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linux-stable-rt/arch/s390/kernel/time.c

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/*
* arch/s390/kernel/time.c
* Time of day based timer functions.
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* 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
*/
#include <linux/config.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/time.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 <asm/uaccess.h>
#include <asm/delay.h>
#include <asm/s390_ext.h>
#include <asm/div64.h>
#include <asm/irq.h>
#include <asm/timer.h>
/* change this if you have some constant time drift */
#define USECS_PER_JIFFY ((unsigned long) 1000000/HZ)
#define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
/*
* Create a small time difference between the timer interrupts
* on the different cpus to avoid lock contention.
*/
#define CPU_DEVIATION (smp_processor_id() << 12)
#define TICK_SIZE tick
u64 jiffies_64 = INITIAL_JIFFIES;
EXPORT_SYMBOL(jiffies_64);
static ext_int_info_t ext_int_info_cc;
static u64 init_timer_cc;
static u64 jiffies_timer_cc;
static u64 xtime_cc;
extern unsigned long wall_jiffies;
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
return ((get_clock() - jiffies_timer_cc) * 1000) >> 12;
}
void tod_to_timeval(__u64 todval, struct timespec *xtime)
{
unsigned long long sec;
sec = todval >> 12;
do_div(sec, 1000000);
xtime->tv_sec = sec;
todval -= (sec * 1000000) << 12;
xtime->tv_nsec = ((todval * 1000) >> 12);
}
static inline unsigned long do_gettimeoffset(void)
{
__u64 now;
now = (get_clock() - jiffies_timer_cc) >> 12;
/* We require the offset from the latest update of xtime */
now -= (__u64) wall_jiffies*USECS_PER_JIFFY;
return (unsigned long) now;
}
/*
* This version of gettimeofday has microsecond resolution.
*/
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
unsigned long seq;
unsigned long usec, sec;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
sec = xtime.tv_sec;
usec = xtime.tv_nsec / 1000 + do_gettimeoffset();
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
while (usec >= 1000000) {
usec -= 1000000;
sec++;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);
int do_settimeofday(struct timespec *tv)
{
time_t wtm_sec, sec = tv->tv_sec;
long wtm_nsec, nsec = tv->tv_nsec;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irq(&xtime_lock);
/* This is revolting. We need to set the xtime.tv_nsec
* correctly. However, the value in this location is
* is value at the last tick.
* Discover what correction gettimeofday
* would have done, and then undo it!
*/
nsec -= do_gettimeoffset() * 1000;
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
set_normalized_timespec(&xtime, sec, nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
time_adjust = 0; /* stop active adjtime() */
time_status |= STA_UNSYNC;
time_maxerror = NTP_PHASE_LIMIT;
time_esterror = NTP_PHASE_LIMIT;
write_sequnlock_irq(&xtime_lock);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
#ifdef CONFIG_PROFILING
#define s390_do_profile(regs) profile_tick(CPU_PROFILING, regs)
#else
#define s390_do_profile(regs) do { ; } while(0)
#endif /* CONFIG_PROFILING */
/*
* timer_interrupt() needs to keep up the real-time clock,
* as well as call the "do_timer()" routine every clocktick
*/
void account_ticks(struct pt_regs *regs)
{
__u64 tmp;
__u32 ticks, xticks;
/* Calculate how many ticks have passed. */
if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) {
/*
* We have to program the clock comparator even if
* no tick has passed. That happens if e.g. an i/o
* interrupt wakes up an idle processor that has
* switched off its hz timer.
*/
tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (tmp));
return;
}
tmp = S390_lowcore.int_clock - S390_lowcore.jiffy_timer;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than two ticks ? */
ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1;
S390_lowcore.jiffy_timer +=
CLK_TICKS_PER_JIFFY * (__u64) ticks;
} else if (tmp >= CLK_TICKS_PER_JIFFY) {
ticks = 2;
S390_lowcore.jiffy_timer += 2*CLK_TICKS_PER_JIFFY;
} else {
ticks = 1;
S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
}
/* set clock comparator for next tick */
tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (tmp));
#ifdef CONFIG_SMP
/*
* Do not rely on the boot cpu to do the calls to do_timer.
* Spread it over all cpus instead.
*/
write_seqlock(&xtime_lock);
if (S390_lowcore.jiffy_timer > xtime_cc) {
tmp = S390_lowcore.jiffy_timer - xtime_cc;
if (tmp >= 2*CLK_TICKS_PER_JIFFY) {
xticks = __div(tmp, CLK_TICKS_PER_JIFFY);
xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY;
} else {
xticks = 1;
xtime_cc += CLK_TICKS_PER_JIFFY;
}
while (xticks--)
do_timer(regs);
}
write_sequnlock(&xtime_lock);
#else
for (xticks = ticks; xticks > 0; xticks--)
do_timer(regs);
#endif
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
account_user_vtime(current);
#else
while (ticks--)
update_process_times(user_mode(regs));
#endif
s390_do_profile(regs);
}
#ifdef CONFIG_NO_IDLE_HZ
#ifdef CONFIG_NO_IDLE_HZ_INIT
int sysctl_hz_timer = 0;
#else
int sysctl_hz_timer = 1;
#endif
/*
* Stop the HZ tick on the current CPU.
* Only cpu_idle may call this function.
*/
static inline void stop_hz_timer(void)
{
__u64 timer, todval;
if (sysctl_hz_timer != 0)
return;
cpu_set(smp_processor_id(), nohz_cpu_mask);
/*
* Leave the clock comparator set up for the next timer
* tick if either rcu or a softirq is pending.
*/
if (rcu_pending(smp_processor_id()) || local_softirq_pending()) {
cpu_clear(smp_processor_id(), nohz_cpu_mask);
return;
}
/*
* This cpu is going really idle. Set up the clock comparator
* for the next event.
*/
timer = (__u64) (next_timer_interrupt() - jiffies) + jiffies_64;
todval = -1ULL;
/* Be careful about overflows. */
if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
if (timer >= jiffies_timer_cc)
todval = timer;
}
asm volatile ("SCKC %0" : : "m" (todval));
}
/*
* Start the HZ tick on the current CPU.
* Only cpu_idle may call this function.
*/
static inline void start_hz_timer(void)
{
if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
return;
account_ticks(__KSTK_PTREGS(current));
cpu_clear(smp_processor_id(), nohz_cpu_mask);
}
static int nohz_idle_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
switch (action) {
case CPU_IDLE:
stop_hz_timer();
break;
case CPU_NOT_IDLE:
start_hz_timer();
break;
}
return NOTIFY_OK;
}
static struct notifier_block nohz_idle_nb = {
.notifier_call = nohz_idle_notify,
};
void __init nohz_init(void)
{
if (register_idle_notifier(&nohz_idle_nb))
panic("Couldn't register idle notifier");
}
#endif
/*
* Start the clock comparator on the current CPU.
*/
void init_cpu_timer(void)
{
unsigned long cr0;
__u64 timer;
timer = jiffies_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY;
S390_lowcore.jiffy_timer = timer + CLK_TICKS_PER_JIFFY;
timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
asm volatile ("SCKC %0" : : "m" (timer));
/* allow clock comparator timer interrupt */
__ctl_store(cr0, 0, 0);
cr0 |= 0x800;
__ctl_load(cr0, 0, 0);
}
extern void vtime_init(void);
/*
* Initialize the TOD clock and the CPU timer of
* the boot cpu.
*/
void __init time_init(void)
{
__u64 set_time_cc;
int cc;
/* kick the TOD clock */
asm volatile ("STCK 0(%1)\n\t"
"IPM %0\n\t"
"SRL %0,28" : "=r" (cc) : "a" (&init_timer_cc)
: "memory", "cc");
switch (cc) {
case 0: /* clock in set state: all is fine */
break;
case 1: /* clock in non-set state: FIXME */
printk("time_init: TOD clock in non-set state\n");
break;
case 2: /* clock in error state: FIXME */
printk("time_init: TOD clock in error state\n");
break;
case 3: /* clock in stopped or not-operational state: FIXME */
printk("time_init: TOD clock stopped/non-operational\n");
break;
}
jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY;
/* set xtime */
xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY;
set_time_cc = init_timer_cc - 0x8126d60e46000000LL +
(0x3c26700LL*1000000*4096);
tod_to_timeval(set_time_cc, &xtime);
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
/* request the clock comparator external interrupt */
if (register_early_external_interrupt(0x1004, 0,
&ext_int_info_cc) != 0)
panic("Couldn't request external interrupt 0x1004");
init_cpu_timer();
#ifdef CONFIG_NO_IDLE_HZ
nohz_init();
#endif
#ifdef CONFIG_VIRT_TIMER
vtime_init();
#endif
}
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