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linux/arch/powerpc/kernel/time.c
Paul Mackerras 5f6b5b973a powerpc: Fix time setting bug on 32-bit 
This fixes a bug where settimeofday would set the wrong parameters
in do_gtod, resulting in gettimeofday returning a value about 4
hours after the correct time.  The bug was that we divided a
negative 64-bit value with do_div, which treated it as unsigned
and gave us a result that was approximately 1.8e10 too large
(since the divisor was 1e9).

Signed-off-by: Paul Mackerras <paulus@samba.org>
2005-10-30 22:55:52 +11:00

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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 <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>
#ifdef CONFIG_PPC64
#include <asm/systemcfg.h>
#include <asm/firmware.h>
#endif
#ifdef CONFIG_PPC_ISERIES
#include <asm/iSeries/ItLpQueue.h>
#include <asm/iSeries/HvCallXm.h>
#endif
u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
EXPORT_SYMBOL(jiffies_64);
/* keep track of when we need to update the rtc */
time_t last_rtc_update;
extern int piranha_simulator;
#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;
u64 tb_to_xs;
unsigned tb_to_us;
unsigned long processor_freq;
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;
void ppc_adjtimex(void);
static unsigned adjusting_time = 0;
unsigned long ppc_proc_freq;
unsigned long ppc_tb_freq;
#ifdef CONFIG_PPC32 /* XXX for now */
#define boot_cpuid 0
#endif
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);
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 &&
jiffies - wall_jiffies == 1) {
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, lost;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
sec = xtime.tv_sec;
nsec = xtime.tv_nsec + tb_ticks_since(tb_last_stamp);
lost = jiffies - wall_jiffies;
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
usec = nsec / 1000 + lost * (1000000 / HZ);
while (usec >= 1000000) {
usec -= 1000000;
++sec;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
return;
}
__do_gettimeofday(tv, get_tb());
}
EXPORT_SYMBOL(do_gettimeofday);
/* Synchronize xtime with do_gettimeofday */
static inline void timer_sync_xtime(unsigned long cur_tb)
{
#ifdef CONFIG_PPC64
/* why do we do this? */
struct timeval my_tv;
__do_gettimeofday(&my_tv, cur_tb);
if (xtime.tv_sec <= my_tv.tv_sec) {
xtime.tv_sec = my_tv.tv_sec;
xtime.tv_nsec = my_tv.tv_usec * 1000;
}
#endif
}
/*
* 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;
#ifdef CONFIG_PPC64
/*
* 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.
*/
++(systemcfg->tb_update_count);
smp_wmb();
systemcfg->tb_orig_stamp = new_tb_stamp;
systemcfg->stamp_xsec = new_stamp_xsec;
systemcfg->tb_to_xs = new_tb_to_xs;
smp_wmb();
++(systemcfg->tb_update_count);
#endif
}
/*
* 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;
if (__USE_RTC())
return;
offset = cur_tb - do_gtod.varp->tb_orig_stamp;
if ((offset & 0x80000000u) == 0)
return;
new_stamp_xsec = do_gtod.varp->stamp_xsec
+ mulhdu(offset, do_gtod.varp->tb_to_xs);
update_gtod(cur_tb, new_stamp_xsec, do_gtod.varp->tb_to_xs);
}
#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;
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;
systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
systemcfg->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);
#ifdef CONFIG_PPC_ISERIES
get_paca()->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))
update_process_times(user_mode(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);
timer_recalc_offset(tb_last_jiffy);
do_timer(regs);
timer_sync_xtime(tb_last_jiffy);
timer_check_rtc();
write_sequnlock(&xtime_lock);
if (adjusting_time && (time_adjust == 0))
ppc_adjtimex();
}
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)
{
int i;
set_dec(tb_ticks_per_jiffy);
/*
* We don't expect this to be called on a machine with a 601,
* so using get_tbl is fine.
*/
tb_last_stamp = tb_last_jiffy = get_tb();
for_each_cpu(i)
per_cpu(last_jiffy, i) = tb_last_stamp;
}
#ifdef CONFIG_SMP
void __init smp_space_timers(unsigned int max_cpus)
{
int i;
unsigned long offset = tb_ticks_per_jiffy / max_cpus;
unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid);
for_each_cpu(i) {
if (i != boot_cpuid) {
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;
long int tb_delta;
u64 new_xsec, tb_delta_xs;
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
tb_delta = tb_ticks_since(tb_last_stamp);
tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;
tb_delta_xs = mulhdu(tb_delta, do_gtod.varp->tb_to_xs);
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 = 0;
if (new_nsec != 0) {
new_xsec = (u64)new_nsec * XSEC_PER_SEC;
do_div(new_xsec, NSEC_PER_SEC);
}
new_xsec += (u64)new_sec * XSEC_PER_SEC - tb_delta_xs;
update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
#ifdef CONFIG_PPC64
systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
systemcfg->tz_dsttime = sys_tz.tz_dsttime;
#endif
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 != 0) {
fp = (unsigned int *)get_property(cpu, "timebase-frequency",
NULL);
if (fp != 0) {
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 != 0) {
fp = (unsigned int *)get_property(cpu, "clock-frequency",
NULL);
if (fp != 0) {
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;
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_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
printk(KERN_INFO "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 = tb_ticks_per_jiffy * HZ;
tb_ticks_per_usec = ppc_tb_freq / 1000000;
tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
div128_by_32(1024*1024, 0, tb_ticks_per_sec, &res);
tb_to_xs = res.result_low;
#ifdef CONFIG_PPC64
get_paca()->default_decr = tb_ticks_per_jiffy;
#endif
/*
* 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;
#ifdef CONFIG_PPC_ISERIES
if (!piranha_simulator)
#endif
tm = get_boot_time();
write_seqlock_irqsave(&xtime_lock, flags);
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;
#ifdef CONFIG_PPC64
systemcfg->tb_orig_stamp = tb_last_jiffy;
systemcfg->tb_update_count = 0;
systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
systemcfg->tb_to_xs = tb_to_xs;
#endif
time_freq = 0;
/* 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;
xtime.tv_sec -= timezone_offset;
}
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);
}
/*
* After adjtimex is called, adjust the conversion of tb ticks
* to microseconds to keep do_gettimeofday synchronized
* with ntpd.
*
* Use the time_adjust, time_freq and time_offset computed by adjtimex to
* adjust the frequency.
*/
/* #define DEBUG_PPC_ADJTIMEX 1 */
void ppc_adjtimex(void)
{
#ifdef CONFIG_PPC64
unsigned long den, new_tb_ticks_per_sec, tb_ticks, old_xsec,
new_tb_to_xs, new_xsec, new_stamp_xsec;
unsigned long tb_ticks_per_sec_delta;
long delta_freq, ltemp;
struct div_result divres;
unsigned long flags;
long singleshot_ppm = 0;
/*
* Compute parts per million frequency adjustment to
* accomplish the time adjustment implied by time_offset to be
* applied over the elapsed time indicated by time_constant.
* Use SHIFT_USEC to get it into the same units as
* time_freq.
*/
if ( time_offset < 0 ) {
ltemp = -time_offset;
ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
ltemp >>= SHIFT_KG + time_constant;
ltemp = -ltemp;
} else {
ltemp = time_offset;
ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
ltemp >>= SHIFT_KG + time_constant;
}
/* If there is a single shot time adjustment in progress */
if ( time_adjust ) {
#ifdef DEBUG_PPC_ADJTIMEX
printk("ppc_adjtimex: ");
if ( adjusting_time == 0 )
printk("starting ");
printk("single shot time_adjust = %ld\n", time_adjust);
#endif
adjusting_time = 1;
/*
* Compute parts per million frequency adjustment
* to match time_adjust
*/
singleshot_ppm = tickadj * HZ;
/*
* The adjustment should be tickadj*HZ to match the code in
* linux/kernel/timer.c, but experiments show that this is too
* large. 3/4 of tickadj*HZ seems about right
*/
singleshot_ppm -= singleshot_ppm / 4;
/* Use SHIFT_USEC to get it into the same units as time_freq */
singleshot_ppm <<= SHIFT_USEC;
if ( time_adjust < 0 )
singleshot_ppm = -singleshot_ppm;
}
else {
#ifdef DEBUG_PPC_ADJTIMEX
if ( adjusting_time )
printk("ppc_adjtimex: ending single shot time_adjust\n");
#endif
adjusting_time = 0;
}
/* Add up all of the frequency adjustments */
delta_freq = time_freq + ltemp + singleshot_ppm;
/*
* Compute a new value for tb_ticks_per_sec based on
* the frequency adjustment
*/
den = 1000000 * (1 << (SHIFT_USEC - 8));
if ( delta_freq < 0 ) {
tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( (-delta_freq) >> (SHIFT_USEC - 8))) / den;
new_tb_ticks_per_sec = tb_ticks_per_sec + tb_ticks_per_sec_delta;
}
else {
tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( delta_freq >> (SHIFT_USEC - 8))) / den;
new_tb_ticks_per_sec = tb_ticks_per_sec - tb_ticks_per_sec_delta;
}
#ifdef DEBUG_PPC_ADJTIMEX
printk("ppc_adjtimex: ltemp = %ld, time_freq = %ld, singleshot_ppm = %ld\n", ltemp, time_freq, singleshot_ppm);
printk("ppc_adjtimex: tb_ticks_per_sec - base = %ld new = %ld\n", tb_ticks_per_sec, new_tb_ticks_per_sec);
#endif
/*
* Compute a new value of tb_to_xs (used to convert tb to
* microseconds) and a new value of stamp_xsec which is the
* time (in 1/2^20 second units) corresponding to
* tb_orig_stamp. This new value of stamp_xsec compensates
* for the change in frequency (implied by the new tb_to_xs)
* which guarantees that the current time remains the same.
*/
write_seqlock_irqsave( &xtime_lock, flags );
tb_ticks = get_tb() - do_gtod.varp->tb_orig_stamp;
div128_by_32(1024*1024, 0, new_tb_ticks_per_sec, &divres);
new_tb_to_xs = divres.result_low;
new_xsec = mulhdu(tb_ticks, new_tb_to_xs);
old_xsec = mulhdu(tb_ticks, do_gtod.varp->tb_to_xs);
new_stamp_xsec = do_gtod.varp->stamp_xsec + old_xsec - new_xsec;
update_gtod(do_gtod.varp->tb_orig_stamp, new_stamp_xsec, new_tb_to_xs);
write_sequnlock_irqrestore( &xtime_lock, flags );
#endif /* CONFIG_PPC64 */
}
#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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