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: David Brownell <dbrownell@users.sourceforge.net> Acked-by: Greg Kroah-Hartman <gregkh@suse.de> Acked-By: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>hifive-unleashed-5.1
David Brownell
Linus Torvalds
parent
cd9662094e
commit
7ca1d488ff
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@ -21,21 +21,31 @@ config RTC_CLASS
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will be called rtc-class.
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config RTC_HCTOSYS
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bool "Set system time from RTC on startup"
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bool "Set system time from RTC on startup and resume"
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depends on RTC_CLASS = y
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default y
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help
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If you say yes here, the system time will be set using
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the value read from the specified RTC device. This is useful
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in order to avoid unnecessary fsck runs.
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If you say yes here, the system time (wall clock) will be set using
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the value read from a specified RTC device. This is useful to avoid
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unnecessary fsck runs at boot time, and to network better.
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config RTC_HCTOSYS_DEVICE
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string "The RTC to read the time from"
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string "RTC used to set the system time"
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depends on RTC_HCTOSYS = y
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default "rtc0"
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help
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The RTC device that will be used as the source for
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the system time, usually rtc0.
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The RTC device that will be used to (re)initialize the system
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clock, usually rtc0. Initialization is done when the system
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starts up, and when it resumes from a low power state.
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This clock should be battery-backed, so that it reads the correct
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time when the system boots from a power-off state. Otherwise, your
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system will need an external clock source (like an NTP server).
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If the clock you specify here is not battery backed, it may still
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be useful to reinitialize system time when resuming from system
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sleep states. Do not specify an RTC here unless it stays powered
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during all this system's supported sleep states.
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config RTC_DEBUG
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bool "RTC debug support"
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@ -32,6 +32,78 @@ static void rtc_device_release(struct device *dev)
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kfree(rtc);
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}
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#if defined(CONFIG_PM) && defined(CONFIG_RTC_HCTOSYS_DEVICE)
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/*
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* On suspend(), measure the delta between one RTC and the
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* system's wall clock; restore it on resume().
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*/
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static struct timespec delta;
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static time_t oldtime;
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static int rtc_suspend(struct device *dev, pm_message_t mesg)
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{
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struct rtc_device *rtc = to_rtc_device(dev);
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struct rtc_time tm;
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if (strncmp(rtc->dev.bus_id,
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CONFIG_RTC_HCTOSYS_DEVICE,
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BUS_ID_SIZE) != 0)
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return 0;
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rtc_read_time(rtc, &tm);
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rtc_tm_to_time(&tm, &oldtime);
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/* RTC precision is 1 second; adjust delta for avg 1/2 sec err */
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set_normalized_timespec(&delta,
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xtime.tv_sec - oldtime,
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xtime.tv_nsec - (NSEC_PER_SEC >> 1));
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return 0;
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}
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static int rtc_resume(struct device *dev)
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{
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struct rtc_device *rtc = to_rtc_device(dev);
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struct rtc_time tm;
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time_t newtime;
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struct timespec time;
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if (strncmp(rtc->dev.bus_id,
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CONFIG_RTC_HCTOSYS_DEVICE,
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BUS_ID_SIZE) != 0)
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return 0;
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rtc_read_time(rtc, &tm);
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if (rtc_valid_tm(&tm) != 0) {
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pr_debug("%s: bogus resume time\n", rtc->dev.bus_id);
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return 0;
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}
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rtc_tm_to_time(&tm, &newtime);
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if (newtime <= oldtime) {
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if (newtime < oldtime)
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pr_debug("%s: time travel!\n", rtc->dev.bus_id);
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return 0;
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}
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/* restore wall clock using delta against this RTC;
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* adjust again for avg 1/2 second RTC sampling error
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*/
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set_normalized_timespec(&time,
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newtime + delta.tv_sec,
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(NSEC_PER_SEC >> 1) + delta.tv_nsec);
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do_settimeofday(&time);
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return 0;
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}
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#else
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#define rtc_suspend NULL
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#define rtc_resume NULL
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#endif
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/**
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* rtc_device_register - register w/ RTC class
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* @dev: the device to register
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@ -143,6 +215,8 @@ static int __init rtc_init(void)
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printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
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return PTR_ERR(rtc_class);
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}
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rtc_class->suspend = rtc_suspend;
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rtc_class->resume = rtc_resume;
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rtc_dev_init();
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rtc_sysfs_init(rtc_class);
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return 0;
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@ -348,21 +348,10 @@ static int __exit at91_rtc_remove(struct platform_device *pdev)
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/* AT91RM9200 RTC Power management control */
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static struct timespec at91_rtc_delta;
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static u32 at91_rtc_imr;
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static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state)
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{
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struct rtc_time tm;
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struct timespec time;
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time.tv_nsec = 0;
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/* calculate time delta for suspend */
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at91_rtc_readtime(&pdev->dev, &tm);
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rtc_tm_to_time(&tm, &time.tv_sec);
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save_time_delta(&at91_rtc_delta, &time);
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/* this IRQ is shared with DBGU and other hardware which isn't
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* necessarily doing PM like we are...
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*/
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@ -374,36 +363,17 @@ static int at91_rtc_suspend(struct platform_device *pdev, pm_message_t state)
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else
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at91_sys_write(AT91_RTC_IDR, at91_rtc_imr);
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}
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pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
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1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
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tm.tm_hour, tm.tm_min, tm.tm_sec);
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return 0;
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}
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static int at91_rtc_resume(struct platform_device *pdev)
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{
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struct rtc_time tm;
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struct timespec time;
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time.tv_nsec = 0;
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at91_rtc_readtime(&pdev->dev, &tm);
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rtc_tm_to_time(&tm, &time.tv_sec);
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restore_time_delta(&at91_rtc_delta, &time);
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if (at91_rtc_imr) {
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if (device_may_wakeup(&pdev->dev))
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disable_irq_wake(AT91_ID_SYS);
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else
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at91_sys_write(AT91_RTC_IER, at91_rtc_imr);
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}
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pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d\n", __FUNCTION__,
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1900 + tm.tm_year, tm.tm_mon, tm.tm_mday,
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tm.tm_hour, tm.tm_min, tm.tm_sec);
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return 0;
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}
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#else
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@ -488,19 +488,10 @@ static int __devexit omap_rtc_remove(struct platform_device *pdev)
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#ifdef CONFIG_PM
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static struct timespec rtc_delta;
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static u8 irqstat;
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static int omap_rtc_suspend(struct platform_device *pdev, pm_message_t state)
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{
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struct rtc_time rtc_tm;
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struct timespec time;
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time.tv_nsec = 0;
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omap_rtc_read_time(NULL, &rtc_tm);
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rtc_tm_to_time(&rtc_tm, &time.tv_sec);
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save_time_delta(&rtc_delta, &time);
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irqstat = rtc_read(OMAP_RTC_INTERRUPTS_REG);
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/* FIXME the RTC alarm is not currently acting as a wakeup event
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@ -517,14 +508,6 @@ static int omap_rtc_suspend(struct platform_device *pdev, pm_message_t state)
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static int omap_rtc_resume(struct platform_device *pdev)
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{
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struct rtc_time rtc_tm;
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struct timespec time;
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time.tv_nsec = 0;
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omap_rtc_read_time(NULL, &rtc_tm);
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rtc_tm_to_time(&rtc_tm, &time.tv_sec);
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restore_time_delta(&rtc_delta, &time);
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if (device_may_wakeup(&pdev->dev))
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disable_irq_wake(omap_rtc_alarm);
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else
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@ -548,37 +548,15 @@ static int ticnt_save;
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static int s3c_rtc_suspend(struct platform_device *pdev, pm_message_t state)
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{
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struct rtc_time tm;
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struct timespec time;
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time.tv_nsec = 0;
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/* save TICNT for anyone using periodic interrupts */
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ticnt_save = readb(s3c_rtc_base + S3C2410_TICNT);
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/* calculate time delta for suspend */
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s3c_rtc_gettime(&pdev->dev, &tm);
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rtc_tm_to_time(&tm, &time.tv_sec);
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save_time_delta(&s3c_rtc_delta, &time);
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s3c_rtc_enable(pdev, 0);
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return 0;
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}
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static int s3c_rtc_resume(struct platform_device *pdev)
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{
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struct rtc_time tm;
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struct timespec time;
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time.tv_nsec = 0;
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s3c_rtc_enable(pdev, 1);
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s3c_rtc_gettime(&pdev->dev, &tm);
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rtc_tm_to_time(&tm, &time.tv_sec);
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restore_time_delta(&s3c_rtc_delta, &time);
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writeb(ticnt_save, s3c_rtc_base + S3C2410_TICNT);
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return 0;
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}
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