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>

1 files changed, 0 insertions, 17 deletions

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index ded35fd13ba0..e6c7b0149f27 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -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