[linux-2.6-block.git] / arch / blackfin / kernel / time.c

/*
 * File:         arch/blackfin/kernel/time.c
 * Based on:     none - original work
 * Author:
 *
 * Created:
 * Description:  This file contains the bfin-specific time handling details.
 *               Most of the stuff is located in the machine specific files.
 *
 * Modified:
 *               Copyright 2004-2006 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/module.h>
#include <linux/profile.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/irq.h>

#include <asm/blackfin.h>

/* This is an NTP setting */
#define	TICK_SIZE (tick_nsec / 1000)

static void time_sched_init(irqreturn_t(*timer_routine)
			(int, void *));
static unsigned long gettimeoffset(void);

static struct irqaction bfin_timer_irq = {
	.name = "BFIN Timer Tick",
	.flags = IRQF_DISABLED
};

/*
 * The way that the Blackfin core timer works is:
 *  - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
 *  - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
 *
 * If you take the fastest clock (1ns, or 1GHz to make the math work easier)
 *    10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
 *    (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
 *    to use TSCALE, and program it to zero (which is pass CCLK through).
 *    If you feel like using it, try to keep HZ * TIMESCALE to some
 *    value that divides easy (like power of 2).
 */

#define TIME_SCALE 1

static void
time_sched_init(irqreturn_t(*timer_routine) (int, void *))
{
	u32 tcount;

	/* power up the timer, but don't enable it just yet */
	bfin_write_TCNTL(1);
	CSYNC();

	/*
	 * the TSCALE prescaler counter.
	 */
	bfin_write_TSCALE((TIME_SCALE - 1));

	tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
	bfin_write_TPERIOD(tcount);
	bfin_write_TCOUNT(tcount);

	/* now enable the timer */
	CSYNC();

	bfin_write_TCNTL(7);

	bfin_timer_irq.handler = (irq_handler_t)timer_routine;
	/* call setup_irq instead of request_irq because request_irq calls
	 * kmalloc which has not been initialized yet
	 */
	setup_irq(IRQ_CORETMR, &bfin_timer_irq);
}

/*
 * Should return useconds since last timer tick
 */
static unsigned long gettimeoffset(void)
{
	unsigned long offset;
	unsigned long clocks_per_jiffy;

	clocks_per_jiffy = bfin_read_TPERIOD();
	offset =
	    (clocks_per_jiffy -
	     bfin_read_TCOUNT()) / (((clocks_per_jiffy + 1) * HZ) /
				    USEC_PER_SEC);

	/* Check if we just wrapped the counters and maybe missed a tick */
	if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
	    && (offset < (100000 / HZ / 2)))
		offset += (USEC_PER_SEC / HZ);

	return offset;
}

static inline int set_rtc_mmss(unsigned long nowtime)
{
	return 0;
}

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
#ifdef CONFIG_CORE_TIMER_IRQ_L1
irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
#endif

irqreturn_t timer_interrupt(int irq, void *dummy)
{
	/* last time the cmos clock got updated */
	static long last_rtc_update;

	write_seqlock(&xtime_lock);

	do_timer(1);

#ifndef CONFIG_SMP
	update_process_times(user_mode(get_irq_regs()));
#endif
	profile_tick(CPU_PROFILING);

	/*
	 * If we have an externally synchronized Linux clock, then update
	 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	 * called as close as possible to 500 ms before the new second starts.
	 */

	if (ntp_synced() &&
	    xtime.tv_sec > last_rtc_update + 660 &&
	    (xtime.tv_nsec / NSEC_PER_USEC) >=
	    500000 - ((unsigned)TICK_SIZE) / 2
	    && (xtime.tv_nsec / NSEC_PER_USEC) <=
	    500000 + ((unsigned)TICK_SIZE) / 2) {
		if (set_rtc_mmss(xtime.tv_sec) == 0)
			last_rtc_update = xtime.tv_sec;
		else
			/* Do it again in 60s. */
			last_rtc_update = xtime.tv_sec - 600;
	}
	write_sequnlock(&xtime_lock);
	return IRQ_HANDLED;
}

void __init time_init(void)
{
	time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60;	/* 1 Jan 2007 */

#ifdef CONFIG_RTC_DRV_BFIN
	/* [#2663] hack to filter junk RTC values that would cause
	 * userspace to have to deal with time values greater than
	 * 2^31 seconds (which uClibc cannot cope with yet)
	 */
	if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
		printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
		bfin_write_RTC_STAT(0);
	}
#endif

	/* Initialize xtime. From now on, xtime is updated with timer interrupts */
	xtime.tv_sec = secs_since_1970;
	xtime.tv_nsec = 0;

	wall_to_monotonic.tv_sec = -xtime.tv_sec;

	time_sched_init(timer_interrupt);
}

#ifndef CONFIG_GENERIC_TIME
void do_gettimeofday(struct timeval *tv)
{
	unsigned long flags;
	unsigned long seq;
	unsigned long usec, sec;

	do {
		seq = read_seqbegin_irqsave(&xtime_lock, flags);
		usec = gettimeoffset();
		sec = xtime.tv_sec;
		usec += (xtime.tv_nsec / NSEC_PER_USEC);
	}
	while (read_seqretry_irqrestore(&xtime_lock, seq, flags));

	while (usec >= USEC_PER_SEC) {
		usec -= USEC_PER_SEC;
		sec++;
	}

	tv->tv_sec = sec;
	tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);

int do_settimeofday(struct timespec *tv)
{
	time_t wtm_sec, sec = tv->tv_sec;
	long wtm_nsec, nsec = tv->tv_nsec;

	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
		return -EINVAL;

	write_seqlock_irq(&xtime_lock);
	/*
	 * This is revolting. We need to set the xtime.tv_usec
	 * correctly. However, the value in this location is
	 * is value at the last tick.
	 * Discover what correction gettimeofday
	 * would have done, and then undo it!
	 */
	nsec -= (gettimeoffset() * NSEC_PER_USEC);

	wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);

	set_normalized_timespec(&xtime, sec, nsec);
	set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);

	ntp_clear();

	write_sequnlock_irq(&xtime_lock);
	clock_was_set();

	return 0;
}
EXPORT_SYMBOL(do_settimeofday);
#endif /* !CONFIG_GENERIC_TIME */

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long sched_clock(void)
{
	return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
}
Commit	Line	Data
1394f032 BW	1	/*
	2	* File: arch/blackfin/kernel/time.c
	3	* Based on: none - original work
	4	* Author:
	5	*
	6	* Created:
	7	* Description: This file contains the bfin-specific time handling details.
	8	* Most of the stuff is located in the machine specific files.
	9	*
	10	* Modified:
	11	* Copyright 2004-2006 Analog Devices Inc.
	12	*
	13	* Bugs: Enter bugs at http://blackfin.uclinux.org/
	14	*
	15	* This program is free software; you can redistribute it and/or modify
	16	* it under the terms of the GNU General Public License as published by
	17	* the Free Software Foundation; either version 2 of the License, or
	18	* (at your option) any later version.
	19	*
	20	* This program is distributed in the hope that it will be useful,
	21	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	22	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	23	* GNU General Public License for more details.
	24	*
	25	* You should have received a copy of the GNU General Public License
	26	* along with this program; if not, see the file COPYING, or write
	27	* to the Free Software Foundation, Inc.,
	28	* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	29	*/
	30
	31	#include <linux/module.h>
	32	#include <linux/profile.h>
	33	#include <linux/interrupt.h>
	34	#include <linux/time.h>
	35	#include <linux/irq.h>
	36
	37	#include <asm/blackfin.h>
	38
	39	/* This is an NTP setting */
	40	#define TICK_SIZE (tick_nsec / 1000)
	41
	42	static void time_sched_init(irqreturn_t(*timer_routine)
	43	(int, void *));
	44	static unsigned long gettimeoffset(void);
1394f032 BW	45
	46	static struct irqaction bfin_timer_irq = {
	47	.name = "BFIN Timer Tick",
	48	.flags = IRQF_DISABLED
	49	};
	50
	51	/*
	52	* The way that the Blackfin core timer works is:
	53	* - CCLK is divided by a programmable 8-bit pre-scaler (TSCALE)
	54	* - Every time TSCALE ticks, a 32bit is counted down (TCOUNT)
	55	*
	56	* If you take the fastest clock (1ns, or 1GHz to make the math work easier)
	57	* 10ms is 10,000,000 clock ticks, which fits easy into a 32-bit counter
	58	* (32 bit counter is 4,294,967,296ns or 4.2 seconds) so, we don't need
	59	* to use TSCALE, and program it to zero (which is pass CCLK through).
	60	* If you feel like using it, try to keep HZ * TIMESCALE to some
	61	* value that divides easy (like power of 2).
	62	*/
	63
	64	#define TIME_SCALE 1
	65
	66	static void
	67	time_sched_init(irqreturn_t(timer_routine) (int, void ))
	68	{
	69	u32 tcount;
	70
	71	/* power up the timer, but don't enable it just yet */
	72	bfin_write_TCNTL(1);
	73	CSYNC();
	74
	75	/*
	76	* the TSCALE prescaler counter.
	77	*/
	78	bfin_write_TSCALE((TIME_SCALE - 1));
	79
	80	tcount = ((get_cclk() / (HZ * TIME_SCALE)) - 1);
	81	bfin_write_TPERIOD(tcount);
	82	bfin_write_TCOUNT(tcount);
	83
	84	/* now enable the timer */
	85	CSYNC();
	86
	87	bfin_write_TCNTL(7);
	88
	89	bfin_timer_irq.handler = (irq_handler_t)timer_routine;
	90	/* call setup_irq instead of request_irq because request_irq calls
	91	* kmalloc which has not been initialized yet
	92	*/
	93	setup_irq(IRQ_CORETMR, &bfin_timer_irq);
	94	}
	95
	96	/*
	97	* Should return useconds since last timer tick
	98	*/
	99	static unsigned long gettimeoffset(void)
	100	{
	101	unsigned long offset;
	102	unsigned long clocks_per_jiffy;
	103
	104	clocks_per_jiffy = bfin_read_TPERIOD();
	105	offset =
	106	(clocks_per_jiffy -
	107	bfin_read_TCOUNT()) / (((clocks_per_jiffy + 1) * HZ) /
	108	USEC_PER_SEC);
109
110	/* Check if we just wrapped the counters and maybe missed a tick */
111	if ((bfin_read_ILAT() & (1 << IRQ_CORETMR))
112	&& (offset < (100000 / HZ / 2)))
113	offset += (USEC_PER_SEC / HZ);
114
115	return offset;
116	}
117
118	static inline int set_rtc_mmss(unsigned long nowtime)
119	{
120	return 0;
121	}
122
123	/*
124	* timer_interrupt() needs to keep up the real-time clock,
125	* as well as call the "do_timer()" routine every clocktick
126	*/
127	#ifdef CONFIG_CORE_TIMER_IRQ_L1
128	irqreturn_t timer_interrupt(int irq, void *dummy)__attribute__((l1_text));
129	#endif
130
131	irqreturn_t timer_interrupt(int irq, void *dummy)
132	{
133	/* last time the cmos clock got updated */
1f83b8f1	134	static long last_rtc_update;
1394f032 BW	135
	136	write_seqlock(&xtime_lock);
	137
	138	do_timer(1);
1394f032 BW	139
	140	#ifndef CONFIG_SMP
	141	update_process_times(user_mode(get_irq_regs()));
	142	#endif
	143	profile_tick(CPU_PROFILING);
	144
	145	/*
	146	* If we have an externally synchronized Linux clock, then update
	147	* CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
	148	* called as close as possible to 500 ms before the new second starts.
	149	*/
	150
	151	if (ntp_synced() &&
	152	xtime.tv_sec > last_rtc_update + 660 &&
	153	(xtime.tv_nsec / NSEC_PER_USEC) >=
	154	500000 - ((unsigned)TICK_SIZE) / 2
	155	&& (xtime.tv_nsec / NSEC_PER_USEC) <=
	156	500000 + ((unsigned)TICK_SIZE) / 2) {
	157	if (set_rtc_mmss(xtime.tv_sec) == 0)
	158	last_rtc_update = xtime.tv_sec;
	159	else
	160	/* Do it again in 60s. */
	161	last_rtc_update = xtime.tv_sec - 600;
	162	}
	163	write_sequnlock(&xtime_lock);
	164	return IRQ_HANDLED;
	165	}
	166
	167	void __init time_init(void)
	168	{
	169	time_t secs_since_1970 = (365 * 37 + 9) * 24 * 60 * 60; /* 1 Jan 2007 */
	170
	171	#ifdef CONFIG_RTC_DRV_BFIN
	172	/* [#2663] hack to filter junk RTC values that would cause
	173	* userspace to have to deal with time values greater than
	174	* 2^31 seconds (which uClibc cannot cope with yet)
	175	*/
	176	if ((bfin_read_RTC_STAT() & 0xC0000000) == 0xC0000000) {
	177	printk(KERN_NOTICE "bfin-rtc: invalid date; resetting\n");
	178	bfin_write_RTC_STAT(0);
	179	}
	180	#endif
	181
	182	/* Initialize xtime. From now on, xtime is updated with timer interrupts */
	183	xtime.tv_sec = secs_since_1970;
	184	xtime.tv_nsec = 0;
	185
	186	wall_to_monotonic.tv_sec = -xtime.tv_sec;
	187
	188	time_sched_init(timer_interrupt);
	189	}
	190
	191	#ifndef CONFIG_GENERIC_TIME
	192	void do_gettimeofday(struct timeval *tv)
	193	{
	194	unsigned long flags;
	195	unsigned long seq;
	196	unsigned long usec, sec;
	197
	198	do {
	199	seq = read_seqbegin_irqsave(&xtime_lock, flags);
	200	usec = gettimeoffset();
	201	sec = xtime.tv_sec;
	202	usec += (xtime.tv_nsec / NSEC_PER_USEC);
203	}
204	while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
205
206	while (usec >= USEC_PER_SEC) {
207	usec -= USEC_PER_SEC;
208	sec++;
209	}
210
211	tv->tv_sec = sec;
212	tv->tv_usec = usec;
213	}
214	EXPORT_SYMBOL(do_gettimeofday);
215
216	int do_settimeofday(struct timespec *tv)
217	{
218	time_t wtm_sec, sec = tv->tv_sec;
219	long wtm_nsec, nsec = tv->tv_nsec;
220
221	if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
222	return -EINVAL;
223
224	write_seqlock_irq(&xtime_lock);
225	/*
226	* This is revolting. We need to set the xtime.tv_usec
227	* correctly. However, the value in this location is
228	* is value at the last tick.
229	* Discover what correction gettimeofday
230	* would have done, and then undo it!
231	*/
232	nsec -= (gettimeoffset() * NSEC_PER_USEC);
233
234	wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
235	wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
236
237	set_normalized_timespec(&xtime, sec, nsec);
238	set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
239
240	ntp_clear();
241
242	write_sequnlock_irq(&xtime_lock);
243	clock_was_set();
244
245	return 0;
246	}
247	EXPORT_SYMBOL(do_settimeofday);
248	#endif /* !CONFIG_GENERIC_TIME */
249
250	/*
251	* Scheduler clock - returns current time in nanosec units.
252	*/
253	unsigned long long sched_clock(void)
254	{
255	return (unsigned long long)jiffies *(NSEC_PER_SEC / HZ);
256	}