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 // SPDX-License-Identifier: GPL-2.0
 /*
  *    Time of day based timer functions.
  *
  *  S390 version
  *    Copyright IBM Corp. 1999, 2008
  *    Author(s): Hartmut Penner (hp@de.ibm.com),
  *               Martin Schwidefsky (schwidefsky@de.ibm.com),
  *               Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
  *
  *  Derived from "arch/i386/kernel/time.c"
  *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
  */
 
 #define KMSG_COMPONENT "time"
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
 
 #include <linux/kernel_stat.h>
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/sched.h>
 #include <linux/sched/clock.h>
 #include <linux/kernel.h>
 #include <linux/param.h>
 #include <linux/string.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/cpu.h>
 #include <linux/stop_machine.h>
 #include <linux/time.h>
 #include <linux/device.h>
 #include <linux/delay.h>
 #include <linux/init.h>
 #include <linux/smp.h>
 #include <linux/types.h>
 #include <linux/profile.h>
 #include <linux/timex.h>
 #include <linux/notifier.h>
 #include <linux/timekeeper_internal.h>
 #include <linux/clockchips.h>
 #include <linux/gfp.h>
 #include <linux/kprobes.h>
 #include <linux/uaccess.h>
 #include <vdso/vsyscall.h>
 #include <vdso/clocksource.h>
 #include <vdso/helpers.h>
 #include <asm/facility.h>
 #include <asm/delay.h>
 #include <asm/div64.h>
 #include <asm/vdso.h>
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
 #include <asm/vtimer.h>
 #include <asm/stp.h>
 #include <asm/cio.h>
 #include "entry.h"
 
 union tod_clock tod_clock_base __section(".data");
 EXPORT_SYMBOL_GPL(tod_clock_base);
 
 u64 clock_comparator_max = -1ULL;
 EXPORT_SYMBOL_GPL(clock_comparator_max);
 
 static DEFINE_PER_CPU(struct clock_event_device, comparators);
 
 ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
 EXPORT_SYMBOL(s390_epoch_delta_notifier);
 
 unsigned char ptff_function_mask[16];
 
 static unsigned long lpar_offset;
 static unsigned long initial_leap_seconds;
 static unsigned long tod_steering_end;
 static long tod_steering_delta;
 
 /*
  * Get time offsets with PTFF
  */
 void __init time_early_init(void)
 {
     struct ptff_qto qto;
     struct ptff_qui qui;
     int cs;
 
     /* Initialize TOD steering parameters */
     tod_steering_end = tod_clock_base.tod;
     for (cs = 0; cs < CS_BASES; cs++)
         vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
 
     if (!test_facility(28))
         return;
 
     ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF);
 
     /* get LPAR offset */
     if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
         lpar_offset = qto.tod_epoch_difference;
 
     /* get initial leap seconds */
     if (ptff_query(PTFF_QUI) && ptff(&qui, sizeof(qui), PTFF_QUI) == 0)
         initial_leap_seconds = (unsigned long)
             ((long) qui.old_leap * 4096000000L);
 }
 
 /*
  * Scheduler clock - returns current time in nanosec units.
  */
 unsigned long long notrace sched_clock(void)
 {
     return tod_to_ns(get_tod_clock_monotonic());
 }
 NOKPROBE_SYMBOL(sched_clock);
 
 static void ext_to_timespec64(union tod_clock *clk, struct timespec64 *xt)
 {
     unsigned long rem, sec, nsec;
 
     sec = clk->us;
     rem = do_div(sec, 1000000);
     nsec = ((clk->sus + (rem << 12)) * 125) >> 9;
     xt->tv_sec = sec;
     xt->tv_nsec = nsec;
 }
 
 void clock_comparator_work(void)
 {
     struct clock_event_device *cd;
 
     S390_lowcore.clock_comparator = clock_comparator_max;
     cd = this_cpu_ptr(&comparators);
     cd->event_handler(cd);
 }
 
 static int s390_next_event(unsigned long delta,
                struct clock_event_device *evt)
 {
     S390_lowcore.clock_comparator = get_tod_clock() + delta;
     set_clock_comparator(S390_lowcore.clock_comparator);
     return 0;
 }
 
 /*
  * Set up lowcore and control register of the current cpu to
  * enable TOD clock and clock comparator interrupts.
  */
 void init_cpu_timer(void)
 {
     struct clock_event_device *cd;
     int cpu;
 
     S390_lowcore.clock_comparator = clock_comparator_max;
     set_clock_comparator(S390_lowcore.clock_comparator);
 
     cpu = smp_processor_id();
     cd = &per_cpu(comparators, cpu);
     cd->name        = "comparator";
     cd->features        = CLOCK_EVT_FEAT_ONESHOT;
     cd->mult        = 16777;
     cd->shift       = 12;
     cd->min_delta_ns    = 1;
     cd->min_delta_ticks = 1;
     cd->max_delta_ns    = LONG_MAX;
     cd->max_delta_ticks = ULONG_MAX;
     cd->rating      = 400;
     cd->cpumask     = cpumask_of(cpu);
     cd->set_next_event  = s390_next_event;
 
     clockevents_register_device(cd);
 
     /* Enable clock comparator timer interrupt. */
     __ctl_set_bit(0,11);
 
     /* Always allow the timing alert external interrupt. */
     __ctl_set_bit(0, 4);
 }
 
 static void clock_comparator_interrupt(struct ext_code ext_code,
                        unsigned int param32,
                        unsigned long param64)
 {
     inc_irq_stat(IRQEXT_CLK);
     if (S390_lowcore.clock_comparator == clock_comparator_max)
         set_clock_comparator(S390_lowcore.clock_comparator);
 }
 
 static void stp_timing_alert(struct stp_irq_parm *);
 
 static void timing_alert_interrupt(struct ext_code ext_code,
                    unsigned int param32, unsigned long param64)
 {
     inc_irq_stat(IRQEXT_TLA);
     if (param32 & 0x00038000)
         stp_timing_alert((struct stp_irq_parm *) &param32);
 }
 
 static void stp_reset(void);
 
 void read_persistent_clock64(struct timespec64 *ts)
 {
     union tod_clock clk;
     u64 delta;
 
     delta = initial_leap_seconds + TOD_UNIX_EPOCH;
     store_tod_clock_ext(&clk);
     clk.eitod -= delta;
     ext_to_timespec64(&clk, ts);
 }
 
 void __init read_persistent_wall_and_boot_offset(struct timespec64 *wall_time,
                          struct timespec64 *boot_offset)
 {
     struct timespec64 boot_time;
     union tod_clock clk;
     u64 delta;
 
     delta = initial_leap_seconds + TOD_UNIX_EPOCH;
     clk = tod_clock_base;
     clk.eitod -= delta;
     ext_to_timespec64(&clk, &boot_time);
 
     read_persistent_clock64(wall_time);
     *boot_offset = timespec64_sub(*wall_time, boot_time);
 }
 
 static u64 read_tod_clock(struct clocksource *cs)
 {
     unsigned long now, adj;
 
     preempt_disable(); /* protect from changes to steering parameters */
     now = get_tod_clock();
     adj = tod_steering_end - now;
     if (unlikely((s64) adj > 0))
         /*
          * manually steer by 1 cycle every 2^16 cycles. This
          * corresponds to shifting the tod delta by 15. 1s is
          * therefore steered in ~9h. The adjust will decrease
          * over time, until it finally reaches 0.
          */
         now += (tod_steering_delta < 0) ? (adj >> 15) : -(adj >> 15);
     preempt_enable();
     return now;
 }
 
 static struct clocksource clocksource_tod = {
     .name       = "tod",
     .rating     = 400,
     .read       = read_tod_clock,
     .mask       = CLOCKSOURCE_MASK(64),
     .mult       = 1000,
     .shift      = 12,
     .flags      = CLOCK_SOURCE_IS_CONTINUOUS,
     .vdso_clock_mode = VDSO_CLOCKMODE_TOD,
 };
 
 struct clocksource * __init clocksource_default_clock(void)
 {
     return &clocksource_tod;
 }
 
 /*
  * Initialize the TOD clock and the CPU timer of
  * the boot cpu.
  */
 void __init time_init(void)
 {
     /* Reset time synchronization interfaces. */
     stp_reset();
 
     /* request the clock comparator external interrupt */
     if (register_external_irq(EXT_IRQ_CLK_COMP, clock_comparator_interrupt))
         panic("Couldn't request external interrupt 0x1004");
 
     /* request the timing alert external interrupt */
     if (register_external_irq(EXT_IRQ_TIMING_ALERT, timing_alert_interrupt))
         panic("Couldn't request external interrupt 0x1406");
 
     if (__clocksource_register(&clocksource_tod) != 0)
         panic("Could not register TOD clock source");
 
     /* Enable TOD clock interrupts on the boot cpu. */
     init_cpu_timer();
 
     /* Enable cpu timer interrupts on the boot cpu. */
     vtime_init();
 }
 
 static DEFINE_PER_CPU(atomic_t, clock_sync_word);
 static DEFINE_MUTEX(stp_mutex);
 static unsigned long clock_sync_flags;
 
 #define CLOCK_SYNC_HAS_STP      0
 #define CLOCK_SYNC_STP          1
 #define CLOCK_SYNC_STPINFO_VALID    2
 
 /*
  * The get_clock function for the physical clock. It will get the current
  * TOD clock, subtract the LPAR offset and write the result to *clock.
  * The function returns 0 if the clock is in sync with the external time
  * source. If the clock mode is local it will return -EOPNOTSUPP and
  * -EAGAIN if the clock is not in sync with the external reference.
  */
 int get_phys_clock(unsigned long *clock)
 {
     atomic_t *sw_ptr;
     unsigned int sw0, sw1;
 
     sw_ptr = &get_cpu_var(clock_sync_word);
     sw0 = atomic_read(sw_ptr);
     *clock = get_tod_clock() - lpar_offset;
     sw1 = atomic_read(sw_ptr);
     put_cpu_var(clock_sync_word);
     if (sw0 == sw1 && (sw0 & 0x80000000U))
         /* Success: time is in sync. */
         return 0;
     if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
         return -EOPNOTSUPP;
     if (!test_bit(CLOCK_SYNC_STP, &clock_sync_flags))
         return -EACCES;
     return -EAGAIN;
 }
 EXPORT_SYMBOL(get_phys_clock);
 
 /*
  * Make get_phys_clock() return -EAGAIN.
  */
 static void disable_sync_clock(void *dummy)
 {
     atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
     /*
      * Clear the in-sync bit 2^31. All get_phys_clock calls will
      * fail until the sync bit is turned back on. In addition
      * increase the "sequence" counter to avoid the race of an
      * stp event and the complete recovery against get_phys_clock.
      */
     atomic_andnot(0x80000000, sw_ptr);
     atomic_inc(sw_ptr);
 }
 
 /*
  * Make get_phys_clock() return 0 again.
  * Needs to be called from a context disabled for preemption.
  */
 static void enable_sync_clock(void)
 {
     atomic_t *sw_ptr = this_cpu_ptr(&clock_sync_word);
     atomic_or(0x80000000, sw_ptr);
 }
 
 /*
  * Function to check if the clock is in sync.
  */
 static inline int check_sync_clock(void)
 {
     atomic_t *sw_ptr;
     int rc;
 
     sw_ptr = &get_cpu_var(clock_sync_word);
     rc = (atomic_read(sw_ptr) & 0x80000000U) != 0;
     put_cpu_var(clock_sync_word);
     return rc;
 }
 
 /*
  * Apply clock delta to the global data structures.
  * This is called once on the CPU that performed the clock sync.
  */
 static void clock_sync_global(long delta)
 {
     unsigned long now, adj;
     struct ptff_qto qto;
     int cs;
 
     /* Fixup the monotonic sched clock. */
     tod_clock_base.eitod += delta;
     /* Adjust TOD steering parameters. */
     now = get_tod_clock();
     adj = tod_steering_end - now;
     if (unlikely((s64) adj >= 0))
         /* Calculate how much of the old adjustment is left. */
         tod_steering_delta = (tod_steering_delta < 0) ?
             -(adj >> 15) : (adj >> 15);
     tod_steering_delta += delta;
     if ((abs(tod_steering_delta) >> 48) != 0)
         panic("TOD clock sync offset %li is too large to drift\n",
               tod_steering_delta);
     tod_steering_end = now + (abs(tod_steering_delta) << 15);
     for (cs = 0; cs < CS_BASES; cs++) {
         vdso_data[cs].arch_data.tod_steering_end = tod_steering_end;
         vdso_data[cs].arch_data.tod_steering_delta = tod_steering_delta;
     }
 
     /* Update LPAR offset. */
     if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
         lpar_offset = qto.tod_epoch_difference;
     /* Call the TOD clock change notifier. */
     atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &delta);
 }
 
 /*
  * Apply clock delta to the per-CPU data structures of this CPU.
  * This is called for each online CPU after the call to clock_sync_global.
  */
 static void clock_sync_local(long delta)
 {
     /* Add the delta to the clock comparator. */
     if (S390_lowcore.clock_comparator != clock_comparator_max) {
         S390_lowcore.clock_comparator += delta;
         set_clock_comparator(S390_lowcore.clock_comparator);
     }
     /* Adjust the last_update_clock time-stamp. */
     S390_lowcore.last_update_clock += delta;
 }
 
 /* Single threaded workqueue used for stp sync events */
 static struct workqueue_struct *time_sync_wq;
 
 static void __init time_init_wq(void)
 {
     if (time_sync_wq)
         return;
     time_sync_wq = create_singlethread_workqueue("timesync");
 }
 
 struct clock_sync_data {
     atomic_t cpus;
     int in_sync;
     long clock_delta;
 };
 
 /*
  * Server Time Protocol (STP) code.
  */
 static bool stp_online;
 static struct stp_sstpi stp_info;
 static void *stp_page;
 
 static void stp_work_fn(struct work_struct *work);
 static DECLARE_WORK(stp_work, stp_work_fn);
 static struct timer_list stp_timer;
 
 static int __init early_parse_stp(char *p)
 {
     return kstrtobool(p, &stp_online);
 }
 early_param("stp", early_parse_stp);
 
 /*
  * Reset STP attachment.
  */
 static void __init stp_reset(void)
 {
     int rc;
 
     stp_page = (void *) get_zeroed_page(GFP_ATOMIC);
     rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
     if (rc == 0)
         set_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags);
     else if (stp_online) {
         pr_warn("The real or virtual hardware system does not provide an STP interface\n");
         free_page((unsigned long) stp_page);
         stp_page = NULL;
         stp_online = false;
     }
 }
 
 static void stp_timeout(struct timer_list *unused)
 {
     queue_work(time_sync_wq, &stp_work);
 }
 
 static int __init stp_init(void)
 {
     if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
         return 0;
     timer_setup(&stp_timer, stp_timeout, 0);
     time_init_wq();
     if (!stp_online)
         return 0;
     queue_work(time_sync_wq, &stp_work);
     return 0;
 }
 
 arch_initcall(stp_init);
 
 /*
  * STP timing alert. There are three causes:
  * 1) timing status change
  * 2) link availability change
  * 3) time control parameter change
  * In all three cases we are only interested in the clock source state.
  * If a STP clock source is now available use it.
  */
 static void stp_timing_alert(struct stp_irq_parm *intparm)
 {
     if (intparm->tsc || intparm->lac || intparm->tcpc)
         queue_work(time_sync_wq, &stp_work);
 }
 
 /*
  * STP sync check machine check. This is called when the timing state
  * changes from the synchronized state to the unsynchronized state.
  * After a STP sync check the clock is not in sync. The machine check
  * is broadcasted to all cpus at the same time.
  */
 int stp_sync_check(void)
 {
     disable_sync_clock(NULL);
     return 1;
 }
 
 /*
  * STP island condition machine check. This is called when an attached
  * server  attempts to communicate over an STP link and the servers
  * have matching CTN ids and have a valid stratum-1 configuration
  * but the configurations do not match.
  */
 int stp_island_check(void)
 {
     disable_sync_clock(NULL);
     return 1;
 }
 
 void stp_queue_work(void)
 {
     queue_work(time_sync_wq, &stp_work);
 }
 
 static int __store_stpinfo(void)
 {
     int rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
 
     if (rc)
         clear_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
     else
         set_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
     return rc;
 }
 
 static int stpinfo_valid(void)
 {
     return stp_online && test_bit(CLOCK_SYNC_STPINFO_VALID, &clock_sync_flags);
 }
 
 static int stp_sync_clock(void *data)
 {
     struct clock_sync_data *sync = data;
     long clock_delta, flags;
     static int first;
     int rc;
 
     enable_sync_clock();
     if (xchg(&first, 1) == 0) {
         /* Wait until all other cpus entered the sync function. */
         while (atomic_read(&sync->cpus) != 0)
             cpu_relax();
         rc = 0;
         if (stp_info.todoff || stp_info.tmd != 2) {
             flags = vdso_update_begin();
             rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0,
                     &clock_delta);
             if (rc == 0) {
                 sync->clock_delta = clock_delta;
                 clock_sync_global(clock_delta);
                 rc = __store_stpinfo();
                 if (rc == 0 && stp_info.tmd != 2)
                     rc = -EAGAIN;
             }
             vdso_update_end(flags);
         }
         sync->in_sync = rc ? -EAGAIN : 1;
         xchg(&first, 0);
     } else {
         /* Slave */
         atomic_dec(&sync->cpus);
         /* Wait for in_sync to be set. */
         while (READ_ONCE(sync->in_sync) == 0)
             __udelay(1);
     }
     if (sync->in_sync != 1)
         /* Didn't work. Clear per-cpu in sync bit again. */
         disable_sync_clock(NULL);
     /* Apply clock delta to per-CPU fields of this CPU. */
     clock_sync_local(sync->clock_delta);
 
     return 0;
 }
 
 static int stp_clear_leap(void)
 {
     struct __kernel_timex txc;
     int ret;
 
     memset(&txc, 0, sizeof(txc));
 
     ret = do_adjtimex(&txc);
     if (ret < 0)
         return ret;
 
     txc.modes = ADJ_STATUS;
     txc.status &= ~(STA_INS|STA_DEL);
     return do_adjtimex(&txc);
 }
 
 static void stp_check_leap(void)
 {
     struct stp_stzi stzi;
     struct stp_lsoib *lsoib = &stzi.lsoib;
     struct __kernel_timex txc;
     int64_t timediff;
     int leapdiff, ret;
 
     if (!stp_info.lu || !check_sync_clock()) {
         /*
          * Either a scheduled leap second was removed by the operator,
          * or STP is out of sync. In both cases, clear the leap second
          * kernel flags.
          */
         if (stp_clear_leap() < 0)
             pr_err("failed to clear leap second flags\n");
         return;
     }
 
     if (chsc_stzi(stp_page, &stzi, sizeof(stzi))) {
         pr_err("stzi failed\n");
         return;
     }
 
     timediff = tod_to_ns(lsoib->nlsout - get_tod_clock()) / NSEC_PER_SEC;
     leapdiff = lsoib->nlso - lsoib->also;
 
     if (leapdiff != 1 && leapdiff != -1) {
         pr_err("Cannot schedule %d leap seconds\n", leapdiff);
         return;
     }
 
     if (timediff < 0) {
         if (stp_clear_leap() < 0)
             pr_err("failed to clear leap second flags\n");
     } else if (timediff < 7200) {
         memset(&txc, 0, sizeof(txc));
         ret = do_adjtimex(&txc);
         if (ret < 0)
             return;
 
         txc.modes = ADJ_STATUS;
         if (leapdiff > 0)
             txc.status |= STA_INS;
         else
             txc.status |= STA_DEL;
         ret = do_adjtimex(&txc);
         if (ret < 0)
             pr_err("failed to set leap second flags\n");
         /* arm Timer to clear leap second flags */
         mod_timer(&stp_timer, jiffies + msecs_to_jiffies(14400 * MSEC_PER_SEC));
     } else {
         /* The day the leap second is scheduled for hasn't been reached. Retry
          * in one hour.
          */
         mod_timer(&stp_timer, jiffies + msecs_to_jiffies(3600 * MSEC_PER_SEC));
     }
 }
 
 /*
  * STP work. Check for the STP state and take over the clock
  * synchronization if the STP clock source is usable.
  */
 static void stp_work_fn(struct work_struct *work)
 {
     struct clock_sync_data stp_sync;
     int rc;
 
     /* prevent multiple execution. */
     mutex_lock(&stp_mutex);
 
     if (!stp_online) {
         chsc_sstpc(stp_page, STP_OP_CTRL, 0x0000, NULL);
         del_timer_sync(&stp_timer);
         goto out_unlock;
     }
 
     rc = chsc_sstpc(stp_page, STP_OP_CTRL, 0xf0e0, NULL);
     if (rc)
         goto out_unlock;
 
     rc = __store_stpinfo();
     if (rc || stp_info.c == 0)
         goto out_unlock;
 
     /* Skip synchronization if the clock is already in sync. */
     if (!check_sync_clock()) {
         memset(&stp_sync, 0, sizeof(stp_sync));
         cpus_read_lock();
         atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
         stop_machine_cpuslocked(stp_sync_clock, &stp_sync, cpu_online_mask);
         cpus_read_unlock();
     }
 
     if (!check_sync_clock())
         /*
          * There is a usable clock but the synchonization failed.
          * Retry after a second.
          */
         mod_timer(&stp_timer, jiffies + msecs_to_jiffies(MSEC_PER_SEC));
     else if (stp_info.lu)
         stp_check_leap();
 
 out_unlock:
     mutex_unlock(&stp_mutex);
 }
 
 /*
  * STP subsys sysfs interface functions
  */
 static struct bus_type stp_subsys = {
     .name       = "stp",
     .dev_name   = "stp",
 };
 
 static ssize_t ctn_id_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid())
         ret = sprintf(buf, "%016lx\n",
                   *(unsigned long *) stp_info.ctnid);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(ctn_id);
 
 static ssize_t ctn_type_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid())
         ret = sprintf(buf, "%i\n", stp_info.ctn);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(ctn_type);
 
 static ssize_t dst_offset_show(struct device *dev,
                    struct device_attribute *attr,
                    char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid() && (stp_info.vbits & 0x2000))
         ret = sprintf(buf, "%i\n", (int)(s16) stp_info.dsto);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(dst_offset);
 
 static ssize_t leap_seconds_show(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid() && (stp_info.vbits & 0x8000))
         ret = sprintf(buf, "%i\n", (int)(s16) stp_info.leaps);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(leap_seconds);
 
 static ssize_t leap_seconds_scheduled_show(struct device *dev,
                         struct device_attribute *attr,
                         char *buf)
 {
     struct stp_stzi stzi;
     ssize_t ret;
 
     mutex_lock(&stp_mutex);
     if (!stpinfo_valid() || !(stp_info.vbits & 0x8000) || !stp_info.lu) {
         mutex_unlock(&stp_mutex);
         return -ENODATA;
     }
 
     ret = chsc_stzi(stp_page, &stzi, sizeof(stzi));
     mutex_unlock(&stp_mutex);
     if (ret < 0)
         return ret;
 
     if (!stzi.lsoib.p)
         return sprintf(buf, "0,0\n");
 
     return sprintf(buf, "%lu,%d\n",
                tod_to_ns(stzi.lsoib.nlsout - TOD_UNIX_EPOCH) / NSEC_PER_SEC,
                stzi.lsoib.nlso - stzi.lsoib.also);
 }
 
 static DEVICE_ATTR_RO(leap_seconds_scheduled);
 
 static ssize_t stratum_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid())
         ret = sprintf(buf, "%i\n", (int)(s16) stp_info.stratum);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(stratum);
 
 static ssize_t time_offset_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid() && (stp_info.vbits & 0x0800))
         ret = sprintf(buf, "%i\n", (int) stp_info.tto);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(time_offset);
 
 static ssize_t time_zone_offset_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid() && (stp_info.vbits & 0x4000))
         ret = sprintf(buf, "%i\n", (int)(s16) stp_info.tzo);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(time_zone_offset);
 
 static ssize_t timing_mode_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid())
         ret = sprintf(buf, "%i\n", stp_info.tmd);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(timing_mode);
 
 static ssize_t timing_state_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     ssize_t ret = -ENODATA;
 
     mutex_lock(&stp_mutex);
     if (stpinfo_valid())
         ret = sprintf(buf, "%i\n", stp_info.tst);
     mutex_unlock(&stp_mutex);
     return ret;
 }
 
 static DEVICE_ATTR_RO(timing_state);
 
 static ssize_t online_show(struct device *dev,
                 struct device_attribute *attr,
                 char *buf)
 {
     return sprintf(buf, "%i\n", stp_online);
 }
 
 static ssize_t online_store(struct device *dev,
                 struct device_attribute *attr,
                 const char *buf, size_t count)
 {
     unsigned int value;
 
     value = simple_strtoul(buf, NULL, 0);
     if (value != 0 && value != 1)
         return -EINVAL;
     if (!test_bit(CLOCK_SYNC_HAS_STP, &clock_sync_flags))
         return -EOPNOTSUPP;
     mutex_lock(&stp_mutex);
     stp_online = value;
     if (stp_online)
         set_bit(CLOCK_SYNC_STP, &clock_sync_flags);
     else
         clear_bit(CLOCK_SYNC_STP, &clock_sync_flags);
     queue_work(time_sync_wq, &stp_work);
     mutex_unlock(&stp_mutex);
     return count;
 }
 
 /*
  * Can't use DEVICE_ATTR because the attribute should be named
  * stp/online but dev_attr_online already exists in this file ..
  */
 static DEVICE_ATTR_RW(online);
 
 static struct attribute *stp_dev_attrs[] = {
     &dev_attr_ctn_id.attr,
     &dev_attr_ctn_type.attr,
     &dev_attr_dst_offset.attr,
     &dev_attr_leap_seconds.attr,
     &dev_attr_online.attr,
     &dev_attr_leap_seconds_scheduled.attr,
     &dev_attr_stratum.attr,
     &dev_attr_time_offset.attr,
     &dev_attr_time_zone_offset.attr,
     &dev_attr_timing_mode.attr,
     &dev_attr_timing_state.attr,
     NULL
 };
 ATTRIBUTE_GROUPS(stp_dev);
 
 static int __init stp_init_sysfs(void)
 {
     return subsys_system_register(&stp_subsys, stp_dev_groups);
 }
 
 device_initcall(stp_init_sysfs);

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