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1da177e4 LT |
1 | /* |
2 | * arch/s390/kernel/time.c | |
3 | * Time of day based timer functions. | |
4 | * | |
5 | * S390 version | |
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) | |
10 | * | |
11 | * Derived from "arch/i386/kernel/time.c" | |
12 | * Copyright (C) 1991, 1992, 1995 Linus Torvalds | |
13 | */ | |
14 | ||
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> | |
22 | #include <linux/mm.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> | |
32 | ||
33 | #include <asm/uaccess.h> | |
34 | #include <asm/delay.h> | |
35 | #include <asm/s390_ext.h> | |
36 | #include <asm/div64.h> | |
37 | #include <asm/irq.h> | |
38 | #include <asm/timer.h> | |
39 | ||
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) | |
43 | ||
44 | /* | |
45 | * Create a small time difference between the timer interrupts | |
46 | * on the different cpus to avoid lock contention. | |
47 | */ | |
48 | #define CPU_DEVIATION (smp_processor_id() << 12) | |
49 | ||
50 | #define TICK_SIZE tick | |
51 | ||
1da177e4 LT |
52 | static ext_int_info_t ext_int_info_cc; |
53 | static u64 init_timer_cc; | |
54 | static u64 jiffies_timer_cc; | |
55 | static u64 xtime_cc; | |
56 | ||
57 | extern unsigned long wall_jiffies; | |
58 | ||
59 | /* | |
60 | * Scheduler clock - returns current time in nanosec units. | |
61 | */ | |
62 | unsigned long long sched_clock(void) | |
63 | { | |
64 | return ((get_clock() - jiffies_timer_cc) * 1000) >> 12; | |
65 | } | |
66 | ||
67 | void tod_to_timeval(__u64 todval, struct timespec *xtime) | |
68 | { | |
69 | unsigned long long sec; | |
70 | ||
71 | sec = todval >> 12; | |
72 | do_div(sec, 1000000); | |
73 | xtime->tv_sec = sec; | |
74 | todval -= (sec * 1000000) << 12; | |
75 | xtime->tv_nsec = ((todval * 1000) >> 12); | |
76 | } | |
77 | ||
78 | static inline unsigned long do_gettimeoffset(void) | |
79 | { | |
80 | __u64 now; | |
81 | ||
82 | now = (get_clock() - jiffies_timer_cc) >> 12; | |
83 | /* We require the offset from the latest update of xtime */ | |
84 | now -= (__u64) wall_jiffies*USECS_PER_JIFFY; | |
85 | return (unsigned long) now; | |
86 | } | |
87 | ||
88 | /* | |
89 | * This version of gettimeofday has microsecond resolution. | |
90 | */ | |
91 | void do_gettimeofday(struct timeval *tv) | |
92 | { | |
93 | unsigned long flags; | |
94 | unsigned long seq; | |
95 | unsigned long usec, sec; | |
96 | ||
97 | do { | |
98 | seq = read_seqbegin_irqsave(&xtime_lock, flags); | |
99 | ||
100 | sec = xtime.tv_sec; | |
101 | usec = xtime.tv_nsec / 1000 + do_gettimeoffset(); | |
102 | } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); | |
103 | ||
104 | while (usec >= 1000000) { | |
105 | usec -= 1000000; | |
106 | sec++; | |
107 | } | |
108 | ||
109 | tv->tv_sec = sec; | |
110 | tv->tv_usec = usec; | |
111 | } | |
112 | ||
113 | EXPORT_SYMBOL(do_gettimeofday); | |
114 | ||
115 | int do_settimeofday(struct timespec *tv) | |
116 | { | |
117 | time_t wtm_sec, sec = tv->tv_sec; | |
118 | long wtm_nsec, nsec = tv->tv_nsec; | |
119 | ||
120 | if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC) | |
121 | return -EINVAL; | |
122 | ||
123 | write_seqlock_irq(&xtime_lock); | |
124 | /* This is revolting. We need to set the xtime.tv_nsec | |
125 | * correctly. However, the value in this location is | |
126 | * is value at the last tick. | |
127 | * Discover what correction gettimeofday | |
128 | * would have done, and then undo it! | |
129 | */ | |
130 | nsec -= do_gettimeoffset() * 1000; | |
131 | ||
132 | wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec); | |
133 | wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec); | |
134 | ||
135 | set_normalized_timespec(&xtime, sec, nsec); | |
136 | set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec); | |
137 | ||
b149ee22 | 138 | ntp_clear(); |
1da177e4 LT |
139 | write_sequnlock_irq(&xtime_lock); |
140 | clock_was_set(); | |
141 | return 0; | |
142 | } | |
143 | ||
144 | EXPORT_SYMBOL(do_settimeofday); | |
145 | ||
146 | ||
147 | #ifdef CONFIG_PROFILING | |
148 | #define s390_do_profile(regs) profile_tick(CPU_PROFILING, regs) | |
149 | #else | |
150 | #define s390_do_profile(regs) do { ; } while(0) | |
151 | #endif /* CONFIG_PROFILING */ | |
152 | ||
153 | ||
154 | /* | |
155 | * timer_interrupt() needs to keep up the real-time clock, | |
156 | * as well as call the "do_timer()" routine every clocktick | |
157 | */ | |
158 | void account_ticks(struct pt_regs *regs) | |
159 | { | |
160 | __u64 tmp; | |
161 | __u32 ticks, xticks; | |
162 | ||
163 | /* Calculate how many ticks have passed. */ | |
164 | if (S390_lowcore.int_clock < S390_lowcore.jiffy_timer) { | |
165 | /* | |
166 | * We have to program the clock comparator even if | |
167 | * no tick has passed. That happens if e.g. an i/o | |
168 | * interrupt wakes up an idle processor that has | |
169 | * switched off its hz timer. | |
170 | */ | |
171 | tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION; | |
172 | asm volatile ("SCKC %0" : : "m" (tmp)); | |
173 | return; | |
174 | } | |
175 | tmp = S390_lowcore.int_clock - S390_lowcore.jiffy_timer; | |
176 | if (tmp >= 2*CLK_TICKS_PER_JIFFY) { /* more than two ticks ? */ | |
177 | ticks = __div(tmp, CLK_TICKS_PER_JIFFY) + 1; | |
178 | S390_lowcore.jiffy_timer += | |
179 | CLK_TICKS_PER_JIFFY * (__u64) ticks; | |
180 | } else if (tmp >= CLK_TICKS_PER_JIFFY) { | |
181 | ticks = 2; | |
182 | S390_lowcore.jiffy_timer += 2*CLK_TICKS_PER_JIFFY; | |
183 | } else { | |
184 | ticks = 1; | |
185 | S390_lowcore.jiffy_timer += CLK_TICKS_PER_JIFFY; | |
186 | } | |
187 | ||
188 | /* set clock comparator for next tick */ | |
189 | tmp = S390_lowcore.jiffy_timer + CPU_DEVIATION; | |
190 | asm volatile ("SCKC %0" : : "m" (tmp)); | |
191 | ||
192 | #ifdef CONFIG_SMP | |
193 | /* | |
194 | * Do not rely on the boot cpu to do the calls to do_timer. | |
195 | * Spread it over all cpus instead. | |
196 | */ | |
197 | write_seqlock(&xtime_lock); | |
198 | if (S390_lowcore.jiffy_timer > xtime_cc) { | |
199 | tmp = S390_lowcore.jiffy_timer - xtime_cc; | |
200 | if (tmp >= 2*CLK_TICKS_PER_JIFFY) { | |
201 | xticks = __div(tmp, CLK_TICKS_PER_JIFFY); | |
202 | xtime_cc += (__u64) xticks * CLK_TICKS_PER_JIFFY; | |
203 | } else { | |
204 | xticks = 1; | |
205 | xtime_cc += CLK_TICKS_PER_JIFFY; | |
206 | } | |
207 | while (xticks--) | |
208 | do_timer(regs); | |
209 | } | |
210 | write_sequnlock(&xtime_lock); | |
211 | #else | |
212 | for (xticks = ticks; xticks > 0; xticks--) | |
213 | do_timer(regs); | |
214 | #endif | |
215 | ||
216 | #ifdef CONFIG_VIRT_CPU_ACCOUNTING | |
1f1c12af | 217 | account_tick_vtime(current); |
1da177e4 LT |
218 | #else |
219 | while (ticks--) | |
220 | update_process_times(user_mode(regs)); | |
221 | #endif | |
222 | ||
223 | s390_do_profile(regs); | |
224 | } | |
225 | ||
226 | #ifdef CONFIG_NO_IDLE_HZ | |
227 | ||
228 | #ifdef CONFIG_NO_IDLE_HZ_INIT | |
229 | int sysctl_hz_timer = 0; | |
230 | #else | |
231 | int sysctl_hz_timer = 1; | |
232 | #endif | |
233 | ||
234 | /* | |
235 | * Stop the HZ tick on the current CPU. | |
236 | * Only cpu_idle may call this function. | |
237 | */ | |
238 | static inline void stop_hz_timer(void) | |
239 | { | |
1b44e98d MS |
240 | unsigned long flags; |
241 | unsigned long seq, next; | |
4b7e0706 | 242 | __u64 timer, todval; |
1da177e4 LT |
243 | |
244 | if (sysctl_hz_timer != 0) | |
245 | return; | |
246 | ||
247 | cpu_set(smp_processor_id(), nohz_cpu_mask); | |
248 | ||
249 | /* | |
250 | * Leave the clock comparator set up for the next timer | |
251 | * tick if either rcu or a softirq is pending. | |
252 | */ | |
253 | if (rcu_pending(smp_processor_id()) || local_softirq_pending()) { | |
254 | cpu_clear(smp_processor_id(), nohz_cpu_mask); | |
255 | return; | |
256 | } | |
257 | ||
258 | /* | |
259 | * This cpu is going really idle. Set up the clock comparator | |
260 | * for the next event. | |
261 | */ | |
1b44e98d MS |
262 | next = next_timer_interrupt(); |
263 | do { | |
264 | seq = read_seqbegin_irqsave(&xtime_lock, flags); | |
265 | timer = (__u64)(next - jiffies) + jiffies_64; | |
266 | } while (read_seqretry_irqrestore(&xtime_lock, seq, flags)); | |
4b7e0706 MS |
267 | todval = -1ULL; |
268 | /* Be careful about overflows. */ | |
269 | if (timer < (-1ULL / CLK_TICKS_PER_JIFFY)) { | |
270 | timer = jiffies_timer_cc + timer * CLK_TICKS_PER_JIFFY; | |
271 | if (timer >= jiffies_timer_cc) | |
272 | todval = timer; | |
273 | } | |
274 | asm volatile ("SCKC %0" : : "m" (todval)); | |
1da177e4 LT |
275 | } |
276 | ||
277 | /* | |
278 | * Start the HZ tick on the current CPU. | |
279 | * Only cpu_idle may call this function. | |
280 | */ | |
281 | static inline void start_hz_timer(void) | |
282 | { | |
283 | if (!cpu_isset(smp_processor_id(), nohz_cpu_mask)) | |
284 | return; | |
c7584fb6 | 285 | account_ticks(task_pt_regs(current)); |
1da177e4 LT |
286 | cpu_clear(smp_processor_id(), nohz_cpu_mask); |
287 | } | |
288 | ||
289 | static int nohz_idle_notify(struct notifier_block *self, | |
290 | unsigned long action, void *hcpu) | |
291 | { | |
292 | switch (action) { | |
293 | case CPU_IDLE: | |
294 | stop_hz_timer(); | |
295 | break; | |
296 | case CPU_NOT_IDLE: | |
297 | start_hz_timer(); | |
298 | break; | |
299 | } | |
300 | return NOTIFY_OK; | |
301 | } | |
302 | ||
303 | static struct notifier_block nohz_idle_nb = { | |
304 | .notifier_call = nohz_idle_notify, | |
305 | }; | |
306 | ||
307 | void __init nohz_init(void) | |
308 | { | |
309 | if (register_idle_notifier(&nohz_idle_nb)) | |
310 | panic("Couldn't register idle notifier"); | |
311 | } | |
312 | ||
313 | #endif | |
314 | ||
315 | /* | |
316 | * Start the clock comparator on the current CPU. | |
317 | */ | |
318 | void init_cpu_timer(void) | |
319 | { | |
320 | unsigned long cr0; | |
321 | __u64 timer; | |
322 | ||
323 | timer = jiffies_timer_cc + jiffies_64 * CLK_TICKS_PER_JIFFY; | |
324 | S390_lowcore.jiffy_timer = timer + CLK_TICKS_PER_JIFFY; | |
325 | timer += CLK_TICKS_PER_JIFFY + CPU_DEVIATION; | |
326 | asm volatile ("SCKC %0" : : "m" (timer)); | |
327 | /* allow clock comparator timer interrupt */ | |
328 | __ctl_store(cr0, 0, 0); | |
329 | cr0 |= 0x800; | |
330 | __ctl_load(cr0, 0, 0); | |
331 | } | |
332 | ||
333 | extern void vtime_init(void); | |
334 | ||
335 | /* | |
336 | * Initialize the TOD clock and the CPU timer of | |
337 | * the boot cpu. | |
338 | */ | |
339 | void __init time_init(void) | |
340 | { | |
341 | __u64 set_time_cc; | |
342 | int cc; | |
343 | ||
344 | /* kick the TOD clock */ | |
345 | asm volatile ("STCK 0(%1)\n\t" | |
346 | "IPM %0\n\t" | |
347 | "SRL %0,28" : "=r" (cc) : "a" (&init_timer_cc) | |
348 | : "memory", "cc"); | |
349 | switch (cc) { | |
350 | case 0: /* clock in set state: all is fine */ | |
351 | break; | |
352 | case 1: /* clock in non-set state: FIXME */ | |
353 | printk("time_init: TOD clock in non-set state\n"); | |
354 | break; | |
355 | case 2: /* clock in error state: FIXME */ | |
356 | printk("time_init: TOD clock in error state\n"); | |
357 | break; | |
358 | case 3: /* clock in stopped or not-operational state: FIXME */ | |
359 | printk("time_init: TOD clock stopped/non-operational\n"); | |
360 | break; | |
361 | } | |
362 | jiffies_timer_cc = init_timer_cc - jiffies_64 * CLK_TICKS_PER_JIFFY; | |
363 | ||
364 | /* set xtime */ | |
365 | xtime_cc = init_timer_cc + CLK_TICKS_PER_JIFFY; | |
366 | set_time_cc = init_timer_cc - 0x8126d60e46000000LL + | |
367 | (0x3c26700LL*1000000*4096); | |
368 | tod_to_timeval(set_time_cc, &xtime); | |
369 | set_normalized_timespec(&wall_to_monotonic, | |
370 | -xtime.tv_sec, -xtime.tv_nsec); | |
371 | ||
372 | /* request the clock comparator external interrupt */ | |
373 | if (register_early_external_interrupt(0x1004, 0, | |
374 | &ext_int_info_cc) != 0) | |
375 | panic("Couldn't request external interrupt 0x1004"); | |
376 | ||
377 | init_cpu_timer(); | |
378 | ||
379 | #ifdef CONFIG_NO_IDLE_HZ | |
380 | nohz_init(); | |
381 | #endif | |
382 | ||
383 | #ifdef CONFIG_VIRT_TIMER | |
384 | vtime_init(); | |
385 | #endif | |
386 | } | |
387 |