time.c
/*
* 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/module.h>
#include <linux/sched.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 <asm/uaccess.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"
u64 sched_clock_base_cc = -1; /* Force to data section. */
EXPORT_SYMBOL_GPL(sched_clock_base_cc);
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];
unsigned long lpar_offset;
unsigned long initial_leap_seconds;
/*
* Get time offsets with PTFF
*/
void __init ptff_init(void)
{
struct ptff_qto qto;
struct ptff_qui qui;
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);
/*
* Monotonic_clock - returns # of nanoseconds passed since time_init()
*/
unsigned long long monotonic_clock(void)
{
return sched_clock();
}
EXPORT_SYMBOL(monotonic_clock);
void tod_to_timeval(__u64 todval, struct timespec64 *xt)
{
unsigned long long sec;
sec = todval >> 12;
do_div(sec, 1000000);
xt->tv_sec = sec;
todval -= (sec * 1000000) << 12;
xt->tv_nsec = ((todval * 1000) >> 12);
}
EXPORT_SYMBOL(tod_to_timeval);
void clock_comparator_work(void)
{
struct clock_event_device *cd;
S390_lowcore.clock_comparator = -1ULL;
cd = this_cpu_ptr(&comparators);
cd->event_handler(cd);
}
/*
* Fixup the clock comparator.
*/
static void fixup_clock_comparator(unsigned long long delta)
{
/* If nobody is waiting there's nothing to fix. */
if (S390_lowcore.clock_comparator == -1ULL)
return;
S390_lowcore.clock_comparator += delta;
set_clock_comparator(S390_lowcore.clock_comparator);
}
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 = -1ULL;
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->max_delta_ns = LONG_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 == -1ULL)
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 *) ¶m32);
}
static void stp_reset(void);
void read_persistent_clock64(struct timespec64 *ts)
{
__u64 clock;
clock = get_tod_clock() - initial_leap_seconds;
tod_to_timeval(clock - TOD_UNIX_EPOCH, ts);
}
void read_boot_clock64(struct timespec64 *ts)
{
__u64 clock;
clock = sched_clock_base_cc - initial_leap_seconds;
tod_to_timeval(clock - TOD_UNIX_EPOCH, ts);
}
static cycle_t read_tod_clock(struct clocksource *cs)
{
return get_tod_clock();
}
static struct clocksource clocksource_tod = {
.name = "tod",
.rating = 400,
.read = read_tod_clock,
.mask = -1ULL,
.mult = 1000,
.shift = 12,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
struct clocksource * __init clocksource_default_clock(void)
{
return &clocksource_tod;
}
void update_vsyscall(struct timekeeper *tk)
{
u64 nsecps;
if (tk->tkr_mono.clock != &clocksource_tod)
return;
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_wmb();
vdso_data->xtime_tod_stamp = tk->tkr_mono.cycle_last;
vdso_data->xtime_clock_sec = tk->xtime_sec;
vdso_data->xtime_clock_nsec = tk->tkr_mono.xtime_nsec;
vdso_data->wtom_clock_sec =
tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
vdso_data->wtom_clock_nsec = tk->tkr_mono.xtime_nsec +
+ ((u64) tk->wall_to_monotonic.tv_nsec << tk->tkr_mono.shift);
nsecps = (u64) NSEC_PER_SEC << tk->tkr_mono.shift;
while (vdso_data->wtom_clock_nsec >= nsecps) {
vdso_data->wtom_clock_nsec -= nsecps;
vdso_data->wtom_clock_sec++;
}
vdso_data->xtime_coarse_sec = tk->xtime_sec;
vdso_data->xtime_coarse_nsec =
(long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
vdso_data->wtom_coarse_sec =
vdso_data->xtime_coarse_sec + tk->wall_to_monotonic.tv_sec;
vdso_data->wtom_coarse_nsec =
vdso_data->xtime_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
while (vdso_data->wtom_coarse_nsec >= NSEC_PER_SEC) {
vdso_data->wtom_coarse_nsec -= NSEC_PER_SEC;
vdso_data->wtom_coarse_sec++;
}
vdso_data->tk_mult = tk->tkr_mono.mult;
vdso_data->tk_shift = tk->tkr_mono.shift;
smp_wmb();
++vdso_data->tb_update_count;
}
extern struct timezone sys_tz;
void update_vsyscall_tz(void)
{
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
}
/*
* 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(clock_sync_mutex);
static unsigned long clock_sync_flags;
#define CLOCK_SYNC_HAS_STP 0
#define CLOCK_SYNC_STP 1
/*
* 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 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;
}
/* 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;
unsigned long long fixup_cc;
};
static void clock_sync_cpu(struct clock_sync_data *sync)
{
atomic_dec(&sync->cpus);
enable_sync_clock();
while (sync->in_sync == 0) {
__udelay(1);
/*
* A different cpu changes *in_sync. Therefore use
* barrier() to force memory access.
*/
barrier();
}
if (sync->in_sync != 1)
/* Didn't work. Clear per-cpu in sync bit again. */
disable_sync_clock(NULL);
/*
* This round of TOD syncing is done. Set the clock comparator
* to the next tick and let the processor continue.
*/
fixup_clock_comparator(sync->fixup_cc);
}
/*
* 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 DEFINE_MUTEX(stp_work_mutex);
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 = 0;
}
}
static void stp_timeout(unsigned long dummy)
{
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;
setup_timer(&stp_timer, stp_timeout, 0UL);
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 stp_sync_clock(void *data)
{
static int first;
unsigned long long clock_delta;
struct clock_sync_data *stp_sync;
struct ptff_qto qto;
int rc;
stp_sync = data;
if (xchg(&first, 1) == 1) {
/* Slave */
clock_sync_cpu(stp_sync);
return 0;
}
/* Wait until all other cpus entered the sync function. */
while (atomic_read(&stp_sync->cpus) != 0)
cpu_relax();
enable_sync_clock();
rc = 0;
if (stp_info.todoff[0] || stp_info.todoff[1] ||
stp_info.todoff[2] || stp_info.todoff[3] ||
stp_info.tmd != 2) {
rc = chsc_sstpc(stp_page, STP_OP_SYNC, 0, &clock_delta);
if (rc == 0) {
/* fixup the monotonic sched clock */
sched_clock_base_cc += clock_delta;
if (ptff_query(PTFF_QTO) &&
ptff(&qto, sizeof(qto), PTFF_QTO) == 0)
/* Update LPAR offset */
lpar_offset = qto.tod_epoch_difference;
atomic_notifier_call_chain(&s390_epoch_delta_notifier,
0, &clock_delta);
stp_sync->fixup_cc = clock_delta;
fixup_clock_comparator(clock_delta);
rc = chsc_sstpi(stp_page, &stp_info,
sizeof(struct stp_sstpi));
if (rc == 0 && stp_info.tmd != 2)
rc = -EAGAIN;
}
}
if (rc) {
disable_sync_clock(NULL);
stp_sync->in_sync = -EAGAIN;
} else
stp_sync->in_sync = 1;
xchg(&first, 0);
return 0;
}
/*
* 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_work_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, 0xb0e0, NULL);
if (rc)
goto out_unlock;
rc = chsc_sstpi(stp_page, &stp_info, sizeof(struct stp_sstpi));
if (rc || stp_info.c == 0)
goto out_unlock;
/* Skip synchronization if the clock is already in sync. */
if (check_sync_clock())
goto out_unlock;
memset(&stp_sync, 0, sizeof(stp_sync));
get_online_cpus();
atomic_set(&stp_sync.cpus, num_online_cpus() - 1);
stop_machine(stp_sync_clock, &stp_sync, cpu_online_mask);
put_online_cpus();
if (!check_sync_clock())
/*
* There is a usable clock but the synchonization failed.
* Retry after a second.
*/
mod_timer(&stp_timer, jiffies + HZ);
out_unlock:
mutex_unlock(&stp_work_mutex);
}
/*
* STP subsys sysfs interface functions
*/
static struct bus_type stp_subsys = {
.name = "stp",
.dev_name = "stp",
};
static ssize_t stp_ctn_id_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online)
return -ENODATA;
return sprintf(buf, "%016llx\n",
*(unsigned long long *) stp_info.ctnid);
}
static DEVICE_ATTR(ctn_id, 0400, stp_ctn_id_show, NULL);
static ssize_t stp_ctn_type_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online)
return -ENODATA;
return sprintf(buf, "%i\n", stp_info.ctn);
}
static DEVICE_ATTR(ctn_type, 0400, stp_ctn_type_show, NULL);
static ssize_t stp_dst_offset_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online || !(stp_info.vbits & 0x2000))
return -ENODATA;
return sprintf(buf, "%i\n", (int)(s16) stp_info.dsto);
}
static DEVICE_ATTR(dst_offset, 0400, stp_dst_offset_show, NULL);
static ssize_t stp_leap_seconds_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online || !(stp_info.vbits & 0x8000))
return -ENODATA;
return sprintf(buf, "%i\n", (int)(s16) stp_info.leaps);
}
static DEVICE_ATTR(leap_seconds, 0400, stp_leap_seconds_show, NULL);
static ssize_t stp_stratum_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online)
return -ENODATA;
return sprintf(buf, "%i\n", (int)(s16) stp_info.stratum);
}
static DEVICE_ATTR(stratum, 0400, stp_stratum_show, NULL);
static ssize_t stp_time_offset_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online || !(stp_info.vbits & 0x0800))
return -ENODATA;
return sprintf(buf, "%i\n", (int) stp_info.tto);
}
static DEVICE_ATTR(time_offset, 0400, stp_time_offset_show, NULL);
static ssize_t stp_time_zone_offset_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online || !(stp_info.vbits & 0x4000))
return -ENODATA;
return sprintf(buf, "%i\n", (int)(s16) stp_info.tzo);
}
static DEVICE_ATTR(time_zone_offset, 0400,
stp_time_zone_offset_show, NULL);
static ssize_t stp_timing_mode_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online)
return -ENODATA;
return sprintf(buf, "%i\n", stp_info.tmd);
}
static DEVICE_ATTR(timing_mode, 0400, stp_timing_mode_show, NULL);
static ssize_t stp_timing_state_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
if (!stp_online)
return -ENODATA;
return sprintf(buf, "%i\n", stp_info.tst);
}
static DEVICE_ATTR(timing_state, 0400, stp_timing_state_show, NULL);
static ssize_t stp_online_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return sprintf(buf, "%i\n", stp_online);
}
static ssize_t stp_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(&clock_sync_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(&clock_sync_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 struct device_attribute dev_attr_stp_online = {
.attr = { .name = "online", .mode = 0600 },
.show = stp_online_show,
.store = stp_online_store,
};
static struct device_attribute *stp_attributes[] = {
&dev_attr_ctn_id,
&dev_attr_ctn_type,
&dev_attr_dst_offset,
&dev_attr_leap_seconds,
&dev_attr_stp_online,
&dev_attr_stratum,
&dev_attr_time_offset,
&dev_attr_time_zone_offset,
&dev_attr_timing_mode,
&dev_attr_timing_state,
NULL
};
static int __init stp_init_sysfs(void)
{
struct device_attribute **attr;
int rc;
rc = subsys_system_register(&stp_subsys, NULL);
if (rc)
goto out;
for (attr = stp_attributes; *attr; attr++) {
rc = device_create_file(stp_subsys.dev_root, *attr);
if (rc)
goto out_unreg;
}
return 0;
out_unreg:
for (; attr >= stp_attributes; attr--)
device_remove_file(stp_subsys.dev_root, *attr);
bus_unregister(&stp_subsys);
out:
return rc;
}
device_initcall(stp_init_sysfs);