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

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/*
* Common time routines among all ppc machines.
*
* Written by Cort Dougan (cort@cs.nmt.edu) to merge
* Paul Mackerras' version and mine for PReP and Pmac.
* MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
* Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
*
* First round of bugfixes by Gabriel Paubert (paubert@iram.es)
* to make clock more stable (2.4.0-test5). The only thing
* that this code assumes is that the timebases have been synchronized
* by firmware on SMP and are never stopped (never do sleep
* on SMP then, nap and doze are OK).
*
* Speeded up do_gettimeofday by getting rid of references to
* xtime (which required locks for consistency). (mikejc@us.ibm.com)
*
* TODO (not necessarily in this file):
* - improve precision and reproducibility of timebase frequency
* measurement at boot time. (for iSeries, we calibrate the timebase
* against the Titan chip's clock.)
* - for astronomical applications: add a new function to get
* non ambiguous timestamps even around leap seconds. This needs
* a new timestamp format and a good name.
*
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#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/timex.h>
#include <linux/kernel_stat.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/cpu.h>
#include <linux/security.h>
#include <linux/percpu.h>
#include <linux/rtc.h>
#include <linux/jiffies.h>
#include <linux/posix-timers.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/nvram.h>
#include <asm/cache.h>
#include <asm/machdep.h>
#include <asm/uaccess.h>
#include <asm/time.h>
#include <asm/prom.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/smp.h>
#include <asm/vdso_datapage.h>
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#endif
#ifdef CONFIG_PPC_ISERIES
#include <asm/iseries/it_lp_queue.h>
#include <asm/iseries/hv_call_xm.h>
#endif
#include <asm/smp.h>
/* keep track of when we need to update the rtc */
time_t last_rtc_update;
#ifdef CONFIG_PPC_ISERIES
unsigned long iSeries_recal_titan = 0;
unsigned long iSeries_recal_tb = 0;
static unsigned long first_settimeofday = 1;
#endif
/* The decrementer counts down by 128 every 128ns on a 601. */
#define DECREMENTER_COUNT_601 (1000000000 / HZ)
#define XSEC_PER_SEC (1024*1024)
#ifdef CONFIG_PPC64
#define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
#else
/* compute ((xsec << 12) * max) >> 32 */
#define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
#endif
unsigned long tb_ticks_per_jiffy;
unsigned long tb_ticks_per_usec = 100; /* sane default */
EXPORT_SYMBOL(tb_ticks_per_usec);
unsigned long tb_ticks_per_sec;
EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
u64 tb_to_xs;
unsigned tb_to_us;
#define TICKLEN_SCALE (SHIFT_SCALE - 10)
u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
u64 ticklen_to_xs; /* 0.64 fraction */
/* If last_tick_len corresponds to about 1/HZ seconds, then
last_tick_len << TICKLEN_SHIFT will be about 2^63. */
#define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL_GPL(rtc_lock);
u64 tb_to_ns_scale;
unsigned tb_to_ns_shift;
struct gettimeofday_struct do_gtod;
extern unsigned long wall_jiffies;
extern struct timezone sys_tz;
static long timezone_offset;
unsigned long ppc_proc_freq;
unsigned long ppc_tb_freq;
u64 tb_last_jiffy __cacheline_aligned_in_smp;
unsigned long tb_last_stamp;
/*
* Note that on ppc32 this only stores the bottom 32 bits of
* the timebase value, but that's enough to tell when a jiffy
* has passed.
*/
DEFINE_PER_CPU(unsigned long, last_jiffy);
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
/*
* Factors for converting from cputime_t (timebase ticks) to
* jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
* These are all stored as 0.64 fixed-point binary fractions.
*/
u64 __cputime_jiffies_factor;
EXPORT_SYMBOL(__cputime_jiffies_factor);
u64 __cputime_msec_factor;
EXPORT_SYMBOL(__cputime_msec_factor);
u64 __cputime_sec_factor;
EXPORT_SYMBOL(__cputime_sec_factor);
u64 __cputime_clockt_factor;
EXPORT_SYMBOL(__cputime_clockt_factor);
static void calc_cputime_factors(void)
{
struct div_result res;
div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
__cputime_jiffies_factor = res.result_low;
div128_by_32(1000, 0, tb_ticks_per_sec, &res);
__cputime_msec_factor = res.result_low;
div128_by_32(1, 0, tb_ticks_per_sec, &res);
__cputime_sec_factor = res.result_low;
div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
__cputime_clockt_factor = res.result_low;
}
/*
* Read the PURR on systems that have it, otherwise the timebase.
*/
static u64 read_purr(void)
{
if (cpu_has_feature(CPU_FTR_PURR))
return mfspr(SPRN_PURR);
return mftb();
}
/*
* Account time for a transition between system, hard irq
* or soft irq state.
*/
void account_system_vtime(struct task_struct *tsk)
{
u64 now, delta;
unsigned long flags;
local_irq_save(flags);
now = read_purr();
delta = now - get_paca()->startpurr;
get_paca()->startpurr = now;
if (!in_interrupt()) {
delta += get_paca()->system_time;
get_paca()->system_time = 0;
}
account_system_time(tsk, 0, delta);
local_irq_restore(flags);
}
/*
* Transfer the user and system times accumulated in the paca
* by the exception entry and exit code to the generic process
* user and system time records.
* Must be called with interrupts disabled.
*/
void account_process_vtime(struct task_struct *tsk)
{
cputime_t utime;
utime = get_paca()->user_time;
get_paca()->user_time = 0;
account_user_time(tsk, utime);
}
static void account_process_time(struct pt_regs *regs)
{
int cpu = smp_processor_id();
account_process_vtime(current);
run_local_timers();
if (rcu_pending(cpu))
rcu_check_callbacks(cpu, user_mode(regs));
scheduler_tick();
run_posix_cpu_timers(current);
}
#ifdef CONFIG_PPC_SPLPAR
/*
* Stuff for accounting stolen time.
*/
struct cpu_purr_data {
int initialized; /* thread is running */
u64 tb0; /* timebase at origin time */
u64 purr0; /* PURR at origin time */
u64 tb; /* last TB value read */
u64 purr; /* last PURR value read */
u64 stolen; /* stolen time so far */
spinlock_t lock;
};
static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
static void snapshot_tb_and_purr(void *data)
{
struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
p->tb0 = mftb();
p->purr0 = mfspr(SPRN_PURR);
p->tb = p->tb0;
p->purr = 0;
wmb();
p->initialized = 1;
}
/*
* Called during boot when all cpus have come up.
*/
void snapshot_timebases(void)
{
int cpu;
if (!cpu_has_feature(CPU_FTR_PURR))
return;
for_each_possible_cpu(cpu)
spin_lock_init(&per_cpu(cpu_purr_data, cpu).lock);
on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1);
}
void calculate_steal_time(void)
{
u64 tb, purr, t0;
s64 stolen;
struct cpu_purr_data *p0, *pme, *phim;
int cpu;
if (!cpu_has_feature(CPU_FTR_PURR))
return;
cpu = smp_processor_id();
pme = &per_cpu(cpu_purr_data, cpu);
if (!pme->initialized)
return; /* this can happen in early boot */
p0 = &per_cpu(cpu_purr_data, cpu & ~1);
phim = &per_cpu(cpu_purr_data, cpu ^ 1);
spin_lock(&p0->lock);
tb = mftb();
purr = mfspr(SPRN_PURR) - pme->purr0;
if (!phim->initialized || !cpu_online(cpu ^ 1)) {
stolen = (tb - pme->tb) - (purr - pme->purr);
} else {
t0 = pme->tb0;
if (phim->tb0 < t0)
t0 = phim->tb0;
stolen = phim->tb - t0 - phim->purr - purr - p0->stolen;
}
if (stolen > 0) {
account_steal_time(current, stolen);
p0->stolen += stolen;
}
pme->tb = tb;
pme->purr = purr;
spin_unlock(&p0->lock);
}
/*
* Must be called before the cpu is added to the online map when
* a cpu is being brought up at runtime.
*/
static void snapshot_purr(void)
{
int cpu;
u64 purr;
struct cpu_purr_data *p0, *pme, *phim;
unsigned long flags;
if (!cpu_has_feature(CPU_FTR_PURR))
return;
cpu = smp_processor_id();
pme = &per_cpu(cpu_purr_data, cpu);
p0 = &per_cpu(cpu_purr_data, cpu & ~1);
phim = &per_cpu(cpu_purr_data, cpu ^ 1);
spin_lock_irqsave(&p0->lock, flags);
pme->tb = pme->tb0 = mftb();
purr = mfspr(SPRN_PURR);
if (!phim->initialized) {
pme->purr = 0;
pme->purr0 = purr;
} else {
/* set p->purr and p->purr0 for no change in p0->stolen */
pme->purr = phim->tb - phim->tb0 - phim->purr - p0->stolen;
pme->purr0 = purr - pme->purr;
}
pme->initialized = 1;
spin_unlock_irqrestore(&p0->lock, flags);
}
#endif /* CONFIG_PPC_SPLPAR */
#else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
#define calc_cputime_factors()
#define account_process_time(regs) update_process_times(user_mode(regs))
#define calculate_steal_time() do { } while (0)
#endif
#if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
#define snapshot_purr() do { } while (0)
#endif
/*
* Called when a cpu comes up after the system has finished booting,
* i.e. as a result of a hotplug cpu action.
*/
void snapshot_timebase(void)
{
__get_cpu_var(last_jiffy) = get_tb();
snapshot_purr();
}
void __delay(unsigned long loops)
{
unsigned long start;
int diff;
if (__USE_RTC()) {
start = get_rtcl();
do {
/* the RTCL register wraps at 1000000000 */
diff = get_rtcl() - start;
if (diff < 0)
diff += 1000000000;
} while (diff < loops);
} else {
start = get_tbl();
while (get_tbl() - start < loops)
HMT_low();
HMT_medium();
}
}
EXPORT_SYMBOL(__delay);
void udelay(unsigned long usecs)
{
__delay(tb_ticks_per_usec * usecs);
}
EXPORT_SYMBOL(udelay);
static __inline__ void timer_check_rtc(void)
{
/*
* update the rtc when needed, this should be performed on the
* right fraction of a second. Half or full second ?
* Full second works on mk48t59 clocks, others need testing.
* Note that this update is basically only used through
* the adjtimex system calls. Setting the HW clock in
* any other way is a /dev/rtc and userland business.
* This is still wrong by -0.5/+1.5 jiffies because of the
* timer interrupt resolution and possible delay, but here we
* hit a quantization limit which can only be solved by higher
* resolution timers and decoupling time management from timer
* interrupts. This is also wrong on the clocks
* which require being written at the half second boundary.
* We should have an rtc call that only sets the minutes and
* seconds like on Intel to avoid problems with non UTC clocks.
*/
if (ppc_md.set_rtc_time && ntp_synced() &&
xtime.tv_sec - last_rtc_update >= 659 &&
abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ) {
struct rtc_time tm;
to_tm(xtime.tv_sec + 1 + timezone_offset, &tm);
tm.tm_year -= 1900;
tm.tm_mon -= 1;
if (ppc_md.set_rtc_time(&tm) == 0)
last_rtc_update = xtime.tv_sec + 1;
else
/* Try again one minute later */
last_rtc_update += 60;
}
}
/*
* This version of gettimeofday has microsecond resolution.
*/
static inline void __do_gettimeofday(struct timeval *tv, u64 tb_val)
{
unsigned long sec, usec;
u64 tb_ticks, xsec;
struct gettimeofday_vars *temp_varp;
u64 temp_tb_to_xs, temp_stamp_xsec;
/*
* These calculations are faster (gets rid of divides)
* if done in units of 1/2^20 rather than microseconds.
* The conversion to microseconds at the end is done
* without a divide (and in fact, without a multiply)
*/
temp_varp = do_gtod.varp;
tb_ticks = tb_val - temp_varp->tb_orig_stamp;
temp_tb_to_xs = temp_varp->tb_to_xs;
temp_stamp_xsec = temp_varp->stamp_xsec;
xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
sec = xsec / XSEC_PER_SEC;
usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
usec = SCALE_XSEC(usec, 1000000);
tv->tv_sec = sec;
tv->tv_usec = usec;
}
void do_gettimeofday(struct timeval *tv)
{
if (__USE_RTC()) {
/* do this the old way */
unsigned long flags, seq;
unsigned int sec, nsec, usec;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
sec = xtime.tv_sec;
nsec = xtime.tv_nsec + tb_ticks_since(tb_last_stamp);
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
usec = nsec / 1000;
while (usec >= 1000000) {
usec -= 1000000;
++sec;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
return;
}
__do_gettimeofday(tv, get_tb());
}
EXPORT_SYMBOL(do_gettimeofday);
/*
* There are two copies of tb_to_xs and stamp_xsec so that no
* lock is needed to access and use these values in
* do_gettimeofday. We alternate the copies and as long as a
* reasonable time elapses between changes, there will never
* be inconsistent values. ntpd has a minimum of one minute
* between updates.
*/
static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
u64 new_tb_to_xs)
{
unsigned temp_idx;
struct gettimeofday_vars *temp_varp;
temp_idx = (do_gtod.var_idx == 0);
temp_varp = &do_gtod.vars[temp_idx];
temp_varp->tb_to_xs = new_tb_to_xs;
temp_varp->tb_orig_stamp = new_tb_stamp;
temp_varp->stamp_xsec = new_stamp_xsec;
smp_mb();
do_gtod.varp = temp_varp;
do_gtod.var_idx = temp_idx;
/*
* tb_update_count is used to allow the userspace gettimeofday code
* to assure itself that it sees a consistent view of the tb_to_xs and
* stamp_xsec variables. It reads the tb_update_count, then reads
* tb_to_xs and stamp_xsec and then reads tb_update_count again. If
* the two values of tb_update_count match and are even then the
* tb_to_xs and stamp_xsec values are consistent. If not, then it
* loops back and reads them again until this criteria is met.
* We expect the caller to have done the first increment of
* vdso_data->tb_update_count already.
*/
vdso_data->tb_orig_stamp = new_tb_stamp;
vdso_data->stamp_xsec = new_stamp_xsec;
vdso_data->tb_to_xs = new_tb_to_xs;
vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
smp_wmb();
++(vdso_data->tb_update_count);
}
/*
* When the timebase - tb_orig_stamp gets too big, we do a manipulation
* between tb_orig_stamp and stamp_xsec. The goal here is to keep the
* difference tb - tb_orig_stamp small enough to always fit inside a
* 32 bits number. This is a requirement of our fast 32 bits userland
* implementation in the vdso. If we "miss" a call to this function
* (interrupt latency, CPU locked in a spinlock, ...) and we end up
* with a too big difference, then the vdso will fallback to calling
* the syscall
*/
static __inline__ void timer_recalc_offset(u64 cur_tb)
{
unsigned long offset;
u64 new_stamp_xsec;
u64 tlen, t2x;
u64 tb, xsec_old, xsec_new;
struct gettimeofday_vars *varp;
if (__USE_RTC())
return;
tlen = current_tick_length();
offset = cur_tb - do_gtod.varp->tb_orig_stamp;
if (tlen == last_tick_len && offset < 0x80000000u)
return;
if (tlen != last_tick_len) {
t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs);
last_tick_len = tlen;
} else
t2x = do_gtod.varp->tb_to_xs;
new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
do_div(new_stamp_xsec, 1000000000);
new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
++vdso_data->tb_update_count;
smp_mb();
/*
* Make sure time doesn't go backwards for userspace gettimeofday.
*/
tb = get_tb();
varp = do_gtod.varp;
xsec_old = mulhdu(tb - varp->tb_orig_stamp, varp->tb_to_xs)
+ varp->stamp_xsec;
xsec_new = mulhdu(tb - cur_tb, t2x) + new_stamp_xsec;
if (xsec_new < xsec_old)
new_stamp_xsec += xsec_old - xsec_new;
update_gtod(cur_tb, new_stamp_xsec, t2x);
}
#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
unsigned long pc = instruction_pointer(regs);
if (in_lock_functions(pc))
return regs->link;
return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif
#ifdef CONFIG_PPC_ISERIES
/*
* This function recalibrates the timebase based on the 49-bit time-of-day
* value in the Titan chip. The Titan is much more accurate than the value
* returned by the service processor for the timebase frequency.
*/
static void iSeries_tb_recal(void)
{
struct div_result divres;
unsigned long titan, tb;
tb = get_tb();
titan = HvCallXm_loadTod();
if ( iSeries_recal_titan ) {
unsigned long tb_ticks = tb - iSeries_recal_tb;
unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
char sign = '+';
/* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
if ( tick_diff < 0 ) {
tick_diff = -tick_diff;
sign = '-';
}
if ( tick_diff ) {
if ( tick_diff < tb_ticks_per_jiffy/25 ) {
printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
new_tb_ticks_per_jiffy, sign, tick_diff );
tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
tb_ticks_per_sec = new_tb_ticks_per_sec;
calc_cputime_factors();
div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
tb_to_xs = divres.result_low;
do_gtod.varp->tb_to_xs = tb_to_xs;
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
vdso_data->tb_to_xs = tb_to_xs;
}
else {
printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
" new tb_ticks_per_jiffy = %lu\n"
" old tb_ticks_per_jiffy = %lu\n",
new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
}
}
}
iSeries_recal_titan = titan;
iSeries_recal_tb = tb;
}
#endif
/*
* For iSeries shared processors, we have to let the hypervisor
* set the hardware decrementer. We set a virtual decrementer
* in the lppaca and call the hypervisor if the virtual
* decrementer is less than the current value in the hardware
* decrementer. (almost always the new decrementer value will
* be greater than the current hardware decementer so the hypervisor
* call will not be needed)
*/
/*
* timer_interrupt - gets called when the decrementer overflows,
* with interrupts disabled.
*/
void timer_interrupt(struct pt_regs * regs)
{
int next_dec;
int cpu = smp_processor_id();
unsigned long ticks;
#ifdef CONFIG_PPC32
if (atomic_read(&ppc_n_lost_interrupts) != 0)
do_IRQ(regs);
#endif
irq_enter();
profile_tick(CPU_PROFILING, regs);
calculate_steal_time();
#ifdef CONFIG_PPC_ISERIES
get_lppaca()->int_dword.fields.decr_int = 0;
#endif
while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu)))
>= tb_ticks_per_jiffy) {
/* Update last_jiffy */
per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy;
/* Handle RTCL overflow on 601 */
if (__USE_RTC() && per_cpu(last_jiffy, cpu) >= 1000000000)
per_cpu(last_jiffy, cpu) -= 1000000000;
/*
* We cannot disable the decrementer, so in the period
* between this cpu's being marked offline in cpu_online_map
* and calling stop-self, it is taking timer interrupts.
* Avoid calling into the scheduler rebalancing code if this
* is the case.
*/
if (!cpu_is_offline(cpu))
account_process_time(regs);
/*
* No need to check whether cpu is offline here; boot_cpuid
* should have been fixed up by now.
*/
if (cpu != boot_cpuid)
continue;
write_seqlock(&xtime_lock);
tb_last_jiffy += tb_ticks_per_jiffy;
tb_last_stamp = per_cpu(last_jiffy, cpu);
do_timer(regs);
timer_recalc_offset(tb_last_jiffy);
timer_check_rtc();
write_sequnlock(&xtime_lock);
}
next_dec = tb_ticks_per_jiffy - ticks;
set_dec(next_dec);
#ifdef CONFIG_PPC_ISERIES
if (hvlpevent_is_pending())
process_hvlpevents(regs);
#endif
#ifdef CONFIG_PPC64
/* collect purr register values often, for accurate calculations */
if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
cu->current_tb = mfspr(SPRN_PURR);
}
#endif
irq_exit();
}
void wakeup_decrementer(void)
{
unsigned long ticks;
/*
* The timebase gets saved on sleep and restored on wakeup,
* so all we need to do is to reset the decrementer.
*/
ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
if (ticks < tb_ticks_per_jiffy)
ticks = tb_ticks_per_jiffy - ticks;
else
ticks = 1;
set_dec(ticks);
}
#ifdef CONFIG_SMP
void __init smp_space_timers(unsigned int max_cpus)
{
int i;
unsigned long half = tb_ticks_per_jiffy / 2;
unsigned long offset = tb_ticks_per_jiffy / max_cpus;
unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid);
/* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
previous_tb -= tb_ticks_per_jiffy;
/*
* The stolen time calculation for POWER5 shared-processor LPAR
* systems works better if the two threads' timebase interrupts
* are staggered by half a jiffy with respect to each other.
*/
for_each_possible_cpu(i) {
if (i == boot_cpuid)
continue;
if (i == (boot_cpuid ^ 1))
per_cpu(last_jiffy, i) =
per_cpu(last_jiffy, boot_cpuid) - half;
else if (i & 1)
per_cpu(last_jiffy, i) =
per_cpu(last_jiffy, i ^ 1) + half;
else {
previous_tb += offset;
per_cpu(last_jiffy, i) = previous_tb;
}
}
}
#endif
/*
* Scheduler clock - returns current time in nanosec units.
*
* Note: mulhdu(a, b) (multiply high double unsigned) returns
* the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
* are 64-bit unsigned numbers.
*/
unsigned long long sched_clock(void)
{
if (__USE_RTC())
return get_rtc();
return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
}
int do_settimeofday(struct timespec *tv)
{
time_t wtm_sec, new_sec = tv->tv_sec;
long wtm_nsec, new_nsec = tv->tv_nsec;
unsigned long flags;
u64 new_xsec;
unsigned long tb_delta;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irqsave(&xtime_lock, flags);
/*
* Updating the RTC is not the job of this code. If the time is
* stepped under NTP, the RTC will be updated after STA_UNSYNC
* is cleared. Tools like clock/hwclock either copy the RTC
* to the system time, in which case there is no point in writing
* to the RTC again, or write to the RTC but then they don't call
* settimeofday to perform this operation.
*/
#ifdef CONFIG_PPC_ISERIES
if (first_settimeofday) {
iSeries_tb_recal();
first_settimeofday = 0;
}
#endif
/* Make userspace gettimeofday spin until we're done. */
++vdso_data->tb_update_count;
smp_mb();
/*
* Subtract off the number of nanoseconds since the
* beginning of the last tick.
* Note that since we don't increment jiffies_64 anywhere other
* than in do_timer (since we don't have a lost tick problem),
* wall_jiffies will always be the same as jiffies,
* and therefore the (jiffies - wall_jiffies) computation
* has been removed.
*/
tb_delta = tb_ticks_since(tb_last_stamp);
tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
set_normalized_timespec(&xtime, new_sec, new_nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
/* In case of a large backwards jump in time with NTP, we want the
* clock to be updated as soon as the PLL is again in lock.
*/
last_rtc_update = new_sec - 658;
ntp_clear();
new_xsec = xtime.tv_nsec;
if (new_xsec != 0) {
new_xsec *= XSEC_PER_SEC;
do_div(new_xsec, NSEC_PER_SEC);
}
new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC;
update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
vdso_data->tz_dsttime = sys_tz.tz_dsttime;
write_sequnlock_irqrestore(&xtime_lock, flags);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
void __init generic_calibrate_decr(void)
{
struct device_node *cpu;
unsigned int *fp;
int node_found;
/*
* The cpu node should have a timebase-frequency property
* to tell us the rate at which the decrementer counts.
*/
cpu = of_find_node_by_type(NULL, "cpu");
ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
node_found = 0;
if (cpu) {
fp = (unsigned int *)get_property(cpu, "timebase-frequency",
NULL);
if (fp) {
node_found = 1;
ppc_tb_freq = *fp;
}
}
if (!node_found)
printk(KERN_ERR "WARNING: Estimating decrementer frequency "
"(not found)\n");
ppc_proc_freq = DEFAULT_PROC_FREQ;
node_found = 0;
if (cpu) {
fp = (unsigned int *)get_property(cpu, "clock-frequency",
NULL);
if (fp) {
node_found = 1;
ppc_proc_freq = *fp;
}
}
#ifdef CONFIG_BOOKE
/* Set the time base to zero */
mtspr(SPRN_TBWL, 0);
mtspr(SPRN_TBWU, 0);
/* Clear any pending timer interrupts */
mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
/* Enable decrementer interrupt */
mtspr(SPRN_TCR, TCR_DIE);
#endif
if (!node_found)
printk(KERN_ERR "WARNING: Estimating processor frequency "
"(not found)\n");
of_node_put(cpu);
}
unsigned long get_boot_time(void)
{
struct rtc_time tm;
if (ppc_md.get_boot_time)
return ppc_md.get_boot_time();
if (!ppc_md.get_rtc_time)
return 0;
ppc_md.get_rtc_time(&tm);
return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec);
}
/* This function is only called on the boot processor */
void __init time_init(void)
{
unsigned long flags;
unsigned long tm = 0;
struct div_result res;
u64 scale, x;
unsigned shift;
if (ppc_md.time_init != NULL)
timezone_offset = ppc_md.time_init();
if (__USE_RTC()) {
/* 601 processor: dec counts down by 128 every 128ns */
ppc_tb_freq = 1000000000;
tb_last_stamp = get_rtcl();
tb_last_jiffy = tb_last_stamp;
} else {
/* Normal PowerPC with timebase register */
ppc_md.calibrate_decr();
printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
tb_last_stamp = tb_last_jiffy = get_tb();
}
tb_ticks_per_jiffy = ppc_tb_freq / HZ;
tb_ticks_per_sec = ppc_tb_freq;
tb_ticks_per_usec = ppc_tb_freq / 1000000;
tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
calc_cputime_factors();
/*
* Calculate the length of each tick in ns. It will not be
* exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
* We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
* rounded up.
*/
x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
do_div(x, ppc_tb_freq);
tick_nsec = x;
last_tick_len = x << TICKLEN_SCALE;
/*
* Compute ticklen_to_xs, which is a factor which gets multiplied
* by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
* It is computed as:
* ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
* where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
* which turns out to be N = 51 - SHIFT_HZ.
* This gives the result as a 0.64 fixed-point fraction.
* That value is reduced by an offset amounting to 1 xsec per
* 2^31 timebase ticks to avoid problems with time going backwards
* by 1 xsec when we do timer_recalc_offset due to losing the
* fractional xsec. That offset is equal to ppc_tb_freq/2^51
* since there are 2^20 xsec in a second.
*/
div128_by_32((1ULL << 51) - ppc_tb_freq, 0,
tb_ticks_per_jiffy << SHIFT_HZ, &res);
div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
ticklen_to_xs = res.result_low;
/* Compute tb_to_xs from tick_nsec */
tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
/*
* Compute scale factor for sched_clock.
* The calibrate_decr() function has set tb_ticks_per_sec,
* which is the timebase frequency.
* We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
* the 128-bit result as a 64.64 fixed-point number.
* We then shift that number right until it is less than 1.0,
* giving us the scale factor and shift count to use in
* sched_clock().
*/
div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
scale = res.result_low;
for (shift = 0; res.result_high != 0; ++shift) {
scale = (scale >> 1) | (res.result_high << 63);
res.result_high >>= 1;
}
tb_to_ns_scale = scale;
tb_to_ns_shift = shift;
tm = get_boot_time();
write_seqlock_irqsave(&xtime_lock, flags);
/* If platform provided a timezone (pmac), we correct the time */
if (timezone_offset) {
sys_tz.tz_minuteswest = -timezone_offset / 60;
sys_tz.tz_dsttime = 0;
tm -= timezone_offset;
}
xtime.tv_sec = tm;
xtime.tv_nsec = 0;
do_gtod.varp = &do_gtod.vars[0];
do_gtod.var_idx = 0;
do_gtod.varp->tb_orig_stamp = tb_last_jiffy;
__get_cpu_var(last_jiffy) = tb_last_stamp;
do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
do_gtod.varp->tb_to_xs = tb_to_xs;
do_gtod.tb_to_us = tb_to_us;
vdso_data->tb_orig_stamp = tb_last_jiffy;
vdso_data->tb_update_count = 0;
vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
vdso_data->tb_to_xs = tb_to_xs;
time_freq = 0;
last_rtc_update = xtime.tv_sec;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
write_sequnlock_irqrestore(&xtime_lock, flags);
/* Not exact, but the timer interrupt takes care of this */
set_dec(tb_ticks_per_jiffy);
}
#define FEBRUARY 2
#define STARTOFTIME 1970
#define SECDAY 86400L
#define SECYR (SECDAY * 365)
#define leapyear(year) ((year) % 4 == 0 && \
((year) % 100 != 0 || (year) % 400 == 0))
#define days_in_year(a) (leapyear(a) ? 366 : 365)
#define days_in_month(a) (month_days[(a) - 1])
static int month_days[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
/*
* This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
*/
void GregorianDay(struct rtc_time * tm)
{
int leapsToDate;
int lastYear;
int day;
int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
lastYear = tm->tm_year - 1;
/*
* Number of leap corrections to apply up to end of last year
*/
leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
/*
* This year is a leap year if it is divisible by 4 except when it is
* divisible by 100 unless it is divisible by 400
*
* e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
*/
day = tm->tm_mon > 2 && leapyear(tm->tm_year);
day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
tm->tm_mday;
tm->tm_wday = day % 7;
}
void to_tm(int tim, struct rtc_time * tm)
{
register int i;
register long hms, day;
day = tim / SECDAY;
hms = tim % SECDAY;
/* Hours, minutes, seconds are easy */
tm->tm_hour = hms / 3600;
tm->tm_min = (hms % 3600) / 60;
tm->tm_sec = (hms % 3600) % 60;
/* Number of years in days */
for (i = STARTOFTIME; day >= days_in_year(i); i++)
day -= days_in_year(i);
tm->tm_year = i;
/* Number of months in days left */
if (leapyear(tm->tm_year))
days_in_month(FEBRUARY) = 29;
for (i = 1; day >= days_in_month(i); i++)
day -= days_in_month(i);
days_in_month(FEBRUARY) = 28;
tm->tm_mon = i;
/* Days are what is left over (+1) from all that. */
tm->tm_mday = day + 1;
/*
* Determine the day of week
*/
GregorianDay(tm);
}
/* Auxiliary function to compute scaling factors */
/* Actually the choice of a timebase running at 1/4 the of the bus
* frequency giving resolution of a few tens of nanoseconds is quite nice.
* It makes this computation very precise (27-28 bits typically) which
* is optimistic considering the stability of most processor clock
* oscillators and the precision with which the timebase frequency
* is measured but does not harm.
*/
unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
{
unsigned mlt=0, tmp, err;
/* No concern for performance, it's done once: use a stupid
* but safe and compact method to find the multiplier.
*/
for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
if (mulhwu(inscale, mlt|tmp) < outscale)
mlt |= tmp;
}
/* We might still be off by 1 for the best approximation.
* A side effect of this is that if outscale is too large
* the returned value will be zero.
* Many corner cases have been checked and seem to work,
* some might have been forgotten in the test however.
*/
err = inscale * (mlt+1);
if (err <= inscale/2)
mlt++;
return mlt;
}
/*
* Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
* result.
*/
void div128_by_32(u64 dividend_high, u64 dividend_low,
unsigned divisor, struct div_result *dr)
{
unsigned long a, b, c, d;
unsigned long w, x, y, z;
u64 ra, rb, rc;
a = dividend_high >> 32;
b = dividend_high & 0xffffffff;
c = dividend_low >> 32;
d = dividend_low & 0xffffffff;
w = a / divisor;
ra = ((u64)(a - (w * divisor)) << 32) + b;
rb = ((u64) do_div(ra, divisor) << 32) + c;
x = ra;
rc = ((u64) do_div(rb, divisor) << 32) + d;
y = rb;
do_div(rc, divisor);
z = rc;
dr->result_high = ((u64)w << 32) + x;
dr->result_low = ((u64)y << 32) + z;
}
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