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, 30 deletions

diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index 2f06b5f9fb7..33795e5a559 100644
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -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