/*
*
* 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/mc146818rtc.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/cpu.h>
#include <linux/security.h>
#include <asm/segment.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/nvram.h>
#include <asm/cache.h>
#include <asm/machdep.h>
#ifdef CONFIG_PPC_ISERIES
#include <asm/iSeries/ItLpQueue.h>
#include <asm/iSeries/HvCallXm.h>
#endif
#include <asm/uaccess.h>
#include <asm/time.h>
#include <asm/ppcdebug.h>
#include <asm/prom.h>
#include <asm/sections.h>
#include <asm/systemcfg.h>
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
#define XSEC_PER_SEC (1024*1024)
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;
unsigned long tb_to_xs;
unsigned tb_to_us;
unsigned long processor_freq;
DEFINE_SPINLOCK(rtc_lock);
unsigned long tb_to_ns_scale;
unsigned long tb_to_ns_shift;
struct gettimeofday_struct do_gtod;
extern unsigned long wall_jiffies;
extern unsigned long lpevent_count;
extern int smp_tb_synchronized;
extern struct timezone sys_tz;
void ppc_adjtimex(void);
static unsigned adjusting_time = 0;
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 ( (time_status & STA_UNSYNC) == 0 &&
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, &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, unsigned long tb_val)
{
unsigned long sec, usec, tb_ticks;
unsigned long xsec, tb_xsec;
struct gettimeofday_vars * temp_varp;
unsigned long 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;
tb_xsec = mulhdu( tb_ticks, temp_tb_to_xs );
xsec = temp_stamp_xsec + tb_xsec;
sec = xsec / XSEC_PER_SEC;
xsec -= sec * XSEC_PER_SEC;
usec = (xsec * USEC_PER_SEC)/XSEC_PER_SEC;
tv->tv_sec = sec;
tv->tv_usec = usec;
}
void do_gettimeofday(struct timeval *tv)
{
__do_gettimeofday(tv, get_tb());
}
EXPORT_SYMBOL(do_gettimeofday);
/* Synchronize xtime with do_gettimeofday */
static inline void timer_sync_xtime(unsigned long cur_tb)
{
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;
}
}
/*
* 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(unsigned long cur_tb)
{
struct gettimeofday_vars * temp_varp;
unsigned temp_idx;
unsigned long offset, new_stamp_xsec, new_tb_orig_stamp;
if (((cur_tb - do_gtod.varp->tb_orig_stamp) & 0x80000000u) == 0)
return;
temp_idx = (do_gtod.var_idx == 0);
temp_varp = &do_gtod.vars[temp_idx];
new_tb_orig_stamp = cur_tb;
offset = new_tb_orig_stamp - do_gtod.varp->tb_orig_stamp;
new_stamp_xsec = do_gtod.varp->stamp_xsec + mulhdu(offset, do_gtod.varp->tb_to_xs);
temp_varp->tb_to_xs = do_gtod.varp->tb_to_xs;
temp_varp->tb_orig_stamp = new_tb_orig_stamp;
temp_varp->stamp_xsec = new_stamp_xsec;
mb();
do_gtod.varp = temp_varp;
do_gtod.var_idx = temp_idx;
++(systemcfg->tb_update_count);
wmb();
systemcfg->tb_orig_stamp = new_tb_orig_stamp;
systemcfg->stamp_xsec = new_stamp_xsec;
wmb();
++(systemcfg->tb_update_count);
}
#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)
*/
unsigned long tb_last_stamp __cacheline_aligned_in_smp;
/*
* timer_interrupt - gets called when the decrementer overflows,
* with interrupts disabled.
*/
int timer_interrupt(struct pt_regs * regs)
{
int next_dec;
unsigned long cur_tb;
struct paca_struct *lpaca = get_paca();
unsigned long cpu = smp_processor_id();
irq_enter();
#ifndef CONFIG_PPC_ISERIES
profile_tick(CPU_PROFILING, regs);
#endif
lpaca->lppaca.int_dword.fields.decr_int = 0;
while (lpaca->next_jiffy_update_tb <= (cur_tb = get_tb())) {
/*
* 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) {
write_seqlock(&xtime_lock);
tb_last_stamp = lpaca->next_jiffy_update_tb;
timer_recalc_offset(lpaca->next_jiffy_update_tb);
do_timer(regs);
timer_sync_xtime(lpaca->next_jiffy_update_tb);
timer_check_rtc();
write_sequnlock(&xtime_lock);
if ( adjusting_time && (time_adjust == 0) )
ppc_adjtimex();
}
lpaca->next_jiffy_update_tb += tb_ticks_per_jiffy;
}
next_dec = lpaca->next_jiffy_update_tb - cur_tb;
if (next_dec > lpaca->default_decr)
next_dec = lpaca->default_decr;
set_dec(next_dec);
#ifdef CONFIG_PPC_ISERIES
{
struct ItLpQueue *lpq = lpaca->lpqueue_ptr;
if (lpq && ItLpQueue_isLpIntPending(lpq))
lpevent_count += ItLpQueue_process(lpq, regs);
}
#endif
/* collect purr register values often, for accurate calculations */
#if defined(CONFIG_PPC_PSERIES)
if (cur_cpu_spec->firmware_features & FW_FEATURE_SPLPAR) {
struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
cu->current_tb = mfspr(SPRN_PURR);
}
#endif
irq_exit();
return 1;
}
/*
* 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)
{
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;
unsigned long delta_xsec;
long int tb_delta;
unsigned long new_xsec;
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 update after STA_UNSYNC
* is cleared. Tool 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;
new_nsec -= tb_delta / tb_ticks_per_usec / 1000;
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;
time_adjust = 0; /* stop active adjtime() */
time_status |= STA_UNSYNC;
time_maxerror = NTP_PHASE_LIMIT;
time_esterror = NTP_PHASE_LIMIT;
delta_xsec = mulhdu( (tb_last_stamp-do_gtod.varp->tb_orig_stamp),
do_gtod.varp->tb_to_xs );
new_xsec = (new_nsec * XSEC_PER_SEC) / NSEC_PER_SEC;
new_xsec += new_sec * XSEC_PER_SEC;
if ( new_xsec > delta_xsec ) {
do_gtod.varp->stamp_xsec = new_xsec - delta_xsec;
systemcfg->stamp_xsec = new_xsec - delta_xsec;
}
else {
/* This is only for the case where the user is setting the time
* way back to a time such that the boot time would have been
* before 1970 ... eg. we booted ten days ago, and we are setting
* the time to Jan 5, 1970 */
do_gtod.varp->stamp_xsec = new_xsec;
do_gtod.varp->tb_orig_stamp = tb_last_stamp;
systemcfg->stamp_xsec = new_xsec;
systemcfg->tb_orig_stamp = tb_last_stamp;
}
systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
systemcfg->tz_dsttime = sys_tz.tz_dsttime;
write_sequnlock_irqrestore(&xtime_lock, flags);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
void __init time_init(void)
{
/* This function is only called on the boot processor */
unsigned long flags;
struct rtc_time tm;
struct div_result res;
unsigned long scale, shift;
ppc_md.calibrate_decr();
/*
* 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
ppc_md.get_boot_time(&tm);
write_seqlock_irqsave(&xtime_lock, flags);
xtime.tv_sec = mktime(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
tm.tm_hour, tm.tm_min, tm.tm_sec);
tb_last_stamp = get_tb();
do_gtod.varp = &do_gtod.vars[0];
do_gtod.var_idx = 0;
do_gtod.varp->tb_orig_stamp = tb_last_stamp;
do_gtod.varp->stamp_xsec = 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;
systemcfg->tb_orig_stamp = tb_last_stamp;
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;
time_freq = 0;
xtime.tv_nsec = 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);
}
/*
* 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)
{
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;
struct gettimeofday_vars * temp_varp;
unsigned temp_idx;
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;
/* 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 */
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->stamp_xsec = new_stamp_xsec;
temp_varp->tb_orig_stamp = do_gtod.varp->tb_orig_stamp;
mb();
do_gtod.varp = temp_varp;
do_gtod.var_idx = temp_idx;
/*
* tb_update_count is used to allow the problem state 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);
wmb();
systemcfg->tb_to_xs = new_tb_to_xs;
systemcfg->stamp_xsec = new_stamp_xsec;
wmb();
++(systemcfg->tb_update_count);
write_sequnlock_irqrestore( &xtime_lock, flags );
}
#define TICK_SIZE tick
#define FEBRUARY 2
#define STARTOFTIME 1970
#define SECDAY 86400L
#define SECYR (SECDAY * 365)
#define leapyear(year) ((year) % 4 == 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 will be
*/
if((tm->tm_year%4==0) &&
((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
(tm->tm_mon>2))
{
/*
* We are past Feb. 29 in a leap year
*/
day=1;
}
else
{
day=0;
}
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( unsigned long dividend_high, unsigned long dividend_low,
unsigned divisor, struct div_result *dr )
{
unsigned long a,b,c,d, w,x,y,z, ra,rb,rc;
a = dividend_high >> 32;
b = dividend_high & 0xffffffff;
c = dividend_low >> 32;
d = dividend_low & 0xffffffff;
w = a/divisor;
ra = (a - (w * divisor)) << 32;
x = (ra + b)/divisor;
rb = ((ra + b) - (x * divisor)) << 32;
y = (rb + c)/divisor;
rc = ((rb + b) - (y * divisor)) << 32;
z = (rc + d)/divisor;
dr->result_high = (w << 32) + x;
dr->result_low = (y << 32) + z;
}
