2 * arch/s390/kernel/time.c
3 * Time of day based timer functions.
6 * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 * Author(s): Hartmut Penner (hp@de.ibm.com),
8 * Martin Schwidefsky (schwidefsky@de.ibm.com),
9 * Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
11 * Derived from "arch/i386/kernel/time.c"
12 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
15 #include <linux/config.h>
16 #include <linux/errno.h>
17 #include <linux/module.h>
18 #include <linux/sched.h>
19 #include <linux/kernel.h>
20 #include <linux/param.h>
21 #include <linux/string.h>
23 #include <linux/interrupt.h>
24 #include <linux/time.h>
25 #include <linux/delay.h>
26 #include <linux/init.h>
27 #include <linux/smp.h>
28 #include <linux/types.h>
29 #include <linux/profile.h>
30 #include <linux/timex.h>
31 #include <linux/notifier.h>
33 #include <asm/uaccess.h>
34 #include <asm/delay.h>
35 #include <asm/s390_ext.h>
36 #include <asm/div64.h>
38 #include <asm/timer.h>
40 /* change this if you have some constant time drift */
41 #define USECS_PER_JIFFY ((unsigned long) 1000000/HZ)
42 #define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
45 * Create a small time difference between the timer interrupts
46 * on the different cpus to avoid lock contention.
48 #define CPU_DEVIATION (smp_processor_id() << 12)
50 #define TICK_SIZE tick
52 static ext_int_info_t ext_int_info_cc
;
53 static u64 init_timer_cc
;
54 static u64 jiffies_timer_cc
;
57 extern unsigned long wall_jiffies
;
60 * Scheduler clock - returns current time in nanosec units.
62 unsigned long long sched_clock(void)
64 return ((get_clock() - jiffies_timer_cc
) * 125) >> 9;
68 * Monotonic_clock - returns # of nanoseconds passed since time_init()
70 unsigned long long monotonic_clock(void)
74 EXPORT_SYMBOL(monotonic_clock
);
76 void tod_to_timeval(__u64 todval
, struct timespec
*xtime
)
78 unsigned long long sec
;
83 todval
-= (sec
* 1000000) << 12;
84 xtime
->tv_nsec
= ((todval
* 1000) >> 12);
87 static inline unsigned long do_gettimeoffset(void)
91 now
= (get_clock() - jiffies_timer_cc
) >> 12;
92 /* We require the offset from the latest update of xtime */
93 now
-= (__u64
) wall_jiffies
*USECS_PER_JIFFY
;
94 return (unsigned long) now
;
98 * This version of gettimeofday has microsecond resolution.
100 void do_gettimeofday(struct timeval
*tv
)
104 unsigned long usec
, sec
;
107 seq
= read_seqbegin_irqsave(&xtime_lock
, flags
);
110 usec
= xtime
.tv_nsec
/ 1000 + do_gettimeoffset();
111 } while (read_seqretry_irqrestore(&xtime_lock
, seq
, flags
));
113 while (usec
>= 1000000) {
122 EXPORT_SYMBOL(do_gettimeofday
);
124 int do_settimeofday(struct timespec
*tv
)
126 time_t wtm_sec
, sec
= tv
->tv_sec
;
127 long wtm_nsec
, nsec
= tv
->tv_nsec
;
129 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
132 write_seqlock_irq(&xtime_lock
);
133 /* This is revolting. We need to set the xtime.tv_nsec
134 * correctly. However, the value in this location is
135 * is value at the last tick.
136 * Discover what correction gettimeofday
137 * would have done, and then undo it!
139 nsec
-= do_gettimeoffset() * 1000;
141 wtm_sec
= wall_to_monotonic
.tv_sec
+ (xtime
.tv_sec
- sec
);
142 wtm_nsec
= wall_to_monotonic
.tv_nsec
+ (xtime
.tv_nsec
- nsec
);
144 set_normalized_timespec(&xtime
, sec
, nsec
);
145 set_normalized_timespec(&wall_to_monotonic
, wtm_sec
, wtm_nsec
);
148 write_sequnlock_irq(&xtime_lock
);
153 EXPORT_SYMBOL(do_settimeofday
);
156 #ifdef CONFIG_PROFILING
157 #define s390_do_profile(regs) profile_tick(CPU_PROFILING, regs)
159 #define s390_do_profile(regs) do { ; } while(0)
160 #endif /* CONFIG_PROFILING */
164 * timer_interrupt() needs to keep up the real-time clock,
165 * as well as call the "do_timer()" routine every clocktick
167 void account_ticks(struct pt_regs
*regs
)
172 /* Calculate how many ticks have passed. */
173 if (S390_lowcore
.int_clock
< S390_lowcore
.jiffy_timer
) {
175 * We have to program the clock comparator even if
176 * no tick has passed. That happens if e.g. an i/o
177 * interrupt wakes up an idle processor that has
178 * switched off its hz timer.
180 tmp
= S390_lowcore
.jiffy_timer
+ CPU_DEVIATION
;
181 asm volatile ("SCKC %0" : : "m" (tmp
));
184 tmp
= S390_lowcore
.int_clock
- S390_lowcore
.jiffy_timer
;
185 if (tmp
>= 2*CLK_TICKS_PER_JIFFY
) { /* more than two ticks ? */
186 ticks
= __div(tmp
, CLK_TICKS_PER_JIFFY
) + 1;
187 S390_lowcore
.jiffy_timer
+=
188 CLK_TICKS_PER_JIFFY
* (__u64
) ticks
;
189 } else if (tmp
>= CLK_TICKS_PER_JIFFY
) {
191 S390_lowcore
.jiffy_timer
+= 2*CLK_TICKS_PER_JIFFY
;
194 S390_lowcore
.jiffy_timer
+= CLK_TICKS_PER_JIFFY
;
197 /* set clock comparator for next tick */
198 tmp
= S390_lowcore
.jiffy_timer
+ CPU_DEVIATION
;
199 asm volatile ("SCKC %0" : : "m" (tmp
));
203 * Do not rely on the boot cpu to do the calls to do_timer.
204 * Spread it over all cpus instead.
206 write_seqlock(&xtime_lock
);
207 if (S390_lowcore
.jiffy_timer
> xtime_cc
) {
208 tmp
= S390_lowcore
.jiffy_timer
- xtime_cc
;
209 if (tmp
>= 2*CLK_TICKS_PER_JIFFY
) {
210 xticks
= __div(tmp
, CLK_TICKS_PER_JIFFY
);
211 xtime_cc
+= (__u64
) xticks
* CLK_TICKS_PER_JIFFY
;
214 xtime_cc
+= CLK_TICKS_PER_JIFFY
;
219 write_sequnlock(&xtime_lock
);
221 for (xticks
= ticks
; xticks
> 0; xticks
--)
225 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
226 account_tick_vtime(current
);
229 update_process_times(user_mode(regs
));
232 s390_do_profile(regs
);
235 #ifdef CONFIG_NO_IDLE_HZ
237 #ifdef CONFIG_NO_IDLE_HZ_INIT
238 int sysctl_hz_timer
= 0;
240 int sysctl_hz_timer
= 1;
244 * Stop the HZ tick on the current CPU.
245 * Only cpu_idle may call this function.
247 static inline void stop_hz_timer(void)
250 unsigned long seq
, next
;
253 if (sysctl_hz_timer
!= 0)
256 cpu_set(smp_processor_id(), nohz_cpu_mask
);
259 * Leave the clock comparator set up for the next timer
260 * tick if either rcu or a softirq is pending.
262 if (rcu_pending(smp_processor_id()) || local_softirq_pending()) {
263 cpu_clear(smp_processor_id(), nohz_cpu_mask
);
268 * This cpu is going really idle. Set up the clock comparator
269 * for the next event.
271 next
= next_timer_interrupt();
273 seq
= read_seqbegin_irqsave(&xtime_lock
, flags
);
274 timer
= (__u64
)(next
- jiffies
) + jiffies_64
;
275 } while (read_seqretry_irqrestore(&xtime_lock
, seq
, flags
));
277 /* Be careful about overflows. */
278 if (timer
< (-1ULL / CLK_TICKS_PER_JIFFY
)) {
279 timer
= jiffies_timer_cc
+ timer
* CLK_TICKS_PER_JIFFY
;
280 if (timer
>= jiffies_timer_cc
)
283 asm volatile ("SCKC %0" : : "m" (todval
));
287 * Start the HZ tick on the current CPU.
288 * Only cpu_idle may call this function.
290 static inline void start_hz_timer(void)
292 if (!cpu_isset(smp_processor_id(), nohz_cpu_mask
))
294 account_ticks(task_pt_regs(current
));
295 cpu_clear(smp_processor_id(), nohz_cpu_mask
);
298 static int nohz_idle_notify(struct notifier_block
*self
,
299 unsigned long action
, void *hcpu
)
312 static struct notifier_block nohz_idle_nb
= {
313 .notifier_call
= nohz_idle_notify
,
316 void __init
nohz_init(void)
318 if (register_idle_notifier(&nohz_idle_nb
))
319 panic("Couldn't register idle notifier");
325 * Start the clock comparator on the current CPU.
327 void init_cpu_timer(void)
332 timer
= jiffies_timer_cc
+ jiffies_64
* CLK_TICKS_PER_JIFFY
;
333 S390_lowcore
.jiffy_timer
= timer
+ CLK_TICKS_PER_JIFFY
;
334 timer
+= CLK_TICKS_PER_JIFFY
+ CPU_DEVIATION
;
335 asm volatile ("SCKC %0" : : "m" (timer
));
336 /* allow clock comparator timer interrupt */
337 __ctl_store(cr0
, 0, 0);
339 __ctl_load(cr0
, 0, 0);
342 extern void vtime_init(void);
345 * Initialize the TOD clock and the CPU timer of
348 void __init
time_init(void)
353 /* kick the TOD clock */
354 asm volatile ("STCK 0(%1)\n\t"
356 "SRL %0,28" : "=r" (cc
) : "a" (&init_timer_cc
)
359 case 0: /* clock in set state: all is fine */
361 case 1: /* clock in non-set state: FIXME */
362 printk("time_init: TOD clock in non-set state\n");
364 case 2: /* clock in error state: FIXME */
365 printk("time_init: TOD clock in error state\n");
367 case 3: /* clock in stopped or not-operational state: FIXME */
368 printk("time_init: TOD clock stopped/non-operational\n");
371 jiffies_timer_cc
= init_timer_cc
- jiffies_64
* CLK_TICKS_PER_JIFFY
;
374 xtime_cc
= init_timer_cc
+ CLK_TICKS_PER_JIFFY
;
375 set_time_cc
= init_timer_cc
- 0x8126d60e46000000LL
+
376 (0x3c26700LL
*1000000*4096);
377 tod_to_timeval(set_time_cc
, &xtime
);
378 set_normalized_timespec(&wall_to_monotonic
,
379 -xtime
.tv_sec
, -xtime
.tv_nsec
);
381 /* request the clock comparator external interrupt */
382 if (register_early_external_interrupt(0x1004, 0,
383 &ext_int_info_cc
) != 0)
384 panic("Couldn't request external interrupt 0x1004");
388 #ifdef CONFIG_NO_IDLE_HZ
392 #ifdef CONFIG_VIRT_TIMER