diff options
| -rw-r--r-- | drivers/rtc/rtc-lib.c | 81 | ||||
| -rw-r--r-- | include/linux/rtc.h | 1 |
2 files changed, 82 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c index ba795a4db1e..7bbc26a34bd 100644 --- a/drivers/rtc/rtc-lib.c +++ b/drivers/rtc/rtc-lib.c @@ -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"); diff --git a/include/linux/rtc.h b/include/linux/rtc.h index 09ff4c3e271..5e22d4510d1 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -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> |