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 #ifdef CONFIG_CHASSIS_LCD_LED
93 /* Only schedule the led tasklet on cpu 0, and only if it
96 if (cpu == 0 && !atomic_read(&led_tasklet.count))
97 tasklet_schedule(&led_tasklet);
100 /* check soft power switch status */
101 if (cpu == 0 && !atomic_read(&power_tasklet.count))
102 tasklet_schedule(&power_tasklet);
107 /*** converted from ia64 ***/
109 * Return the number of micro-seconds that elapsed since the last
110 * update to wall time (aka xtime aka wall_jiffies). The xtime_lock
111 * must be at least read-locked when calling this routine.
113 static inline unsigned long
118 * FIXME: This won't work on smp because jiffies are updated by cpu 0.
119 * Once parisc-linux learns the cr16 difference between processors,
120 * this could be made to work.
125 /* it_value is the intended time of the next tick */
126 last_tick = cpu_data[smp_processor_id()].it_value;
128 /* Subtract one tick and account for possible difference between
129 * when we expected the tick and when it actually arrived.
132 last_tick -= clocktick * (jiffies - wall_jiffies + 1);
133 elapsed_cycles = mfctl(16) - last_tick;
135 /* the precision of this math could be improved */
136 return elapsed_cycles / (PAGE0->mem_10msec / 10000);
143 do_gettimeofday (struct timeval *tv)
145 unsigned long flags, seq, usec, sec;
148 seq = read_seqbegin_irqsave(&xtime_lock, flags);
149 usec = gettimeoffset();
151 usec += (xtime.tv_nsec / 1000);
152 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
154 while (usec >= 1000000) {
163 EXPORT_SYMBOL(do_gettimeofday);
166 do_settimeofday (struct timespec *tv)
168 time_t wtm_sec, sec = tv->tv_sec;
169 long wtm_nsec, nsec = tv->tv_nsec;
171 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
174 write_seqlock_irq(&xtime_lock);
177 * This is revolting. We need to set "xtime"
178 * correctly. However, the value in this location is
179 * the value at the most recent update of wall time.
180 * Discover what correction gettimeofday would have
181 * done, and then undo it!
183 nsec -= gettimeoffset() * 1000;
185 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
186 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
188 set_normalized_timespec(&xtime, sec, nsec);
189 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
193 write_sequnlock_irq(&xtime_lock);
197 EXPORT_SYMBOL(do_settimeofday);
200 * XXX: We can do better than this.
201 * Returns nanoseconds
204 unsigned long long sched_clock(void)
206 return (unsigned long long)jiffies * (1000000000 / HZ);
210 void __init time_init(void)
212 unsigned long next_tick;
213 static struct pdc_tod tod_data;
215 clocktick = (100 * PAGE0->mem_10msec) / HZ;
216 halftick = clocktick / 2;
218 /* Setup clock interrupt timing */
220 next_tick = mfctl(16);
221 next_tick += clocktick;
222 cpu_data[smp_processor_id()].it_value = next_tick;
224 /* kick off Itimer (CR16) */
225 mtctl(next_tick, 16);
227 if(pdc_tod_read(&tod_data) == 0) {
228 write_seqlock_irq(&xtime_lock);
229 xtime.tv_sec = tod_data.tod_sec;
230 xtime.tv_nsec = tod_data.tod_usec * 1000;
231 set_normalized_timespec(&wall_to_monotonic,
232 -xtime.tv_sec, -xtime.tv_nsec);
233 write_sequnlock_irq(&xtime_lock);
235 printk(KERN_ERR "Error reading tod clock\n");