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Diffstat (limited to 'arch/mips/kernel/time.c')
| -rw-r--r-- | arch/mips/kernel/time.c | 755 |
1 files changed, 755 insertions, 0 deletions
diff --git a/arch/mips/kernel/time.c b/arch/mips/kernel/time.c new file mode 100644 index 00000000000..648c82292ed --- /dev/null +++ b/arch/mips/kernel/time.c @@ -0,0 +1,755 @@ +/* + * 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); +} |