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rtc: add the support for alarm time relative to current time in sysfs

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In current kernel if we want to set the alarm time, the absolute time the
seconds relative to 1970-01-01 00:00:00) should be written into
/sys/class/rtc/rtc0/wakealarm.  It is not convenient.

It is more reasonable to add the support for the alarm time relative to
current RTC time.(the unit is second)

For example:
If the RTC is required to generate alarm after 2 minutes, the following
will be OK.
	echo +120 > /sys/class/rtc/rtc0/wakealarm
or      echo +0x78 > /sys/class/rtc/rtc0/wakealarm

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: 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:
Zhao Yakui 2008-04-28 02:11:58 -07:00 committed by Linus Torvalds
parent e2bfe3424b
commit c116bc2ae5
1 changed files with 11 additions and 1 deletions
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12
drivers/rtc/rtc-sysfs.c
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@ -145,6 +145,8 @@ rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
unsigned long now, alarm;
struct rtc_wkalrm alm;
struct rtc_device *rtc = to_rtc_device(dev);
char *buf_ptr;
int adjust = 0;
/* Only request alarms that trigger in the future. Disable them
* by writing another time, e.g. 0 meaning Jan 1 1970 UTC.
@ -154,7 +156,15 @@ rtc_sysfs_set_wakealarm(struct device *dev, struct device_attribute *attr,
return retval;
rtc_tm_to_time(&alm.time, &now);
alarm = simple_strtoul(buf, NULL, 0);
buf_ptr = (char *)buf;
if (*buf_ptr == '+') {
buf_ptr++;
adjust = 1;
}
alarm = simple_strtoul(buf_ptr, NULL, 0);
if (adjust) {
alarm += now;
}
if (alarm > now) {
/* Avoid accidentally clobbering active alarms; we can't
* entirely prevent that here, without even the minimal