File: /usr/src/linux/arch/m68k/kernel/time.c
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/sched.h>
16 #include <linux/kernel.h>
17 #include <linux/param.h>
18 #include <linux/string.h>
19 #include <linux/mm.h>
20
21 #include <asm/machdep.h>
22 #include <asm/io.h>
23
24 #include <linux/timex.h>
25
26
27 static inline int set_rtc_mmss(unsigned long nowtime)
28 {
29 if (mach_set_clock_mmss)
30 return mach_set_clock_mmss (nowtime);
31 return -1;
32 }
33
34 static inline void do_profile (unsigned long pc)
35 {
36 if (prof_buffer && current->pid) {
37 extern int _stext;
38 pc -= (unsigned long) &_stext;
39 pc >>= prof_shift;
40 if (pc < prof_len)
41 ++prof_buffer[pc];
42 else
43 /*
44 * Don't ignore out-of-bounds PC values silently,
45 * put them into the last histogram slot, so if
46 * present, they will show up as a sharp peak.
47 */
48 ++prof_buffer[prof_len-1];
49 }
50 }
51
52 /*
53 * timer_interrupt() needs to keep up the real-time clock,
54 * as well as call the "do_timer()" routine every clocktick
55 */
56 static void timer_interrupt(int irq, void *dummy, struct pt_regs * regs)
57 {
58 /* last time the cmos clock got updated */
59 static long last_rtc_update=0;
60
61 do_timer(regs);
62
63 if (!user_mode(regs))
64 do_profile(regs->pc);
65
66 /*
67 * If we have an externally synchronized Linux clock, then update
68 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
69 * called as close as possible to 500 ms before the new second starts.
70 */
71 if ((time_status & STA_UNSYNC) == 0 &&
72 xtime.tv_sec > last_rtc_update + 660 &&
73 xtime.tv_usec >= 500000 - ((unsigned) tick) / 2 &&
74 xtime.tv_usec <= 500000 + ((unsigned) tick) / 2) {
75 if (set_rtc_mmss(xtime.tv_sec) == 0)
76 last_rtc_update = xtime.tv_sec;
77 else
78 last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
79 }
80 #ifdef CONFIG_HEARTBEAT
81 /* use power LED as a heartbeat instead -- much more useful
82 for debugging -- based on the version for PReP by Cort */
83 /* acts like an actual heart beat -- ie thump-thump-pause... */
84 if (mach_heartbeat) {
85 static unsigned cnt = 0, period = 0, dist = 0;
86
87 if (cnt == 0 || cnt == dist)
88 mach_heartbeat( 1 );
89 else if (cnt == 7 || cnt == dist+7)
90 mach_heartbeat( 0 );
91
92 if (++cnt > period) {
93 cnt = 0;
94 /* The hyperbolic function below modifies the heartbeat period
95 * length in dependency of the current (5min) load. It goes
96 * through the points f(0)=126, f(1)=86, f(5)=51,
97 * f(inf)->30. */
98 period = ((672<<FSHIFT)/(5*avenrun[0]+(7<<FSHIFT))) + 30;
99 dist = period / 4;
100 }
101 }
102 #endif /* CONFIG_HEARTBEAT */
103 }
104
105 void time_init(void)
106 {
107 unsigned int year, mon, day, hour, min, sec;
108
109 extern void arch_gettod(int *year, int *mon, int *day, int *hour,
110 int *min, int *sec);
111
112 arch_gettod (&year, &mon, &day, &hour, &min, &sec);
113
114 if ((year += 1900) < 1970)
115 year += 100;
116 xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
117 xtime.tv_usec = 0;
118
119 mach_sched_init(timer_interrupt);
120 }
121
122 extern rwlock_t xtime_lock;
123
124 /*
125 * This version of gettimeofday has near microsecond resolution.
126 */
127 void do_gettimeofday(struct timeval *tv)
128 {
129 extern unsigned long wall_jiffies;
130 unsigned long flags;
131 unsigned long usec, sec, lost;
132
133 read_lock_irqsave(&xtime_lock, flags);
134 usec = mach_gettimeoffset();
135 lost = jiffies - wall_jiffies;
136 if (lost)
137 usec += lost * (1000000/HZ);
138 sec = xtime.tv_sec;
139 usec += xtime.tv_usec;
140 read_unlock_irqrestore(&xtime_lock, flags);
141
142 while (usec >= 1000000) {
143 usec -= 1000000;
144 sec++;
145 }
146
147 tv->tv_sec = sec;
148 tv->tv_usec = usec;
149 }
150
151 void do_settimeofday(struct timeval *tv)
152 {
153 write_lock_irq(&xtime_lock);
154 /* This is revolting. We need to set the xtime.tv_usec
155 * correctly. However, the value in this location is
156 * is value at the last tick.
157 * Discover what correction gettimeofday
158 * would have done, and then undo it!
159 */
160 tv->tv_usec -= mach_gettimeoffset();
161
162 while (tv->tv_usec < 0) {
163 tv->tv_usec += 1000000;
164 tv->tv_sec--;
165 }
166
167 xtime = *tv;
168 time_adjust = 0; /* stop active adjtime() */
169 time_status |= STA_UNSYNC;
170 time_maxerror = NTP_PHASE_LIMIT;
171 time_esterror = NTP_PHASE_LIMIT;
172 write_unlock_irq(&xtime_lock);
173 }
174