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
vtime_account_user(struct task_struct * tsk)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 */
arch_vtime_task_switch(struct task_struct * prev)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 */
vtime_delta(struct task_struct * tsk)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
vtime_account_system(struct task_struct * tsk)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
vtime_account_idle(struct task_struct * tsk)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
timer_interrupt(int irq,void * dev_id)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
ia64_cpu_local_tick(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
nojitter_setup(char * str)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
ia64_init_itm(void)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
itc_get_cycles(struct clocksource * cs)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
read_persistent_clock(struct timespec * ts)358 void read_persistent_clock(struct timespec *ts)
359 {
360 efi_gettimeofday(ts);
361 }
362
363 void __init
time_init(void)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
ia64_itc_udelay(unsigned long usecs)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
udelay(unsigned long usecs)388 udelay (unsigned long usecs)
389 {
390 (*ia64_udelay)(usecs);
391 }
392 EXPORT_SYMBOL(udelay);
393
394 /* IA64 doesn't cache the timezone */
update_vsyscall_tz(void)395 void update_vsyscall_tz(void)
396 {
397 }
398
update_vsyscall_old(struct timespec * wall,struct timespec * wtm,struct clocksource * c,u32 mult,cycle_t cycle_last)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