/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 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 #define USECS_PER_JIFFY_FRAC ((unsigned long)(u32)((1000000ULL << 32) / HZ)) /* * forward reference */ extern rwlock_t xtime_lock; extern volatile unsigned long wall_jiffies; spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED; /* * whether we emulate local_timer_interrupts for SMP machines. */ int emulate_local_timer_interrupt; /* * 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); /* * timeofday services, for syscalls. */ void do_gettimeofday(struct timeval *tv) { unsigned long flags, lost; read_lock_irqsave(&xtime_lock, flags); *tv = xtime; tv->tv_usec += do_gettimeoffset(); /* * xtime is atomically updated in timer_bh. jiffies - wall_jiffies * is nonzero if the timer bottom half hasn't executed yet. */ lost = jiffies - wall_jiffies; if (lost) tv->tv_usec += lost * USECS_PER_JIFFY; read_unlock_irqrestore(&xtime_lock, flags); while (tv->tv_usec >= 1000000) { tv->tv_usec -= 1000000; tv->tv_sec++; } } void do_settimeofday(struct timeval *tv) { write_lock_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! */ tv->tv_usec -= do_gettimeoffset(); tv->tv_usec -= (jiffies - wall_jiffies) * USECS_PER_JIFFY; while (tv->tv_usec < 0) { tv->tv_usec += 1000000; tv->tv_sec--; } xtime = *tv; time_adjust = 0; /* stop active adjtime() */ time_status |= STA_UNSYNC; time_maxerror = NTP_PHASE_LIMIT; time_esterror = NTP_PHASE_LIMIT; write_unlock_irq(&xtime_lock); } /* * 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 (!user_mode(regs)) { if (prof_buffer && current->pid) { extern int _stext; unsigned long pc = regs->cp0_epc; pc -= (unsigned long) &_stext; pc >>= prof_shift; /* * Dont ignore out-of-bounds pc values silently, * put them into the last histogram slot, so if * present, they will show up as a sharp peak. */ if (pc > prof_len - 1) pc = prof_len - 1; atomic_inc((atomic_t *)&prof_buffer[pc]); } } #ifdef CONFIG_SMP /* in UP mode, update_process_times() is invoked by do_timer() */ update_process_times(user_mode(regs)); #endif } /* * High-level timer interrupt service routines. This function * is set as irqaction->handler and is invoked through do_IRQ. */ void 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. */ read_lock(&xtime_lock); if ((time_status & STA_UNSYNC) == 0 && xtime.tv_sec > last_rtc_update + 660 && xtime.tv_usec >= 500000 - ((unsigned) tick) / 2 && xtime.tv_usec <= 500000 + ((unsigned) tick) / 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; } } read_unlock(&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; } } #if !defined(CONFIG_SMP) /* * 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); #else /* CONFIG_SMP */ if (emulate_local_timer_interrupt) { /* * this is the place where we send out inter-process * interrupts and let each CPU do its own profiling * and process accouting. * * Obviously we need to call local_timer_interrupt() for * the current CPU too. */ panic("Not implemented yet!!!"); } #endif /* CONFIG_SMP */ } asmlinkage void ll_timer_interrupt(int irq, struct pt_regs *regs) { int cpu = smp_processor_id(); irq_enter(cpu, irq); kstat.irqs[cpu][irq]++; /* we keep interrupt disabled all the time */ timer_interrupt(irq, NULL, regs); irq_exit(cpu, irq); if (softirq_pending(cpu)) do_softirq(); } asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs) { int cpu = smp_processor_id(); irq_enter(cpu, irq); if (cpu != 0) kstat.irqs[cpu][irq]++; /* we keep interrupt disabled all the time */ local_timer_interrupt(irq, NULL, regs); irq_exit(cpu, irq); if (softirq_pending(cpu)) do_softirq(); } /* * 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_usec = 0; /* 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);