2 * linux/arch/parisc/kernel/time.c
4 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
5 * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
6 * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
8 * 1994-07-02 Alan Modra
9 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
10 * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
11 * "A Kernel Model for Precision Timekeeping" by Dave Mills
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>
21 #include <linux/interrupt.h>
22 #include <linux/time.h>
23 #include <linux/init.h>
24 #include <linux/smp.h>
25 #include <linux/profile.h>
27 #include <asm/uaccess.h>
30 #include <asm/param.h>
34 #include <linux/timex.h>
36 u64 jiffies_64 = INITIAL_JIFFIES;
38 EXPORT_SYMBOL(jiffies_64);
40 /* xtime and wall_jiffies keep wall-clock time */
41 extern unsigned long wall_jiffies;
43 static long clocktick; /* timer cycles per tick */
47 extern void smp_do_timer(struct pt_regs *regs);
50 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
55 int cpu = smp_processor_id();
57 profile_tick(CPU_PROFILING, regs);
60 /* initialize next_tick to time at last clocktick */
61 next_tick = cpu_data[cpu].it_value;
63 /* since time passes between the interrupt and the mfctl()
64 * above, it is never true that last_tick + clocktick == now. If we
65 * never miss a clocktick, we could set next_tick = last_tick + clocktick
66 * but maybe we'll miss ticks, hence the loop.
68 * Variables are *signed*.
72 while((next_tick - now) < halftick) {
73 next_tick += clocktick;
77 cpu_data[cpu].it_value = next_tick;
83 update_process_times(user_mode(regs));
86 write_seqlock(&xtime_lock);
88 write_sequnlock(&xtime_lock);
92 /* check soft power switch status */
93 if (cpu == 0 && !atomic_read(&power_tasklet.count))
94 tasklet_schedule(&power_tasklet);
100 unsigned long profile_pc(struct pt_regs *regs)
102 unsigned long pc = instruction_pointer(regs);
104 if (regs->gr[0] & PSW_N)
108 if (in_lock_functions(pc))
114 EXPORT_SYMBOL(profile_pc);
117 /*** converted from ia64 ***/
119 * Return the number of micro-seconds that elapsed since the last
120 * update to wall time (aka xtime aka wall_jiffies). The xtime_lock
121 * must be at least read-locked when calling this routine.
123 static inline unsigned long
128 * FIXME: This won't work on smp because jiffies are updated by cpu 0.
129 * Once parisc-linux learns the cr16 difference between processors,
130 * this could be made to work.
135 /* it_value is the intended time of the next tick */
136 last_tick = cpu_data[smp_processor_id()].it_value;
138 /* Subtract one tick and account for possible difference between
139 * when we expected the tick and when it actually arrived.
142 last_tick -= clocktick * (jiffies - wall_jiffies + 1);
143 elapsed_cycles = mfctl(16) - last_tick;
145 /* the precision of this math could be improved */
146 return elapsed_cycles / (PAGE0->mem_10msec / 10000);
153 do_gettimeofday (struct timeval *tv)
155 unsigned long flags, seq, usec, sec;
158 seq = read_seqbegin_irqsave(&xtime_lock, flags);
159 usec = gettimeoffset();
161 usec += (xtime.tv_nsec / 1000);
162 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
164 while (usec >= 1000000) {
173 EXPORT_SYMBOL(do_gettimeofday);
176 do_settimeofday (struct timespec *tv)
178 time_t wtm_sec, sec = tv->tv_sec;
179 long wtm_nsec, nsec = tv->tv_nsec;
181 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
184 write_seqlock_irq(&xtime_lock);
187 * This is revolting. We need to set "xtime"
188 * correctly. However, the value in this location is
189 * the value at the most recent update of wall time.
190 * Discover what correction gettimeofday would have
191 * done, and then undo it!
193 nsec -= gettimeoffset() * 1000;
195 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
196 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
198 set_normalized_timespec(&xtime, sec, nsec);
199 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
203 write_sequnlock_irq(&xtime_lock);
207 EXPORT_SYMBOL(do_settimeofday);
210 * XXX: We can do better than this.
211 * Returns nanoseconds
214 unsigned long long sched_clock(void)
216 return (unsigned long long)jiffies * (1000000000 / HZ);
220 void __init time_init(void)
222 unsigned long next_tick;
223 static struct pdc_tod tod_data;
225 clocktick = (100 * PAGE0->mem_10msec) / HZ;
226 halftick = clocktick / 2;
228 /* Setup clock interrupt timing */
230 next_tick = mfctl(16);
231 next_tick += clocktick;
232 cpu_data[smp_processor_id()].it_value = next_tick;
234 /* kick off Itimer (CR16) */
235 mtctl(next_tick, 16);
237 if(pdc_tod_read(&tod_data) == 0) {
238 write_seqlock_irq(&xtime_lock);
239 xtime.tv_sec = tod_data.tod_sec;
240 xtime.tv_nsec = tod_data.tod_usec * 1000;
241 set_normalized_timespec(&wall_to_monotonic,
242 -xtime.tv_sec, -xtime.tv_nsec);
243 write_sequnlock_irq(&xtime_lock);
245 printk(KERN_ERR "Error reading tod clock\n");