xref: /openbmc/linux/arch/ia64/kernel/time.c (revision cd9f5c3d)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * linux/arch/ia64/kernel/time.c
4  *
5  * Copyright (C) 1998-2003 Hewlett-Packard Co
6  *	Stephane Eranian <eranian@hpl.hp.com>
7  *	David Mosberger <davidm@hpl.hp.com>
8  * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
9  * Copyright (C) 1999-2000 VA Linux Systems
10  * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
11  */
12 
13 #include <linux/cpu.h>
14 #include <linux/init.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/profile.h>
18 #include <linux/sched.h>
19 #include <linux/time.h>
20 #include <linux/nmi.h>
21 #include <linux/interrupt.h>
22 #include <linux/efi.h>
23 #include <linux/timex.h>
24 #include <linux/timekeeper_internal.h>
25 #include <linux/platform_device.h>
26 #include <linux/sched/cputime.h>
27 
28 #include <asm/cputime.h>
29 #include <asm/delay.h>
30 #include <asm/efi.h>
31 #include <asm/hw_irq.h>
32 #include <asm/ptrace.h>
33 #include <asm/sal.h>
34 #include <asm/sections.h>
35 
36 #include "fsyscall_gtod_data.h"
37 #include "irq.h"
38 
39 static u64 itc_get_cycles(struct clocksource *cs);
40 
41 struct fsyscall_gtod_data_t fsyscall_gtod_data;
42 
43 struct itc_jitter_data_t itc_jitter_data;
44 
45 volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
46 
47 #ifdef CONFIG_IA64_DEBUG_IRQ
48 
49 unsigned long last_cli_ip;
50 EXPORT_SYMBOL(last_cli_ip);
51 
52 #endif
53 
54 static struct clocksource clocksource_itc = {
55 	.name           = "itc",
56 	.rating         = 350,
57 	.read           = itc_get_cycles,
58 	.mask           = CLOCKSOURCE_MASK(64),
59 	.flags          = CLOCK_SOURCE_IS_CONTINUOUS,
60 };
61 static struct clocksource *itc_clocksource;
62 
63 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
64 
65 #include <linux/kernel_stat.h>
66 
67 extern u64 cycle_to_nsec(u64 cyc);
68 
vtime_flush(struct task_struct * tsk)69 void vtime_flush(struct task_struct *tsk)
70 {
71 	struct thread_info *ti = task_thread_info(tsk);
72 	u64 delta;
73 
74 	if (ti->utime)
75 		account_user_time(tsk, cycle_to_nsec(ti->utime));
76 
77 	if (ti->gtime)
78 		account_guest_time(tsk, cycle_to_nsec(ti->gtime));
79 
80 	if (ti->idle_time)
81 		account_idle_time(cycle_to_nsec(ti->idle_time));
82 
83 	if (ti->stime) {
84 		delta = cycle_to_nsec(ti->stime);
85 		account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
86 	}
87 
88 	if (ti->hardirq_time) {
89 		delta = cycle_to_nsec(ti->hardirq_time);
90 		account_system_index_time(tsk, delta, CPUTIME_IRQ);
91 	}
92 
93 	if (ti->softirq_time) {
94 		delta = cycle_to_nsec(ti->softirq_time);
95 		account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
96 	}
97 
98 	ti->utime = 0;
99 	ti->gtime = 0;
100 	ti->idle_time = 0;
101 	ti->stime = 0;
102 	ti->hardirq_time = 0;
103 	ti->softirq_time = 0;
104 }
105 
106 /*
107  * Called from the context switch with interrupts disabled, to charge all
108  * accumulated times to the current process, and to prepare accounting on
109  * the next process.
110  */
arch_vtime_task_switch(struct task_struct * prev)111 void arch_vtime_task_switch(struct task_struct *prev)
112 {
113 	struct thread_info *pi = task_thread_info(prev);
114 	struct thread_info *ni = task_thread_info(current);
115 
116 	ni->ac_stamp = pi->ac_stamp;
117 	ni->ac_stime = ni->ac_utime = 0;
118 }
119 
120 /*
121  * Account time for a transition between system, hard irq or soft irq state.
122  * Note that this function is called with interrupts enabled.
123  */
vtime_delta(struct task_struct * tsk)124 static __u64 vtime_delta(struct task_struct *tsk)
125 {
126 	struct thread_info *ti = task_thread_info(tsk);
127 	__u64 now, delta_stime;
128 
129 	WARN_ON_ONCE(!irqs_disabled());
130 
131 	now = ia64_get_itc();
132 	delta_stime = now - ti->ac_stamp;
133 	ti->ac_stamp = now;
134 
135 	return delta_stime;
136 }
137 
vtime_account_kernel(struct task_struct * tsk)138 void vtime_account_kernel(struct task_struct *tsk)
139 {
140 	struct thread_info *ti = task_thread_info(tsk);
141 	__u64 stime = vtime_delta(tsk);
142 
143 	if (tsk->flags & PF_VCPU)
144 		ti->gtime += stime;
145 	else
146 		ti->stime += stime;
147 }
148 EXPORT_SYMBOL_GPL(vtime_account_kernel);
149 
vtime_account_idle(struct task_struct * tsk)150 void vtime_account_idle(struct task_struct *tsk)
151 {
152 	struct thread_info *ti = task_thread_info(tsk);
153 
154 	ti->idle_time += vtime_delta(tsk);
155 }
156 
vtime_account_softirq(struct task_struct * tsk)157 void vtime_account_softirq(struct task_struct *tsk)
158 {
159 	struct thread_info *ti = task_thread_info(tsk);
160 
161 	ti->softirq_time += vtime_delta(tsk);
162 }
163 
vtime_account_hardirq(struct task_struct * tsk)164 void vtime_account_hardirq(struct task_struct *tsk)
165 {
166 	struct thread_info *ti = task_thread_info(tsk);
167 
168 	ti->hardirq_time += vtime_delta(tsk);
169 }
170 
171 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
172 
173 static irqreturn_t
timer_interrupt(int irq,void * dev_id)174 timer_interrupt (int irq, void *dev_id)
175 {
176 	unsigned long new_itm;
177 
178 	if (cpu_is_offline(smp_processor_id())) {
179 		return IRQ_HANDLED;
180 	}
181 
182 	new_itm = local_cpu_data->itm_next;
183 
184 	if (!time_after(ia64_get_itc(), new_itm))
185 		printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
186 		       ia64_get_itc(), new_itm);
187 
188 	while (1) {
189 		new_itm += local_cpu_data->itm_delta;
190 
191 		legacy_timer_tick(smp_processor_id() == time_keeper_id);
192 
193 		local_cpu_data->itm_next = new_itm;
194 
195 		if (time_after(new_itm, ia64_get_itc()))
196 			break;
197 
198 		/*
199 		 * Allow IPIs to interrupt the timer loop.
200 		 */
201 		local_irq_enable();
202 		local_irq_disable();
203 	}
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  */
226 void
ia64_cpu_local_tick(void)227 ia64_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 
248 static int nojitter;
249 
nojitter_setup(char * str)250 static 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 
ia64_init_itm(void)260 void ia64_init_itm(void)
261 {
262 	unsigned long platform_base_freq, itc_freq;
263 	struct pal_freq_ratio itc_ratio, proc_ratio;
264 	long status, platform_base_drift, itc_drift;
265 
266 	/*
267 	 * According to SAL v2.6, we need to use a SAL call to determine the platform base
268 	 * frequency and then a PAL call to determine the frequency ratio between the ITC
269 	 * and the base frequency.
270 	 */
271 	status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
272 				    &platform_base_freq, &platform_base_drift);
273 	if (status != 0) {
274 		printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
275 	} else {
276 		status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
277 		if (status != 0)
278 			printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
279 	}
280 	if (status != 0) {
281 		/* invent "random" values */
282 		printk(KERN_ERR
283 		       "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
284 		platform_base_freq = 100000000;
285 		platform_base_drift = -1;	/* no drift info */
286 		itc_ratio.num = 3;
287 		itc_ratio.den = 1;
288 	}
289 	if (platform_base_freq < 40000000) {
290 		printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
291 		       platform_base_freq);
292 		platform_base_freq = 75000000;
293 		platform_base_drift = -1;
294 	}
295 	if (!proc_ratio.den)
296 		proc_ratio.den = 1;	/* avoid division by zero */
297 	if (!itc_ratio.den)
298 		itc_ratio.den = 1;	/* avoid division by zero */
299 
300 	itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
301 
302 	local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
303 	printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
304 	       "ITC freq=%lu.%03luMHz", smp_processor_id(),
305 	       platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
306 	       itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
307 
308 	if (platform_base_drift != -1) {
309 		itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
310 		printk("+/-%ldppm\n", itc_drift);
311 	} else {
312 		itc_drift = -1;
313 		printk("\n");
314 	}
315 
316 	local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
317 	local_cpu_data->itc_freq = itc_freq;
318 	local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
319 	local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
320 					+ itc_freq/2)/itc_freq;
321 
322 	if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
323 #ifdef CONFIG_SMP
324 		/* On IA64 in an SMP configuration ITCs are never accurately synchronized.
325 		 * Jitter compensation requires a cmpxchg which may limit
326 		 * the scalability of the syscalls for retrieving time.
327 		 * The ITC synchronization is usually successful to within a few
328 		 * ITC ticks but this is not a sure thing. If you need to improve
329 		 * timer performance in SMP situations then boot the kernel with the
330 		 * "nojitter" option. However, doing so may result in time fluctuating (maybe
331 		 * even going backward) if the ITC offsets between the individual CPUs
332 		 * are too large.
333 		 */
334 		if (!nojitter)
335 			itc_jitter_data.itc_jitter = 1;
336 #endif
337 	} else
338 		/*
339 		 * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
340 		 * ITC values may fluctuate significantly between processors.
341 		 * Clock should not be used for hrtimers. Mark itc as only
342 		 * useful for boot and testing.
343 		 *
344 		 * Note that jitter compensation is off! There is no point of
345 		 * synchronizing ITCs since they may be large differentials
346 		 * that change over time.
347 		 *
348 		 * The only way to fix this would be to repeatedly sync the
349 		 * ITCs. Until that time we have to avoid ITC.
350 		 */
351 		clocksource_itc.rating = 50;
352 
353 	/* avoid softlock up message when cpu is unplug and plugged again. */
354 	touch_softlockup_watchdog();
355 
356 	/* Setup the CPU local timer tick */
357 	ia64_cpu_local_tick();
358 
359 	if (!itc_clocksource) {
360 		clocksource_register_hz(&clocksource_itc,
361 						local_cpu_data->itc_freq);
362 		itc_clocksource = &clocksource_itc;
363 	}
364 }
365 
itc_get_cycles(struct clocksource * cs)366 static u64 itc_get_cycles(struct clocksource *cs)
367 {
368 	unsigned long lcycle, now, ret;
369 
370 	if (!itc_jitter_data.itc_jitter)
371 		return get_cycles();
372 
373 	lcycle = itc_jitter_data.itc_lastcycle;
374 	now = get_cycles();
375 	if (lcycle && time_after(lcycle, now))
376 		return lcycle;
377 
378 	/*
379 	 * Keep track of the last timer value returned.
380 	 * In an SMP environment, you could lose out in contention of
381 	 * cmpxchg. If so, your cmpxchg returns new value which the
382 	 * winner of contention updated to. Use the new value instead.
383 	 */
384 	ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
385 	if (unlikely(ret != lcycle))
386 		return ret;
387 
388 	return now;
389 }
390 
read_persistent_clock64(struct timespec64 * ts)391 void read_persistent_clock64(struct timespec64 *ts)
392 {
393 	efi_gettimeofday(ts);
394 }
395 
396 void __init
time_init(void)397 time_init (void)
398 {
399 	register_percpu_irq(IA64_TIMER_VECTOR, timer_interrupt, IRQF_IRQPOLL,
400 			    "timer");
401 	ia64_init_itm();
402 }
403 
404 /*
405  * Generic udelay assumes that if preemption is allowed and the thread
406  * migrates to another CPU, that the ITC values are synchronized across
407  * all CPUs.
408  */
409 static void
ia64_itc_udelay(unsigned long usecs)410 ia64_itc_udelay (unsigned long usecs)
411 {
412 	unsigned long start = ia64_get_itc();
413 	unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
414 
415 	while (time_before(ia64_get_itc(), end))
416 		cpu_relax();
417 }
418 
419 void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
420 
421 void
udelay(unsigned long usecs)422 udelay (unsigned long usecs)
423 {
424 	(*ia64_udelay)(usecs);
425 }
426 EXPORT_SYMBOL(udelay);
427 
428 /* IA64 doesn't cache the timezone */
update_vsyscall_tz(void)429 void update_vsyscall_tz(void)
430 {
431 }
432 
update_vsyscall(struct timekeeper * tk)433 void update_vsyscall(struct timekeeper *tk)
434 {
435 	write_seqcount_begin(&fsyscall_gtod_data.seq);
436 
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;
443 
444 	fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
445 	fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
446 
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);
452 
453 	/* normalize */
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++;
459 	}
460 
461 	write_seqcount_end(&fsyscall_gtod_data.seq);
462 }
463 
464