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, 22 deletions

diff --git a/drivers/rtc/rtc-s3c.c b/drivers/rtc/rtc-s3c.c
index 3617c970caaa..54b613053468 100644
--- a/drivers/rtc/rtc-s3c.c
+++ b/drivers/rtc/rtc-s3c.c
@@ -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;
 }