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

source code of linux/arch/s390/kernel/time.c