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[PATCH] rtc: Add rtc_merge_alarm()

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Add rtc_merge_alarm(), which can be used by rtc drivers to turn a partially
specified alarm expiry (i.e.  most significant fields set to -1, as with the
RTC_ALM_SET ioctl()) into a fully specified expiry.

If the most significant specified field is earlier than the current time, the
least significant unspecified field is incremented.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Scott Wood 2006-12-10 02:19:00 -08:00 committed by Linus Torvalds
parent 9080d0ae0f
commit 884b4aaaa2
2 changed files with 82 additions and 0 deletions
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81
drivers/rtc/rtc-lib.c
View File

@ -117,4 +117,85 @@ int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time)
}
EXPORT_SYMBOL(rtc_tm_to_time);
/* Merge the valid (i.e. non-negative) fields of alarm into the current
* time. If the valid alarm fields are earlier than the equivalent
* fields in the time, carry one into the least significant invalid
* field, so that the alarm expiry is in the future. It assumes that the
* least significant invalid field is more significant than the most
* significant valid field, and that the seconds field is valid.
*
* This is used by alarms that take relative (rather than absolute)
* times, and/or have a simple binary second counter instead of
* day/hour/minute/sec registers.
*/
void rtc_merge_alarm(struct rtc_time *now, struct rtc_time *alarm)
{
int *alarmp = &alarm->tm_sec;
int *timep = &now->tm_sec;
int carry_into, i;
/* Ignore everything past the 6th element (tm_year). */
for (i = 5; i > 0; i--) {
if (alarmp[i] < 0)
alarmp[i] = timep[i];
else
break;
}
/* No carry needed if all fields are valid. */
if (i == 5)
return;
for (carry_into = i + 1; i >= 0; i--) {
if (alarmp[i] < timep[i])
break;
if (alarmp[i] > timep[i])
return;
}
switch (carry_into) {
case 1:
alarm->tm_min++;
if (alarm->tm_min < 60)
return;
alarm->tm_min = 0;
/* fall-through */
case 2:
alarm->tm_hour++;
if (alarm->tm_hour < 60)
return;
alarm->tm_hour = 0;
/* fall-through */
case 3:
alarm->tm_mday++;
if (alarm->tm_mday <= rtc_days_in_month[alarm->tm_mon])
return;
alarm->tm_mday = 1;
/* fall-through */
case 4:
alarm->tm_mon++;
if (alarm->tm_mon <= 12)
return;
alarm->tm_mon = 1;
/* fall-through */
case 5:
alarm->tm_year++;
}
}
EXPORT_SYMBOL(rtc_merge_alarm);
MODULE_LICENSE("GPL");

1
include/linux/rtc.h
View File

@ -106,6 +106,7 @@ extern int rtc_year_days(unsigned int day, unsigned int month, unsigned int year
extern int rtc_valid_tm(struct rtc_time *tm);
extern int rtc_tm_to_time(struct rtc_time *tm, unsigned long *time);
extern void rtc_time_to_tm(unsigned long time, struct rtc_time *tm);
extern void rtc_merge_alarm(struct rtc_time *now, struct rtc_time *alarm);
#include <linux/device.h>
#include <linux/seq_file.h>