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Commit 884b4aaa authored by Scott Wood's avatar Scott Wood Committed by Linus Torvalds
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[PATCH] rtc: Add rtc_merge_alarm() 



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: default avatarScott Wood <scottwood@freescale.com>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 9080d0ae

drivers/rtc/rtc-lib.c

+81 −0
Original line number Diff line number Diff line
@@ -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");

include/linux/rtc.h

+1 −0
Original line number Diff line number Diff line
@@ -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>