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/clockchips.h>
40 #include <linux/gfp.h>
41 #include <linux/kprobes.h>
42 #include <linux/uaccess.h>
43 #include <vdso/vsyscall.h>
44 #include <vdso/clocksource.h>
45 #include <vdso/helpers.h>
46 #include <asm/facility.h>
47 #include <asm/delay.h>
48 #include <asm/div64.h>
49 #include <asm/vdso.h>
50 #include <asm/irq.h>
51 #include <asm/irq_regs.h>
52 #include <asm/vtimer.h>
53 #include <asm/stp.h>
54 #include <asm/cio.h>
55 #include "entry.h"
56 
57 union tod_clock __bootdata_preserved(tod_clock_base);
58 EXPORT_SYMBOL_GPL(tod_clock_base);
59 
60 u64 __bootdata_preserved(clock_comparator_max);
61 EXPORT_SYMBOL_GPL(clock_comparator_max);
62 
63 static DEFINE_PER_CPU(struct clock_event_device, comparators);
64 
65 ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
66 EXPORT_SYMBOL(s390_epoch_delta_notifier);
67 
68 unsigned char ptff_function_mask[16];
69 
70 static unsigned long lpar_offset;
71 static unsigned long initial_leap_seconds;
72 static unsigned long tod_steering_end;
73 static long tod_steering_delta;
74 
75 /*
76  * Get time offsets with PTFF
77  */
78 void __init time_early_init(void)
79 {
80 	struct ptff_qto qto;
81 	struct ptff_qui qui;
82 
83 	/* Initialize TOD steering parameters */
84 	tod_steering_end = tod_clock_base.tod;
85 	vdso_k_time_data->arch_data.tod_steering_end = tod_steering_end;
86 
87 	if (!test_facility(28))
88 		return;
89 
90 	ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF);
91 
92 	/* get LPAR offset */
93 	if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
94 		lpar_offset = qto.tod_epoch_difference;
95 
96 	/* get initial leap seconds */
97 	if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
98 		initial_leap_seconds = (unsigned long)
99 			((long) qui.old_leap * 4096000000L);
100 }
101 
102 unsigned long long noinstr sched_clock_noinstr(void)
103 {
104 	return tod_to_ns(__get_tod_clock_monotonic());
105 }
106 
107 /*
108  * Scheduler clock - returns current time in nanosec units.
109  */
110 unsigned long long notrace sched_clock(void)
111 {
112 	return tod_to_ns(get_tod_clock_monotonic());
113 }
114 NOKPROBE_SYMBOL(sched_clock);
115 
116 static void ext_to_timespec64(union tod_clock *clk, struct timespec64 *xt)
117 {
118 	unsigned long rem, sec, nsec;
119 
120 	sec = clk->us;
121 	rem = do_div(sec, 1000000);
122 	nsec = ((clk->sus + (rem << 12)) * 125) >> 9;
123 	xt->tv_sec = sec;
124 	xt->tv_nsec = nsec;
125 }
126 
127 void clock_comparator_work(void)
128 {
129 	struct clock_event_device *cd;
130 
131 	get_lowcore()->clock_comparator = clock_comparator_max;
132 	cd = this_cpu_ptr(&comparators);
133 	cd->event_handler(cd);
134 }
135 
136 static int s390_next_event(unsigned long delta,
137 			   struct clock_event_device *evt)
138 {
139 	get_lowcore()->clock_comparator = get_tod_clock() + delta;
140 	set_clock_comparator(get_lowcore()->clock_comparator);
141 	return 0;
142 }
143 
144 /*
145  * Set up lowcore and control register of the current cpu to
146  * enable TOD clock and clock comparator interrupts.
147  */
148 void init_cpu_timer(void)
149 {
150 	struct clock_event_device *cd;
151 	int cpu;
152 
153 	get_lowcore()->clock_comparator = clock_comparator_max;
154 	set_clock_comparator(get_lowcore()->clock_comparator);
155 
156 	cpu = smp_processor_id();
157 	cd = &per_cpu(comparators, cpu);
158 	cd->name		= "comparator";
159 	cd->features		= CLOCK_EVT_FEAT_ONESHOT;
160 	cd->mult		= 16777;
161 	cd->shift		= 12;
162 	cd->min_delta_ns	= 1;
163 	cd->min_delta_ticks	= 1;
164 	cd->max_delta_ns	= LONG_MAX;
165 	cd->max_delta_ticks	= ULONG_MAX;
166 	cd->rating		= 400;
167 	cd->cpumask		= cpumask_of(cpu);
168 	cd->set_next_event	= s390_next_event;
169 
170 	clockevents_register_device(cd);
171 
172 	/* Enable clock comparator timer interrupt. */
173 	local_ctl_set_bit(0, CR0_CLOCK_COMPARATOR_SUBMASK_BIT);
174 
175 	/* Always allow the timing alert external interrupt. */
176 	local_ctl_set_bit(0, CR0_ETR_SUBMASK_BIT);
177 }
178 
179 static void clock_comparator_interrupt(struct ext_code ext_code,
180 				       unsigned int param32,
181 				       unsigned long param64)
182 {
183 	inc_irq_stat(IRQEXT_CLK);
184 	if (get_lowcore()->clock_comparator == clock_comparator_max)
185 		set_clock_comparator(get_lowcore()->clock_comparator);
186 }
187 
188 static void stp_timing_alert(struct stp_irq_parm *);
189 
190 static void timing_alert_interrupt(struct ext_code ext_code,
191 				   unsigned int param32, unsigned long param64)
192 {
193 	inc_irq_stat(IRQEXT_TLA);
194 	if (param32 & 0x00038000)
195 		stp_timing_alert((struct stp_irq_parm *) &param32);
196 }
197 
198 static void stp_reset(void);
199 
200 void read_persistent_clock64(struct timespec64 *ts)
201 {
202 	union tod_clock clk;
203 	u64 delta;
204 
205 	delta = initial_leap_seconds + TOD_UNIX_EPOCH;
206 	store_tod_clock_ext(&clk);
207 	clk.eitod -= delta;
208 	ext_to_timespec64(&clk, ts);
209 }
210 
211 void __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
212 						 struct timespec64 *boot_offset)
213 {
214 	struct timespec64 boot_time;
215 	union tod_clock clk;
216 	u64 delta;
217 
218 	delta = initial_leap_seconds + TOD_UNIX_EPOCH;
219 	clk = tod_clock_base;
220 	clk.eitod -= delta;
221 	ext_to_timespec64(&clk, &boot_time);
222 
223 	read_persistent_clock64(wall_time);
224 	*boot_offset = timespec64_sub(*wall_time, boot_time);
225 }
226 
227 static u64 read_tod_clock(struct clocksource *cs)
228 {
229 	unsigned long now, adj;
230 
231 	preempt_disable(); /* protect from changes to steering parameters */
232 	now = get_tod_clock();
233 	adj = tod_steering_end - now;
234 	if (unlikely((s64) adj > 0))
235 		/*
236 		 * manually steer by 1 cycle every 2^16 cycles. This
237 		 * corresponds to shifting the tod delta by 15. 1s is
238 		 * therefore steered in ~9h. The adjust will decrease
239 		 * over time, until it finally reaches 0.
240 		 */
241 		now += (tod_steering_delta < 0) ? (adj >> 15) : -(adj >> 15);
242 	preempt_enable();
243 	return now;
244 }
245 
246 static struct clocksource clocksource_tod = {
247 	.name		= "tod",
248 	.rating		= 400,
249 	.read		= read_tod_clock,
250 	.mask		= CLOCKSOURCE_MASK(64),
251 	.mult		= 4096000,
252 	.shift		= 24,
253 	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
254 	.vdso_clock_mode = VDSO_CLOCKMODE_TOD,
255 	.id		= CSID_S390_TOD,
256 };
257 
258 struct clocksource * __init clocksource_default_clock(void)
259 {
260 	return &clocksource_tod;
261 }
262 
263 /*
264  * Initialize the TOD clock and the CPU timer of
265  * the boot cpu.
266  */
267 void __init time_init(void)
268 {
269 	/* Reset time synchronization interfaces. */
270 	stp_reset();
271 
272 	/* request the clock comparator external interrupt */
273 	if (register_external_irq(EXT_IRQ_CLK_COMP, clock_comparator_interrupt))
274 		panic("Couldn't request external interrupt 0x1004");
275 
276 	/* request the timing alert external interrupt */
277 	if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
278 		panic("Couldn't request external interrupt 0x1406");
279 
280 	if (__clocksource_register(&clocksource_tod) != 0)
281 		panic("Could not register TOD clock source");
282 
283 	/* Enable TOD clock interrupts on the boot cpu. */
284 	init_cpu_timer();
285 
286 	/* Enable cpu timer interrupts on the boot cpu. */
287 	vtime_init();
288 }
289 
290 static DEFINE_PER_CPU(atomic_t, clock_sync_word);
291 static DEFINE_MUTEX(stp_mutex);
292 static unsigned long clock_sync_flags;
293 
294 #define CLOCK_SYNC_HAS_STP		0
295 #define CLOCK_SYNC_STP			1
296 #define CLOCK_SYNC_STPINFO_VALID	2
297 
298 /*
299  * The get_clock function for the physical clock. It will get the current
300  * TOD clock, subtract the LPAR offset and write the result to *clock.
301  * The function returns 0 if the clock is in sync with the external time
302  * source. If the clock mode is local it will return -EOPNOTSUPP and
303  * -EAGAIN if the clock is not in sync with the external reference.
304  */
305 int get_phys_clock(unsigned long *clock)
306 {
307 	atomic_t *sw_ptr;
308 	unsigned int sw0, sw1;
309 
310 	sw_ptr = &get_cpu_var(clock_sync_word);
311 	sw0 = atomic_read(sw_ptr);
312 	*clock = get_tod_clock() - lpar_offset;
313 	sw1 = atomic_read(sw_ptr);
314 	put_cpu_var(clock_sync_word);
315 	if (sw0 == sw1 && (sw0 & 0x80000000U))
316 		/* Success: time is in sync. */
317 		return 0;
318 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
319 		return -EOPNOTSUPP;
320 	if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
321 		return -EACCES;
322 	return -EAGAIN;
323 }
324 EXPORT_SYMBOL(get_phys_clock);
325 
326 /*
327  * Make get_phys_clock() return -EAGAIN.
328  */
329 static void disable_sync_clock(void *dummy)
330 {
331 	atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
332 	/*
333 	 * Clear the in-sync bit 2^31. All get_phys_clock calls will
334 	 * fail until the sync bit is turned back on. In addition
335 	 * increase the "sequence" counter to avoid the race of an
336 	 * stp event and the complete recovery against get_phys_clock.
337 	 */
338 	atomic_andnot(0x80000000, sw_ptr);
339 	atomic_inc(sw_ptr);
340 }
341 
342 /*
343  * Make get_phys_clock() return 0 again.
344  * Needs to be called from a context disabled for preemption.
345  */
346 static void enable_sync_clock(void)
347 {
348 	atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
349 	atomic_or(0x80000000, sw_ptr);
350 }
351 
352 /*
353  * Function to check if the clock is in sync.
354  */
355 static inline int check_sync_clock(void)
356 {
357 	atomic_t *sw_ptr;
358 	int rc;
359 
360 	sw_ptr = &get_cpu_var(clock_sync_word);
361 	rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;
362 	put_cpu_var(clock_sync_word);
363 	return rc;
364 }
365 
366 /*
367  * Apply clock delta to the global data structures.
368  * This is called once on the CPU that performed the clock sync.
369  */
370 static void clock_sync_global(long delta)
371 {
372 	unsigned long now, adj;
373 	struct ptff_qto qto;
374 
375 	/* Fixup the monotonic sched clock. */
376 	tod_clock_base.eitod += delta;
377 	/* Adjust TOD steering parameters. */
378 	now = get_tod_clock();
379 	adj = tod_steering_end - now;
380 	if (unlikely((s64) adj >= 0))
381 		/* Calculate how much of the old adjustment is left. */
382 		tod_steering_delta = (tod_steering_delta < 0) ?
383 			-(adj >> 15) : (adj >> 15);
384 	tod_steering_delta += delta;
385 	if ((abs(tod_steering_delta) >> 48) != 0)
386 		panic("TOD clock sync offset %li is too large to drift\n",
387 		      tod_steering_delta);
388 	tod_steering_end = now + (abs(tod_steering_delta) << 15);
389 	vdso_k_time_data->arch_data.tod_steering_end = tod_steering_end;
390 	vdso_k_time_data->arch_data.tod_steering_delta = tod_steering_delta;
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 (get_lowcore()->clock_comparator != clock_comparator_max) {
407 		get_lowcore()->clock_comparator += delta;
408 		set_clock_comparator(get_lowcore()->clock_comparator);
409 	}
410 	/* Adjust the last_update_clock time-stamp. */
411 	get_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 bool stp_enabled(void)
467 {
468 	return test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags) && stp_online;
469 }
470 EXPORT_SYMBOL(stp_enabled);
471 
472 static void stp_timeout(struct timer_list *unused)
473 {
474 	queue_work(time_sync_wq, &stp_work);
475 }
476 
477 static int __init stp_init(void)
478 {
479 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
480 		return 0;
481 	timer_setup(&stp_timer, stp_timeout, 0);
482 	time_init_wq();
483 	if (!stp_online)
484 		return 0;
485 	queue_work(time_sync_wq, &stp_work);
486 	return 0;
487 }
488 
489 arch_initcall(stp_init);
490 
491 /*
492  * STP timing alert. There are three causes:
493  * 1) timing status change
494  * 2) link availability change
495  * 3) time control parameter change
496  * In all three cases we are only interested in the clock source state.
497  * If a STP clock source is now available use it.
498  */
499 static void stp_timing_alert(struct stp_irq_parm *intparm)
500 {
501 	if (intparm->tsc || intparm->lac || intparm->tcpc)
502 		queue_work(time_sync_wq, &stp_work);
503 }
504 
505 /*
506  * STP sync check machine check. This is called when the timing state
507  * changes from the synchronized state to the unsynchronized state.
508  * After a STP sync check the clock is not in sync. The machine check
509  * is broadcasted to all cpus at the same time.
510  */
511 int stp_sync_check(void)
512 {
513 	disable_sync_clock(NULL);
514 	return 1;
515 }
516 
517 /*
518  * STP island condition machine check. This is called when an attached
519  * server  attempts to communicate over an STP link and the servers
520  * have matching CTN ids and have a valid stratum-1 configuration
521  * but the configurations do not match.
522  */
523 int stp_island_check(void)
524 {
525 	disable_sync_clock(NULL);
526 	return 1;
527 }
528 
529 void stp_queue_work(void)
530 {
531 	queue_work(time_sync_wq, &stp_work);
532 }
533 
534 static int __store_stpinfo(void)
535 {
536 	int rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
537 
538 	if (rc)
539 		clear_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
540 	else
541 		set_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
542 	return rc;
543 }
544 
545 static int stpinfo_valid(void)
546 {
547 	return stp_online && test_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
548 }
549 
550 static int stp_sync_clock(void *data)
551 {
552 	struct clock_sync_data *sync = data;
553 	long clock_delta, flags;
554 	static int first;
555 	int rc;
556 
557 	enable_sync_clock();
558 	if (xchg(&first, 1) == 0) {
559 		/* Wait until all other cpus entered the sync function. */
560 		while (atomic_read(&sync->cpus) != 0)
561 			cpu_relax();
562 		rc = 0;
563 		if (stp_info.todoff || stp_info.tmd != 2) {
564 			flags = vdso_update_begin();
565 			rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
566 					&clock_delta);
567 			if (rc == 0) {
568 				sync->clock_delta = clock_delta;
569 				clock_sync_global(clock_delta);
570 				rc = __store_stpinfo();
571 				if (rc == 0 && stp_info.tmd != 2)
572 					rc = -EAGAIN;
573 			}
574 			vdso_update_end(flags);
575 		}
576 		sync->in_sync = rc ? -EAGAIN : 1;
577 		xchg(&first, 0);
578 	} else {
579 		/* Slave */
580 		atomic_dec(&sync->cpus);
581 		/* Wait for in_sync to be set. */
582 		while (READ_ONCE(sync->in_sync) == 0)
583 			__udelay(1);
584 	}
585 	if (sync->in_sync != 1)
586 		/* Didn't work. Clear per-cpu in sync bit again. */
587 		disable_sync_clock(NULL);
588 	/* Apply clock delta to per-CPU fields of this CPU. */
589 	clock_sync_local(sync->clock_delta);
590 
591 	return 0;
592 }
593 
594 static int stp_clear_leap(void)
595 {
596 	struct __kernel_timex txc;
597 	int ret;
598 
599 	memset(&txc, 0, sizeof(txc));
600 
601 	ret = do_adjtimex(&txc);
602 	if (ret < 0)
603 		return ret;
604 
605 	txc.modes = ADJ_STATUS;
606 	txc.status &= ~(STA_INS|STA_DEL);
607 	return do_adjtimex(&txc);
608 }
609 
610 static void stp_check_leap(void)
611 {
612 	struct stp_stzi stzi;
613 	struct stp_lsoib *lsoib = &stzi.lsoib;
614 	struct __kernel_timex txc;
615 	int64_t timediff;
616 	int leapdiff, ret;
617 
618 	if (!stp_info.lu || !check_sync_clock()) {
619 		/*
620 		 * Either a scheduled leap second was removed by the operator,
621 		 * or STP is out of sync. In both cases, clear the leap second
622 		 * kernel flags.
623 		 */
624 		if (stp_clear_leap() < 0)
625 			pr_err("failed to clear leap second flags\n");
626 		return;
627 	}
628 
629 	if (chsc_stzi(stp_page, &stzi, sizeof(stzi))) {
630 		pr_err("stzi failed\n");
631 		return;
632 	}
633 
634 	timediff = tod_to_ns(lsoib->nlsout - get_tod_clock()) / NSEC_PER_SEC;
635 	leapdiff = lsoib->nlso - lsoib->also;
636 
637 	if (leapdiff != 1 && leapdiff != -1) {
638 		pr_err("Cannot schedule %d leap seconds\n", leapdiff);
639 		return;
640 	}
641 
642 	if (timediff < 0) {
643 		if (stp_clear_leap() < 0)
644 			pr_err("failed to clear leap second flags\n");
645 	} else if (timediff < 7200) {
646 		memset(&txc, 0, sizeof(txc));
647 		ret = do_adjtimex(&txc);
648 		if (ret < 0)
649 			return;
650 
651 		txc.modes = ADJ_STATUS;
652 		if (leapdiff > 0)
653 			txc.status |= STA_INS;
654 		else
655 			txc.status |= STA_DEL;
656 		ret = do_adjtimex(&txc);
657 		if (ret < 0)
658 			pr_err("failed to set leap second flags\n");
659 		/* arm Timer to clear leap second flags */
660 		mod_timer(&stp_timer, jiffies + secs_to_jiffies(14400));
661 	} else {
662 		/* The day the leap second is scheduled for hasn't been reached. Retry
663 		 * in one hour.
664 		 */
665 		mod_timer(&stp_timer, jiffies + secs_to_jiffies(3600));
666 	}
667 }
668 
669 /*
670  * STP work. Check for the STP state and take over the clock
671  * synchronization if the STP clock source is usable.
672  */
673 static void stp_work_fn(struct work_struct *work)
674 {
675 	struct clock_sync_data stp_sync;
676 	int rc;
677 
678 	/* prevent multiple execution. */
679 	mutex_lock(&stp_mutex);
680 
681 	if (!stp_online) {
682 		chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
683 		timer_delete_sync(&stp_timer);
684 		goto out_unlock;
685 	}
686 
687 	rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xf0e0, NULL);
688 	if (rc)
689 		goto out_unlock;
690 
691 	rc = __store_stpinfo();
692 	if (rc || stp_info.c == 0)
693 		goto out_unlock;
694 
695 	/* Skip synchronization if the clock is already in sync. */
696 	if (!check_sync_clock()) {
697 		memset(&stp_sync, 0, sizeof(stp_sync));
698 		cpus_read_lock();
699 		atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
700 		stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
701 		cpus_read_unlock();
702 	}
703 
704 	if (!check_sync_clock())
705 		/*
706 		 * There is a usable clock but the synchronization failed.
707 		 * Retry after a second.
708 		 */
709 		mod_timer(&stp_timer, jiffies + msecs_to_jiffies(MSEC_PER_SEC));
710 	else if (stp_info.lu)
711 		stp_check_leap();
712 
713 out_unlock:
714 	mutex_unlock(&stp_mutex);
715 }
716 
717 /*
718  * STP subsys sysfs interface functions
719  */
720 static const struct bus_type stp_subsys = {
721 	.name		= "stp",
722 	.dev_name	= "stp",
723 };
724 
725 static ssize_t ctn_id_show(struct device *dev,
726 				struct device_attribute *attr,
727 				char *buf)
728 {
729 	ssize_t ret = -ENODATA;
730 
731 	mutex_lock(&stp_mutex);
732 	if (stpinfo_valid())
733 		ret = sysfs_emit(buf, "%016lx\n",
734 				 *(unsigned long *)stp_info.ctnid);
735 	mutex_unlock(&stp_mutex);
736 	return ret;
737 }
738 
739 static DEVICE_ATTR_RO(ctn_id);
740 
741 static ssize_t ctn_type_show(struct device *dev,
742 				struct device_attribute *attr,
743 				char *buf)
744 {
745 	ssize_t ret = -ENODATA;
746 
747 	mutex_lock(&stp_mutex);
748 	if (stpinfo_valid())
749 		ret = sysfs_emit(buf, "%i\n", stp_info.ctn);
750 	mutex_unlock(&stp_mutex);
751 	return ret;
752 }
753 
754 static DEVICE_ATTR_RO(ctn_type);
755 
756 static ssize_t dst_offset_show(struct device *dev,
757 				   struct device_attribute *attr,
758 				   char *buf)
759 {
760 	ssize_t ret = -ENODATA;
761 
762 	mutex_lock(&stp_mutex);
763 	if (stpinfo_valid() && (stp_info.vbits & 0x2000))
764 		ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.dsto);
765 	mutex_unlock(&stp_mutex);
766 	return ret;
767 }
768 
769 static DEVICE_ATTR_RO(dst_offset);
770 
771 static ssize_t leap_seconds_show(struct device *dev,
772 					struct device_attribute *attr,
773 					char *buf)
774 {
775 	ssize_t ret = -ENODATA;
776 
777 	mutex_lock(&stp_mutex);
778 	if (stpinfo_valid() && (stp_info.vbits & 0x8000))
779 		ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.leaps);
780 	mutex_unlock(&stp_mutex);
781 	return ret;
782 }
783 
784 static DEVICE_ATTR_RO(leap_seconds);
785 
786 static ssize_t leap_seconds_scheduled_show(struct device *dev,
787 						struct device_attribute *attr,
788 						char *buf)
789 {
790 	struct stp_stzi stzi;
791 	ssize_t ret;
792 
793 	mutex_lock(&stp_mutex);
794 	if (!stpinfo_valid() || !(stp_info.vbits & 0x8000) || !stp_info.lu) {
795 		mutex_unlock(&stp_mutex);
796 		return -ENODATA;
797 	}
798 
799 	ret = chsc_stzi(stp_page, &stzi, sizeof(stzi));
800 	mutex_unlock(&stp_mutex);
801 	if (ret < 0)
802 		return ret;
803 
804 	if (!stzi.lsoib.p)
805 		return sysfs_emit(buf, "0,0\n");
806 
807 	return sysfs_emit(buf, "%lu,%d\n",
808 			  tod_to_ns(stzi.lsoib.nlsout - TOD_UNIX_EPOCH) / NSEC_PER_SEC,
809 			  stzi.lsoib.nlso - stzi.lsoib.also);
810 }
811 
812 static DEVICE_ATTR_RO(leap_seconds_scheduled);
813 
814 static ssize_t stratum_show(struct device *dev,
815 				struct device_attribute *attr,
816 				char *buf)
817 {
818 	ssize_t ret = -ENODATA;
819 
820 	mutex_lock(&stp_mutex);
821 	if (stpinfo_valid())
822 		ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.stratum);
823 	mutex_unlock(&stp_mutex);
824 	return ret;
825 }
826 
827 static DEVICE_ATTR_RO(stratum);
828 
829 static ssize_t time_offset_show(struct device *dev,
830 				struct device_attribute *attr,
831 				char *buf)
832 {
833 	ssize_t ret = -ENODATA;
834 
835 	mutex_lock(&stp_mutex);
836 	if (stpinfo_valid() && (stp_info.vbits & 0x0800))
837 		ret = sysfs_emit(buf, "%i\n", (int)stp_info.tto);
838 	mutex_unlock(&stp_mutex);
839 	return ret;
840 }
841 
842 static DEVICE_ATTR_RO(time_offset);
843 
844 static ssize_t time_zone_offset_show(struct device *dev,
845 				struct device_attribute *attr,
846 				char *buf)
847 {
848 	ssize_t ret = -ENODATA;
849 
850 	mutex_lock(&stp_mutex);
851 	if (stpinfo_valid() && (stp_info.vbits & 0x4000))
852 		ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.tzo);
853 	mutex_unlock(&stp_mutex);
854 	return ret;
855 }
856 
857 static DEVICE_ATTR_RO(time_zone_offset);
858 
859 static ssize_t timing_mode_show(struct device *dev,
860 				struct device_attribute *attr,
861 				char *buf)
862 {
863 	ssize_t ret = -ENODATA;
864 
865 	mutex_lock(&stp_mutex);
866 	if (stpinfo_valid())
867 		ret = sysfs_emit(buf, "%i\n", stp_info.tmd);
868 	mutex_unlock(&stp_mutex);
869 	return ret;
870 }
871 
872 static DEVICE_ATTR_RO(timing_mode);
873 
874 static ssize_t timing_state_show(struct device *dev,
875 				struct device_attribute *attr,
876 				char *buf)
877 {
878 	ssize_t ret = -ENODATA;
879 
880 	mutex_lock(&stp_mutex);
881 	if (stpinfo_valid())
882 		ret = sysfs_emit(buf, "%i\n", stp_info.tst);
883 	mutex_unlock(&stp_mutex);
884 	return ret;
885 }
886 
887 static DEVICE_ATTR_RO(timing_state);
888 
889 static ssize_t online_show(struct device *dev,
890 				struct device_attribute *attr,
891 				char *buf)
892 {
893 	return sysfs_emit(buf, "%i\n", stp_online);
894 }
895 
896 static ssize_t online_store(struct device *dev,
897 				struct device_attribute *attr,
898 				const char *buf, size_t count)
899 {
900 	unsigned int value;
901 
902 	value = simple_strtoul(buf, NULL, 0);
903 	if (value != 0 && value != 1)
904 		return -EINVAL;
905 	if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
906 		return -EOPNOTSUPP;
907 	mutex_lock(&stp_mutex);
908 	stp_online = value;
909 	if (stp_online)
910 		set_bit(CLOCK_SYNC_STP, &clock_sync_flags);
911 	else
912 		clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
913 	queue_work(time_sync_wq, &stp_work);
914 	mutex_unlock(&stp_mutex);
915 	return count;
916 }
917 
918 /*
919  * Can't use DEVICE_ATTR because the attribute should be named
920  * stp/online but dev_attr_online already exists in this file ..
921  */
922 static DEVICE_ATTR_RW(online);
923 
924 static struct attribute *stp_dev_attrs[] = {
925 	&dev_attr_ctn_id.attr,
926 	&dev_attr_ctn_type.attr,
927 	&dev_attr_dst_offset.attr,
928 	&dev_attr_leap_seconds.attr,
929 	&dev_attr_online.attr,
930 	&dev_attr_leap_seconds_scheduled.attr,
931 	&dev_attr_stratum.attr,
932 	&dev_attr_time_offset.attr,
933 	&dev_attr_time_zone_offset.attr,
934 	&dev_attr_timing_mode.attr,
935 	&dev_attr_timing_state.attr,
936 	NULL
937 };
938 ATTRIBUTE_GROUPS(stp_dev);
939 
940 static int __init stp_init_sysfs(void)
941 {
942 	return subsys_system_register(&stp_subsys, stp_dev_groups);
943 }
944 
945 device_initcall(stp_init_sysfs);
946