time.c

  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(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, 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, &boot_time);
217
218	read_persistent_clock64(wall_time);
219	*boot_offset = timespec64_sub(*wall_time, 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("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("Couldn't request external interrupt 0x1406");
260
261	if (__clocksource_register(&clocksource_tod) != 0)
262		panic("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(sw_ptr);
293	*clock = get_tod_clock() - lpar_offset;
294	sw1 = atomic_read(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(0x80000000, sw_ptr);
320	atomic_inc(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(0x80000000, 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(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(&s390_epoch_delta_notifier, 0, &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(p, &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, &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(time_sync_wq, &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(time_sync_wq, &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(time_sync_wq, &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(time_sync_wq, &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, &clock_sync_flags);
505	else
506		set_bit(CLOCK_SYNC_STPINFO_VALID, &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(&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(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(&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(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(&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(&stp_sync.cpus, num_online_cpus() - 1);
590		stop_machine_cpuslocked(stp_sync_clock, &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(&stp_timer, jiffies + msecs_to_jiffies(MSEC_PER_SEC));
600
601out_unlock:
602	mutex_unlock(&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, "%016lx\n",
622				 *(unsigned long *)stp_info.ctnid);
623	mutex_unlock(&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, "%i\n", stp_info.ctn);
638	mutex_unlock(&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, "%i\n", (int)(s16)stp_info.dsto);
653	mutex_unlock(&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, "%i\n", (int)(s16)stp_info.leaps);
668	mutex_unlock(&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(&stp_mutex);
684		return -ENODATA;
685	}
686
687	ret = chsc_stzi(stp_page, &stzi, sizeof(stzi));
688	mutex_unlock(&stp_mutex);
689	if (ret < 0)
690		return ret;
691
692	if (!stzi.lsoib.p)
693		return sysfs_emit(buf, "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, "%i\n", (int)(s16)stp_info.stratum);
711	mutex_unlock(&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, "%i\n", (int)stp_info.tto);
726	mutex_unlock(&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, "%i\n", (int)(s16)stp_info.tzo);
741	mutex_unlock(&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, "%i\n", stp_info.tmd);
756	mutex_unlock(&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, "%i\n", stp_info.tst);
771	mutex_unlock(&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, "%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, &clock_sync_flags);
799	else
800		clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
801	queue_work(time_sync_wq, &stp_work);
802	mutex_unlock(&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(&stp_subsys, stp_dev_groups);
831}
832
833device_initcall(stp_init_sysfs);