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Linux/arch/m68knommu/kernel/time.c

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  1 /*
  2  *  linux/arch/m68knommu/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>
 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/profile.h>
 22 #include <linux/time.h>
 23 #include <linux/timex.h>
 24 
 25 #include <asm/machdep.h>
 26 #include <asm/io.h>
 27 
 28 #define TICK_SIZE (tick_nsec / 1000)
 29 
 30 u64 jiffies_64 = INITIAL_JIFFIES;
 31 
 32 EXPORT_SYMBOL(jiffies_64);
 33 
 34 extern unsigned long wall_jiffies;
 35 
 36 
 37 static inline int set_rtc_mmss(unsigned long nowtime)
 38 {
 39         if (mach_set_clock_mmss)
 40                 return mach_set_clock_mmss (nowtime);
 41         return -1;
 42 }
 43 
 44 static inline void do_profile (unsigned long pc)
 45 {
 46         if (prof_buffer && current->pid) {
 47                 extern int _stext;
 48                 pc -= (unsigned long) &_stext;
 49                 pc >>= prof_shift;
 50                 if (pc < prof_len)
 51                         ++prof_buffer[pc];
 52                 else
 53                 /*
 54                  * Don't ignore out-of-bounds PC values silently,
 55                  * put them into the last histogram slot, so if
 56                  * present, they will show up as a sharp peak.
 57                  */
 58                         ++prof_buffer[prof_len-1];
 59         }
 60 }
 61 
 62 /*
 63  * timer_interrupt() needs to keep up the real-time clock,
 64  * as well as call the "do_timer()" routine every clocktick
 65  */
 66 static irqreturn_t timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
 67 {
 68         /* last time the cmos clock got updated */
 69         static long last_rtc_update=0;
 70 
 71         /* may need to kick the hardware timer */
 72         if (mach_tick)
 73           mach_tick();
 74 
 75         write_seqlock(&xtime_lock);
 76 
 77         do_timer(regs);
 78 
 79         if (!user_mode(regs))
 80                 do_profile(regs->pc);
 81 
 82         /*
 83          * If we have an externally synchronized Linux clock, then update
 84          * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
 85          * called as close as possible to 500 ms before the new second starts.
 86          */
 87         if ((time_status & STA_UNSYNC) == 0 &&
 88             xtime.tv_sec > last_rtc_update + 660 &&
 89             (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
 90             (xtime.tv_nsec  / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
 91           if (set_rtc_mmss(xtime.tv_sec) == 0)
 92             last_rtc_update = xtime.tv_sec;
 93           else
 94             last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
 95         }
 96 #ifdef CONFIG_HEARTBEAT
 97         /* use power LED as a heartbeat instead -- much more useful
 98            for debugging -- based on the version for PReP by Cort */
 99         /* acts like an actual heart beat -- ie thump-thump-pause... */
100         if (mach_heartbeat) {
101             static unsigned cnt = 0, period = 0, dist = 0;
102 
103             if (cnt == 0 || cnt == dist)
104                 mach_heartbeat( 1 );
105             else if (cnt == 7 || cnt == dist+7)
106                 mach_heartbeat( 0 );
107 
108             if (++cnt > period) {
109                 cnt = 0;
110                 /* The hyperbolic function below modifies the heartbeat period
111                  * length in dependency of the current (5min) load. It goes
112                  * through the points f(0)=126, f(1)=86, f(5)=51,
113                  * f(inf)->30. */
114                 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
115                 dist = period / 4;
116             }
117         }
118 #endif /* CONFIG_HEARTBEAT */
119 
120         write_sequnlock(&xtime_lock);
121         return(IRQ_HANDLED);
122 }
123 
124 void time_init(void)
125 {
126         unsigned int year, mon, day, hour, min, sec;
127 
128         extern void arch_gettod(int *year, int *mon, int *day, int *hour,
129                                 int *min, int *sec);
130 
131         arch_gettod(&year, &mon, &day, &hour, &min, &sec);
132 
133         if ((year += 1900) < 1970)
134                 year += 100;
135         xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
136         xtime.tv_nsec = 0;
137         wall_to_monotonic.tv_sec = -xtime.tv_sec;
138 
139         mach_sched_init(timer_interrupt);
140 }
141 
142 /*
143  * This version of gettimeofday has near microsecond resolution.
144  */
145 void do_gettimeofday(struct timeval *tv)
146 {
147         unsigned long flags;
148         unsigned long lost, seq;
149         unsigned long usec, sec;
150 
151         do {
152                 seq = read_seqbegin_irqsave(&xtime_lock, flags);
153                 usec = mach_gettimeoffset ? mach_gettimeoffset() : 0;
154                 lost = jiffies - wall_jiffies;
155                 if (lost)
156                         usec += lost * (1000000 / HZ);
157                 sec = xtime.tv_sec;
158                 usec += (xtime.tv_nsec / 1000);
159         } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
160 
161         while (usec >= 1000000) {
162                 usec -= 1000000;
163                 sec++;
164         }
165 
166         tv->tv_sec = sec;
167         tv->tv_usec = usec;
168 }
169 
170 EXPORT_SYMBOL(do_gettimeofday);
171 
172 int do_settimeofday(struct timespec *tv)
173 {
174         time_t wtm_sec, sec = tv->tv_sec;
175         long wtm_nsec, nsec = tv->tv_nsec;
176 
177         if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
178                 return -EINVAL;
179 
180         write_seqlock_irq(&xtime_lock);
181         /*
182          * This is revolting. We need to set the xtime.tv_usec
183          * correctly. However, the value in this location is
184          * is value at the last tick.
185          * Discover what correction gettimeofday
186          * would have done, and then undo it!
187          */
188         if (mach_gettimeoffset)
189                 nsec -= (mach_gettimeoffset() * 1000);
190 
191         wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
192         wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
193 
194         set_normalized_timespec(&xtime, sec, nsec);
195         set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
196 
197         time_adjust = 0;                /* stop active adjtime() */
198         time_status |= STA_UNSYNC;
199         time_maxerror = NTP_PHASE_LIMIT;
200         time_esterror = NTP_PHASE_LIMIT;
201         write_sequnlock_irq(&xtime_lock);
202         return 0;
203 }
204 
205 EXPORT_SYMBOL(do_settimeofday);
206 

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