/*
* Copyright 2001 MontaVista Software Inc.
* Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
* Copyright (c) 2003, 2004 Maciej W. Rozycki
*
* Common time service routines for MIPS machines. See
* Documentation/mips/time.README.
*
* 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/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/param.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/smp.h>
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <asm/bootinfo.h>
#include <asm/compiler.h>
#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/div64.h>
#include <asm/sections.h>
#include <asm/time.h>
/*
* The integer part of the number of usecs per jiffy is taken from tick,
* but the fractional part is not recorded, so we calculate it using the
* initial value of HZ. This aids systems where tick isn't really an
* integer (e.g. for HZ = 128).
*/
#define USECS_PER_JIFFY TICK_SIZE
#define USECS_PER_JIFFY_FRAC ((unsigned long)(u32)((1000000ULL << 32) / HZ))
#define TICK_SIZE (tick_nsec / 1000)
u64 jiffies_64 = INITIAL_JIFFIES;
EXPORT_SYMBOL(jiffies_64);
/*
* forward reference
*/
extern volatile unsigned long wall_jiffies;
DEFINE_SPINLOCK(rtc_lock);
/*
* By default we provide the null RTC ops
*/
static unsigned long null_rtc_get_time(void)
{
return mktime(2000, 1, 1, 0, 0, 0);
}
static int null_rtc_set_time(unsigned long sec)
{
return 0;
}
unsigned long (*rtc_get_time)(void) = null_rtc_get_time;
int (*rtc_set_time)(unsigned long) = null_rtc_set_time;
int (*rtc_set_mmss)(unsigned long);
/* usecs per counter cycle, shifted to left by 32 bits */
static unsigned int sll32_usecs_per_cycle;
/* how many counter cycles in a jiffy */
static unsigned long cycles_per_jiffy;
/* Cycle counter value at the previous timer interrupt.. */
static unsigned int timerhi, timerlo;
/* expirelo is the count value for next CPU timer interrupt */
static unsigned int expirelo;
/*
* Null timer ack for systems not needing one (e.g. i8254).
*/
static void null_timer_ack(void) { /* nothing */ }
/*
* Null high precision timer functions for systems lacking one.
*/
static unsigned int null_hpt_read(void)
{
return 0;
}
static void null_hpt_init(unsigned int count) { /* nothing */ }
/*
* Timer ack for an R4k-compatible timer of a known frequency.
*/
static void c0_timer_ack(void)
{
unsigned int count;
/* Ack this timer interrupt and set the next one. */
expirelo += cycles_per_jiffy;
write_c0_compare(expirelo);
/* Check to see if we have missed any timer interrupts. */
count = read_c0_count();
if ((count - expirelo) < 0x7fffffff) {
/* missed_timer_count++; */
expirelo = count + cycles_per_jiffy;
write_c0_compare(expirelo);
}
}
/*
* High precision timer functions for a R4k-compatible timer.
*/
static unsigned int c0_hpt_read(void)
{
return read_c0_count();
}
/* For use solely as a high precision timer. */
static void c0_hpt_init(unsigned int count)
{
write_c0_count(read_c0_count() - count);
}
/* For use both as a high precision timer and an interrupt source. */
static void c0_hpt_timer_init(unsigned int count)
{
count = read_c0_count() - count;
expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
write_c0_count(expirelo - cycles_per_jiffy);
write_c0_compare(expirelo);
write_c0_count(count);
}
int (*mips_timer_state)(void);
void (*mips_timer_ack)(void);
unsigned int (*mips_hpt_read)(void);
void (*mips_hpt_init)(unsigned int);
/*
* This version of gettimeofday has microsecond resolution and better than
* microsecond precision on fast machines with cycle counter.
*/
void do_gettimeofday(struct timeval *tv)
{
unsigned long seq;
unsigned long lost;
unsigned long usec, sec;
unsigned long max_ntp_tick = tick_usec - tickadj;
do {
seq = read_seqbegin(&xtime_lock);
usec = do_gettimeoffset();
lost = jiffies - wall_jiffies;
/*
* If time_adjust is negative then NTP is slowing the clock
* so make sure not to go into next possible interval.
* Better to lose some accuracy than have time go backwards..
*/
if (unlikely(time_adjust < 0)) {
usec = min(usec, max_ntp_tick);
if (lost)
usec += lost * max_ntp_tick;
} else if (unlikely(lost))
usec += lost * tick_usec;
sec = xtime.tv_sec;
usec += (xtime.tv_nsec / 1000);
} while (read_seqretry(&xtime_lock, seq));
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 "xtime" correctly. However,
* the value in this location is the value at the most recent update
* of wall time. Discover what correction gettimeofday() would have
* made, and then undo it!
*/
nsec -= do_gettimeoffset() * NSEC_PER_USEC;
nsec -= (jiffies - wall_jiffies) * tick_nsec;
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);
/*
* Gettimeoffset routines. These routines returns the time duration
* since last timer interrupt in usecs.
*
* If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
* Otherwise use calibrate_gettimeoffset()
*
* If the CPU does not have the counter register, you can either supply
* your own gettimeoffset() routine, or use null_gettimeoffset(), which
* gives the same resolution as HZ.
*/
static unsigned long null_gettimeoffset(void)
{
return 0;
}
/* The function pointer to one of the gettimeoffset funcs. */
unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;
static unsigned long fixed_rate_gettimeoffset(void)
{
u32 count;
unsigned long res;
/* Get last timer tick in absolute kernel time */
count = mips_hpt_read();
/* .. relative to previous jiffy (32 bits is enough) */
count -= timerlo;
__asm__("multu %1,%2"
: "=h" (res)
: "r" (count), "r" (sll32_usecs_per_cycle)
: "lo", GCC_REG_ACCUM);
/*
* Due to possible jiffies inconsistencies, we need to check
* the result so that we'll get a timer that is monotonic.
*/
if (res >= USECS_PER_JIFFY)
res = USECS_PER_JIFFY - 1;
return res;
}
/*
* Cached "1/(clocks per usec) * 2^32" value.
* It has to be recalculated once each jiffy.
*/
static unsigned long cached_quotient;
/* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
static unsigned long last_jiffies;
/*
* This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
*/
static unsigned long calibrate_div32_gettimeoffset(void)
{
u32 count;
unsigned long res, tmp;
unsigned long quotient;
tmp = jiffies;
quotient = cached_quotient;
if (last_jiffies != tmp) {
last_jiffies = tmp;
if (last_jiffies != 0) {
unsigned long r0;
do_div64_32(r0, timerhi, timerlo, tmp);
do_div64_32(quotient, USECS_PER_JIFFY,
USECS_PER_JIFFY_FRAC, r0);
cached_quotient = quotient;
}
}
/* Get last timer tick in absolute kernel time */
count = mips_hpt_read();
/* .. relative to previous jiffy (32 bits is enough) */
count -= timerlo;
__asm__("multu %1,%2"
: "=h" (res)
: "r" (count), "r" (quotient)
: "lo", GCC_REG_ACCUM);
/*
* Due to possible jiffies inconsistencies, we need to check
* the result so that we'll get a timer that is monotonic.
*/
if (res >= USECS_PER_JIFFY)
res = USECS_PER_JIFFY - 1;
return res;
}
static unsigned long calibrate_div64_gettimeoffset(void)
{
u32 count;
unsigned long res, tmp;
unsigned long quotient;
tmp = jiffies;
quotient = cached_quotient;
if (last_jiffies != tmp) {
last_jiffies = tmp;
if (last_jiffies) {
unsigned long r0;
__asm__(".set push\n\t"
".set mips3\n\t"
"lwu %0,%3\n\t"
"dsll32 %1,%2,0\n\t"
"or %1,%1,%0\n\t"
"ddivu $0,%1,%4\n\t"
"mflo %1\n\t"
"dsll32 %0,%5,0\n\t"
"or %0,%0,%6\n\t"
"ddivu $0,%0,%1\n\t"
"mflo %0\n\t"
".set pop"
: "=&r" (quotient), "=&r" (r0)
: "r" (timerhi), "m" (timerlo),
"r" (tmp), "r" (USECS_PER_JIFFY),
"r" (USECS_PER_JIFFY_FRAC)
: "hi", "lo", GCC_REG_ACCUM);
cached_quotient = quotient;
}
}
/* Get last timer tick in absolute kernel time */
count = mips_hpt_read();
/* .. relative to previous jiffy (32 bits is enough) */
count -= timerlo;
__asm__("multu %1,%2"
: "=h" (res)
: "r" (count), "r" (quotient)
: "lo", GCC_REG_ACCUM);
/*
* Due to possible jiffies inconsistencies, we need to check
* the result so that we'll get a timer that is monotonic.
*/
if (res >= USECS_PER_JIFFY)
res = USECS_PER_JIFFY - 1;
return res;
}
/* last time when xtime and rtc are sync'ed up */
static long last_rtc_update;
/*
* local_timer_interrupt() does profiling and process accounting
* on a per-CPU basis.
*
* In UP mode, it is invoked from the (global) timer_interrupt.
*
* In SMP mode, it might invoked by per-CPU timer interrupt, or
* a broadcasted inter-processor interrupt which itself is triggered
* by the global timer interrupt.
*/
void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
if (current->pid)
profile_tick(CPU_PROFILING, regs);
update_process_times(user_mode(regs));
}
/*
* High-level timer interrupt service routines. This function
* is set as irqaction->handler and is invoked through do_IRQ.
*/
irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
unsigned long j;
unsigned int count;
count = mips_hpt_read();
mips_timer_ack();
/* Update timerhi/timerlo for intra-jiffy calibration. */
timerhi += count < timerlo; /* Wrap around */
timerlo = count;
/*
* call the generic timer interrupt handling
*/
do_timer(regs);
/*
* If we have an externally synchronized Linux clock, then update
* CMOS clock accordingly every ~11 minutes. rtc_set_time() has to be
* called as close as possible to 500 ms before the new second starts.
*/
write_seqlock(&xtime_lock);
if ((time_status & STA_UNSYNC) == 0 &&
xtime.tv_sec > last_rtc_update + 660 &&
(xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
(xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
if (rtc_set_mmss(xtime.tv_sec) == 0) {
last_rtc_update = xtime.tv_sec;
} else {
/* do it again in 60 s */
last_rtc_update = xtime.tv_sec - 600;
}
}
write_sequnlock(&xtime_lock);
/*
* If jiffies has overflown in this timer_interrupt, we must
* update the timer[hi]/[lo] to make fast gettimeoffset funcs
* quotient calc still valid. -arca
*
* The first timer interrupt comes late as interrupts are
* enabled long after timers are initialized. Therefore the
* high precision timer is fast, leading to wrong gettimeoffset()
* calculations. We deal with it by setting it based on the
* number of its ticks between the second and the third interrupt.
* That is still somewhat imprecise, but it's a good estimate.
* --macro
*/
j = jiffies;
if (j < 4) {
static unsigned int prev_count;
static int hpt_initialized;
switch (j) {
case 0:
timerhi = timerlo = 0;
mips_hpt_init(count);
break;
case 2:
prev_count = count;
break;
case 3:
if (!hpt_initialized) {
unsigned int c3 = 3 * (count - prev_count);
timerhi = 0;
timerlo = c3;
mips_hpt_init(count - c3);
hpt_initialized = 1;
}
break;
default:
break;
}
}
/*
* In UP mode, we call local_timer_interrupt() to do profiling
* and process accouting.
*
* In SMP mode, local_timer_interrupt() is invoked by appropriate
* low-level local timer interrupt handler.
*/
local_timer_interrupt(irq, dev_id, regs);
return IRQ_HANDLED;
}
asmlinkage void ll_timer_interrupt(int irq, struct pt_regs *regs)
{
irq_enter();
kstat_this_cpu.irqs[irq]++;
/* we keep interrupt disabled all the time */
timer_interrupt(irq, NULL, regs);
irq_exit();
}
asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs)
{
irq_enter();
if (smp_processor_id() != 0)
kstat_this_cpu.irqs[irq]++;
/* we keep interrupt disabled all the time */
local_timer_interrupt(irq, NULL, regs);
irq_exit();
}
/*
* time_init() - it does the following things.
*
* 1) board_time_init() -
* a) (optional) set up RTC routines,
* b) (optional) calibrate and set the mips_hpt_frequency
* (only needed if you intended to use fixed_rate_gettimeoffset
* or use cpu counter as timer interrupt source)
* 2) setup xtime based on rtc_get_time().
* 3) choose a appropriate gettimeoffset routine.
* 4) calculate a couple of cached variables for later usage
* 5) board_timer_setup() -
* a) (optional) over-write any choices made above by time_init().
* b) machine specific code should setup the timer irqaction.
* c) enable the timer interrupt
*/
void (*board_time_init)(void);
void (*board_timer_setup)(struct irqaction *irq);
unsigned int mips_hpt_frequency;
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = SA_INTERRUPT,
.name = "timer",
};
static unsigned int __init calibrate_hpt(void)
{
u64 frequency;
u32 hpt_start, hpt_end, hpt_count, hz;
const int loops = HZ / 10;
int log_2_loops = 0;
int i;
/*
* We want to calibrate for 0.1s, but to avoid a 64-bit
* division we round the number of loops up to the nearest
* power of 2.
*/
while (loops > 1 << log_2_loops)
log_2_loops++;
i = 1 << log_2_loops;
/*
* Wait for a rising edge of the timer interrupt.
*/
while (mips_timer_state());
while (!mips_timer_state());
/*
* Now see how many high precision timer ticks happen
* during the calculated number of periods between timer
* interrupts.
*/
hpt_start = mips_hpt_read();
do {
while (mips_timer_state());
while (!mips_timer_state());
} while (--i);
hpt_end = mips_hpt_read();
hpt_count = hpt_end - hpt_start;
hz = HZ;
frequency = (u64)hpt_count * (u64)hz;
return frequency >> log_2_loops;
}
void __init time_init(void)
{
if (board_time_init)
board_time_init();
if (!rtc_set_mmss)
rtc_set_mmss = rtc_set_time;
xtime.tv_sec = rtc_get_time();
xtime.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
/* Choose appropriate high precision timer routines. */
if (!cpu_has_counter && !mips_hpt_read) {
/* No high precision timer -- sorry. */
mips_hpt_read = null_hpt_read;
mips_hpt_init = null_hpt_init;
} else if (!mips_hpt_frequency && !mips_timer_state) {
/* A high precision timer of unknown frequency. */
if (!mips_hpt_read) {
/* No external high precision timer -- use R4k. */
mips_hpt_read = c0_hpt_read;
mips_hpt_init = c0_hpt_init;
}
if ((current_cpu_data.isa_level == MIPS_CPU_ISA_M32) ||
(current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
(current_cpu_data.isa_level == MIPS_CPU_ISA_II))
/*
* We need to calibrate the counter but we don't have
* 64-bit division.
*/
do_gettimeoffset = calibrate_div32_gettimeoffset;
else
/*
* We need to calibrate the counter but we *do* have
* 64-bit division.
*/
do_gettimeoffset = calibrate_div64_gettimeoffset;
} else {
/* We know counter frequency. Or we can get it. */
if (!mips_hpt_read) {
/* No external high precision timer -- use R4k. */
mips_hpt_read = c0_hpt_read;
if (mips_timer_state)
mips_hpt_init = c0_hpt_init;
else {
/* No external timer interrupt -- use R4k. */
mips_hpt_init = c0_hpt_timer_init;
mips_timer_ack = c0_timer_ack;
}
}
if (!mips_hpt_frequency)
mips_hpt_frequency = calibrate_hpt();
do_gettimeoffset = fixed_rate_gettimeoffset;
/* Calculate cache parameters. */
cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;
/* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
do_div64_32(sll32_usecs_per_cycle,
1000000, mips_hpt_frequency / 2,
mips_hpt_frequency);
/* Report the high precision timer rate for a reference. */
printk("Using %u.%03u MHz high precision timer.\n",
((mips_hpt_frequency + 500) / 1000) / 1000,
((mips_hpt_frequency + 500) / 1000) % 1000);
}
if (!mips_timer_ack)
/* No timer interrupt ack (e.g. i8254). */
mips_timer_ack = null_timer_ack;
/* This sets up the high precision timer for the first interrupt. */
mips_hpt_init(mips_hpt_read());
/*
* Call board specific timer interrupt setup.
*
* this pointer must be setup in machine setup routine.
*
* Even if a machine chooses to use a low-level timer interrupt,
* it still needs to setup the timer_irqaction.
* In that case, it might be better to set timer_irqaction.handler
* to be NULL function so that we are sure the high-level code
* is not invoked accidentally.
*/
board_timer_setup(&timer_irqaction);
}
#define FEBRUARY 2
#define STARTOFTIME 1970
#define SECDAY 86400L
#define SECYR (SECDAY * 365)
#define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
#define days_in_year(y) (leapyear(y) ? 366 : 365)
#define days_in_month(m) (month_days[(m) - 1])
static int month_days[12] = {
31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
void to_tm(unsigned long tim, struct rtc_time *tm)
{
long hms, day, gday;
int i;
gday = 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 - 1; /* tm_mon starts from 0 to 11 */
/* Days are what is left over (+1) from all that. */
tm->tm_mday = day + 1;
/*
* Determine the day of week
*/
tm->tm_wday = (gday + 4) % 7; /* 1970/1/1 was Thursday */
}
EXPORT_SYMBOL(rtc_lock);
EXPORT_SYMBOL(to_tm);
EXPORT_SYMBOL(rtc_set_time);
EXPORT_SYMBOL(rtc_get_time);
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies*(1000000000/HZ);
}
