diff options
Diffstat (limited to 'include/linux/rtc.h')
| -rw-r--r-- | include/linux/rtc.h | 43 |
1 files changed, 42 insertions, 1 deletions
diff --git a/include/linux/rtc.h b/include/linux/rtc.h index f6d7ee98d93c..41319a2e409b 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -136,6 +136,14 @@ struct rtc_device { /* Some hardware can't support UIE mode */ int uie_unsupported; + /* Number of nsec it takes to set the RTC clock. This influences when + * the set ops are called. An offset: + * - of 0.5 s will call RTC set for wall clock time 10.0 s at 9.5 s + * - of 1.5 s will call RTC set for wall clock time 10.0 s at 8.5 s + * - of -0.5 s will call RTC set for wall clock time 10.0 s at 10.5 s + */ + long set_offset_nsec; + bool registered; struct nvmem_config *nvmem_config; @@ -173,7 +181,7 @@ extern void devm_rtc_device_unregister(struct device *dev, extern int rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm); extern int rtc_set_time(struct rtc_device *rtc, struct rtc_time *tm); -extern int rtc_set_ntp_time(struct timespec64 now); +extern int rtc_set_ntp_time(struct timespec64 now, unsigned long *target_nsec); int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm); extern int rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alrm); @@ -222,6 +230,39 @@ static inline bool is_leap_year(unsigned int year) return (!(year % 4) && (year % 100)) || !(year % 400); } +/* Determine if we can call to driver to set the time. Drivers can only be + * called to set a second aligned time value, and the field set_offset_nsec + * specifies how far away from the second aligned time to call the driver. + * + * This also computes 'to_set' which is the time we are trying to set, and has + * a zero in tv_nsecs, such that: + * to_set - set_delay_nsec == now +/- FUZZ + * + */ +static inline bool rtc_tv_nsec_ok(s64 set_offset_nsec, + struct timespec64 *to_set, + const struct timespec64 *now) +{ + /* Allowed error in tv_nsec, arbitarily set to 5 jiffies in ns. */ + const unsigned long TIME_SET_NSEC_FUZZ = TICK_NSEC * 5; + struct timespec64 delay = {.tv_sec = 0, + .tv_nsec = set_offset_nsec}; + + *to_set = timespec64_add(*now, delay); + + if (to_set->tv_nsec < TIME_SET_NSEC_FUZZ) { + to_set->tv_nsec = 0; + return true; + } + + if (to_set->tv_nsec > NSEC_PER_SEC - TIME_SET_NSEC_FUZZ) { + to_set->tv_sec++; + to_set->tv_nsec = 0; + return true; + } + return false; +} + #define rtc_register_device(device) \ __rtc_register_device(THIS_MODULE, device) |