2 * Copyright 2001 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 * Copyright (c) 2003, 2004 Maciej W. Rozycki
6 * Common time service routines for MIPS machines. See
7 * Documentation/mips/time.README.
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
14 #include <linux/types.h>
15 #include <linux/kernel.h>
16 #include <linux/init.h>
17 #include <linux/sched.h>
18 #include <linux/param.h>
19 #include <linux/profile.h>
20 #include <linux/time.h>
21 #include <linux/timex.h>
22 #include <linux/smp.h>
23 #include <linux/kernel_stat.h>
24 #include <linux/spinlock.h>
25 #include <linux/interrupt.h>
26 #include <linux/module.h>
28 #include <asm/bootinfo.h>
29 #include <asm/cache.h>
30 #include <asm/compiler.h>
32 #include <asm/cpu-features.h>
33 #include <asm/div64.h>
34 #include <asm/sections.h>
38 * The integer part of the number of usecs per jiffy is taken from tick,
39 * but the fractional part is not recorded, so we calculate it using the
40 * initial value of HZ. This aids systems where tick isn't really an
41 * integer (e.g. for HZ = 128).
43 #define USECS_PER_JIFFY TICK_SIZE
44 #define USECS_PER_JIFFY_FRAC ((unsigned long)(u32)((1000000ULL << 32) / HZ))
46 #define TICK_SIZE (tick_nsec / 1000)
51 DEFINE_SPINLOCK(rtc_lock);
52 EXPORT_SYMBOL(rtc_lock);
54 int __weak rtc_mips_set_time(unsigned long sec)
58 EXPORT_SYMBOL(rtc_mips_set_time);
60 int __weak rtc_mips_set_mmss(unsigned long nowtime)
62 return rtc_mips_set_time(nowtime);
65 int update_persistent_clock(struct timespec now)
67 return rtc_mips_set_mmss(now.tv_sec);
70 /* how many counter cycles in a jiffy */
71 static unsigned long cycles_per_jiffy __read_mostly;
73 /* expirelo is the count value for next CPU timer interrupt */
74 static unsigned int expirelo;
78 * Null timer ack for systems not needing one (e.g. i8254).
80 static void null_timer_ack(void) { /* nothing */ }
83 * Null high precision timer functions for systems lacking one.
85 static cycle_t null_hpt_read(void)
91 * Timer ack for an R4k-compatible timer of a known frequency.
93 static void c0_timer_ack(void)
97 /* Ack this timer interrupt and set the next one. */
98 expirelo += cycles_per_jiffy;
99 write_c0_compare(expirelo);
101 /* Check to see if we have missed any timer interrupts. */
102 while (((count = read_c0_count()) - expirelo) < 0x7fffffff) {
103 /* missed_timer_count++; */
104 expirelo = count + cycles_per_jiffy;
105 write_c0_compare(expirelo);
110 * High precision timer functions for a R4k-compatible timer.
112 static cycle_t c0_hpt_read(void)
114 return read_c0_count();
117 /* For use both as a high precision timer and an interrupt source. */
118 static void __init c0_hpt_timer_init(void)
120 expirelo = read_c0_count() + cycles_per_jiffy;
121 write_c0_compare(expirelo);
124 int (*mips_timer_state)(void);
125 void (*mips_timer_ack)(void);
128 * local_timer_interrupt() does profiling and process accounting
129 * on a per-CPU basis.
131 * In UP mode, it is invoked from the (global) timer_interrupt.
133 * In SMP mode, it might invoked by per-CPU timer interrupt, or
134 * a broadcasted inter-processor interrupt which itself is triggered
135 * by the global timer interrupt.
137 void local_timer_interrupt(int irq, void *dev_id)
139 profile_tick(CPU_PROFILING);
140 update_process_times(user_mode(get_irq_regs()));
144 * High-level timer interrupt service routines. This function
145 * is set as irqaction->handler and is invoked through do_IRQ.
147 irqreturn_t timer_interrupt(int irq, void *dev_id)
149 write_seqlock(&xtime_lock);
154 * call the generic timer interrupt handling
158 write_sequnlock(&xtime_lock);
161 * In UP mode, we call local_timer_interrupt() to do profiling
162 * and process accouting.
164 * In SMP mode, local_timer_interrupt() is invoked by appropriate
165 * low-level local timer interrupt handler.
167 local_timer_interrupt(irq, dev_id);
172 int null_perf_irq(void)
177 int (*perf_irq)(void) = null_perf_irq;
179 EXPORT_SYMBOL(null_perf_irq);
180 EXPORT_SYMBOL(perf_irq);
188 * Performance counter IRQ or -1 if shared with timer
190 int cp0_perfcount_irq;
191 EXPORT_SYMBOL_GPL(cp0_perfcount_irq);
194 * Possibly handle a performance counter interrupt.
195 * Return true if the timer interrupt should not be checked
197 static inline int handle_perf_irq (int r2)
200 * The performance counter overflow interrupt may be shared with the
201 * timer interrupt (cp0_perfcount_irq < 0). If it is and a
202 * performance counter has overflowed (perf_irq() == IRQ_HANDLED)
203 * and we can't reliably determine if a counter interrupt has also
204 * happened (!r2) then don't check for a timer interrupt.
206 return (cp0_perfcount_irq < 0) &&
207 perf_irq() == IRQ_HANDLED &&
211 asmlinkage void ll_timer_interrupt(int irq)
213 int r2 = cpu_has_mips_r2;
216 kstat_this_cpu.irqs[irq]++;
218 if (handle_perf_irq(r2))
221 if (r2 && ((read_c0_cause() & (1 << 30)) == 0))
224 timer_interrupt(irq, NULL);
230 asmlinkage void ll_local_timer_interrupt(int irq)
233 if (smp_processor_id() != 0)
234 kstat_this_cpu.irqs[irq]++;
236 /* we keep interrupt disabled all the time */
237 local_timer_interrupt(irq, NULL);
243 * time_init() - it does the following things.
245 * 1) plat_time_init() -
246 * a) (optional) set up RTC routines,
247 * b) (optional) calibrate and set the mips_hpt_frequency
248 * (only needed if you intended to use cpu counter as timer interrupt
250 * 2) calculate a couple of cached variables for later usage
251 * 3) plat_timer_setup() -
252 * a) (optional) over-write any choices made above by time_init().
253 * b) machine specific code should setup the timer irqaction.
254 * c) enable the timer interrupt
257 unsigned int mips_hpt_frequency;
259 static struct irqaction timer_irqaction = {
260 .handler = timer_interrupt,
261 .flags = IRQF_DISABLED | IRQF_PERCPU,
265 static unsigned int __init calibrate_hpt(void)
267 cycle_t frequency, hpt_start, hpt_end, hpt_count, hz;
269 const int loops = HZ / 10;
274 * We want to calibrate for 0.1s, but to avoid a 64-bit
275 * division we round the number of loops up to the nearest
278 while (loops > 1 << log_2_loops)
280 i = 1 << log_2_loops;
283 * Wait for a rising edge of the timer interrupt.
285 while (mips_timer_state());
286 while (!mips_timer_state());
289 * Now see how many high precision timer ticks happen
290 * during the calculated number of periods between timer
293 hpt_start = clocksource_mips.read();
295 while (mips_timer_state());
296 while (!mips_timer_state());
298 hpt_end = clocksource_mips.read();
300 hpt_count = (hpt_end - hpt_start) & clocksource_mips.mask;
302 frequency = hpt_count * hz;
304 return frequency >> log_2_loops;
307 struct clocksource clocksource_mips = {
309 .mask = CLOCKSOURCE_MASK(32),
310 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
313 static void __init init_mips_clocksource(void)
318 if (!mips_hpt_frequency || clocksource_mips.read == null_hpt_read)
321 /* Calclate a somewhat reasonable rating value */
322 clocksource_mips.rating = 200 + mips_hpt_frequency / 10000000;
323 /* Find a shift value */
324 for (shift = 32; shift > 0; shift--) {
325 temp = (u64) NSEC_PER_SEC << shift;
326 do_div(temp, mips_hpt_frequency);
327 if ((temp >> 32) == 0)
330 clocksource_mips.shift = shift;
331 clocksource_mips.mult = (u32)temp;
333 clocksource_register(&clocksource_mips);
336 void __init __weak plat_time_init(void)
340 void __init time_init(void)
344 /* Choose appropriate high precision timer routines. */
345 if (!cpu_has_counter && !clocksource_mips.read)
346 /* No high precision timer -- sorry. */
347 clocksource_mips.read = null_hpt_read;
348 else if (!mips_hpt_frequency && !mips_timer_state) {
349 /* A high precision timer of unknown frequency. */
350 if (!clocksource_mips.read)
351 /* No external high precision timer -- use R4k. */
352 clocksource_mips.read = c0_hpt_read;
354 /* We know counter frequency. Or we can get it. */
355 if (!clocksource_mips.read) {
356 /* No external high precision timer -- use R4k. */
357 clocksource_mips.read = c0_hpt_read;
359 if (!mips_timer_state) {
360 /* No external timer interrupt -- use R4k. */
361 mips_timer_ack = c0_timer_ack;
362 /* Calculate cache parameters. */
364 (mips_hpt_frequency + HZ / 2) / HZ;
366 * This sets up the high precision
367 * timer for the first interrupt.
372 if (!mips_hpt_frequency)
373 mips_hpt_frequency = calibrate_hpt();
375 /* Report the high precision timer rate for a reference. */
376 printk("Using %u.%03u MHz high precision timer.\n",
377 ((mips_hpt_frequency + 500) / 1000) / 1000,
378 ((mips_hpt_frequency + 500) / 1000) % 1000);
382 /* No timer interrupt ack (e.g. i8254). */
383 mips_timer_ack = null_timer_ack;
386 * Call board specific timer interrupt setup.
388 * this pointer must be setup in machine setup routine.
390 * Even if a machine chooses to use a low-level timer interrupt,
391 * it still needs to setup the timer_irqaction.
392 * In that case, it might be better to set timer_irqaction.handler
393 * to be NULL function so that we are sure the high-level code
394 * is not invoked accidentally.
396 plat_timer_setup(&timer_irqaction);
398 init_mips_clocksource();
402 #define STARTOFTIME 1970
403 #define SECDAY 86400L
404 #define SECYR (SECDAY * 365)
405 #define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
406 #define days_in_year(y) (leapyear(y) ? 366 : 365)
407 #define days_in_month(m) (month_days[(m) - 1])
409 static int month_days[12] = {
410 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
413 void to_tm(unsigned long tim, struct rtc_time *tm)
418 gday = day = tim / SECDAY;
421 /* Hours, minutes, seconds are easy */
422 tm->tm_hour = hms / 3600;
423 tm->tm_min = (hms % 3600) / 60;
424 tm->tm_sec = (hms % 3600) % 60;
426 /* Number of years in days */
427 for (i = STARTOFTIME; day >= days_in_year(i); i++)
428 day -= days_in_year(i);
431 /* Number of months in days left */
432 if (leapyear(tm->tm_year))
433 days_in_month(FEBRUARY) = 29;
434 for (i = 1; day >= days_in_month(i); i++)
435 day -= days_in_month(i);
436 days_in_month(FEBRUARY) = 28;
437 tm->tm_mon = i - 1; /* tm_mon starts from 0 to 11 */
439 /* Days are what is left over (+1) from all that. */
440 tm->tm_mday = day + 1;
443 * Determine the day of week
445 tm->tm_wday = (gday + 4) % 7; /* 1970/1/1 was Thursday */
448 EXPORT_SYMBOL(to_tm);