xref: /openbmc/linux/arch/s390/kernel/time.c (revision 9a29f5fc)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *    Time of day based timer functions.
4  *
5  *  S390 version
6  *    Copyright IBM Corp. 1999, 2008
7  *    Author(s): Hartmut Penner (hp@de.ibm.com),
8  *               Martin Schwidefsky (schwidefsky@de.ibm.com),
9  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
10  *
11  *  Derived from "arch/i386/kernel/time.c"
12  *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
13  */
14 
15 #define KMSG_COMPONENT "time"
16 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
17 
18 #include <linux/kernel_stat.h>
19 #include <linux/errno.h>
20 #include <linux/export.h>
21 #include <linux/sched.h>
22 #include <linux/sched/clock.h>
23 #include <linux/kernel.h>
24 #include <linux/param.h>
25 #include <linux/string.h>
26 #include <linux/mm.h>
27 #include <linux/interrupt.h>
28 #include <linux/cpu.h>
29 #include <linux/stop_machine.h>
30 #include <linux/time.h>
31 #include <linux/device.h>
32 #include <linux/delay.h>
33 #include <linux/init.h>
34 #include <linux/smp.h>
35 #include <linux/types.h>
36 #include <linux/profile.h>
37 #include <linux/timex.h>
38 #include <linux/notifier.h>
39 #include <linux/timekeeper_internal.h>
40 #include <linux/clockchips.h>
41 #include <linux/gfp.h>
42 #include <linux/kprobes.h>
43 #include <linux/uaccess.h>
44 #include <vdso/vsyscall.h>
45 #include <vdso/clocksource.h>
46 #include <vdso/helpers.h>
47 #include <asm/facility.h>
48 #include <asm/delay.h>
49 #include <asm/div64.h>
50 #include <asm/vdso.h>
51 #include <asm/irq.h>
52 #include <asm/irq_regs.h>
53 #include <asm/vtimer.h>
54 #include <asm/stp.h>
55 #include <asm/cio.h>
56 #include "entry.h"
57 
58 union tod_clock tod_clock_base __section(".data");
59 EXPORT_SYMBOL_GPL(tod_clock_base);
60 
61 u64 clock_comparator_max = -1ULL;
62 EXPORT_SYMBOL_GPL(clock_comparator_max);
63 
64 static DEFINE_PER_CPU(struct clock_event_device, comparators);
65 
66 ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
67 EXPORT_SYMBOL(s390_epoch_delta_notifier);
68 
69 unsigned char ptff_function_mask[16];
70 
71 static unsigned long lpar_offset;
72 static unsigned long initial_leap_seconds;
73 static unsigned long tod_steering_end;
74 static long tod_steering_delta;
75 
76 /*
77  * Get time offsets with PTFF
78  */
79 void __init time_early_init(void)
80 {
81 	struct ptff_qto qto;
82 	struct ptff_qui qui;
83 	int cs;
84 
85 	/* Initialize TOD steering parameters */
86 	tod_steering_end = tod_clock_base.tod;
87 	for (cs = 0; cs < CS_BASES; cs++)
88 		vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
89 
90 	if (!test_facility(28))
91 		return;
92 
93 	ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF);
94 
95 	/* get LPAR offset */
96 	if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
97 		lpar_offset = qto.tod_epoch_difference;
98 
99 	/* get initial leap seconds */
100 	if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
101 		initial_leap_seconds = (unsigned long)
102 			((long) qui.old_leap * 4096000000L);
103 }
104 
105 /*
106  * Scheduler clock - returns current time in nanosec units.
107  */
108 unsigned long long notrace sched_clock(void)
109 {
110 	return tod_to_ns(get_tod_clock_monotonic());
111 }
112 NOKPROBE_SYMBOL(sched_clock);
113 
114 static void ext_to_timespec64(union tod_clock *clk, struct timespec64 *xt)
115 {
116 	unsigned long rem, sec, nsec;
117 
118 	sec = clk->us;
119 	rem = do_div(sec, 1000000);
120 	nsec = ((clk->sus + (rem << 12)) * 125) >> 9;
121 	xt->tv_sec = sec;
122 	xt->tv_nsec = nsec;
123 }
124 
125 void clock_comparator_work(void)
126 {
127 	struct clock_event_device *cd;
128 
129 	S390_lowcore.clock_comparator = clock_comparator_max;
130 	cd = this_cpu_ptr(&comparators);
131 	cd->event_handler(cd);
132 }
133 
134 static int s390_next_event(unsigned long delta,
135 			   struct clock_event_device *evt)
136 {
137 	S390_lowcore.clock_comparator = get_tod_clock() + delta;
138 	set_clock_comparator(S390_lowcore.clock_comparator);
139 	return 0;
140 }
141 
142 /*
143  * Set up lowcore and control register of the current cpu to
144  * enable TOD clock and clock comparator interrupts.
145  */
146 void init_cpu_timer(void)
147 {
148 	struct clock_event_device *cd;
149 	int cpu;
150 
151 	S390_lowcore.clock_comparator = clock_comparator_max;
152 	set_clock_comparator(S390_lowcore.clock_comparator);
153 
154 	cpu = smp_processor_id();
155 	cd = &per_cpu(comparators, cpu);
156 	cd->name		= "comparator";
157 	cd->features		= CLOCK_EVT_FEAT_ONESHOT;
158 	cd->mult		= 16777;
159 	cd->shift		= 12;
160 	cd->min_delta_ns	= 1;
161 	cd->min_delta_ticks	= 1;
162 	cd->max_delta_ns	= LONG_MAX;
163 	cd->max_delta_ticks	= ULONG_MAX;
164 	cd->rating		= 400;
165 	cd->cpumask		= cpumask_of(cpu);
166 	cd->set_next_event	= s390_next_event;
167 
168 	clockevents_register_device(cd);
169 
170 	/* Enable clock comparator timer interrupt. */
171 	__ctl_set_bit(0,11);
172 
173 	/* Always allow the timing alert external interrupt. */
174 	__ctl_set_bit(0, 4);
175 }
176 
177 static void clock_comparator_interrupt(struct ext_code ext_code,
178 				       unsigned int param32,
179 				       unsigned long param64)
180 {
181 	inc_irq_stat(IRQEXT_CLK);
182 	if (S390_lowcore.clock_comparator == clock_comparator_max)
183 		set_clock_comparator(S390_lowcore.clock_comparator);
184 }
185 
186 static void stp_timing_alert(struct stp_irq_parm *);
187 
188 static void timing_alert_interrupt(struct ext_code ext_code,
189 				   unsigned int param32, unsigned long param64)
190 {
191 	inc_irq_stat(IRQEXT_TLA);
192 	if (param32 & 0x00038000)
193 		stp_timing_alert((struct stp_irq_parm *) &param32);
194 }
195 
196 static void stp_reset(void);
197 
198 void read_persistent_clock64(struct timespec64 *ts)
199 {
200 	union tod_clock clk;
201 	u64 delta;
202 
203 	delta = initial_leap_seconds + TOD_UNIX_EPOCH;
204 	store_tod_clock_ext(&clk);
205 	clk.eitod -= delta;
206 	ext_to_timespec64(&clk, ts);
207 }
208 
209 void __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
210 						 struct timespec64 *boot_offset)
211 {
212 	struct timespec64 boot_time;
213 	union tod_clock clk;
214 	u64 delta;
215 
216 	delta = initial_leap_seconds + TOD_UNIX_EPOCH;
217 	clk = tod_clock_base;
218 	clk.eitod -= delta;
219 	ext_to_timespec64(&clk, &boot_time);
220 
221 	read_persistent_clock64(wall_time);
222 	*boot_offset = timespec64_sub(*wall_time, boot_time);
223 }
224 
225 static u64 read_tod_clock(struct clocksource *cs)
226 {
227 	unsigned long now, adj;
228 
229 	preempt_disable(); /* protect from changes to steering parameters */
230 	now = get_tod_clock();
231 	adj = tod_steering_end - now;
232 	if (unlikely((s64) adj > 0))
233 		/*
234 		 * manually steer by 1 cycle every 2^16 cycles. This
235 		 * corresponds to shifting the tod delta by 15. 1s is
236 		 * therefore steered in ~9h. The adjust will decrease
237 		 * over time, until it finally reaches 0.
238 		 */
239 		now += (tod_steering_delta < 0) ? (adj >> 15) : -(adj >> 15);
240 	preempt_enable();
241 	return now;
242 }
243 
244 static struct clocksource clocksource_tod = {
245 	.name		= "tod",
246 	.rating		= 400,
247 	.read		= read_tod_clock,
248 	.mask		= CLOCKSOURCE_MASK(64),
249 	.mult		= 1000,
250 	.shift		= 12,
251 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
252 	.vdso_clock_mode = VDSO_CLOCKMODE_TOD,
253 };
254 
255 struct clocksource * __init clocksource_default_clock(void)
256 {
257 	return &clocksource_tod;
258 }
259 
260 /*
261  * Initialize the TOD clock and the CPU timer of
262  * the boot cpu.
263  */
264 void __init time_init(void)
265 {
266 	/* Reset time synchronization interfaces. */
267 	stp_reset();
268 
269 	/* request the clock comparator external interrupt */
270 	if (register_external_irq(EXT_IRQ_CLK_COMP, clock_comparator_interrupt))
271 		panic("Couldn't request external interrupt 0x1004");
272 
273 	/* request the timing alert external interrupt */
274 	if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
275 		panic("Couldn't request external interrupt 0x1406");
276 
277 	if (__clocksource_register(&clocksource_tod) != 0)
278 		panic("Could not register TOD clock source");
279 
280 	/* Enable TOD clock interrupts on the boot cpu. */
281 	init_cpu_timer();
282 
283 	/* Enable cpu timer interrupts on the boot cpu. */
284 	vtime_init();
285 }
286 
287 static DEFINE_PER_CPU(atomic_t, clock_sync_word);
288 static DEFINE_MUTEX(stp_mutex);
289 static unsigned long clock_sync_flags;
290 
291 #define CLOCK_SYNC_HAS_STP		0
292 #define CLOCK_SYNC_STP			1
293 #define CLOCK_SYNC_STPINFO_VALID	2
294 
295 /*
296  * The get_clock function for the physical clock. It will get the current
297  * TOD clock, subtract the LPAR offset and write the result to *clock.
298  * The function returns 0 if the clock is in sync with the external time
299  * source. If the clock mode is local it will return -EOPNOTSUPP and
300  * -EAGAIN if the clock is not in sync with the external reference.
301  */
302 int get_phys_clock(unsigned long *clock)
303 {
304 	atomic_t *sw_ptr;
305 	unsigned int sw0, sw1;
306 
307 	sw_ptr = &get_cpu_var(clock_sync_word);
308 	sw0 = atomic_read(sw_ptr);
309 	*clock = get_tod_clock() - lpar_offset;
310 	sw1 = atomic_read(sw_ptr);
311 	put_cpu_var(clock_sync_word);
312 	if (sw0 == sw1 && (sw0 & 0x80000000U))
313 		/* Success: time is in sync. */
314 		return 0;
315 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
316 		return -EOPNOTSUPP;
317 	if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
318 		return -EACCES;
319 	return -EAGAIN;
320 }
321 EXPORT_SYMBOL(get_phys_clock);
322 
323 /*
324  * Make get_phys_clock() return -EAGAIN.
325  */
326 static void disable_sync_clock(void *dummy)
327 {
328 	atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
329 	/*
330 	 * Clear the in-sync bit 2^31. All get_phys_clock calls will
331 	 * fail until the sync bit is turned back on. In addition
332 	 * increase the "sequence" counter to avoid the race of an
333 	 * stp event and the complete recovery against get_phys_clock.
334 	 */
335 	atomic_andnot(0x80000000, sw_ptr);
336 	atomic_inc(sw_ptr);
337 }
338 
339 /*
340  * Make get_phys_clock() return 0 again.
341  * Needs to be called from a context disabled for preemption.
342  */
343 static void enable_sync_clock(void)
344 {
345 	atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
346 	atomic_or(0x80000000, sw_ptr);
347 }
348 
349 /*
350  * Function to check if the clock is in sync.
351  */
352 static inline int check_sync_clock(void)
353 {
354 	atomic_t *sw_ptr;
355 	int rc;
356 
357 	sw_ptr = &get_cpu_var(clock_sync_word);
358 	rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;
359 	put_cpu_var(clock_sync_word);
360 	return rc;
361 }
362 
363 /*
364  * Apply clock delta to the global data structures.
365  * This is called once on the CPU that performed the clock sync.
366  */
367 static void clock_sync_global(long delta)
368 {
369 	unsigned long now, adj;
370 	struct ptff_qto qto;
371 	int cs;
372 
373 	/* Fixup the monotonic sched clock. */
374 	tod_clock_base.eitod += delta;
375 	/* Adjust TOD steering parameters. */
376 	now = get_tod_clock();
377 	adj = tod_steering_end - now;
378 	if (unlikely((s64) adj >= 0))
379 		/* Calculate how much of the old adjustment is left. */
380 		tod_steering_delta = (tod_steering_delta < 0) ?
381 			-(adj >> 15) : (adj >> 15);
382 	tod_steering_delta += delta;
383 	if ((abs(tod_steering_delta) >> 48) != 0)
384 		panic("TOD clock sync offset %li is too large to drift\n",
385 		      tod_steering_delta);
386 	tod_steering_end = now + (abs(tod_steering_delta) << 15);
387 	for (cs = 0; cs < CS_BASES; cs++) {
388 		vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
389 		vdso_data[cs].arch_data.tod_steering_delta = tod_steering_delta;
390 	}
391 
392 	/* Update LPAR offset. */
393 	if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
394 		lpar_offset = qto.tod_epoch_difference;
395 	/* Call the TOD clock change notifier. */
396 	atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);
397 }
398 
399 /*
400  * Apply clock delta to the per-CPU data structures of this CPU.
401  * This is called for each online CPU after the call to clock_sync_global.
402  */
403 static void clock_sync_local(long delta)
404 {
405 	/* Add the delta to the clock comparator. */
406 	if (S390_lowcore.clock_comparator != clock_comparator_max) {
407 		S390_lowcore.clock_comparator += delta;
408 		set_clock_comparator(S390_lowcore.clock_comparator);
409 	}
410 	/* Adjust the last_update_clock time-stamp. */
411 	S390_lowcore.last_update_clock += delta;
412 }
413 
414 /* Single threaded workqueue used for stp sync events */
415 static struct workqueue_struct *time_sync_wq;
416 
417 static void __init time_init_wq(void)
418 {
419 	if (time_sync_wq)
420 		return;
421 	time_sync_wq = create_singlethread_workqueue("timesync");
422 }
423 
424 struct clock_sync_data {
425 	atomic_t cpus;
426 	int in_sync;
427 	long clock_delta;
428 };
429 
430 /*
431  * Server Time Protocol (STP) code.
432  */
433 static bool stp_online;
434 static struct stp_sstpi stp_info;
435 static void *stp_page;
436 
437 static void stp_work_fn(struct work_struct *work);
438 static DECLARE_WORK(stp_work, stp_work_fn);
439 static struct timer_list stp_timer;
440 
441 static int __init early_parse_stp(char *p)
442 {
443 	return kstrtobool(p, &stp_online);
444 }
445 early_param("stp", early_parse_stp);
446 
447 /*
448  * Reset STP attachment.
449  */
450 static void __init stp_reset(void)
451 {
452 	int rc;
453 
454 	stp_page = (void *) get_zeroed_page(GFP_ATOMIC);
455 	rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
456 	if (rc == 0)
457 		set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags);
458 	else if (stp_online) {
459 		pr_warn("The real or virtual hardware system does not provide an STP interface\n");
460 		free_page((unsigned long) stp_page);
461 		stp_page = NULL;
462 		stp_online = false;
463 	}
464 }
465 
466 static void stp_timeout(struct timer_list *unused)
467 {
468 	queue_work(time_sync_wq, &stp_work);
469 }
470 
471 static int __init stp_init(void)
472 {
473 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
474 		return 0;
475 	timer_setup(&stp_timer, stp_timeout, 0);
476 	time_init_wq();
477 	if (!stp_online)
478 		return 0;
479 	queue_work(time_sync_wq, &stp_work);
480 	return 0;
481 }
482 
483 arch_initcall(stp_init);
484 
485 /*
486  * STP timing alert. There are three causes:
487  * 1) timing status change
488  * 2) link availability change
489  * 3) time control parameter change
490  * In all three cases we are only interested in the clock source state.
491  * If a STP clock source is now available use it.
492  */
493 static void stp_timing_alert(struct stp_irq_parm *intparm)
494 {
495 	if (intparm->tsc || intparm->lac || intparm->tcpc)
496 		queue_work(time_sync_wq, &stp_work);
497 }
498 
499 /*
500  * STP sync check machine check. This is called when the timing state
501  * changes from the synchronized state to the unsynchronized state.
502  * After a STP sync check the clock is not in sync. The machine check
503  * is broadcasted to all cpus at the same time.
504  */
505 int stp_sync_check(void)
506 {
507 	disable_sync_clock(NULL);
508 	return 1;
509 }
510 
511 /*
512  * STP island condition machine check. This is called when an attached
513  * server  attempts to communicate over an STP link and the servers
514  * have matching CTN ids and have a valid stratum-1 configuration
515  * but the configurations do not match.
516  */
517 int stp_island_check(void)
518 {
519 	disable_sync_clock(NULL);
520 	return 1;
521 }
522 
523 void stp_queue_work(void)
524 {
525 	queue_work(time_sync_wq, &stp_work);
526 }
527 
528 static int __store_stpinfo(void)
529 {
530 	int rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
531 
532 	if (rc)
533 		clear_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
534 	else
535 		set_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
536 	return rc;
537 }
538 
539 static int stpinfo_valid(void)
540 {
541 	return stp_online && test_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
542 }
543 
544 static int stp_sync_clock(void *data)
545 {
546 	struct clock_sync_data *sync = data;
547 	long clock_delta, flags;
548 	static int first;
549 	int rc;
550 
551 	enable_sync_clock();
552 	if (xchg(&first, 1) == 0) {
553 		/* Wait until all other cpus entered the sync function. */
554 		while (atomic_read(&sync->cpus) != 0)
555 			cpu_relax();
556 		rc = 0;
557 		if (stp_info.todoff || stp_info.tmd != 2) {
558 			flags = vdso_update_begin();
559 			rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
560 					&clock_delta);
561 			if (rc == 0) {
562 				sync->clock_delta = clock_delta;
563 				clock_sync_global(clock_delta);
564 				rc = __store_stpinfo();
565 				if (rc == 0 && stp_info.tmd != 2)
566 					rc = -EAGAIN;
567 			}
568 			vdso_update_end(flags);
569 		}
570 		sync->in_sync = rc ? -EAGAIN : 1;
571 		xchg(&first, 0);
572 	} else {
573 		/* Slave */
574 		atomic_dec(&sync->cpus);
575 		/* Wait for in_sync to be set. */
576 		while (READ_ONCE(sync->in_sync) == 0)
577 			__udelay(1);
578 	}
579 	if (sync->in_sync != 1)
580 		/* Didn't work. Clear per-cpu in sync bit again. */
581 		disable_sync_clock(NULL);
582 	/* Apply clock delta to per-CPU fields of this CPU. */
583 	clock_sync_local(sync->clock_delta);
584 
585 	return 0;
586 }
587 
588 static int stp_clear_leap(void)
589 {
590 	struct __kernel_timex txc;
591 	int ret;
592 
593 	memset(&txc, 0, sizeof(txc));
594 
595 	ret = do_adjtimex(&txc);
596 	if (ret < 0)
597 		return ret;
598 
599 	txc.modes = ADJ_STATUS;
600 	txc.status &= ~(STA_INS|STA_DEL);
601 	return do_adjtimex(&txc);
602 }
603 
604 static void stp_check_leap(void)
605 {
606 	struct stp_stzi stzi;
607 	struct stp_lsoib *lsoib = &stzi.lsoib;
608 	struct __kernel_timex txc;
609 	int64_t timediff;
610 	int leapdiff, ret;
611 
612 	if (!stp_info.lu || !check_sync_clock()) {
613 		/*
614 		 * Either a scheduled leap second was removed by the operator,
615 		 * or STP is out of sync. In both cases, clear the leap second
616 		 * kernel flags.
617 		 */
618 		if (stp_clear_leap() < 0)
619 			pr_err("failed to clear leap second flags\n");
620 		return;
621 	}
622 
623 	if (chsc_stzi(stp_page, &stzi, sizeof(stzi))) {
624 		pr_err("stzi failed\n");
625 		return;
626 	}
627 
628 	timediff = tod_to_ns(lsoib->nlsout - get_tod_clock()) / NSEC_PER_SEC;
629 	leapdiff = lsoib->nlso - lsoib->also;
630 
631 	if (leapdiff != 1 && leapdiff != -1) {
632 		pr_err("Cannot schedule %d leap seconds\n", leapdiff);
633 		return;
634 	}
635 
636 	if (timediff < 0) {
637 		if (stp_clear_leap() < 0)
638 			pr_err("failed to clear leap second flags\n");
639 	} else if (timediff < 7200) {
640 		memset(&txc, 0, sizeof(txc));
641 		ret = do_adjtimex(&txc);
642 		if (ret < 0)
643 			return;
644 
645 		txc.modes = ADJ_STATUS;
646 		if (leapdiff > 0)
647 			txc.status |= STA_INS;
648 		else
649 			txc.status |= STA_DEL;
650 		ret = do_adjtimex(&txc);
651 		if (ret < 0)
652 			pr_err("failed to set leap second flags\n");
653 		/* arm Timer to clear leap second flags */
654 		mod_timer(&stp_timer, jiffies + msecs_to_jiffies(14400 * MSEC_PER_SEC));
655 	} else {
656 		/* The day the leap second is scheduled for hasn't been reached. Retry
657 		 * in one hour.
658 		 */
659 		mod_timer(&stp_timer, jiffies + msecs_to_jiffies(3600 * MSEC_PER_SEC));
660 	}
661 }
662 
663 /*
664  * STP work. Check for the STP state and take over the clock
665  * synchronization if the STP clock source is usable.
666  */
667 static void stp_work_fn(struct work_struct *work)
668 {
669 	struct clock_sync_data stp_sync;
670 	int rc;
671 
672 	/* prevent multiple execution. */
673 	mutex_lock(&stp_mutex);
674 
675 	if (!stp_online) {
676 		chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
677 		del_timer_sync(&stp_timer);
678 		goto out_unlock;
679 	}
680 
681 	rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xf0e0, NULL);
682 	if (rc)
683 		goto out_unlock;
684 
685 	rc = __store_stpinfo();
686 	if (rc || stp_info.c == 0)
687 		goto out_unlock;
688 
689 	/* Skip synchronization if the clock is already in sync. */
690 	if (!check_sync_clock()) {
691 		memset(&stp_sync, 0, sizeof(stp_sync));
692 		cpus_read_lock();
693 		atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
694 		stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
695 		cpus_read_unlock();
696 	}
697 
698 	if (!check_sync_clock())
699 		/*
700 		 * There is a usable clock but the synchonization failed.
701 		 * Retry after a second.
702 		 */
703 		mod_timer(&stp_timer, jiffies + msecs_to_jiffies(MSEC_PER_SEC));
704 	else if (stp_info.lu)
705 		stp_check_leap();
706 
707 out_unlock:
708 	mutex_unlock(&stp_mutex);
709 }
710 
711 /*
712  * STP subsys sysfs interface functions
713  */
714 static struct bus_type stp_subsys = {
715 	.name		= "stp",
716 	.dev_name	= "stp",
717 };
718 
719 static ssize_t ctn_id_show(struct device *dev,
720 				struct device_attribute *attr,
721 				char *buf)
722 {
723 	ssize_t ret = -ENODATA;
724 
725 	mutex_lock(&stp_mutex);
726 	if (stpinfo_valid())
727 		ret = sprintf(buf, "%016lx\n",
728 			      *(unsigned long *) stp_info.ctnid);
729 	mutex_unlock(&stp_mutex);
730 	return ret;
731 }
732 
733 static DEVICE_ATTR_RO(ctn_id);
734 
735 static ssize_t ctn_type_show(struct device *dev,
736 				struct device_attribute *attr,
737 				char *buf)
738 {
739 	ssize_t ret = -ENODATA;
740 
741 	mutex_lock(&stp_mutex);
742 	if (stpinfo_valid())
743 		ret = sprintf(buf, "%i\n", stp_info.ctn);
744 	mutex_unlock(&stp_mutex);
745 	return ret;
746 }
747 
748 static DEVICE_ATTR_RO(ctn_type);
749 
750 static ssize_t dst_offset_show(struct device *dev,
751 				   struct device_attribute *attr,
752 				   char *buf)
753 {
754 	ssize_t ret = -ENODATA;
755 
756 	mutex_lock(&stp_mutex);
757 	if (stpinfo_valid() && (stp_info.vbits & 0x2000))
758 		ret = sprintf(buf, "%i\n", (int)(s16) stp_info.dsto);
759 	mutex_unlock(&stp_mutex);
760 	return ret;
761 }
762 
763 static DEVICE_ATTR_RO(dst_offset);
764 
765 static ssize_t leap_seconds_show(struct device *dev,
766 					struct device_attribute *attr,
767 					char *buf)
768 {
769 	ssize_t ret = -ENODATA;
770 
771 	mutex_lock(&stp_mutex);
772 	if (stpinfo_valid() && (stp_info.vbits & 0x8000))
773 		ret = sprintf(buf, "%i\n", (int)(s16) stp_info.leaps);
774 	mutex_unlock(&stp_mutex);
775 	return ret;
776 }
777 
778 static DEVICE_ATTR_RO(leap_seconds);
779 
780 static ssize_t leap_seconds_scheduled_show(struct device *dev,
781 						struct device_attribute *attr,
782 						char *buf)
783 {
784 	struct stp_stzi stzi;
785 	ssize_t ret;
786 
787 	mutex_lock(&stp_mutex);
788 	if (!stpinfo_valid() || !(stp_info.vbits & 0x8000) || !stp_info.lu) {
789 		mutex_unlock(&stp_mutex);
790 		return -ENODATA;
791 	}
792 
793 	ret = chsc_stzi(stp_page, &stzi, sizeof(stzi));
794 	mutex_unlock(&stp_mutex);
795 	if (ret < 0)
796 		return ret;
797 
798 	if (!stzi.lsoib.p)
799 		return sprintf(buf, "0,0\n");
800 
801 	return sprintf(buf, "%lu,%d\n",
802 		       tod_to_ns(stzi.lsoib.nlsout - TOD_UNIX_EPOCH) / NSEC_PER_SEC,
803 		       stzi.lsoib.nlso - stzi.lsoib.also);
804 }
805 
806 static DEVICE_ATTR_RO(leap_seconds_scheduled);
807 
808 static ssize_t stratum_show(struct device *dev,
809 				struct device_attribute *attr,
810 				char *buf)
811 {
812 	ssize_t ret = -ENODATA;
813 
814 	mutex_lock(&stp_mutex);
815 	if (stpinfo_valid())
816 		ret = sprintf(buf, "%i\n", (int)(s16) stp_info.stratum);
817 	mutex_unlock(&stp_mutex);
818 	return ret;
819 }
820 
821 static DEVICE_ATTR_RO(stratum);
822 
823 static ssize_t time_offset_show(struct device *dev,
824 				struct device_attribute *attr,
825 				char *buf)
826 {
827 	ssize_t ret = -ENODATA;
828 
829 	mutex_lock(&stp_mutex);
830 	if (stpinfo_valid() && (stp_info.vbits & 0x0800))
831 		ret = sprintf(buf, "%i\n", (int) stp_info.tto);
832 	mutex_unlock(&stp_mutex);
833 	return ret;
834 }
835 
836 static DEVICE_ATTR_RO(time_offset);
837 
838 static ssize_t time_zone_offset_show(struct device *dev,
839 				struct device_attribute *attr,
840 				char *buf)
841 {
842 	ssize_t ret = -ENODATA;
843 
844 	mutex_lock(&stp_mutex);
845 	if (stpinfo_valid() && (stp_info.vbits & 0x4000))
846 		ret = sprintf(buf, "%i\n", (int)(s16) stp_info.tzo);
847 	mutex_unlock(&stp_mutex);
848 	return ret;
849 }
850 
851 static DEVICE_ATTR_RO(time_zone_offset);
852 
853 static ssize_t timing_mode_show(struct device *dev,
854 				struct device_attribute *attr,
855 				char *buf)
856 {
857 	ssize_t ret = -ENODATA;
858 
859 	mutex_lock(&stp_mutex);
860 	if (stpinfo_valid())
861 		ret = sprintf(buf, "%i\n", stp_info.tmd);
862 	mutex_unlock(&stp_mutex);
863 	return ret;
864 }
865 
866 static DEVICE_ATTR_RO(timing_mode);
867 
868 static ssize_t timing_state_show(struct device *dev,
869 				struct device_attribute *attr,
870 				char *buf)
871 {
872 	ssize_t ret = -ENODATA;
873 
874 	mutex_lock(&stp_mutex);
875 	if (stpinfo_valid())
876 		ret = sprintf(buf, "%i\n", stp_info.tst);
877 	mutex_unlock(&stp_mutex);
878 	return ret;
879 }
880 
881 static DEVICE_ATTR_RO(timing_state);
882 
883 static ssize_t online_show(struct device *dev,
884 				struct device_attribute *attr,
885 				char *buf)
886 {
887 	return sprintf(buf, "%i\n", stp_online);
888 }
889 
890 static ssize_t online_store(struct device *dev,
891 				struct device_attribute *attr,
892 				const char *buf, size_t count)
893 {
894 	unsigned int value;
895 
896 	value = simple_strtoul(buf, NULL, 0);
897 	if (value != 0 && value != 1)
898 		return -EINVAL;
899 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
900 		return -EOPNOTSUPP;
901 	mutex_lock(&stp_mutex);
902 	stp_online = value;
903 	if (stp_online)
904 		set_bit(CLOCK_SYNC_STP, &clock_sync_flags);
905 	else
906 		clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
907 	queue_work(time_sync_wq, &stp_work);
908 	mutex_unlock(&stp_mutex);
909 	return count;
910 }
911 
912 /*
913  * Can't use DEVICE_ATTR because the attribute should be named
914  * stp/online but dev_attr_online already exists in this file ..
915  */
916 static DEVICE_ATTR_RW(online);
917 
918 static struct attribute *stp_dev_attrs[] = {
919 	&dev_attr_ctn_id.attr,
920 	&dev_attr_ctn_type.attr,
921 	&dev_attr_dst_offset.attr,
922 	&dev_attr_leap_seconds.attr,
923 	&dev_attr_online.attr,
924 	&dev_attr_leap_seconds_scheduled.attr,
925 	&dev_attr_stratum.attr,
926 	&dev_attr_time_offset.attr,
927 	&dev_attr_time_zone_offset.attr,
928 	&dev_attr_timing_mode.attr,
929 	&dev_attr_timing_state.attr,
930 	NULL
931 };
932 ATTRIBUTE_GROUPS(stp_dev);
933 
934 static int __init stp_init_sysfs(void)
935 {
936 	return subsys_system_register(&stp_subsys, stp_dev_groups);
937 }
938 
939 device_initcall(stp_init_sysfs);
940