Commit 7ca1d488 authored by David Brownell's avatar David Brownell Committed by Linus Torvalds
Browse files

rtc: suspend()/resume() restores system clock 



RTC class suspend/resume support, re-initializing the system clock on resume
from the clock used to initialize it at boot time.

 - The reinit-on-resume is hooked to the existing RTC_HCTOSYS config
   option, on the grounds that a clock good enough for init must also
   be good enough for re-init.

 - Inlining a version of the code used by ARM, to save and restore the
   delta between a selected RTC and the current system wall-clock time.

 - Removes calls to that ARM code from AT91, OMAP1, and S3C RTCs.  This
   means that systems using those RTCs across suspend/resume will likely
   want to change their kernel configs to enable RTC_HCTOSYS.

   If HCTOSYS isn't using a second RTC (with battery?), this changes the
   system's initial date from Jan 1970 to the epoch this hardware uses:
   1998 for AT91, 2000 for OMAP1 (assuming no split power mode), etc.

This goes on top of the patch series removing "struct class_device" usage
from the RTC framework.  That's all needed for class suspend()/resume().

Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
Acked-By: default avatarAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent cd966209

drivers/rtc/Kconfig

+17 −7
Original line number Diff line number Diff line
@@ -21,21 +21,31 @@ config RTC_CLASS 
	  will be called rtc-class.



config RTC_HCTOSYS

	bool "Set system time from RTC on startup"

	bool "Set system time from RTC on startup and resume"

	depends on RTC_CLASS = y

	default y

	help

	  If you say yes here, the system time will be set using

	  the value read from the specified RTC device. This is useful

	  in order to avoid unnecessary fsck runs.

	  If you say yes here, the system time (wall clock) will be set using

	  the value read from a specified RTC device. This is useful to avoid

	  unnecessary fsck runs at boot time, and to network better.



config RTC_HCTOSYS_DEVICE

	string "The RTC to read the time from"

	string "RTC used to set the system time"

	depends on RTC_HCTOSYS = y

	default "rtc0"

	help

	  The RTC device that will be used as the source for

	  the system time, usually rtc0.

	  The RTC device that will be used to (re)initialize the system

	  clock, usually rtc0.  Initialization is done when the system

	  starts up, and when it resumes from a low power state.



	  This clock should be battery-backed, so that it reads the correct

	  time when the system boots from a power-off state.  Otherwise, your

	  system will need an external clock source (like an NTP server).



	  If the clock you specify here is not battery backed, it may still

	  be useful to reinitialize system time when resuming from system

	  sleep states.  Do not specify an RTC here unless it stays powered

	  during all this system's supported sleep states.



config RTC_DEBUG

	bool "RTC debug support"

drivers/rtc/class.c

+74 −0
Original line number Diff line number Diff line
@@ -32,6 +32,78 @@ static void rtc_device_release(struct device *dev) 
	kfree(rtc);

}



#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)



/*

 * On suspend(), measure the delta between one RTC and the

 * system's wall clock; restore it on resume().

 */



static struct timespec	delta;

static time_t		oldtime;



static int rtc_suspend(struct device *dev, pm_message_t mesg)

{

	struct rtc_device	*rtc = to_rtc_device(dev);

	struct rtc_time		tm;



	if (strncmp(rtc->dev.bus_id,

				CONFIG_RTC_HCTOSYS_DEVICE,

				BUS_ID_SIZE) != 0)

		return 0;



	rtc_read_time(rtc, &tm);

	rtc_tm_to_time(&tm, &oldtime);



	/* RTC precision is 1 second; adjust delta for avg 1/2 sec err */

	set_normalized_timespec(&delta,

				xtime.tv_sec - oldtime,

				xtime.tv_nsec - (NSEC_PER_SEC >> 1));



	return 0;

}



static int rtc_resume(struct device *dev)

{

	struct rtc_device	*rtc = to_rtc_device(dev);

	struct rtc_time		tm;

	time_t			newtime;

	struct timespec		time;



	if (strncmp(rtc->dev.bus_id,

				CONFIG_RTC_HCTOSYS_DEVICE,

				BUS_ID_SIZE) != 0)

		return 0;



	rtc_read_time(rtc, &tm);

	if (rtc_valid_tm(&tm) != 0) {

		pr_debug("%s:  bogus resume time\n", rtc->dev.bus_id);

		return 0;

	}

	rtc_tm_to_time(&tm, &newtime);

	if (newtime <= oldtime) {

		if (newtime < oldtime)

			pr_debug("%s:  time travel!\n", rtc->dev.bus_id);

		return 0;

	}



	/* restore wall clock using delta against this RTC;

	 * adjust again for avg 1/2 second RTC sampling error

	 */

	set_normalized_timespec(&time,

				newtime + delta.tv_sec,

				(NSEC_PER_SEC >> 1) + delta.tv_nsec);

	do_settimeofday(&time);



	return 0;

}



#else

#define rtc_suspend	NULL

#define rtc_resume	NULL

#endif





/**

 * rtc_device_register - register w/ RTC class

 * @dev: the device to register
@@ -143,6 +215,8 @@ static int __init rtc_init(void) 
		printk(KERN_ERR "%s: couldn't create class\n", __FILE__);

		return PTR_ERR(rtc_class);

	}

	rtc_class->suspend = rtc_suspend;

	rtc_class->resume = rtc_resume;

	rtc_dev_init();

	rtc_sysfs_init(rtc_class);

	return 0;

drivers/rtc/rtc-at91rm9200.c

+0 −30
Original line number Diff line number Diff line
@@ -348,21 +348,10 @@ static int __exit at91_rtc_remove(struct platform_device *pdev) 


/* AT91RM9200 RTC Power management control */



static struct timespec at91_rtc_delta;

static u32 at91_rtc_imr;



static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state)

{

	struct rtc_time tm;

	struct timespec time;



	time.tv_nsec = 0;



	/* calculate time delta for suspend */

	at91_rtc_readtime(&pdev->dev, &tm);

	rtc_tm_to_time(&tm, &time.tv_sec);

	save_time_delta(&at91_rtc_delta, &time);



	/* this IRQ is shared with DBGU and other hardware which isn't

	 * necessarily doing PM like we are...

	 */
@@ -374,36 +363,17 @@ static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state) 
		else

			at91_sys_write(AT91_RTC_IDR, at91_rtc_imr);

	}



	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,

		1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,

		tm.tm_hour, tm.tm_min, tm.tm_sec);



	return 0;

}



static int at91_rtc_resume(struct platform_device *pdev)

{

	struct rtc_time tm;

	struct timespec time;



	time.tv_nsec = 0;



	at91_rtc_readtime(&pdev->dev, &tm);

	rtc_tm_to_time(&tm, &time.tv_sec);

	restore_time_delta(&at91_rtc_delta, &time);



	if (at91_rtc_imr) {

		if (device_may_wakeup(&pdev->dev))

			disable_irq_wake(AT91_ID_SYS);

		else

			at91_sys_write(AT91_RTC_IER, at91_rtc_imr);

	}



	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,

		1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,

		tm.tm_hour, tm.tm_min, tm.tm_sec);



	return 0;

}

#else

drivers/rtc/rtc-omap.c

+0 −17
Original line number Diff line number Diff line
@@ -488,19 +488,10 @@ static int __devexit omap_rtc_remove(struct platform_device *pdev) 


#ifdef CONFIG_PM



static struct timespec rtc_delta;

static u8 irqstat;



static int omap_rtc_suspend(struct platform_device *pdev, pm_message_t state)

{

	struct rtc_time rtc_tm;

	struct timespec time;



	time.tv_nsec = 0;

	omap_rtc_read_time(NULL, &rtc_tm);

	rtc_tm_to_time(&rtc_tm, &time.tv_sec);



	save_time_delta(&rtc_delta, &time);

	irqstat = rtc_read(OMAP_RTC_INTERRUPTS_REG);



	/* FIXME the RTC alarm is not currently acting as a wakeup event
@@ -517,14 +508,6 @@ static int omap_rtc_suspend(struct platform_device *pdev, pm_message_t state) 


static int omap_rtc_resume(struct platform_device *pdev)

{

	struct rtc_time rtc_tm;

	struct timespec time;



	time.tv_nsec = 0;

	omap_rtc_read_time(NULL, &rtc_tm);

	rtc_tm_to_time(&rtc_tm, &time.tv_sec);



	restore_time_delta(&rtc_delta, &time);

	if (device_may_wakeup(&pdev->dev))

		disable_irq_wake(omap_rtc_alarm);

	else

drivers/rtc/rtc-s3c.c

+0 −22
Original line number Diff line number Diff line
@@ -548,37 +548,15 @@ static int ticnt_save; 


static int s3c_rtc_suspend(struct platform_device *pdev, pm_message_t state)

{

	struct rtc_time tm;

	struct timespec time;



	time.tv_nsec = 0;



	/* save TICNT for anyone using periodic interrupts */



	ticnt_save = readb(s3c_rtc_base + S3C2410_TICNT);



	/* calculate time delta for suspend */



	s3c_rtc_gettime(&pdev->dev, &tm);

	rtc_tm_to_time(&tm, &time.tv_sec);

	save_time_delta(&s3c_rtc_delta, &time);

	s3c_rtc_enable(pdev, 0);



	return 0;

}



static int s3c_rtc_resume(struct platform_device *pdev)

{

	struct rtc_time tm;

	struct timespec time;



	time.tv_nsec = 0;



	s3c_rtc_enable(pdev, 1);

	s3c_rtc_gettime(&pdev->dev, &tm);

	rtc_tm_to_time(&tm, &time.tv_sec);

	restore_time_delta(&s3c_rtc_delta, &time);



	writeb(ticnt_save, s3c_rtc_base + S3C2410_TICNT);

	return 0;

}

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