/arch/arm/kernel/time.c

  1/*
  2 *  linux/arch/arm/kernel/time.c
  3 *
  4 *  Copyright (C) 1991, 1992, 1995  Linus Torvalds
  5 *  Modifications for ARM (C) 1994-2001 Russell King
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 *
 11 *  This file contains the ARM-specific time handling details:
 12 *  reading the RTC at bootup, etc...
 13 *
 14 *  1994-07-02  Alan Modra
 15 *              fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
 16 *  1998-12-20  Updated NTP code according to technical memorandum Jan '96
 17 *              "A Kernel Model for Precision Timekeeping" by Dave Mills
 18 */
 19#include <linux/config.h>
 20#include <linux/module.h>
 21#include <linux/kernel.h>
 22#include <linux/interrupt.h>
 23#include <linux/time.h>
 24#include <linux/init.h>
 25#include <linux/smp.h>
 26#include <linux/timex.h>
 27#include <linux/errno.h>
 28#include <linux/profile.h>
 29#include <linux/sysdev.h>
 30#include <linux/timer.h>
 31
 32#include <asm/hardware.h>
 33#include <asm/io.h>
 34#include <asm/irq.h>
 35#include <asm/leds.h>
 36#include <asm/thread_info.h>
 37#include <asm/mach/time.h>
 38
 39u64 jiffies_64 = INITIAL_JIFFIES;
 40
 41EXPORT_SYMBOL(jiffies_64);
 42
 43/*
 44 * Our system timer.
 45 */
 46struct sys_timer *system_timer;
 47
 48extern unsigned long wall_jiffies;
 49
 50/* this needs a better home */
 51DEFINE_SPINLOCK(rtc_lock);
 52
 53#ifdef CONFIG_SA1100_RTC_MODULE
 54EXPORT_SYMBOL(rtc_lock);
 55#endif
 56
 57/* change this if you have some constant time drift */
 58#define USECS_PER_JIFFY	(1000000/HZ)
 59
 60#ifdef CONFIG_SMP
 61unsigned long profile_pc(struct pt_regs *regs)
 62{
 63	unsigned long fp, pc = instruction_pointer(regs);
 64
 65	if (in_lock_functions(pc)) {
 66		fp = regs->ARM_fp;
 67		pc = pc_pointer(((unsigned long *)fp)[-1]);
 68	}
 69
 70	return pc;
 71}
 72EXPORT_SYMBOL(profile_pc);
 73#endif
 74
 75/*
 76 * hook for setting the RTC's idea of the current time.
 77 */
 78int (*set_rtc)(void);
 79
 80static unsigned long dummy_gettimeoffset(void)
 81{
 82	return 0;
 83}
 84
 85/*
 86 * Scheduler clock - returns current time in nanosec units.
 87 * This is the default implementation.  Sub-architecture
 88 * implementations can override this.
 89 */
 90unsigned long long __attribute__((weak)) sched_clock(void)
 91{
 92	return (unsigned long long)jiffies * (1000000000 / HZ);
 93}
 94
 95static unsigned long next_rtc_update;
 96
 97/*
 98 * If we have an externally synchronized linux clock, then update
 99 * CMOS clock accordingly every ~11 minutes.  set_rtc() has to be
100 * called as close as possible to 500 ms before the new second
101 * starts.
102 */
103static inline void do_set_rtc(void)
104{
105	if (time_status & STA_UNSYNC || set_rtc == NULL)
106		return;
107
108	if (next_rtc_update &&
109	    time_before((unsigned long)xtime.tv_sec, next_rtc_update))
110		return;
111
112	if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
113	    xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
114		return;
115
116	if (set_rtc())
117		/*
118		 * rtc update failed.  Try again in 60s
119		 */
120		next_rtc_update = xtime.tv_sec + 60;
121	else
122		next_rtc_update = xtime.tv_sec + 660;
123}
124
125#ifdef CONFIG_LEDS
126
127static void dummy_leds_event(led_event_t evt)
128{
129}
130
131void (*leds_event)(led_event_t) = dummy_leds_event;
132
133struct leds_evt_name {
134	const char	name[8];
135	int		on;
136	int		off;
137};
138
139static const struct leds_evt_name evt_names[] = {
140	{ "amber", led_amber_on, led_amber_off },
141	{ "blue",  led_blue_on,  led_blue_off  },
142	{ "green", led_green_on, led_green_off },
143	{ "red",   led_red_on,   led_red_off   },
144};
145
146static ssize_t leds_store(struct sys_device *dev, const char *buf, size_t size)
147{
148	int ret = -EINVAL, len = strcspn(buf, " ");
149
150	if (len > 0 && buf[len] == '\0')
151		len--;
152
153	if (strncmp(buf, "claim", len) == 0) {
154		leds_event(led_claim);
155		ret = size;
156	} else if (strncmp(buf, "release", len) == 0) {
157		leds_event(led_release);
158		ret = size;
159	} else {
160		int i;
161
162		for (i = 0; i < ARRAY_SIZE(evt_names); i++) {
163			if (strlen(evt_names[i].name) != len ||
164			    strncmp(buf, evt_names[i].name, len) != 0)
165				continue;
166			if (strncmp(buf+len, " on", 3) == 0) {
167				leds_event(evt_names[i].on);
168				ret = size;
169			} else if (strncmp(buf+len, " off", 4) == 0) {
170				leds_event(evt_names[i].off);
171				ret = size;
172			}
173			break;
174		}
175	}
176	return ret;
177}
178
179static SYSDEV_ATTR(event, 0200, NULL, leds_store);
180
181static int leds_suspend(struct sys_device *dev, pm_message_t state)
182{
183	leds_event(led_stop);
184	return 0;
185}
186
187static int leds_resume(struct sys_device *dev)
188{
189	leds_event(led_start);
190	return 0;
191}
192
193static int leds_shutdown(struct sys_device *dev)
194{
195	leds_event(led_halted);
196	return 0;
197}
198
199static struct sysdev_class leds_sysclass = {
200	set_kset_name("leds"),
201	.shutdown	= leds_shutdown,
202	.suspend	= leds_suspend,
203	.resume		= leds_resume,
204};
205
206static struct sys_device leds_device = {
207	.id		= 0,
208	.cls		= &leds_sysclass,
209};
210
211static int __init leds_init(void)
212{
213	int ret;
214	ret = sysdev_class_register(&leds_sysclass);
215	if (ret == 0)
216		ret = sysdev_register(&leds_device);
217	if (ret == 0)
218		ret = sysdev_create_file(&leds_device, &attr_event);
219	return ret;
220}
221
222device_initcall(leds_init);
223
224EXPORT_SYMBOL(leds_event);
225#endif
226
227#ifdef CONFIG_LEDS_TIMER
228static inline void do_leds(void)
229{
230	static unsigned int count = 50;
231
232	if (--count == 0) {
233		count = 50;
234		leds_event(led_timer);
235	}
236}
237#else
238#define	do_leds()
239#endif
240
241void do_gettimeofday(struct timeval *tv)
242{
243	unsigned long flags;
244	unsigned long seq;
245	unsigned long usec, sec, lost;
246
247	do {
248		seq = read_seqbegin_irqsave(&xtime_lock, flags);
249		usec = system_timer->offset();
250
251		lost = jiffies - wall_jiffies;
252		if (lost)
253			usec += lost * USECS_PER_JIFFY;
254
255		sec = xtime.tv_sec;
256		usec += xtime.tv_nsec / 1000;
257	} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
258
259	/* usec may have gone up a lot: be safe */
260	while (usec >= 1000000) {
261		usec -= 1000000;
262		sec++;
263	}
264
265	tv->tv_sec = sec;
266	tv->tv_usec = usec;
267}
268
269EXPORT_SYMBOL(do_gettimeofday);
270
271int do_settimeofday(struct timespec *tv)
272{
273	time_t wtm_sec, sec = tv->tv_sec;
274	long wtm_nsec, nsec = tv->tv_nsec;
275
276	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
277		return -EINVAL;
278
279	write_seqlock_irq(&xtime_lock);
280	/*
281	 * This is revolting. We need to set "xtime" correctly. However, the
282	 * value in this location is the value at the most recent update of
283	 * wall time.  Discover what correction gettimeofday() would have
284	 * done, and then undo it!
285	 */
286	nsec -= system_timer->offset() * NSEC_PER_USEC;
287	nsec -= (jiffies - wall_jiffies) * TICK_NSEC;
288
289	wtm_sec  = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
290	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
291
292	set_normalized_timespec(&xtime, sec, nsec);
293	set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
294
295	time_adjust = 0;		/* stop active adjtime() */
296	time_status |= STA_UNSYNC;
297	time_maxerror = NTP_PHASE_LIMIT;
298	time_esterror = NTP_PHASE_LIMIT;
299	write_sequnlock_irq(&xtime_lock);
300	clock_was_set();
301	return 0;
302}
303
304EXPORT_SYMBOL(do_settimeofday);
305
306/**
307 * save_time_delta - Save the offset between system time and RTC time
308 * @delta: pointer to timespec to store delta
309 * @rtc: pointer to timespec for current RTC time
310 *
311 * Return a delta between the system time and the RTC time, such
312 * that system time can be restored later with restore_time_delta()
313 */
314void save_time_delta(struct timespec *delta, struct timespec *rtc)
315{
316	set_normalized_timespec(delta,
317				xtime.tv_sec - rtc->tv_sec,
318				xtime.tv_nsec - rtc->tv_nsec);
319}
320EXPORT_SYMBOL(save_time_delta);
321
322/**
323 * restore_time_delta - Restore the current system time
324 * @delta: delta returned by save_time_delta()
325 * @rtc: pointer to timespec for current RTC time
326 */
327void restore_time_delta(struct timespec *delta, struct timespec *rtc)
328{
329	struct timespec ts;
330
331	set_normalized_timespec(&ts,
332				delta->tv_sec + rtc->tv_sec,
333				delta->tv_nsec + rtc->tv_nsec);
334
335	do_settimeofday(&ts);
336}
337EXPORT_SYMBOL(restore_time_delta);
338
339/*
340 * Kernel system timer support.
341 */
342void timer_tick(struct pt_regs *regs)
343{
344	profile_tick(CPU_PROFILING, regs);
345	do_leds();
346	do_set_rtc();
347	do_timer(regs);
348#ifndef CONFIG_SMP
349	update_process_times(user_mode(regs));
350#endif
351}
352
353#ifdef CONFIG_PM
354static int timer_suspend(struct sys_device *dev, pm_message_t state)
355{
356	struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
357
358	if (timer->suspend != NULL)
359		timer->suspend();
360
361	return 0;
362}
363
364static int timer_resume(struct sys_device *dev)
365{
366	struct sys_timer *timer = container_of(dev, struct sys_timer, dev);
367
368	if (timer->resume != NULL)
369		timer->resume();
370
371	return 0;
372}
373#else
374#define timer_suspend NULL
375#define timer_resume NULL
376#endif
377
378static struct sysdev_class timer_sysclass = {
379	set_kset_name("timer"),
380	.suspend	= timer_suspend,
381	.resume		= timer_resume,
382};
383
384static int __init timer_init_sysfs(void)
385{
386	int ret = sysdev_class_register(&timer_sysclass);
387	if (ret == 0) {
388		system_timer->dev.cls = &timer_sysclass;
389		ret = sysdev_register(&system_timer->dev);
390	}
391	return ret;
392}
393
394device_initcall(timer_init_sysfs);
395
396void __init time_init(void)
397{
398	if (system_timer->offset == NULL)
399		system_timer->offset = dummy_gettimeoffset;
400	system_timer->init();
401}
402