arch/s390/kernel/time.c

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This source file includes following definitions.
time_early_init
sched_clock
monotonic_clock
ext_to_timespec64
clock_comparator_work
s390_next_event
init_cpu_timer
clock_comparator_interrupt
timing_alert_interrupt
read_persistent_clock64
read_persistent_wall_and_boot_offset
read_tod_clock
clocksource_default_clock
update_vsyscall
update_vsyscall_tz
time_init
get_phys_clock
disable_sync_clock
enable_sync_clock
check_sync_clock
clock_sync_global
clock_sync_local
time_init_wq
early_parse_stp
stp_reset
stp_timeout
stp_init
stp_timing_alert
stp_sync_check
stp_island_check
stp_queue_work
stp_sync_clock
stp_work_fn
stp_ctn_id_show
stp_ctn_type_show
stp_dst_offset_show
stp_leap_seconds_show
stp_stratum_show
stp_time_offset_show
stp_time_zone_offset_show
stp_timing_mode_show
stp_timing_state_show
stp_online_show
stp_online_store
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 
  55 unsigned 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 };
  60 EXPORT_SYMBOL_GPL(tod_clock_base);
  61 
  62 u64 clock_comparator_max = -1ULL;
  63 EXPORT_SYMBOL_GPL(clock_comparator_max);
  64 
  65 static DEFINE_PER_CPU(struct clock_event_device, comparators);
  66 
  67 ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
  68 EXPORT_SYMBOL(s390_epoch_delta_notifier);
  69 
  70 unsigned char ptff_function_mask[16];
  71 
  72 static unsigned long long lpar_offset;
  73 static unsigned long long initial_leap_seconds;
  74 static unsigned long long tod_steering_end;
  75 static long long tod_steering_delta;
  76 
  77 /*
  78  * Get time offsets with PTFF
  79  */
  80 void __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  */
 107 unsigned long long notrace sched_clock(void)
 108 {
 109         return tod_to_ns(get_tod_clock_monotonic());
 110 }
 111 NOKPROBE_SYMBOL(sched_clock);
 112 
 113 /*
 114  * Monotonic_clock - returns # of nanoseconds passed since time_init()
 115  */
 116 unsigned long long monotonic_clock(void)
 117 {
 118         return sched_clock();
 119 }
 120 EXPORT_SYMBOL(monotonic_clock);
 121 
 122 static void ext_to_timespec64(unsigned char *clk, struct timespec64 *xt)
 123 {
 124         unsigned long long high, low, rem, sec, nsec;
 125 
 126         /* Split extendnd TOD clock to micro-seconds and sub-micro-seconds */
 127         high = (*(unsigned long long *) clk) >> 4;
 128         low = (*(unsigned long long *)&clk[7]) << 4;
 129         /* Calculate seconds and nano-seconds */
 130         sec = high;
 131         rem = do_div(sec, 1000000);
 132         nsec = (((low >> 32) + (rem << 32)) * 1000) >> 32;
 133 
 134         xt->tv_sec = sec;
 135         xt->tv_nsec = nsec;
 136 }
 137 
 138 void clock_comparator_work(void)
 139 {
 140         struct clock_event_device *cd;
 141 
 142         S390_lowcore.clock_comparator = clock_comparator_max;
 143         cd = this_cpu_ptr(&comparators);
 144         cd->event_handler(cd);
 145 }
 146 
 147 static int s390_next_event(unsigned long delta,
 148                            struct clock_event_device *evt)
 149 {
 150         S390_lowcore.clock_comparator = get_tod_clock() + delta;
 151         set_clock_comparator(S390_lowcore.clock_comparator);
 152         return 0;
 153 }
 154 
 155 /*
 156  * Set up lowcore and control register of the current cpu to
 157  * enable TOD clock and clock comparator interrupts.
 158  */
 159 void init_cpu_timer(void)
 160 {
 161         struct clock_event_device *cd;
 162         int cpu;
 163 
 164         S390_lowcore.clock_comparator = clock_comparator_max;
 165         set_clock_comparator(S390_lowcore.clock_comparator);
 166 
 167         cpu = smp_processor_id();
 168         cd = &per_cpu(comparators, cpu);
 169         cd->name                = "comparator";
 170         cd->features            = CLOCK_EVT_FEAT_ONESHOT;
 171         cd->mult                = 16777;
 172         cd->shift               = 12;
 173         cd->min_delta_ns        = 1;
 174         cd->min_delta_ticks     = 1;
 175         cd->max_delta_ns        = LONG_MAX;
 176         cd->max_delta_ticks     = ULONG_MAX;
 177         cd->rating              = 400;
 178         cd->cpumask             = cpumask_of(cpu);
 179         cd->set_next_event      = s390_next_event;
 180 
 181         clockevents_register_device(cd);
 182 
 183         /* Enable clock comparator timer interrupt. */
 184         __ctl_set_bit(0,11);
 185 
 186         /* Always allow the timing alert external interrupt. */
 187         __ctl_set_bit(0, 4);
 188 }
 189 
 190 static void clock_comparator_interrupt(struct ext_code ext_code,
 191                                        unsigned int param32,
 192                                        unsigned long param64)
 193 {
 194         inc_irq_stat(IRQEXT_CLK);
 195         if (S390_lowcore.clock_comparator == clock_comparator_max)
 196                 set_clock_comparator(S390_lowcore.clock_comparator);
 197 }
 198 
 199 static void stp_timing_alert(struct stp_irq_parm *);
 200 
 201 static void timing_alert_interrupt(struct ext_code ext_code,
 202                                    unsigned int param32, unsigned long param64)
 203 {
 204         inc_irq_stat(IRQEXT_TLA);
 205         if (param32 & 0x00038000)
 206                 stp_timing_alert((struct stp_irq_parm *) &param32);
 207 }
 208 
 209 static void stp_reset(void);
 210 
 211 void read_persistent_clock64(struct timespec64 *ts)
 212 {
 213         unsigned char clk[STORE_CLOCK_EXT_SIZE];
 214         __u64 delta;
 215 
 216         delta = initial_leap_seconds + TOD_UNIX_EPOCH;
 217         get_tod_clock_ext(clk);
 218         *(__u64 *) &clk[1] -= delta;
 219         if (*(__u64 *) &clk[1] > delta)
 220                 clk[0]--;
 221         ext_to_timespec64(clk, ts);
 222 }
 223 
 224 void __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
 225                                                  struct timespec64 *boot_offset)
 226 {
 227         unsigned char clk[STORE_CLOCK_EXT_SIZE];
 228         struct timespec64 boot_time;
 229         __u64 delta;
 230 
 231         delta = initial_leap_seconds + TOD_UNIX_EPOCH;
 232         memcpy(clk, tod_clock_base, STORE_CLOCK_EXT_SIZE);
 233         *(__u64 *)&clk[1] -= delta;
 234         if (*(__u64 *)&clk[1] > delta)
 235                 clk[0]--;
 236         ext_to_timespec64(clk, &boot_time);
 237 
 238         read_persistent_clock64(wall_time);
 239         *boot_offset = timespec64_sub(*wall_time, boot_time);
 240 }
 241 
 242 static u64 read_tod_clock(struct clocksource *cs)
 243 {
 244         unsigned long long now, adj;
 245 
 246         preempt_disable(); /* protect from changes to steering parameters */
 247         now = get_tod_clock();
 248         adj = tod_steering_end - now;
 249         if (unlikely((s64) adj >= 0))
 250                 /*
 251                  * manually steer by 1 cycle every 2^16 cycles. This
 252                  * corresponds to shifting the tod delta by 15. 1s is
 253                  * therefore steered in ~9h. The adjust will decrease
 254                  * over time, until it finally reaches 0.
 255                  */
 256                 now += (tod_steering_delta < 0) ? (adj >> 15) : -(adj >> 15);
 257         preempt_enable();
 258         return now;
 259 }
 260 
 261 static struct clocksource clocksource_tod = {
 262         .name           = "tod",
 263         .rating         = 400,
 264         .read           = read_tod_clock,
 265         .mask           = -1ULL,
 266         .mult           = 1000,
 267         .shift          = 12,
 268         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 269 };
 270 
 271 struct clocksource * __init clocksource_default_clock(void)
 272 {
 273         return &clocksource_tod;
 274 }
 275 
 276 void update_vsyscall(struct timekeeper *tk)
 277 {
 278         u64 nsecps;
 279 
 280         if (tk->tkr_mono.clock != &clocksource_tod)
 281                 return;
 282 
 283         /* Make userspace gettimeofday spin until we're done. */
 284         ++vdso_data->tb_update_count;
 285         smp_wmb();
 286         vdso_data->xtime_tod_stamp = tk->tkr_mono.cycle_last;
 287         vdso_data->xtime_clock_sec = tk->xtime_sec;
 288         vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
 289         vdso_data->wtom_clock_sec =
 290                 tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
 291         vdso_data->wtom_clock_nsec = tk->tkr_mono.xtime_nsec +
 292                 + ((u64) tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
 293         nsecps = (u64) NSEC_PER_SEC << tk->tkr_mono.shift;
 294         while (vdso_data->wtom_clock_nsec >= nsecps) {
 295                 vdso_data->wtom_clock_nsec -= nsecps;
 296                 vdso_data->wtom_clock_sec++;
 297         }
 298 
 299         vdso_data->xtime_coarse_sec = tk->xtime_sec;
 300         vdso_data->xtime_coarse_nsec =
 301                 (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
 302         vdso_data->wtom_coarse_sec =
 303                 vdso_data->xtime_coarse_sec + tk->wall_to_monotonic.tv_sec;
 304         vdso_data->wtom_coarse_nsec =
 305                 vdso_data->xtime_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
 306         while (vdso_data->wtom_coarse_nsec >= NSEC_PER_SEC) {
 307                 vdso_data->wtom_coarse_nsec -= NSEC_PER_SEC;
 308                 vdso_data->wtom_coarse_sec++;
 309         }
 310 
 311         vdso_data->tk_mult = tk->tkr_mono.mult;
 312         vdso_data->tk_shift = tk->tkr_mono.shift;
 313         smp_wmb();
 314         ++vdso_data->tb_update_count;
 315 }
 316 
 317 extern struct timezone sys_tz;
 318 
 319 void update_vsyscall_tz(void)
 320 {
 321         vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
 322         vdso_data->tz_dsttime = sys_tz.tz_dsttime;
 323 }
 324 
 325 /*
 326  * Initialize the TOD clock and the CPU timer of
 327  * the boot cpu.
 328  */
 329 void __init time_init(void)
 330 {
 331         /* Reset time synchronization interfaces. */
 332         stp_reset();
 333 
 334         /* request the clock comparator external interrupt */
 335         if (register_external_irq(EXT_IRQ_CLK_COMP, clock_comparator_interrupt))
 336                 panic("Couldn't request external interrupt 0x1004");
 337 
 338         /* request the timing alert external interrupt */
 339         if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
 340                 panic("Couldn't request external interrupt 0x1406");
 341 
 342         if (__clocksource_register(&clocksource_tod) != 0)
 343                 panic("Could not register TOD clock source");
 344 
 345         /* Enable TOD clock interrupts on the boot cpu. */
 346         init_cpu_timer();
 347 
 348         /* Enable cpu timer interrupts on the boot cpu. */
 349         vtime_init();
 350 }
 351 
 352 static DEFINE_PER_CPU(atomic_t, clock_sync_word);
 353 static DEFINE_MUTEX(clock_sync_mutex);
 354 static unsigned long clock_sync_flags;
 355 
 356 #define CLOCK_SYNC_HAS_STP      0
 357 #define CLOCK_SYNC_STP          1
 358 
 359 /*
 360  * The get_clock function for the physical clock. It will get the current
 361  * TOD clock, subtract the LPAR offset and write the result to *clock.
 362  * The function returns 0 if the clock is in sync with the external time
 363  * source. If the clock mode is local it will return -EOPNOTSUPP and
 364  * -EAGAIN if the clock is not in sync with the external reference.
 365  */
 366 int get_phys_clock(unsigned long *clock)
 367 {
 368         atomic_t *sw_ptr;
 369         unsigned int sw0, sw1;
 370 
 371         sw_ptr = &get_cpu_var(clock_sync_word);
 372         sw0 = atomic_read(sw_ptr);
 373         *clock = get_tod_clock() - lpar_offset;
 374         sw1 = atomic_read(sw_ptr);
 375         put_cpu_var(clock_sync_word);
 376         if (sw0 == sw1 && (sw0 & 0x80000000U))
 377                 /* Success: time is in sync. */
 378                 return 0;
 379         if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
 380                 return -EOPNOTSUPP;
 381         if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
 382                 return -EACCES;
 383         return -EAGAIN;
 384 }
 385 EXPORT_SYMBOL(get_phys_clock);
 386 
 387 /*
 388  * Make get_phys_clock() return -EAGAIN.
 389  */
 390 static void disable_sync_clock(void *dummy)
 391 {
 392         atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
 393         /*
 394          * Clear the in-sync bit 2^31. All get_phys_clock calls will
 395          * fail until the sync bit is turned back on. In addition
 396          * increase the "sequence" counter to avoid the race of an
 397          * stp event and the complete recovery against get_phys_clock.
 398          */
 399         atomic_andnot(0x80000000, sw_ptr);
 400         atomic_inc(sw_ptr);
 401 }
 402 
 403 /*
 404  * Make get_phys_clock() return 0 again.
 405  * Needs to be called from a context disabled for preemption.
 406  */
 407 static void enable_sync_clock(void)
 408 {
 409         atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
 410         atomic_or(0x80000000, sw_ptr);
 411 }
 412 
 413 /*
 414  * Function to check if the clock is in sync.
 415  */
 416 static inline int check_sync_clock(void)
 417 {
 418         atomic_t *sw_ptr;
 419         int rc;
 420 
 421         sw_ptr = &get_cpu_var(clock_sync_word);
 422         rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;
 423         put_cpu_var(clock_sync_word);
 424         return rc;
 425 }
 426 
 427 /*
 428  * Apply clock delta to the global data structures.
 429  * This is called once on the CPU that performed the clock sync.
 430  */
 431 static void clock_sync_global(unsigned long long delta)
 432 {
 433         unsigned long now, adj;
 434         struct ptff_qto qto;
 435 
 436         /* Fixup the monotonic sched clock. */
 437         *(unsigned long long *) &tod_clock_base[1] += delta;
 438         if (*(unsigned long long *) &tod_clock_base[1] < delta)
 439                 /* Epoch overflow */
 440                 tod_clock_base[0]++;
 441         /* Adjust TOD steering parameters. */
 442         vdso_data->tb_update_count++;
 443         now = get_tod_clock();
 444         adj = tod_steering_end - now;
 445         if (unlikely((s64) adj >= 0))
 446                 /* Calculate how much of the old adjustment is left. */
 447                 tod_steering_delta = (tod_steering_delta < 0) ?
 448                         -(adj >> 15) : (adj >> 15);
 449         tod_steering_delta += delta;
 450         if ((abs(tod_steering_delta) >> 48) != 0)
 451                 panic("TOD clock sync offset %lli is too large to drift\n",
 452                       tod_steering_delta);
 453         tod_steering_end = now + (abs(tod_steering_delta) << 15);
 454         vdso_data->ts_dir = (tod_steering_delta < 0) ? 0 : 1;
 455         vdso_data->ts_end = tod_steering_end;
 456         vdso_data->tb_update_count++;
 457         /* Update LPAR offset. */
 458         if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
 459                 lpar_offset = qto.tod_epoch_difference;
 460         /* Call the TOD clock change notifier. */
 461         atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);
 462 }
 463 
 464 /*
 465  * Apply clock delta to the per-CPU data structures of this CPU.
 466  * This is called for each online CPU after the call to clock_sync_global.
 467  */
 468 static void clock_sync_local(unsigned long long delta)
 469 {
 470         /* Add the delta to the clock comparator. */
 471         if (S390_lowcore.clock_comparator != clock_comparator_max) {
 472                 S390_lowcore.clock_comparator += delta;
 473                 set_clock_comparator(S390_lowcore.clock_comparator);
 474         }
 475         /* Adjust the last_update_clock time-stamp. */
 476         S390_lowcore.last_update_clock += delta;
 477 }
 478 
 479 /* Single threaded workqueue used for stp sync events */
 480 static struct workqueue_struct *time_sync_wq;
 481 
 482 static void __init time_init_wq(void)
 483 {
 484         if (time_sync_wq)
 485                 return;
 486         time_sync_wq = create_singlethread_workqueue("timesync");
 487 }
 488 
 489 struct clock_sync_data {
 490         atomic_t cpus;
 491         int in_sync;
 492         unsigned long long clock_delta;
 493 };
 494 
 495 /*
 496  * Server Time Protocol (STP) code.
 497  */
 498 static bool stp_online;
 499 static struct stp_sstpi stp_info;
 500 static void *stp_page;
 501 
 502 static void stp_work_fn(struct work_struct *work);
 503 static DEFINE_MUTEX(stp_work_mutex);
 504 static DECLARE_WORK(stp_work, stp_work_fn);
 505 static struct timer_list stp_timer;
 506 
 507 static int __init early_parse_stp(char *p)
 508 {
 509         return kstrtobool(p, &stp_online);
 510 }
 511 early_param("stp", early_parse_stp);
 512 
 513 /*
 514  * Reset STP attachment.
 515  */
 516 static void __init stp_reset(void)
 517 {
 518         int rc;
 519 
 520         stp_page = (void *) get_zeroed_page(GFP_ATOMIC);
 521         rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
 522         if (rc == 0)
 523                 set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags);
 524         else if (stp_online) {
 525                 pr_warn("The real or virtual hardware system does not provide an STP interface\n");
 526                 free_page((unsigned long) stp_page);
 527                 stp_page = NULL;
 528                 stp_online = false;
 529         }
 530 }
 531 
 532 static void stp_timeout(struct timer_list *unused)
 533 {
 534         queue_work(time_sync_wq, &stp_work);
 535 }
 536 
 537 static int __init stp_init(void)
 538 {
 539         if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
 540                 return 0;
 541         timer_setup(&stp_timer, stp_timeout, 0);
 542         time_init_wq();
 543         if (!stp_online)
 544                 return 0;
 545         queue_work(time_sync_wq, &stp_work);
 546         return 0;
 547 }
 548 
 549 arch_initcall(stp_init);
 550 
 551 /*
 552  * STP timing alert. There are three causes:
 553  * 1) timing status change
 554  * 2) link availability change
 555  * 3) time control parameter change
 556  * In all three cases we are only interested in the clock source state.
 557  * If a STP clock source is now available use it.
 558  */
 559 static void stp_timing_alert(struct stp_irq_parm *intparm)
 560 {
 561         if (intparm->tsc || intparm->lac || intparm->tcpc)
 562                 queue_work(time_sync_wq, &stp_work);
 563 }
 564 
 565 /*
 566  * STP sync check machine check. This is called when the timing state
 567  * changes from the synchronized state to the unsynchronized state.
 568  * After a STP sync check the clock is not in sync. The machine check
 569  * is broadcasted to all cpus at the same time.
 570  */
 571 int stp_sync_check(void)
 572 {
 573         disable_sync_clock(NULL);
 574         return 1;
 575 }
 576 
 577 /*
 578  * STP island condition machine check. This is called when an attached
 579  * server  attempts to communicate over an STP link and the servers
 580  * have matching CTN ids and have a valid stratum-1 configuration
 581  * but the configurations do not match.
 582  */
 583 int stp_island_check(void)
 584 {
 585         disable_sync_clock(NULL);
 586         return 1;
 587 }
 588 
 589 void stp_queue_work(void)
 590 {
 591         queue_work(time_sync_wq, &stp_work);
 592 }
 593 
 594 static int stp_sync_clock(void *data)
 595 {
 596         struct clock_sync_data *sync = data;
 597         unsigned long long clock_delta;
 598         static int first;
 599         int rc;
 600 
 601         enable_sync_clock();
 602         if (xchg(&first, 1) == 0) {
 603                 /* Wait until all other cpus entered the sync function. */
 604                 while (atomic_read(&sync->cpus) != 0)
 605                         cpu_relax();
 606                 rc = 0;
 607                 if (stp_info.todoff[0] || stp_info.todoff[1] ||
 608                     stp_info.todoff[2] || stp_info.todoff[3] ||
 609                     stp_info.tmd != 2) {
 610                         rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
 611                                         &clock_delta);
 612                         if (rc == 0) {
 613                                 sync->clock_delta = clock_delta;
 614                                 clock_sync_global(clock_delta);
 615                                 rc = chsc_sstpi(stp_page, &stp_info,
 616                                                 sizeof(struct stp_sstpi));
 617                                 if (rc == 0 && stp_info.tmd != 2)
 618                                         rc = -EAGAIN;
 619                         }
 620                 }
 621                 sync->in_sync = rc ? -EAGAIN : 1;
 622                 xchg(&first, 0);
 623         } else {
 624                 /* Slave */
 625                 atomic_dec(&sync->cpus);
 626                 /* Wait for in_sync to be set. */
 627                 while (READ_ONCE(sync->in_sync) == 0)
 628                         __udelay(1);
 629         }
 630         if (sync->in_sync != 1)
 631                 /* Didn't work. Clear per-cpu in sync bit again. */
 632                 disable_sync_clock(NULL);
 633         /* Apply clock delta to per-CPU fields of this CPU. */
 634         clock_sync_local(sync->clock_delta);
 635 
 636         return 0;
 637 }
 638 
 639 /*
 640  * STP work. Check for the STP state and take over the clock
 641  * synchronization if the STP clock source is usable.
 642  */
 643 static void stp_work_fn(struct work_struct *work)
 644 {
 645         struct clock_sync_data stp_sync;
 646         int rc;
 647 
 648         /* prevent multiple execution. */
 649         mutex_lock(&stp_work_mutex);
 650 
 651         if (!stp_online) {
 652                 chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
 653                 del_timer_sync(&stp_timer);
 654                 goto out_unlock;
 655         }
 656 
 657         rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xb0e0, NULL);
 658         if (rc)
 659                 goto out_unlock;
 660 
 661         rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
 662         if (rc || stp_info.c == 0)
 663                 goto out_unlock;
 664 
 665         /* Skip synchronization if the clock is already in sync. */
 666         if (check_sync_clock())
 667                 goto out_unlock;
 668 
 669         memset(&stp_sync, 0, sizeof(stp_sync));
 670         cpus_read_lock();
 671         atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
 672         stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
 673         cpus_read_unlock();
 674 
 675         if (!check_sync_clock())
 676                 /*
 677                  * There is a usable clock but the synchonization failed.
 678                  * Retry after a second.
 679                  */
 680                 mod_timer(&stp_timer, jiffies + HZ);
 681 
 682 out_unlock:
 683         mutex_unlock(&stp_work_mutex);
 684 }
 685 
 686 /*
 687  * STP subsys sysfs interface functions
 688  */
 689 static struct bus_type stp_subsys = {
 690         .name           = "stp",
 691         .dev_name       = "stp",
 692 };
 693 
 694 static ssize_t stp_ctn_id_show(struct device *dev,
 695                                 struct device_attribute *attr,
 696                                 char *buf)
 697 {
 698         if (!stp_online)
 699                 return -ENODATA;
 700         return sprintf(buf, "%016llx\n",
 701                        *(unsigned long long *) stp_info.ctnid);
 702 }
 703 
 704 static DEVICE_ATTR(ctn_id, 0400, stp_ctn_id_show, NULL);
 705 
 706 static ssize_t stp_ctn_type_show(struct device *dev,
 707                                 struct device_attribute *attr,
 708                                 char *buf)
 709 {
 710         if (!stp_online)
 711                 return -ENODATA;
 712         return sprintf(buf, "%i\n", stp_info.ctn);
 713 }
 714 
 715 static DEVICE_ATTR(ctn_type, 0400, stp_ctn_type_show, NULL);
 716 
 717 static ssize_t stp_dst_offset_show(struct device *dev,
 718                                    struct device_attribute *attr,
 719                                    char *buf)
 720 {
 721         if (!stp_online || !(stp_info.vbits & 0x2000))
 722                 return -ENODATA;
 723         return sprintf(buf, "%i\n", (int)(s16) stp_info.dsto);
 724 }
 725 
 726 static DEVICE_ATTR(dst_offset, 0400, stp_dst_offset_show, NULL);
 727 
 728 static ssize_t stp_leap_seconds_show(struct device *dev,
 729                                         struct device_attribute *attr,
 730                                         char *buf)
 731 {
 732         if (!stp_online || !(stp_info.vbits & 0x8000))
 733                 return -ENODATA;
 734         return sprintf(buf, "%i\n", (int)(s16) stp_info.leaps);
 735 }
 736 
 737 static DEVICE_ATTR(leap_seconds, 0400, stp_leap_seconds_show, NULL);
 738 
 739 static ssize_t stp_stratum_show(struct device *dev,
 740                                 struct device_attribute *attr,
 741                                 char *buf)
 742 {
 743         if (!stp_online)
 744                 return -ENODATA;
 745         return sprintf(buf, "%i\n", (int)(s16) stp_info.stratum);
 746 }
 747 
 748 static DEVICE_ATTR(stratum, 0400, stp_stratum_show, NULL);
 749 
 750 static ssize_t stp_time_offset_show(struct device *dev,
 751                                 struct device_attribute *attr,
 752                                 char *buf)
 753 {
 754         if (!stp_online || !(stp_info.vbits & 0x0800))
 755                 return -ENODATA;
 756         return sprintf(buf, "%i\n", (int) stp_info.tto);
 757 }
 758 
 759 static DEVICE_ATTR(time_offset, 0400, stp_time_offset_show, NULL);
 760 
 761 static ssize_t stp_time_zone_offset_show(struct device *dev,
 762                                 struct device_attribute *attr,
 763                                 char *buf)
 764 {
 765         if (!stp_online || !(stp_info.vbits & 0x4000))
 766                 return -ENODATA;
 767         return sprintf(buf, "%i\n", (int)(s16) stp_info.tzo);
 768 }
 769 
 770 static DEVICE_ATTR(time_zone_offset, 0400,
 771                          stp_time_zone_offset_show, NULL);
 772 
 773 static ssize_t stp_timing_mode_show(struct device *dev,
 774                                 struct device_attribute *attr,
 775                                 char *buf)
 776 {
 777         if (!stp_online)
 778                 return -ENODATA;
 779         return sprintf(buf, "%i\n", stp_info.tmd);
 780 }
 781 
 782 static DEVICE_ATTR(timing_mode, 0400, stp_timing_mode_show, NULL);
 783 
 784 static ssize_t stp_timing_state_show(struct device *dev,
 785                                 struct device_attribute *attr,
 786                                 char *buf)
 787 {
 788         if (!stp_online)
 789                 return -ENODATA;
 790         return sprintf(buf, "%i\n", stp_info.tst);
 791 }
 792 
 793 static DEVICE_ATTR(timing_state, 0400, stp_timing_state_show, NULL);
 794 
 795 static ssize_t stp_online_show(struct device *dev,
 796                                 struct device_attribute *attr,
 797                                 char *buf)
 798 {
 799         return sprintf(buf, "%i\n", stp_online);
 800 }
 801 
 802 static ssize_t stp_online_store(struct device *dev,
 803                                 struct device_attribute *attr,
 804                                 const char *buf, size_t count)
 805 {
 806         unsigned int value;
 807 
 808         value = simple_strtoul(buf, NULL, 0);
 809         if (value != 0 && value != 1)
 810                 return -EINVAL;
 811         if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
 812                 return -EOPNOTSUPP;
 813         mutex_lock(&clock_sync_mutex);
 814         stp_online = value;
 815         if (stp_online)
 816                 set_bit(CLOCK_SYNC_STP, &clock_sync_flags);
 817         else
 818                 clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
 819         queue_work(time_sync_wq, &stp_work);
 820         mutex_unlock(&clock_sync_mutex);
 821         return count;
 822 }
 823 
 824 /*
 825  * Can't use DEVICE_ATTR because the attribute should be named
 826  * stp/online but dev_attr_online already exists in this file ..
 827  */
 828 static struct device_attribute dev_attr_stp_online = {
 829         .attr = { .name = "online", .mode = 0600 },
 830         .show   = stp_online_show,
 831         .store  = stp_online_store,
 832 };
 833 
 834 static struct device_attribute *stp_attributes[] = {
 835         &dev_attr_ctn_id,
 836         &dev_attr_ctn_type,
 837         &dev_attr_dst_offset,
 838         &dev_attr_leap_seconds,
 839         &dev_attr_stp_online,
 840         &dev_attr_stratum,
 841         &dev_attr_time_offset,
 842         &dev_attr_time_zone_offset,
 843         &dev_attr_timing_mode,
 844         &dev_attr_timing_state,
 845         NULL
 846 };
 847 
 848 static int __init stp_init_sysfs(void)
 849 {
 850         struct device_attribute **attr;
 851         int rc;
 852 
 853         rc = subsys_system_register(&stp_subsys, NULL);
 854         if (rc)
 855                 goto out;
 856         for (attr = stp_attributes; *attr; attr++) {
 857                 rc = device_create_file(stp_subsys.dev_root, *attr);
 858                 if (rc)
 859                         goto out_unreg;
 860         }
 861         return 0;
 862 out_unreg:
 863         for (; attr >= stp_attributes; attr--)
 864                 device_remove_file(stp_subsys.dev_root, *attr);
 865         bus_unregister(&stp_subsys);
 866 out:
 867         return rc;
 868 }
 869 
 870 device_initcall(stp_init_sysfs);
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root/arch/s390/kernel/time.c

DEFINITIONS
