1 /* 2 * linux/arch/m68k/kernel/time.c 3 * 4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds 5 * 6 * This file contains the m68k-specific time handling details. 7 * Most of the stuff is located in the machine specific files. 8 * 9 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96 10 * "A Kernel Model for Precision Timekeeping" by Dave Mills 11 */ 12 13 #include <linux/config.h> /* CONFIG_HEARTBEAT */ 14 #include <linux/errno.h> 15 #include <linux/module.h> 16 #include <linux/sched.h> 17 #include <linux/kernel.h> 18 #include <linux/param.h> 19 #include <linux/string.h> 20 #include <linux/mm.h> 21 #include <linux/rtc.h> 22 23 #include <asm/machdep.h> 24 #include <asm/io.h> 25 26 #include <linux/time.h> 27 #include <linux/timex.h> 28 #include <linux/profile.h> 29 30 static inline int set_rtc_mmss(unsigned long nowtime) 31 { 32 if (mach_set_clock_mmss) 33 return mach_set_clock_mmss (nowtime); 34 return -1; 35 } 36 37 /* 38 * timer_interrupt() needs to keep up the real-time clock, 39 * as well as call the "do_timer()" routine every clocktick 40 */ 41 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs) 42 { 43 do_timer(regs); 44 #ifndef CONFIG_SMP 45 update_process_times(user_mode(regs)); 46 #endif 47 profile_tick(CPU_PROFILING, regs); 48 49 #ifdef CONFIG_HEARTBEAT 50 /* use power LED as a heartbeat instead -- much more useful 51 for debugging -- based on the version for PReP by Cort */ 52 /* acts like an actual heart beat -- ie thump-thump-pause... */ 53 if (mach_heartbeat) { 54 static unsigned cnt = 0, period = 0, dist = 0; 55 56 if (cnt == 0 || cnt == dist) 57 mach_heartbeat( 1 ); 58 else if (cnt == 7 || cnt == dist+7) 59 mach_heartbeat( 0 ); 60 61 if (++cnt > period) { 62 cnt = 0; 63 /* The hyperbolic function below modifies the heartbeat period 64 * length in dependency of the current (5min) load. It goes 65 * through the points f(0)=126, f(1)=86, f(5)=51, 66 * f(inf)->30. */ 67 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30; 68 dist = period / 4; 69 } 70 } 71 #endif /* CONFIG_HEARTBEAT */ 72 return IRQ_HANDLED; 73 } 74 75 void time_init(void) 76 { 77 struct rtc_time time; 78 79 if (mach_hwclk) { 80 mach_hwclk(0, &time); 81 82 if ((time.tm_year += 1900) < 1970) 83 time.tm_year += 100; 84 xtime.tv_sec = mktime(time.tm_year, time.tm_mon, time.tm_mday, 85 time.tm_hour, time.tm_min, time.tm_sec); 86 xtime.tv_nsec = 0; 87 } 88 wall_to_monotonic.tv_sec = -xtime.tv_sec; 89 90 mach_sched_init(timer_interrupt); 91 } 92 93 /* 94 * This version of gettimeofday has near microsecond resolution. 95 */ 96 void do_gettimeofday(struct timeval *tv) 97 { 98 unsigned long flags; 99 extern unsigned long wall_jiffies; 100 unsigned long seq; 101 unsigned long usec, sec, lost; 102 unsigned long max_ntp_tick = tick_usec - tickadj; 103 104 do { 105 seq = read_seqbegin_irqsave(&xtime_lock, flags); 106 107 usec = mach_gettimeoffset(); 108 lost = jiffies - wall_jiffies; 109 110 /* 111 * If time_adjust is negative then NTP is slowing the clock 112 * so make sure not to go into next possible interval. 113 * Better to lose some accuracy than have time go backwards.. 114 */ 115 if (unlikely(time_adjust < 0)) { 116 usec = min(usec, max_ntp_tick); 117 118 if (lost) 119 usec += lost * max_ntp_tick; 120 } 121 else if (unlikely(lost)) 122 usec += lost * tick_usec; 123 124 sec = xtime.tv_sec; 125 usec += xtime.tv_nsec/1000; 126 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); 127 128 129 while (usec >= 1000000) { 130 usec -= 1000000; 131 sec++; 132 } 133 134 tv->tv_sec = sec; 135 tv->tv_usec = usec; 136 } 137 138 EXPORT_SYMBOL(do_gettimeofday); 139 140 int do_settimeofday(struct timespec *tv) 141 { 142 time_t wtm_sec, sec = tv->tv_sec; 143 long wtm_nsec, nsec = tv->tv_nsec; 144 extern unsigned long wall_jiffies; 145 146 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) 147 return -EINVAL; 148 149 write_seqlock_irq(&xtime_lock); 150 /* This is revolting. We need to set the xtime.tv_nsec 151 * correctly. However, the value in this location is 152 * is value at the last tick. 153 * Discover what correction gettimeofday 154 * would have done, and then undo it! 155 */ 156 nsec -= 1000 * (mach_gettimeoffset() + 157 (jiffies - wall_jiffies) * (1000000 / HZ)); 158 159 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); 160 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); 161 162 set_normalized_timespec(&xtime, sec, nsec); 163 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); 164 165 ntp_clear(); 166 write_sequnlock_irq(&xtime_lock); 167 clock_was_set(); 168 return 0; 169 } 170 171 EXPORT_SYMBOL(do_settimeofday); 172 173 /* 174 * Scheduler clock - returns current time in ns units. 175 */ 176 unsigned long long sched_clock(void) 177 { 178 return (unsigned long long)jiffies*(1000000000/HZ); 179 } 180 181