arch/blackfin/kernel/time.c - maze/linux - Git at Google

 /*
  * 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.
  *		 FIXME: (This file is subject for removal)
  *
  * Modified:
  *               Copyright 2004-2008 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>
 #include <asm/time.h>

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

 static void time_sched_init(irq_handler_t timer_routine);
 static unsigned long gettimeoffset(void);

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

 static void
 time_sched_init(irq_handler_t timer_routine)
 {
 	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);

 	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);

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

 	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);
 }
	/*
	* 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.
	* FIXME: (This file is subject for removal)
	*
	* Modified:
	* Copyright 2004-2008 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>
	#include <asm/time.h>

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

	static void time_sched_init(irq_handler_t timer_routine);
	static unsigned long gettimeoffset(void);

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

	static void
	time_sched_init(irq_handler_t timer_routine)
	{
	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);

	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);

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

	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);
	}