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/errno.h>
16 #include <linux/module.h>
17 #include <linux/sched.h>
18 #include <linux/kernel.h>
19 #include <linux/param.h>
20 #include <linux/string.h>
22 #include <linux/interrupt.h>
23 #include <linux/time.h>
24 #include <linux/delay.h>
25 #include <linux/init.h>
26 #include <linux/smp.h>
27 #include <linux/types.h>
28 #include <linux/profile.h>
29 #include <linux/timex.h>
30 #include <linux/notifier.h>
32 #include <asm/uaccess.h>
33 #include <asm/delay.h>
34 #include <asm/s390_ext.h>
35 #include <asm/div64.h>
37 #include <asm/timer.h>
39 /* change this if you have some constant time drift */
40 #define USECS_PER_JIFFY ((unsigned long) 1000000/HZ)
41 #define CLK_TICKS_PER_JIFFY ((unsigned long) USECS_PER_JIFFY << 12)
44 * Create a small time difference between the timer interrupts
45 * on the different cpus to avoid lock contention.
47 #define CPU_DEVIATION (smp_processor_id() << 12)
49 #define TICK_SIZE tick
51 static ext_int_info_t ext_int_info_cc;
52 static u64 init_timer_cc;
53 static u64 jiffies_timer_cc;
56 extern unsigned long wall_jiffies;
59 * Scheduler clock - returns current time in nanosec units.
61 unsigned long long sched_clock(void)
63 return ((get_clock() - jiffies_timer_cc) * 125) >> 9;
67 * Monotonic_clock - returns # of nanoseconds passed since time_init()
69 unsigned long long monotonic_clock(void)
73 EXPORT_SYMBOL(monotonic_clock);
75 void tod_to_timeval(__u64 todval, struct timespec *xtime)
77 unsigned long long sec;
82 todval -= (sec * 1000000) << 12;
83 xtime->tv_nsec = ((todval * 1000) >> 12);
86 static inline unsigned long do_gettimeoffset(void)
90 now = (get_clock() - jiffies_timer_cc) >> 12;
91 /* We require the offset from the latest update of xtime */
92 now -= (__u64) wall_jiffies*USECS_PER_JIFFY;
93 return (unsigned long) now;
97 * This version of gettimeofday has microsecond resolution.
99 void do_gettimeofday(struct timeval *tv)
103 unsigned long usec, sec;
106 seq = read_seqbegin_irqsave(&xtime_lock, flags);
109 usec = xtime.tv_nsec / 1000 + do_gettimeoffset();
110 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
112 while (usec >= 1000000) {
121 EXPORT_SYMBOL(do_gettimeofday);
123 int do_settimeofday(struct timespec *tv)
125 time_t wtm_sec, sec = tv->tv_sec;
126 long wtm_nsec, nsec = tv->tv_nsec;
128 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
131 write_seqlock_irq(&xtime_lock);
132 /* This is revolting. We need to set the xtime.tv_nsec
133 * correctly. However, the value in this location is
134 * is value at the last tick.
135 * Discover what correction gettimeofday
136 * would have done, and then undo it!
138 nsec -= do_gettimeoffset() * 1000;
140 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
141 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
143 set_normalized_timespec(&xtime, sec, nsec);
144 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
147 write_sequnlock_irq(&xtime_lock);
152 EXPORT_SYMBOL(do_settimeofday);
155 #ifdef CONFIG_PROFILING
156 #define s390_do_profile(regs) profile_tick(CPU_PROFILING, regs)
158 #define s390_do_profile(regs) do { ; } while(0)
159 #endif /* CONFIG_PROFILING */
163 * timer_interrupt() needs to keep up the real-time clock,
164 * as well as call the "do_timer()" routine every clocktick
166 void account_ticks(struct pt_regs *regs)
171 /* Calculate how many ticks have passed. */
172 if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) {
174 * We have to program the clock comparator even if
175 * no tick has passed. That happens if e.g. an i/o
176 * interrupt wakes up an idle processor that has
177 * switched off its hz timer.
179 tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
180 asm volatile ("SCKC %0" : : "m" (tmp));
183 tmp = S390_lowcore.int_clock - S390_lowcore.jiffy_timer;
184 if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than two ticks ? */
185 ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1;
186 S390_lowcore.jiffy_timer +=
187 CLK_TICKS_PER_JIFFY * (__u64) ticks;
188 } else if (tmp >= CLK_TICKS_PER_JIFFY) {
190 S390_lowcore.jiffy_timer += 2*CLK_TICKS_PER_JIFFY;
193 S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY;
196 /* set clock comparator for next tick */
197 tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION;
198 asm volatile ("SCKC %0" : : "m" (tmp));
202 * Do not rely on the boot cpu to do the calls to do_timer.
203 * Spread it over all cpus instead.
205 write_seqlock(&xtime_lock);
206 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;
218 write_sequnlock(&xtime_lock);
223 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
224 account_tick_vtime(current);
227 update_process_times(user_mode(regs));
230 s390_do_profile(regs);
233 #ifdef CONFIG_NO_IDLE_HZ
235 #ifdef CONFIG_NO_IDLE_HZ_INIT
236 int sysctl_hz_timer = 0;
238 int sysctl_hz_timer = 1;
242 * Stop the HZ tick on the current CPU.
243 * Only cpu_idle may call this function.
245 static inline void stop_hz_timer(void)
248 unsigned long seq, next;
250 int cpu = smp_processor_id();
252 if (sysctl_hz_timer != 0)
255 cpu_set(cpu, nohz_cpu_mask);
258 * Leave the clock comparator set up for the next timer
259 * tick if either rcu or a softirq is pending.
261 if (rcu_needs_cpu(cpu) || local_softirq_pending()) {
262 cpu_clear(cpu, nohz_cpu_mask);
267 * This cpu is going really idle. Set up the clock comparator
268 * for the next event.
270 next = next_timer_interrupt();
272 seq = read_seqbegin_irqsave(&xtime_lock, flags);
273 timer = ((__u64) next) - ((__u64) jiffies) + jiffies_64;
274 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
276 /* Be careful about overflows. */
277 if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) {
278 timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY;
279 if (timer >= jiffies_timer_cc)
282 asm volatile ("SCKC %0" : : "m" (todval));
286 * Start the HZ tick on the current CPU.
287 * Only cpu_idle may call this function.
289 static inline void start_hz_timer(void)
291 if (!cpu_isset(smp_processor_id(), nohz_cpu_mask))
293 account_ticks(task_pt_regs(current));
294 cpu_clear(smp_processor_id(), nohz_cpu_mask);
297 static int nohz_idle_notify(struct notifier_block *self,
298 unsigned long action, void *hcpu)
311 static struct notifier_block nohz_idle_nb = {
312 .notifier_call = nohz_idle_notify,
315 void __init nohz_init(void)
317 if (register_idle_notifier(&nohz_idle_nb))
318 panic("Couldn't register idle notifier");
324 * Start the clock comparator on the current CPU.
326 void init_cpu_timer(void)
331 timer = jiffies_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY;
332 S390_lowcore.jiffy_timer = timer + CLK_TICKS_PER_JIFFY;
333 timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION;
334 asm volatile ("SCKC %0" : : "m" (timer));
335 /* allow clock comparator timer interrupt */
336 __ctl_store(cr0, 0, 0);
338 __ctl_load(cr0, 0, 0);
341 extern void vtime_init(void);
344 * Initialize the TOD clock and the CPU timer of
347 void __init time_init(void)
352 /* kick the TOD clock */
357 : "=d" (cc), "=m" (init_timer_cc)
358 : "a" (&init_timer_cc) : "cc");
360 case 0: /* clock in set state: all is fine */
362 case 1: /* clock in non-set state: FIXME */
363 printk("time_init: TOD clock in non-set state\n");
365 case 2: /* clock in error state: FIXME */
366 printk("time_init: TOD clock in error state\n");
368 case 3: /* clock in stopped or not-operational state: FIXME */
369 printk("time_init: TOD clock stopped/non-operational\n");
372 jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY;
375 xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY;
376 set_time_cc = init_timer_cc - 0x8126d60e46000000LL +
377 (0x3c26700LL*1000000*4096);
378 tod_to_timeval(set_time_cc, &xtime);
379 set_normalized_timespec(&wall_to_monotonic,
380 -xtime.tv_sec, -xtime.tv_nsec);
382 /* request the clock comparator external interrupt */
383 if (register_early_external_interrupt(0x1004, NULL,
384 &ext_int_info_cc) != 0)
385 panic("Couldn't request external interrupt 0x1004");
389 #ifdef CONFIG_NO_IDLE_HZ
393 #ifdef CONFIG_VIRT_TIMER