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

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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>
This commit is contained in:
David Brownell
2007-05-08 00:33:42 -07:00
committed by Linus Torvalds
parent cd9662094e
commit 7ca1d488ff
5 changed files with 91 additions and 76 deletions
Download Patch File Download Diff File Expand all files Collapse all files

74
drivers/rtc/class.c
View File

@ -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;