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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
57union tod_clock tod_clock_base __section(".data");
58EXPORT_SYMBOL_GPL(tod_clock_base);
59
60u64 clock_comparator_max = -1ULL;
61EXPORT_SYMBOL_GPL(clock_comparator_max);
62
63static DEFINE_PER_CPU(struct clock_event_device, comparators);
64
65ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
66EXPORT_SYMBOL(s390_epoch_delta_notifier);
67
68unsigned char ptff_function_mask[16];
69
70static unsigned long lpar_offset;
71static unsigned long initial_leap_seconds;
72static unsigned long tod_steering_end;
73static long tod_steering_delta;
74
75/*
76 * Get time offsets with PTFF
77 */
78void __init time_early_init(void)
79{
80 struct ptff_qto qto;
81 struct ptff_qui qui;
82 int cs;
83
84 /* Initialize TOD steering parameters */
85 tod_steering_end = tod_clock_base.tod;
86 for (cs = 0; cs < CS_BASES; cs++)
87 vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
88
89 if (!test_facility(28))
90 return;
91
92 ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF);
93
94 /* get LPAR offset */
95 if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
96 lpar_offset = qto.tod_epoch_difference;
97
98 /* get initial leap seconds */
99 if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
100 initial_leap_seconds = (unsigned long)
101 ((long) qui.old_leap * 4096000000L);
102}
103
104unsigned long long noinstr sched_clock_noinstr(void)
105{
106 return tod_to_ns(__get_tod_clock_monotonic());
107}
108
109/*
110 * Scheduler clock - returns current time in nanosec units.
111 */
112unsigned long long notrace sched_clock(void)
113{
114 return tod_to_ns(get_tod_clock_monotonic());
115}
116NOKPROBE_SYMBOL(sched_clock);
117
118static void ext_to_timespec64(union tod_clock *clk, struct timespec64 *xt)
119{
120 unsigned long rem, sec, nsec;
121
122 sec = clk->us;
123 rem = do_div(sec, 1000000);
124 nsec = ((clk->sus + (rem << 12)) * 125) >> 9;
125 xt->tv_sec = sec;
126 xt->tv_nsec = nsec;
127}
128
129void clock_comparator_work(void)
130{
131 struct clock_event_device *cd;
132
133 get_lowcore()->clock_comparator = clock_comparator_max;
134 cd = this_cpu_ptr(&comparators);
135 cd->event_handler(cd);
136}
137
138static int s390_next_event(unsigned long delta,
139 struct clock_event_device *evt)
140{
141 get_lowcore()->clock_comparator = get_tod_clock() + delta;
142 set_clock_comparator(get_lowcore()->clock_comparator);
143 return 0;
144}
145
146/*
147 * Set up lowcore and control register of the current cpu to
148 * enable TOD clock and clock comparator interrupts.
149 */
150void init_cpu_timer(void)
151{
152 struct clock_event_device *cd;
153 int cpu;
154
155 get_lowcore()->clock_comparator = clock_comparator_max;
156 set_clock_comparator(get_lowcore()->clock_comparator);
157
158 cpu = smp_processor_id();
159 cd = &per_cpu(comparators, cpu);
160 cd->name = "comparator";
161 cd->features = CLOCK_EVT_FEAT_ONESHOT;
162 cd->mult = 16777;
163 cd->shift = 12;
164 cd->min_delta_ns = 1;
165 cd->min_delta_ticks = 1;
166 cd->max_delta_ns = LONG_MAX;
167 cd->max_delta_ticks = ULONG_MAX;
168 cd->rating = 400;
169 cd->cpumask = cpumask_of(cpu);
170 cd->set_next_event = s390_next_event;
171
172 clockevents_register_device(cd);
173
174 /* Enable clock comparator timer interrupt. */
175 local_ctl_set_bit(0, CR0_CLOCK_COMPARATOR_SUBMASK_BIT);
176
177 /* Always allow the timing alert external interrupt. */
178 local_ctl_set_bit(0, CR0_ETR_SUBMASK_BIT);
179}
180
181static void clock_comparator_interrupt(struct ext_code ext_code,
182 unsigned int param32,
183 unsigned long param64)
184{
185 inc_irq_stat(IRQEXT_CLK);
186 if (get_lowcore()->clock_comparator == clock_comparator_max)
187 set_clock_comparator(get_lowcore()->clock_comparator);
188}
189
190static void stp_timing_alert(struct stp_irq_parm *);
191
192static void timing_alert_interrupt(struct ext_code ext_code,
193 unsigned int param32, unsigned long param64)
194{
195 inc_irq_stat(IRQEXT_TLA);
196 if (param32 & 0x00038000)
197 stp_timing_alert((struct stp_irq_parm *) ¶m32);
198}
199
200static void stp_reset(void);
201
202void read_persistent_clock64(struct timespec64 *ts)
203{
204 union tod_clock clk;
205 u64 delta;
206
207 delta = initial_leap_seconds + TOD_UNIX_EPOCH;
208 store_tod_clock_ext(&clk);
209 clk.eitod -= delta;
210 ext_to_timespec64(&clk, ts);
211}
212
213void __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
214 struct timespec64 *boot_offset)
215{
216 struct timespec64 boot_time;
217 union tod_clock clk;
218 u64 delta;
219
220 delta = initial_leap_seconds + TOD_UNIX_EPOCH;
221 clk = tod_clock_base;
222 clk.eitod -= delta;
223 ext_to_timespec64(&clk, &boot_time);
224
225 read_persistent_clock64(wall_time);
226 *boot_offset = timespec64_sub(*wall_time, boot_time);
227}
228
229static u64 read_tod_clock(struct clocksource *cs)
230{
231 unsigned long now, adj;
232
233 preempt_disable(); /* protect from changes to steering parameters */
234 now = get_tod_clock();
235 adj = tod_steering_end - now;
236 if (unlikely((s64) adj > 0))
237 /*
238 * manually steer by 1 cycle every 2^16 cycles. This
239 * corresponds to shifting the tod delta by 15. 1s is
240 * therefore steered in ~9h. The adjust will decrease
241 * over time, until it finally reaches 0.
242 */
243 now += (tod_steering_delta < 0) ? (adj >> 15) : -(adj >> 15);
244 preempt_enable();
245 return now;
246}
247
248static struct clocksource clocksource_tod = {
249 .name = "tod",
250 .rating = 400,
251 .read = read_tod_clock,
252 .mask = CLOCKSOURCE_MASK(64),
253 .mult = 4096000,
254 .shift = 24,
255 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
256 .vdso_clock_mode = VDSO_CLOCKMODE_TOD,
257 .id = CSID_S390_TOD,
258};
259
260struct clocksource * __init clocksource_default_clock(void)
261{
262 return &clocksource_tod;
263}
264
265/*
266 * Initialize the TOD clock and the CPU timer of
267 * the boot cpu.
268 */
269void __init time_init(void)
270{
271 /* Reset time synchronization interfaces. */
272 stp_reset();
273
274 /* request the clock comparator external interrupt */
275 if (register_external_irq(EXT_IRQ_CLK_COMP, clock_comparator_interrupt))
276 panic("Couldn't request external interrupt 0x1004");
277
278 /* request the timing alert external interrupt */
279 if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
280 panic("Couldn't request external interrupt 0x1406");
281
282 if (__clocksource_register(&clocksource_tod) != 0)
283 panic("Could not register TOD clock source");
284
285 /* Enable TOD clock interrupts on the boot cpu. */
286 init_cpu_timer();
287
288 /* Enable cpu timer interrupts on the boot cpu. */
289 vtime_init();
290}
291
292static DEFINE_PER_CPU(atomic_t, clock_sync_word);
293static DEFINE_MUTEX(stp_mutex);
294static unsigned long clock_sync_flags;
295
296#define CLOCK_SYNC_HAS_STP 0
297#define CLOCK_SYNC_STP 1
298#define CLOCK_SYNC_STPINFO_VALID 2
299
300/*
301 * The get_clock function for the physical clock. It will get the current
302 * TOD clock, subtract the LPAR offset and write the result to *clock.
303 * The function returns 0 if the clock is in sync with the external time
304 * source. If the clock mode is local it will return -EOPNOTSUPP and
305 * -EAGAIN if the clock is not in sync with the external reference.
306 */
307int get_phys_clock(unsigned long *clock)
308{
309 atomic_t *sw_ptr;
310 unsigned int sw0, sw1;
311
312 sw_ptr = &get_cpu_var(clock_sync_word);
313 sw0 = atomic_read(sw_ptr);
314 *clock = get_tod_clock() - lpar_offset;
315 sw1 = atomic_read(sw_ptr);
316 put_cpu_var(clock_sync_word);
317 if (sw0 == sw1 && (sw0 & 0x80000000U))
318 /* Success: time is in sync. */
319 return 0;
320 if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
321 return -EOPNOTSUPP;
322 if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
323 return -EACCES;
324 return -EAGAIN;
325}
326EXPORT_SYMBOL(get_phys_clock);
327
328/*
329 * Make get_phys_clock() return -EAGAIN.
330 */
331static void disable_sync_clock(void *dummy)
332{
333 atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
334 /*
335 * Clear the in-sync bit 2^31. All get_phys_clock calls will
336 * fail until the sync bit is turned back on. In addition
337 * increase the "sequence" counter to avoid the race of an
338 * stp event and the complete recovery against get_phys_clock.
339 */
340 atomic_andnot(0x80000000, sw_ptr);
341 atomic_inc(sw_ptr);
342}
343
344/*
345 * Make get_phys_clock() return 0 again.
346 * Needs to be called from a context disabled for preemption.
347 */
348static void enable_sync_clock(void)
349{
350 atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
351 atomic_or(0x80000000, sw_ptr);
352}
353
354/*
355 * Function to check if the clock is in sync.
356 */
357static inline int check_sync_clock(void)
358{
359 atomic_t *sw_ptr;
360 int rc;
361
362 sw_ptr = &get_cpu_var(clock_sync_word);
363 rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;
364 put_cpu_var(clock_sync_word);
365 return rc;
366}
367
368/*
369 * Apply clock delta to the global data structures.
370 * This is called once on the CPU that performed the clock sync.
371 */
372static void clock_sync_global(long delta)
373{
374 unsigned long now, adj;
375 struct ptff_qto qto;
376 int cs;
377
378 /* Fixup the monotonic sched clock. */
379 tod_clock_base.eitod += delta;
380 /* Adjust TOD steering parameters. */
381 now = get_tod_clock();
382 adj = tod_steering_end - now;
383 if (unlikely((s64) adj >= 0))
384 /* Calculate how much of the old adjustment is left. */
385 tod_steering_delta = (tod_steering_delta < 0) ?
386 -(adj >> 15) : (adj >> 15);
387 tod_steering_delta += delta;
388 if ((abs(tod_steering_delta) >> 48) != 0)
389 panic("TOD clock sync offset %li is too large to drift\n",
390 tod_steering_delta);
391 tod_steering_end = now + (abs(tod_steering_delta) << 15);
392 for (cs = 0; cs < CS_BASES; cs++) {
393 vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
394 vdso_data[cs].arch_data.tod_steering_delta = tod_steering_delta;
395 }
396
397 /* Update LPAR offset. */
398 if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
399 lpar_offset = qto.tod_epoch_difference;
400 /* Call the TOD clock change notifier. */
401 atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);
402}
403
404/*
405 * Apply clock delta to the per-CPU data structures of this CPU.
406 * This is called for each online CPU after the call to clock_sync_global.
407 */
408static void clock_sync_local(long delta)
409{
410 /* Add the delta to the clock comparator. */
411 if (get_lowcore()->clock_comparator != clock_comparator_max) {
412 get_lowcore()->clock_comparator += delta;
413 set_clock_comparator(get_lowcore()->clock_comparator);
414 }
415 /* Adjust the last_update_clock time-stamp. */
416 get_lowcore()->last_update_clock += delta;
417}
418
419/* Single threaded workqueue used for stp sync events */
420static struct workqueue_struct *time_sync_wq;
421
422static void __init time_init_wq(void)
423{
424 if (time_sync_wq)
425 return;
426 time_sync_wq = create_singlethread_workqueue("timesync");
427}
428
429struct clock_sync_data {
430 atomic_t cpus;
431 int in_sync;
432 long clock_delta;
433};
434
435/*
436 * Server Time Protocol (STP) code.
437 */
438static bool stp_online;
439static struct stp_sstpi stp_info;
440static void *stp_page;
441
442static void stp_work_fn(struct work_struct *work);
443static DECLARE_WORK(stp_work, stp_work_fn);
444static struct timer_list stp_timer;
445
446static int __init early_parse_stp(char *p)
447{
448 return kstrtobool(p, &stp_online);
449}
450early_param("stp", early_parse_stp);
451
452/*
453 * Reset STP attachment.
454 */
455static void __init stp_reset(void)
456{
457 int rc;
458
459 stp_page = (void *) get_zeroed_page(GFP_ATOMIC);
460 rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
461 if (rc == 0)
462 set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags);
463 else if (stp_online) {
464 pr_warn("The real or virtual hardware system does not provide an STP interface\n");
465 free_page((unsigned long) stp_page);
466 stp_page = NULL;
467 stp_online = false;
468 }
469}
470
471bool stp_enabled(void)
472{
473 return test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags) && stp_online;
474}
475EXPORT_SYMBOL(stp_enabled);
476
477static void stp_timeout(struct timer_list *unused)
478{
479 queue_work(time_sync_wq, &stp_work);
480}
481
482static int __init stp_init(void)
483{
484 if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
485 return 0;
486 timer_setup(&stp_timer, stp_timeout, 0);
487 time_init_wq();
488 if (!stp_online)
489 return 0;
490 queue_work(time_sync_wq, &stp_work);
491 return 0;
492}
493
494arch_initcall(stp_init);
495
496/*
497 * STP timing alert. There are three causes:
498 * 1) timing status change
499 * 2) link availability change
500 * 3) time control parameter change
501 * In all three cases we are only interested in the clock source state.
502 * If a STP clock source is now available use it.
503 */
504static void stp_timing_alert(struct stp_irq_parm *intparm)
505{
506 if (intparm->tsc || intparm->lac || intparm->tcpc)
507 queue_work(time_sync_wq, &stp_work);
508}
509
510/*
511 * STP sync check machine check. This is called when the timing state
512 * changes from the synchronized state to the unsynchronized state.
513 * After a STP sync check the clock is not in sync. The machine check
514 * is broadcasted to all cpus at the same time.
515 */
516int stp_sync_check(void)
517{
518 disable_sync_clock(NULL);
519 return 1;
520}
521
522/*
523 * STP island condition machine check. This is called when an attached
524 * server attempts to communicate over an STP link and the servers
525 * have matching CTN ids and have a valid stratum-1 configuration
526 * but the configurations do not match.
527 */
528int stp_island_check(void)
529{
530 disable_sync_clock(NULL);
531 return 1;
532}
533
534void stp_queue_work(void)
535{
536 queue_work(time_sync_wq, &stp_work);
537}
538
539static int __store_stpinfo(void)
540{
541 int rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
542
543 if (rc)
544 clear_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
545 else
546 set_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
547 return rc;
548}
549
550static int stpinfo_valid(void)
551{
552 return stp_online && test_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
553}
554
555static int stp_sync_clock(void *data)
556{
557 struct clock_sync_data *sync = data;
558 long clock_delta, flags;
559 static int first;
560 int rc;
561
562 enable_sync_clock();
563 if (xchg(&first, 1) == 0) {
564 /* Wait until all other cpus entered the sync function. */
565 while (atomic_read(&sync->cpus) != 0)
566 cpu_relax();
567 rc = 0;
568 if (stp_info.todoff || stp_info.tmd != 2) {
569 flags = vdso_update_begin();
570 rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
571 &clock_delta);
572 if (rc == 0) {
573 sync->clock_delta = clock_delta;
574 clock_sync_global(clock_delta);
575 rc = __store_stpinfo();
576 if (rc == 0 && stp_info.tmd != 2)
577 rc = -EAGAIN;
578 }
579 vdso_update_end(flags);
580 }
581 sync->in_sync = rc ? -EAGAIN : 1;
582 xchg(&first, 0);
583 } else {
584 /* Slave */
585 atomic_dec(&sync->cpus);
586 /* Wait for in_sync to be set. */
587 while (READ_ONCE(sync->in_sync) == 0)
588 __udelay(1);
589 }
590 if (sync->in_sync != 1)
591 /* Didn't work. Clear per-cpu in sync bit again. */
592 disable_sync_clock(NULL);
593 /* Apply clock delta to per-CPU fields of this CPU. */
594 clock_sync_local(sync->clock_delta);
595
596 return 0;
597}
598
599static int stp_clear_leap(void)
600{
601 struct __kernel_timex txc;
602 int ret;
603
604 memset(&txc, 0, sizeof(txc));
605
606 ret = do_adjtimex(&txc);
607 if (ret < 0)
608 return ret;
609
610 txc.modes = ADJ_STATUS;
611 txc.status &= ~(STA_INS|STA_DEL);
612 return do_adjtimex(&txc);
613}
614
615static void stp_check_leap(void)
616{
617 struct stp_stzi stzi;
618 struct stp_lsoib *lsoib = &stzi.lsoib;
619 struct __kernel_timex txc;
620 int64_t timediff;
621 int leapdiff, ret;
622
623 if (!stp_info.lu || !check_sync_clock()) {
624 /*
625 * Either a scheduled leap second was removed by the operator,
626 * or STP is out of sync. In both cases, clear the leap second
627 * kernel flags.
628 */
629 if (stp_clear_leap() < 0)
630 pr_err("failed to clear leap second flags\n");
631 return;
632 }
633
634 if (chsc_stzi(stp_page, &stzi, sizeof(stzi))) {
635 pr_err("stzi failed\n");
636 return;
637 }
638
639 timediff = tod_to_ns(lsoib->nlsout - get_tod_clock()) / NSEC_PER_SEC;
640 leapdiff = lsoib->nlso - lsoib->also;
641
642 if (leapdiff != 1 && leapdiff != -1) {
643 pr_err("Cannot schedule %d leap seconds\n", leapdiff);
644 return;
645 }
646
647 if (timediff < 0) {
648 if (stp_clear_leap() < 0)
649 pr_err("failed to clear leap second flags\n");
650 } else if (timediff < 7200) {
651 memset(&txc, 0, sizeof(txc));
652 ret = do_adjtimex(&txc);
653 if (ret < 0)
654 return;
655
656 txc.modes = ADJ_STATUS;
657 if (leapdiff > 0)
658 txc.status |= STA_INS;
659 else
660 txc.status |= STA_DEL;
661 ret = do_adjtimex(&txc);
662 if (ret < 0)
663 pr_err("failed to set leap second flags\n");
664 /* arm Timer to clear leap second flags */
665 mod_timer(&stp_timer, jiffies + msecs_to_jiffies(14400 * MSEC_PER_SEC));
666 } else {
667 /* The day the leap second is scheduled for hasn't been reached. Retry
668 * in one hour.
669 */
670 mod_timer(&stp_timer, jiffies + msecs_to_jiffies(3600 * MSEC_PER_SEC));
671 }
672}
673
674/*
675 * STP work. Check for the STP state and take over the clock
676 * synchronization if the STP clock source is usable.
677 */
678static void stp_work_fn(struct work_struct *work)
679{
680 struct clock_sync_data stp_sync;
681 int rc;
682
683 /* prevent multiple execution. */
684 mutex_lock(&stp_mutex);
685
686 if (!stp_online) {
687 chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
688 del_timer_sync(&stp_timer);
689 goto out_unlock;
690 }
691
692 rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xf0e0, NULL);
693 if (rc)
694 goto out_unlock;
695
696 rc = __store_stpinfo();
697 if (rc || stp_info.c == 0)
698 goto out_unlock;
699
700 /* Skip synchronization if the clock is already in sync. */
701 if (!check_sync_clock()) {
702 memset(&stp_sync, 0, sizeof(stp_sync));
703 cpus_read_lock();
704 atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
705 stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
706 cpus_read_unlock();
707 }
708
709 if (!check_sync_clock())
710 /*
711 * There is a usable clock but the synchronization failed.
712 * Retry after a second.
713 */
714 mod_timer(&stp_timer, jiffies + msecs_to_jiffies(MSEC_PER_SEC));
715 else if (stp_info.lu)
716 stp_check_leap();
717
718out_unlock:
719 mutex_unlock(&stp_mutex);
720}
721
722/*
723 * STP subsys sysfs interface functions
724 */
725static const struct bus_type stp_subsys = {
726 .name = "stp",
727 .dev_name = "stp",
728};
729
730static ssize_t ctn_id_show(struct device *dev,
731 struct device_attribute *attr,
732 char *buf)
733{
734 ssize_t ret = -ENODATA;
735
736 mutex_lock(&stp_mutex);
737 if (stpinfo_valid())
738 ret = sysfs_emit(buf, "%016lx\n",
739 *(unsigned long *)stp_info.ctnid);
740 mutex_unlock(&stp_mutex);
741 return ret;
742}
743
744static DEVICE_ATTR_RO(ctn_id);
745
746static ssize_t ctn_type_show(struct device *dev,
747 struct device_attribute *attr,
748 char *buf)
749{
750 ssize_t ret = -ENODATA;
751
752 mutex_lock(&stp_mutex);
753 if (stpinfo_valid())
754 ret = sysfs_emit(buf, "%i\n", stp_info.ctn);
755 mutex_unlock(&stp_mutex);
756 return ret;
757}
758
759static DEVICE_ATTR_RO(ctn_type);
760
761static ssize_t dst_offset_show(struct device *dev,
762 struct device_attribute *attr,
763 char *buf)
764{
765 ssize_t ret = -ENODATA;
766
767 mutex_lock(&stp_mutex);
768 if (stpinfo_valid() && (stp_info.vbits & 0x2000))
769 ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.dsto);
770 mutex_unlock(&stp_mutex);
771 return ret;
772}
773
774static DEVICE_ATTR_RO(dst_offset);
775
776static ssize_t leap_seconds_show(struct device *dev,
777 struct device_attribute *attr,
778 char *buf)
779{
780 ssize_t ret = -ENODATA;
781
782 mutex_lock(&stp_mutex);
783 if (stpinfo_valid() && (stp_info.vbits & 0x8000))
784 ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.leaps);
785 mutex_unlock(&stp_mutex);
786 return ret;
787}
788
789static DEVICE_ATTR_RO(leap_seconds);
790
791static ssize_t leap_seconds_scheduled_show(struct device *dev,
792 struct device_attribute *attr,
793 char *buf)
794{
795 struct stp_stzi stzi;
796 ssize_t ret;
797
798 mutex_lock(&stp_mutex);
799 if (!stpinfo_valid() || !(stp_info.vbits & 0x8000) || !stp_info.lu) {
800 mutex_unlock(&stp_mutex);
801 return -ENODATA;
802 }
803
804 ret = chsc_stzi(stp_page, &stzi, sizeof(stzi));
805 mutex_unlock(&stp_mutex);
806 if (ret < 0)
807 return ret;
808
809 if (!stzi.lsoib.p)
810 return sysfs_emit(buf, "0,0\n");
811
812 return sysfs_emit(buf, "%lu,%d\n",
813 tod_to_ns(stzi.lsoib.nlsout - TOD_UNIX_EPOCH) / NSEC_PER_SEC,
814 stzi.lsoib.nlso - stzi.lsoib.also);
815}
816
817static DEVICE_ATTR_RO(leap_seconds_scheduled);
818
819static ssize_t stratum_show(struct device *dev,
820 struct device_attribute *attr,
821 char *buf)
822{
823 ssize_t ret = -ENODATA;
824
825 mutex_lock(&stp_mutex);
826 if (stpinfo_valid())
827 ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.stratum);
828 mutex_unlock(&stp_mutex);
829 return ret;
830}
831
832static DEVICE_ATTR_RO(stratum);
833
834static ssize_t time_offset_show(struct device *dev,
835 struct device_attribute *attr,
836 char *buf)
837{
838 ssize_t ret = -ENODATA;
839
840 mutex_lock(&stp_mutex);
841 if (stpinfo_valid() && (stp_info.vbits & 0x0800))
842 ret = sysfs_emit(buf, "%i\n", (int)stp_info.tto);
843 mutex_unlock(&stp_mutex);
844 return ret;
845}
846
847static DEVICE_ATTR_RO(time_offset);
848
849static ssize_t time_zone_offset_show(struct device *dev,
850 struct device_attribute *attr,
851 char *buf)
852{
853 ssize_t ret = -ENODATA;
854
855 mutex_lock(&stp_mutex);
856 if (stpinfo_valid() && (stp_info.vbits & 0x4000))
857 ret = sysfs_emit(buf, "%i\n", (int)(s16)stp_info.tzo);
858 mutex_unlock(&stp_mutex);
859 return ret;
860}
861
862static DEVICE_ATTR_RO(time_zone_offset);
863
864static ssize_t timing_mode_show(struct device *dev,
865 struct device_attribute *attr,
866 char *buf)
867{
868 ssize_t ret = -ENODATA;
869
870 mutex_lock(&stp_mutex);
871 if (stpinfo_valid())
872 ret = sysfs_emit(buf, "%i\n", stp_info.tmd);
873 mutex_unlock(&stp_mutex);
874 return ret;
875}
876
877static DEVICE_ATTR_RO(timing_mode);
878
879static ssize_t timing_state_show(struct device *dev,
880 struct device_attribute *attr,
881 char *buf)
882{
883 ssize_t ret = -ENODATA;
884
885 mutex_lock(&stp_mutex);
886 if (stpinfo_valid())
887 ret = sysfs_emit(buf, "%i\n", stp_info.tst);
888 mutex_unlock(&stp_mutex);
889 return ret;
890}
891
892static DEVICE_ATTR_RO(timing_state);
893
894static ssize_t online_show(struct device *dev,
895 struct device_attribute *attr,
896 char *buf)
897{
898 return sysfs_emit(buf, "%i\n", stp_online);
899}
900
901static ssize_t online_store(struct device *dev,
902 struct device_attribute *attr,
903 const char *buf, size_t count)
904{
905 unsigned int value;
906
907 value = simple_strtoul(buf, NULL, 0);
908 if (value != 0 && value != 1)
909 return -EINVAL;
910 if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
911 return -EOPNOTSUPP;
912 mutex_lock(&stp_mutex);
913 stp_online = value;
914 if (stp_online)
915 set_bit(CLOCK_SYNC_STP, &clock_sync_flags);
916 else
917 clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
918 queue_work(time_sync_wq, &stp_work);
919 mutex_unlock(&stp_mutex);
920 return count;
921}
922
923/*
924 * Can't use DEVICE_ATTR because the attribute should be named
925 * stp/online but dev_attr_online already exists in this file ..
926 */
927static DEVICE_ATTR_RW(online);
928
929static struct attribute *stp_dev_attrs[] = {
930 &dev_attr_ctn_id.attr,
931 &dev_attr_ctn_type.attr,
932 &dev_attr_dst_offset.attr,
933 &dev_attr_leap_seconds.attr,
934 &dev_attr_online.attr,
935 &dev_attr_leap_seconds_scheduled.attr,
936 &dev_attr_stratum.attr,
937 &dev_attr_time_offset.attr,
938 &dev_attr_time_zone_offset.attr,
939 &dev_attr_timing_mode.attr,
940 &dev_attr_timing_state.attr,
941 NULL
942};
943ATTRIBUTE_GROUPS(stp_dev);
944
945static int __init stp_init_sysfs(void)
946{
947 return subsys_system_register(&stp_subsys, stp_dev_groups);
948}
949
950device_initcall(stp_init_sysfs);
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 <asm/facility.h>
45#include <asm/delay.h>
46#include <asm/div64.h>
47#include <asm/vdso.h>
48#include <asm/irq.h>
49#include <asm/irq_regs.h>
50#include <asm/vtimer.h>
51#include <asm/stp.h>
52#include <asm/cio.h>
53#include "entry.h"
54
55unsigned char tod_clock_base[16] __aligned(8) = {
56 /* Force to data section. */
57 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
58 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff
59};
60EXPORT_SYMBOL_GPL(tod_clock_base);
61
62u64 clock_comparator_max = -1ULL;
63EXPORT_SYMBOL_GPL(clock_comparator_max);
64
65static DEFINE_PER_CPU(struct clock_event_device, comparators);
66
67ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
68EXPORT_SYMBOL(s390_epoch_delta_notifier);
69
70unsigned char ptff_function_mask[16];
71
72static unsigned long long lpar_offset;
73static unsigned long long initial_leap_seconds;
74static unsigned long long tod_steering_end;
75static long long tod_steering_delta;
76
77/*
78 * Get time offsets with PTFF
79 */
80void __init time_early_init(void)
81{
82 struct ptff_qto qto;
83 struct ptff_qui qui;
84
85 /* Initialize TOD steering parameters */
86 tod_steering_end = *(unsigned long long *) &tod_clock_base[1];
87 vdso_data->ts_end = tod_steering_end;
88
89 if (!test_facility(28))
90 return;
91
92 ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF);
93
94 /* get LPAR offset */
95 if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
96 lpar_offset = qto.tod_epoch_difference;
97
98 /* get initial leap seconds */
99 if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
100 initial_leap_seconds = (unsigned long long)
101 ((long) qui.old_leap * 4096000000L);
102}
103
104/*
105 * Scheduler clock - returns current time in nanosec units.
106 */
107unsigned long long notrace sched_clock(void)
108{
109 return tod_to_ns(get_tod_clock_monotonic());
110}
111NOKPROBE_SYMBOL(sched_clock);
112
113static void ext_to_timespec64(unsigned char *clk, struct timespec64 *xt)
114{
115 unsigned long long high, low, rem, sec, nsec;
116
117 /* Split extendnd TOD clock to micro-seconds and sub-micro-seconds */
118 high = (*(unsigned long long *) clk) >> 4;
119 low = (*(unsigned long long *)&clk[7]) << 4;
120 /* Calculate seconds and nano-seconds */
121 sec = high;
122 rem = do_div(sec, 1000000);
123 nsec = (((low >> 32) + (rem << 32)) * 1000) >> 32;
124
125 xt->tv_sec = sec;
126 xt->tv_nsec = nsec;
127}
128
129void clock_comparator_work(void)
130{
131 struct clock_event_device *cd;
132
133 S390_lowcore.clock_comparator = clock_comparator_max;
134 cd = this_cpu_ptr(&comparators);
135 cd->event_handler(cd);
136}
137
138static int s390_next_event(unsigned long delta,
139 struct clock_event_device *evt)
140{
141 S390_lowcore.clock_comparator = get_tod_clock() + delta;
142 set_clock_comparator(S390_lowcore.clock_comparator);
143 return 0;
144}
145
146/*
147 * Set up lowcore and control register of the current cpu to
148 * enable TOD clock and clock comparator interrupts.
149 */
150void init_cpu_timer(void)
151{
152 struct clock_event_device *cd;
153 int cpu;
154
155 S390_lowcore.clock_comparator = clock_comparator_max;
156 set_clock_comparator(S390_lowcore.clock_comparator);
157
158 cpu = smp_processor_id();
159 cd = &per_cpu(comparators, cpu);
160 cd->name = "comparator";
161 cd->features = CLOCK_EVT_FEAT_ONESHOT;
162 cd->mult = 16777;
163 cd->shift = 12;
164 cd->min_delta_ns = 1;
165 cd->min_delta_ticks = 1;
166 cd->max_delta_ns = LONG_MAX;
167 cd->max_delta_ticks = ULONG_MAX;
168 cd->rating = 400;
169 cd->cpumask = cpumask_of(cpu);
170 cd->set_next_event = s390_next_event;
171
172 clockevents_register_device(cd);
173
174 /* Enable clock comparator timer interrupt. */
175 __ctl_set_bit(0,11);
176
177 /* Always allow the timing alert external interrupt. */
178 __ctl_set_bit(0, 4);
179}
180
181static void clock_comparator_interrupt(struct ext_code ext_code,
182 unsigned int param32,
183 unsigned long param64)
184{
185 inc_irq_stat(IRQEXT_CLK);
186 if (S390_lowcore.clock_comparator == clock_comparator_max)
187 set_clock_comparator(S390_lowcore.clock_comparator);
188}
189
190static void stp_timing_alert(struct stp_irq_parm *);
191
192static void timing_alert_interrupt(struct ext_code ext_code,
193 unsigned int param32, unsigned long param64)
194{
195 inc_irq_stat(IRQEXT_TLA);
196 if (param32 & 0x00038000)
197 stp_timing_alert((struct stp_irq_parm *) ¶m32);
198}
199
200static void stp_reset(void);
201
202void read_persistent_clock64(struct timespec64 *ts)
203{
204 unsigned char clk[STORE_CLOCK_EXT_SIZE];
205 __u64 delta;
206
207 delta = initial_leap_seconds + TOD_UNIX_EPOCH;
208 get_tod_clock_ext(clk);
209 *(__u64 *) &clk[1] -= delta;
210 if (*(__u64 *) &clk[1] > delta)
211 clk[0]--;
212 ext_to_timespec64(clk, ts);
213}
214
215void __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
216 struct timespec64 *boot_offset)
217{
218 unsigned char clk[STORE_CLOCK_EXT_SIZE];
219 struct timespec64 boot_time;
220 __u64 delta;
221
222 delta = initial_leap_seconds + TOD_UNIX_EPOCH;
223 memcpy(clk, tod_clock_base, STORE_CLOCK_EXT_SIZE);
224 *(__u64 *)&clk[1] -= delta;
225 if (*(__u64 *)&clk[1] > delta)
226 clk[0]--;
227 ext_to_timespec64(clk, &boot_time);
228
229 read_persistent_clock64(wall_time);
230 *boot_offset = timespec64_sub(*wall_time, boot_time);
231}
232
233static u64 read_tod_clock(struct clocksource *cs)
234{
235 unsigned long long now, adj;
236
237 preempt_disable(); /* protect from changes to steering parameters */
238 now = get_tod_clock();
239 adj = tod_steering_end - now;
240 if (unlikely((s64) adj > 0))
241 /*
242 * manually steer by 1 cycle every 2^16 cycles. This
243 * corresponds to shifting the tod delta by 15. 1s is
244 * therefore steered in ~9h. The adjust will decrease
245 * over time, until it finally reaches 0.
246 */
247 now += (tod_steering_delta < 0) ? (adj >> 15) : -(adj >> 15);
248 preempt_enable();
249 return now;
250}
251
252static struct clocksource clocksource_tod = {
253 .name = "tod",
254 .rating = 400,
255 .read = read_tod_clock,
256 .mask = CLOCKSOURCE_MASK(64),
257 .mult = 1000,
258 .shift = 12,
259 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
260};
261
262struct clocksource * __init clocksource_default_clock(void)
263{
264 return &clocksource_tod;
265}
266
267void update_vsyscall(struct timekeeper *tk)
268{
269 u64 nsecps;
270
271 if (tk->tkr_mono.clock != &clocksource_tod)
272 return;
273
274 /* Make userspace gettimeofday spin until we're done. */
275 ++vdso_data->tb_update_count;
276 smp_wmb();
277 vdso_data->xtime_tod_stamp = tk->tkr_mono.cycle_last;
278 vdso_data->xtime_clock_sec = tk->xtime_sec;
279 vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
280 vdso_data->wtom_clock_sec =
281 tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
282 vdso_data->wtom_clock_nsec = tk->tkr_mono.xtime_nsec +
283 + ((u64) tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
284 nsecps = (u64) NSEC_PER_SEC << tk->tkr_mono.shift;
285 while (vdso_data->wtom_clock_nsec >= nsecps) {
286 vdso_data->wtom_clock_nsec -= nsecps;
287 vdso_data->wtom_clock_sec++;
288 }
289
290 vdso_data->xtime_coarse_sec = tk->xtime_sec;
291 vdso_data->xtime_coarse_nsec =
292 (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
293 vdso_data->wtom_coarse_sec =
294 vdso_data->xtime_coarse_sec + tk->wall_to_monotonic.tv_sec;
295 vdso_data->wtom_coarse_nsec =
296 vdso_data->xtime_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
297 while (vdso_data->wtom_coarse_nsec >= NSEC_PER_SEC) {
298 vdso_data->wtom_coarse_nsec -= NSEC_PER_SEC;
299 vdso_data->wtom_coarse_sec++;
300 }
301
302 vdso_data->tk_mult = tk->tkr_mono.mult;
303 vdso_data->tk_shift = tk->tkr_mono.shift;
304 vdso_data->hrtimer_res = hrtimer_resolution;
305 smp_wmb();
306 ++vdso_data->tb_update_count;
307}
308
309extern struct timezone sys_tz;
310
311void update_vsyscall_tz(void)
312{
313 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
314 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
315}
316
317/*
318 * Initialize the TOD clock and the CPU timer of
319 * the boot cpu.
320 */
321void __init time_init(void)
322{
323 /* Reset time synchronization interfaces. */
324 stp_reset();
325
326 /* request the clock comparator external interrupt */
327 if (register_external_irq(EXT_IRQ_CLK_COMP, clock_comparator_interrupt))
328 panic("Couldn't request external interrupt 0x1004");
329
330 /* request the timing alert external interrupt */
331 if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
332 panic("Couldn't request external interrupt 0x1406");
333
334 if (__clocksource_register(&clocksource_tod) != 0)
335 panic("Could not register TOD clock source");
336
337 /* Enable TOD clock interrupts on the boot cpu. */
338 init_cpu_timer();
339
340 /* Enable cpu timer interrupts on the boot cpu. */
341 vtime_init();
342}
343
344static DEFINE_PER_CPU(atomic_t, clock_sync_word);
345static DEFINE_MUTEX(clock_sync_mutex);
346static unsigned long clock_sync_flags;
347
348#define CLOCK_SYNC_HAS_STP 0
349#define CLOCK_SYNC_STP 1
350
351/*
352 * The get_clock function for the physical clock. It will get the current
353 * TOD clock, subtract the LPAR offset and write the result to *clock.
354 * The function returns 0 if the clock is in sync with the external time
355 * source. If the clock mode is local it will return -EOPNOTSUPP and
356 * -EAGAIN if the clock is not in sync with the external reference.
357 */
358int get_phys_clock(unsigned long *clock)
359{
360 atomic_t *sw_ptr;
361 unsigned int sw0, sw1;
362
363 sw_ptr = &get_cpu_var(clock_sync_word);
364 sw0 = atomic_read(sw_ptr);
365 *clock = get_tod_clock() - lpar_offset;
366 sw1 = atomic_read(sw_ptr);
367 put_cpu_var(clock_sync_word);
368 if (sw0 == sw1 && (sw0 & 0x80000000U))
369 /* Success: time is in sync. */
370 return 0;
371 if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
372 return -EOPNOTSUPP;
373 if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
374 return -EACCES;
375 return -EAGAIN;
376}
377EXPORT_SYMBOL(get_phys_clock);
378
379/*
380 * Make get_phys_clock() return -EAGAIN.
381 */
382static void disable_sync_clock(void *dummy)
383{
384 atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
385 /*
386 * Clear the in-sync bit 2^31. All get_phys_clock calls will
387 * fail until the sync bit is turned back on. In addition
388 * increase the "sequence" counter to avoid the race of an
389 * stp event and the complete recovery against get_phys_clock.
390 */
391 atomic_andnot(0x80000000, sw_ptr);
392 atomic_inc(sw_ptr);
393}
394
395/*
396 * Make get_phys_clock() return 0 again.
397 * Needs to be called from a context disabled for preemption.
398 */
399static void enable_sync_clock(void)
400{
401 atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
402 atomic_or(0x80000000, sw_ptr);
403}
404
405/*
406 * Function to check if the clock is in sync.
407 */
408static inline int check_sync_clock(void)
409{
410 atomic_t *sw_ptr;
411 int rc;
412
413 sw_ptr = &get_cpu_var(clock_sync_word);
414 rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;
415 put_cpu_var(clock_sync_word);
416 return rc;
417}
418
419/*
420 * Apply clock delta to the global data structures.
421 * This is called once on the CPU that performed the clock sync.
422 */
423static void clock_sync_global(unsigned long long delta)
424{
425 unsigned long now, adj;
426 struct ptff_qto qto;
427
428 /* Fixup the monotonic sched clock. */
429 *(unsigned long long *) &tod_clock_base[1] += delta;
430 if (*(unsigned long long *) &tod_clock_base[1] < delta)
431 /* Epoch overflow */
432 tod_clock_base[0]++;
433 /* Adjust TOD steering parameters. */
434 vdso_data->tb_update_count++;
435 now = get_tod_clock();
436 adj = tod_steering_end - now;
437 if (unlikely((s64) adj >= 0))
438 /* Calculate how much of the old adjustment is left. */
439 tod_steering_delta = (tod_steering_delta < 0) ?
440 -(adj >> 15) : (adj >> 15);
441 tod_steering_delta += delta;
442 if ((abs(tod_steering_delta) >> 48) != 0)
443 panic("TOD clock sync offset %lli is too large to drift\n",
444 tod_steering_delta);
445 tod_steering_end = now + (abs(tod_steering_delta) << 15);
446 vdso_data->ts_dir = (tod_steering_delta < 0) ? 0 : 1;
447 vdso_data->ts_end = tod_steering_end;
448 vdso_data->tb_update_count++;
449 /* Update LPAR offset. */
450 if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
451 lpar_offset = qto.tod_epoch_difference;
452 /* Call the TOD clock change notifier. */
453 atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);
454}
455
456/*
457 * Apply clock delta to the per-CPU data structures of this CPU.
458 * This is called for each online CPU after the call to clock_sync_global.
459 */
460static void clock_sync_local(unsigned long long delta)
461{
462 /* Add the delta to the clock comparator. */
463 if (S390_lowcore.clock_comparator != clock_comparator_max) {
464 S390_lowcore.clock_comparator += delta;
465 set_clock_comparator(S390_lowcore.clock_comparator);
466 }
467 /* Adjust the last_update_clock time-stamp. */
468 S390_lowcore.last_update_clock += delta;
469}
470
471/* Single threaded workqueue used for stp sync events */
472static struct workqueue_struct *time_sync_wq;
473
474static void __init time_init_wq(void)
475{
476 if (time_sync_wq)
477 return;
478 time_sync_wq = create_singlethread_workqueue("timesync");
479}
480
481struct clock_sync_data {
482 atomic_t cpus;
483 int in_sync;
484 unsigned long long clock_delta;
485};
486
487/*
488 * Server Time Protocol (STP) code.
489 */
490static bool stp_online;
491static struct stp_sstpi stp_info;
492static void *stp_page;
493
494static void stp_work_fn(struct work_struct *work);
495static DEFINE_MUTEX(stp_work_mutex);
496static DECLARE_WORK(stp_work, stp_work_fn);
497static struct timer_list stp_timer;
498
499static int __init early_parse_stp(char *p)
500{
501 return kstrtobool(p, &stp_online);
502}
503early_param("stp", early_parse_stp);
504
505/*
506 * Reset STP attachment.
507 */
508static void __init stp_reset(void)
509{
510 int rc;
511
512 stp_page = (void *) get_zeroed_page(GFP_ATOMIC);
513 rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
514 if (rc == 0)
515 set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags);
516 else if (stp_online) {
517 pr_warn("The real or virtual hardware system does not provide an STP interface\n");
518 free_page((unsigned long) stp_page);
519 stp_page = NULL;
520 stp_online = false;
521 }
522}
523
524static void stp_timeout(struct timer_list *unused)
525{
526 queue_work(time_sync_wq, &stp_work);
527}
528
529static int __init stp_init(void)
530{
531 if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
532 return 0;
533 timer_setup(&stp_timer, stp_timeout, 0);
534 time_init_wq();
535 if (!stp_online)
536 return 0;
537 queue_work(time_sync_wq, &stp_work);
538 return 0;
539}
540
541arch_initcall(stp_init);
542
543/*
544 * STP timing alert. There are three causes:
545 * 1) timing status change
546 * 2) link availability change
547 * 3) time control parameter change
548 * In all three cases we are only interested in the clock source state.
549 * If a STP clock source is now available use it.
550 */
551static void stp_timing_alert(struct stp_irq_parm *intparm)
552{
553 if (intparm->tsc || intparm->lac || intparm->tcpc)
554 queue_work(time_sync_wq, &stp_work);
555}
556
557/*
558 * STP sync check machine check. This is called when the timing state
559 * changes from the synchronized state to the unsynchronized state.
560 * After a STP sync check the clock is not in sync. The machine check
561 * is broadcasted to all cpus at the same time.
562 */
563int stp_sync_check(void)
564{
565 disable_sync_clock(NULL);
566 return 1;
567}
568
569/*
570 * STP island condition machine check. This is called when an attached
571 * server attempts to communicate over an STP link and the servers
572 * have matching CTN ids and have a valid stratum-1 configuration
573 * but the configurations do not match.
574 */
575int stp_island_check(void)
576{
577 disable_sync_clock(NULL);
578 return 1;
579}
580
581void stp_queue_work(void)
582{
583 queue_work(time_sync_wq, &stp_work);
584}
585
586static int stp_sync_clock(void *data)
587{
588 struct clock_sync_data *sync = data;
589 unsigned long long clock_delta;
590 static int first;
591 int rc;
592
593 enable_sync_clock();
594 if (xchg(&first, 1) == 0) {
595 /* Wait until all other cpus entered the sync function. */
596 while (atomic_read(&sync->cpus) != 0)
597 cpu_relax();
598 rc = 0;
599 if (stp_info.todoff[0] || stp_info.todoff[1] ||
600 stp_info.todoff[2] || stp_info.todoff[3] ||
601 stp_info.tmd != 2) {
602 rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
603 &clock_delta);
604 if (rc == 0) {
605 sync->clock_delta = clock_delta;
606 clock_sync_global(clock_delta);
607 rc = chsc_sstpi(stp_page, &stp_info,
608 sizeof(struct stp_sstpi));
609 if (rc == 0 && stp_info.tmd != 2)
610 rc = -EAGAIN;
611 }
612 }
613 sync->in_sync = rc ? -EAGAIN : 1;
614 xchg(&first, 0);
615 } else {
616 /* Slave */
617 atomic_dec(&sync->cpus);
618 /* Wait for in_sync to be set. */
619 while (READ_ONCE(sync->in_sync) == 0)
620 __udelay(1);
621 }
622 if (sync->in_sync != 1)
623 /* Didn't work. Clear per-cpu in sync bit again. */
624 disable_sync_clock(NULL);
625 /* Apply clock delta to per-CPU fields of this CPU. */
626 clock_sync_local(sync->clock_delta);
627
628 return 0;
629}
630
631/*
632 * STP work. Check for the STP state and take over the clock
633 * synchronization if the STP clock source is usable.
634 */
635static void stp_work_fn(struct work_struct *work)
636{
637 struct clock_sync_data stp_sync;
638 int rc;
639
640 /* prevent multiple execution. */
641 mutex_lock(&stp_work_mutex);
642
643 if (!stp_online) {
644 chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
645 del_timer_sync(&stp_timer);
646 goto out_unlock;
647 }
648
649 rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xb0e0, NULL);
650 if (rc)
651 goto out_unlock;
652
653 rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
654 if (rc || stp_info.c == 0)
655 goto out_unlock;
656
657 /* Skip synchronization if the clock is already in sync. */
658 if (check_sync_clock())
659 goto out_unlock;
660
661 memset(&stp_sync, 0, sizeof(stp_sync));
662 cpus_read_lock();
663 atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
664 stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
665 cpus_read_unlock();
666
667 if (!check_sync_clock())
668 /*
669 * There is a usable clock but the synchonization failed.
670 * Retry after a second.
671 */
672 mod_timer(&stp_timer, jiffies + msecs_to_jiffies(MSEC_PER_SEC));
673
674out_unlock:
675 mutex_unlock(&stp_work_mutex);
676}
677
678/*
679 * STP subsys sysfs interface functions
680 */
681static struct bus_type stp_subsys = {
682 .name = "stp",
683 .dev_name = "stp",
684};
685
686static ssize_t ctn_id_show(struct device *dev,
687 struct device_attribute *attr,
688 char *buf)
689{
690 if (!stp_online)
691 return -ENODATA;
692 return sprintf(buf, "%016llx\n",
693 *(unsigned long long *) stp_info.ctnid);
694}
695
696static DEVICE_ATTR_RO(ctn_id);
697
698static ssize_t ctn_type_show(struct device *dev,
699 struct device_attribute *attr,
700 char *buf)
701{
702 if (!stp_online)
703 return -ENODATA;
704 return sprintf(buf, "%i\n", stp_info.ctn);
705}
706
707static DEVICE_ATTR_RO(ctn_type);
708
709static ssize_t dst_offset_show(struct device *dev,
710 struct device_attribute *attr,
711 char *buf)
712{
713 if (!stp_online || !(stp_info.vbits & 0x2000))
714 return -ENODATA;
715 return sprintf(buf, "%i\n", (int)(s16) stp_info.dsto);
716}
717
718static DEVICE_ATTR_RO(dst_offset);
719
720static ssize_t leap_seconds_show(struct device *dev,
721 struct device_attribute *attr,
722 char *buf)
723{
724 if (!stp_online || !(stp_info.vbits & 0x8000))
725 return -ENODATA;
726 return sprintf(buf, "%i\n", (int)(s16) stp_info.leaps);
727}
728
729static DEVICE_ATTR_RO(leap_seconds);
730
731static ssize_t stratum_show(struct device *dev,
732 struct device_attribute *attr,
733 char *buf)
734{
735 if (!stp_online)
736 return -ENODATA;
737 return sprintf(buf, "%i\n", (int)(s16) stp_info.stratum);
738}
739
740static DEVICE_ATTR_RO(stratum);
741
742static ssize_t time_offset_show(struct device *dev,
743 struct device_attribute *attr,
744 char *buf)
745{
746 if (!stp_online || !(stp_info.vbits & 0x0800))
747 return -ENODATA;
748 return sprintf(buf, "%i\n", (int) stp_info.tto);
749}
750
751static DEVICE_ATTR_RO(time_offset);
752
753static ssize_t time_zone_offset_show(struct device *dev,
754 struct device_attribute *attr,
755 char *buf)
756{
757 if (!stp_online || !(stp_info.vbits & 0x4000))
758 return -ENODATA;
759 return sprintf(buf, "%i\n", (int)(s16) stp_info.tzo);
760}
761
762static DEVICE_ATTR_RO(time_zone_offset);
763
764static ssize_t timing_mode_show(struct device *dev,
765 struct device_attribute *attr,
766 char *buf)
767{
768 if (!stp_online)
769 return -ENODATA;
770 return sprintf(buf, "%i\n", stp_info.tmd);
771}
772
773static DEVICE_ATTR_RO(timing_mode);
774
775static ssize_t timing_state_show(struct device *dev,
776 struct device_attribute *attr,
777 char *buf)
778{
779 if (!stp_online)
780 return -ENODATA;
781 return sprintf(buf, "%i\n", stp_info.tst);
782}
783
784static DEVICE_ATTR_RO(timing_state);
785
786static ssize_t online_show(struct device *dev,
787 struct device_attribute *attr,
788 char *buf)
789{
790 return sprintf(buf, "%i\n", stp_online);
791}
792
793static ssize_t online_store(struct device *dev,
794 struct device_attribute *attr,
795 const char *buf, size_t count)
796{
797 unsigned int value;
798
799 value = simple_strtoul(buf, NULL, 0);
800 if (value != 0 && value != 1)
801 return -EINVAL;
802 if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
803 return -EOPNOTSUPP;
804 mutex_lock(&clock_sync_mutex);
805 stp_online = value;
806 if (stp_online)
807 set_bit(CLOCK_SYNC_STP, &clock_sync_flags);
808 else
809 clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
810 queue_work(time_sync_wq, &stp_work);
811 mutex_unlock(&clock_sync_mutex);
812 return count;
813}
814
815/*
816 * Can't use DEVICE_ATTR because the attribute should be named
817 * stp/online but dev_attr_online already exists in this file ..
818 */
819static DEVICE_ATTR_RW(online);
820
821static struct device_attribute *stp_attributes[] = {
822 &dev_attr_ctn_id,
823 &dev_attr_ctn_type,
824 &dev_attr_dst_offset,
825 &dev_attr_leap_seconds,
826 &dev_attr_online,
827 &dev_attr_stratum,
828 &dev_attr_time_offset,
829 &dev_attr_time_zone_offset,
830 &dev_attr_timing_mode,
831 &dev_attr_timing_state,
832 NULL
833};
834
835static int __init stp_init_sysfs(void)
836{
837 struct device_attribute **attr;
838 int rc;
839
840 rc = subsys_system_register(&stp_subsys, NULL);
841 if (rc)
842 goto out;
843 for (attr = stp_attributes; *attr; attr++) {
844 rc = device_create_file(stp_subsys.dev_root, *attr);
845 if (rc)
846 goto out_unreg;
847 }
848 return 0;
849out_unreg:
850 for (; attr >= stp_attributes; attr--)
851 device_remove_file(stp_subsys.dev_root, *attr);
852 bus_unregister(&stp_subsys);
853out:
854 return rc;
855}
856
857device_initcall(stp_init_sysfs);