_to_nsec(ti
->idle_time
));
81 delta
= cycle_to_nsec(ti
->stime
);
82 account_system_index_time(tsk
, delta
, CPUTIME_SYSTEM
);
85 if (ti
->hardirq_time
) {
86 delta
= cycle_to_nsec(ti
->hardirq_time
);
87 account_system_index_time(tsk
, delta
, CPUTIME_IRQ
);
90 if (ti
->softirq_time
) {
91 delta
= cycle_to_nsec(ti
->softirq_time
));
92 account_system_index_time(tsk
, delta
, CPUTIME_SOFTIRQ
);
100 ti
->softirq_time
= 0;
104 * Called from the context switch with interrupts disabled, to charge all
105 * accumulated times to the current process, and to prepare accounting on
108 void arch_vtime_task_switch(struct task_struct
*prev
)
110 struct thread_info
*pi
= task_thread_info(prev
);
111 struct thread_info
*ni
= task_thread_info(current
);
113 ni
->ac_stamp
= pi
->ac_stamp
;
114 ni
->ac_stime
= ni
->ac_utime
= 0;
118 * Account time for a transition between system, hard irq or soft irq state.
119 * Note that this function is called with interrupts enabled.
121 static __u64
vtime_delta(struct task_struct
*tsk
)
123 struct thread_info
*ti
= task_thread_info(tsk
);
124 __u64 now
, delta_stime
;
126 WARN_ON_ONCE(!irqs_disabled());
128 now
= ia64_get_itc();
129 delta_stime
= now
- ti
->ac_stamp
;
135 void vtime_account_system(struct task_struct
*tsk
)
137 struct thread_info
*ti
= task_thread_info(tsk
);
138 __u64 stime
= vtime_delta(tsk
);
140 if ((tsk
->flags
& PF_VCPU
) && !irq_count())
142 else if (hardirq_count())
143 ti
->hardirq_time
+= stime
;
144 else if (in_serving_softirq())
145 ti
->softirq_time
+= stime
;
149 EXPORT_SYMBOL_GPL(vtime_account_system
);
151 void vtime_account_idle(struct task_struct
*tsk
)
153 struct thread_info
*ti
= task_thread_info(tsk
);
155 ti
->idle_time
+= vtime_delta(tsk
);
158 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
161 timer_interrupt (int irq
, void *dev_id
)
163 unsigned long new_itm
;
165 if (cpu_is_offline(smp_processor_id())) {
169 platform_timer_interrupt(irq
, dev_id
);
171 new_itm
= local_cpu_data
->itm_next
;
173 if (!time_after(ia64_get_itc(), new_itm
))
174 printk(KERN_ERR
"Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
175 ia64_get_itc(), new_itm
);
177 profile_tick(CPU_PROFILING
);
180 update_process_times(user_mode(get_irq_regs()));
182 new_itm
+= local_cpu_data
->itm_delta
;
184 if (smp_processor_id() == time_keeper_id
)
187 local_cpu_data
->itm_next
= new_itm
;
189 if (time_after(new_itm
, ia64_get_itc()))
193 * Allow IPIs to interrupt the timer loop.
201 * If we're too close to the next clock tick for
202 * comfort, we increase the safety margin by
203 * intentionally dropping the next tick(s). We do NOT
204 * update itm.next because that would force us to call
205 * xtime_update() which in turn would let our clock run
206 * too fast (with the potentially devastating effect
207 * of losing monotony of time).
209 while (!time_after(new_itm
, ia64_get_itc() + local_cpu_data
->itm_delta
/2))
210 new_itm
+= local_cpu_data
->itm_delta
;
211 ia64_set_itm(new_itm
);
212 /* double check, in case we got hit by a (slow) PMI: */
213 } while (time_after_eq(ia64_get_itc(), new_itm
));
218 * Encapsulate access to the itm structure for SMP.
221 ia64_cpu_local_tick (void)
223 int cpu
= smp_processor_id();
224 unsigned long shift
= 0, delta
;
226 /* arrange for the cycle counter to generate a timer interrupt: */
227 ia64_set_itv(IA64_TIMER_VECTOR
);
229 delta
= local_cpu_data
->itm_delta
;
231 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
235 unsigned long hi
= 1UL << ia64_fls(cpu
);
236 shift
= (2*(cpu
- hi
) + 1) * delta
/hi
/2;
238 local_cpu_data
->itm_next
= ia64_get_itc() + delta
+ shift
;
239 ia64_set_itm(local_cpu_data
->itm_next
);
244 static int __init
nojitter_setup(char *str
)
247 printk("Jitter checking for ITC timers disabled\n");
251 __setup("nojitter", nojitter_setup
);
254 void ia64_init_itm(void)
256 unsigned long platform_base_freq
, itc_freq
;
257 struct pal_freq_ratio itc_ratio
, proc_ratio
;
258 long status
, platform_base_drift
, itc_drift
;
261 * According to SAL v2.6, we need to use a SAL call to determine the platform base
262 * frequency and then a PAL call to determine the frequency ratio between the ITC
263 * and the base frequency.
265 status
= ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM
,
266 &platform_base_freq
, &platform_base_drift
);
268 printk(KERN_ERR
"SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status
));
270 status
= ia64_pal_freq_ratios(&proc_ratio
, NULL
, &itc_ratio
);
272 printk(KERN_ERR
"PAL_FREQ_RATIOS failed with status=%ld\n", status
);
275 /* invent "random" values */
277 "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
278 platform_base_freq
= 100000000;
279 platform_base_drift
= -1; /* no drift info */
283 if (platform_base_freq
< 40000000) {
284 printk(KERN_ERR
"Platform base frequency %lu bogus---resetting to 75MHz!\n",
286 platform_base_freq
= 75000000;
287 platform_base_drift
= -1;
290 proc_ratio
.den
= 1; /* avoid division by zero */
292 itc_ratio
.den
= 1; /* avoid division by zero */
294 itc_freq
= (platform_base_freq
*itc_ratio
.num
)/itc_ratio
.den
;
296 local_cpu_data
->itm_delta
= (itc_freq
+ HZ
/2) / HZ
;
297 printk(KERN_DEBUG
"CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
298 "ITC freq=%lu.%03luMHz", smp_processor_id(),
299 platform_base_freq
/ 1000000, (platform_base_freq
/ 1000) % 1000,
300 itc_ratio
.num
, itc_ratio
.den
, itc_freq
/ 1000000, (itc_freq
/ 1000) % 1000);
302 if (platform_base_drift
!= -1) {
303 itc_drift
= platform_base_drift
*itc_ratio
.num
/itc_ratio
.den
;
304 printk("+/-%ldppm\n", itc_drift
);
310 local_cpu_data
->proc_freq
= (platform_base_freq
*proc_ratio
.num
)/proc_ratio
.den
;
311 local_cpu_data
->itc_freq
= itc_freq
;
312 local_cpu_data
->cyc_per_usec
= (itc_freq
+ USEC_PER_SEC
/2) / USEC_PER_SEC
;
313 local_cpu_data
->nsec_per_cyc
= ((NSEC_PER_SEC
<<IA64_NSEC_PER_CYC_SHIFT
)
314 + itc_freq
/2)/itc_freq
;
316 if (!(sal_platform_features
& IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT
)) {
318 /* On IA64 in an SMP configuration ITCs are never accurately synchronized.
319 * Jitter compensation requires a cmpxchg which may limit
320 * the scalability of the syscalls for retrieving time.
321 * The ITC synchronization is usually successful to within a few
322 * ITC ticks but this is not a sure thing. If you need to improve
323 * timer performance in SMP situations then boot the kernel with the
324 * "nojitter" option. However, doing so may result in time fluctuating (maybe
325 * even going backward) if the ITC offsets between the individual CPUs
329 itc_jitter_data
.itc_jitter
= 1;
333 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
334 * ITC values may fluctuate significantly between processors.
335 * Clock should not be used for hrtimers. Mark itc as only
336 * useful for boot and testing.
338 * Note that jitter compensation is off! There is no point of
339 * synchronizing ITCs since they may be large differentials
340 * that change over time.
342 * The only way to fix this would be to repeatedly sync the
343 * ITCs. Until that time we have to avoid ITC.
345 clocksource_itc
.rating
= 50;
347 /* avoid softlock up message when cpu is unplug and plugged again. */
348 touch_softlockup_watchdog();
350 /* Setup the CPU local timer tick */
351 ia64_cpu_local_tick();
353 if (!itc_clocksource
) {
354 clocksource_register_hz(&clocksource_itc
,
355 local_cpu_data
->itc_freq
);
356 itc_clocksource
= &clocksource_itc
;
360 static u64
itc_get_cycles(struct clocksource
*cs
)
362 unsigned long lcycle
, now
, ret
;
364 if (!itc_jitter_data
.itc_jitter
)
367 lcycle
= itc_jitter_data
.itc_lastcycle
;
369 if (lcycle
&& time_after(lcycle
, now
))
373 * Keep track of the last timer value returned.
374 * In an SMP environment, you could lose out in contention of
375 * cmpxchg. If so, your cmpxchg returns new value which the
376 * winner of contention updated to. Use the new value instead.
378 ret
= cmpxchg(&itc_jitter_data
.itc_lastcycle
, lcycle
, now
);
379 if (unlikely(ret
!= lcycle
))
386 static struct irqaction timer_irqaction
= {
387 .handler
= timer_interrupt
,
388 .flags
= IRQF_IRQPOLL
,
392 void read_persistent_clock64(struct timespec64
*ts
)
394 efi_gettimeofday(ts
);
400 register_percpu_irq(IA64_TIMER_VECTOR
, &timer_irqaction
);
405 * Generic udelay assumes that if preemption is allowed and the thread
406 * migrates to another CPU, that the ITC values are synchronized across
410 ia64_itc_udelay (unsigned long usecs
)
412 unsigned long start
= ia64_get_itc();
413 unsigned long end
= start
+ usecs
*local_cpu_data
->cyc_per_usec
;
415 while (time_before(ia64_get_itc(), end
))
419 void (*ia64_udelay
)(unsigned long usecs
) = &ia64_itc_udelay
;
422 udelay (unsigned long usecs
)
424 (*ia64_udelay
)(usecs
);
426 EXPORT_SYMBOL(udelay
);
428 /* IA64 doesn't cache the timezone */
429 void update_vsyscall_tz(void)
433 void update_vsyscall(struct timekeeper
*tk
)
435 write_seqcount_begin(&fsyscall_gtod_data
.seq
);
437 /* copy vsyscall data */
438 fsyscall_gtod_data
.clk_mask
= tk
->tkr_mono
.mask
;
439 fsyscall_gtod_data
.clk_mult
= tk
->tkr_mono
.mult
;
440 fsyscall_gtod_data
.clk_shift
= tk
->tkr_mono
.shift
;
441 fsyscall_gtod_data
.clk_fsys_mmio
= tk
->tkr_mono
.clock
->archdata
.fsys_mmio
;
442 fsyscall_gtod_data
.clk_cycle_last
= tk
->tkr_mono
.cycle_last
;
444 fsyscall_gtod_data
.wall_time
.sec
= tk
->xtime_sec
;
445 fsyscall_gtod_data
.wall_time
.snsec
= tk
->tkr_mono
.xtime_nsec
;
447 fsyscall_gtod_data
.monotonic_time
.sec
= tk
->xtime_sec
448 + tk
->wall_to_monotonic
.tv_sec
;
449 fsyscall_gtod_data
.monotonic_time
.snsec
= tk
->tkr_mono
.xtime_nsec
450 + ((u64
)tk
->wall_to_monotonic
.tv_nsec
451 << tk
->tkr_mono
.shift
);
454 while (fsyscall_gtod_data
.monotonic_time
.snsec
>=
455 (((u64
)NSEC_PER_SEC
) << tk
->tkr_mono
.shift
)) {
456 fsyscall_gtod_data
.monotonic_time
.snsec
-=
457 ((u64
)NSEC_PER_SEC
) << tk
->tkr_mono
.shift
;
458 fsyscall_gtod_data
.monotonic_time
.sec
++;
461 write_seqcount_end(&fsyscall_gtod_data
.seq
);