diff options
Diffstat (limited to 'include/linux/time.h')
| -rw-r--r-- | include/linux/time.h | 70 |
1 files changed, 56 insertions, 14 deletions
diff --git a/include/linux/time.h b/include/linux/time.h index 6fad88e1a37d..fdab2abc43be 100644 --- a/include/linux/time.h +++ b/include/linux/time.h @@ -26,6 +26,16 @@ struct timezone { #include <linux/spinlock.h> #include <linux/seqlock.h> +#include <linux/timex.h> +#include <asm/div64.h> +#ifndef div_long_long_rem + +#define div_long_long_rem(dividend,divisor,remainder) ({ \ + u64 result = dividend; \ + *remainder = do_div(result,divisor); \ + result; }) + +#endif /* * Have the 32 bit jiffies value wrap 5 minutes after boot @@ -59,25 +69,52 @@ struct timezone { #ifndef NSEC_PER_USEC #define NSEC_PER_USEC (1000L) #endif +/* + * We want to do realistic conversions of time so we need to use the same + * values the update wall clock code uses as the jiffie size. This value + * is: TICK_NSEC(TICK_USEC) (both of which are defined in timex.h). This + * is a constant and is in nanoseconds. We will used scaled math and + * with a scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and + * NSEC_JIFFIE_SC. Note that these defines contain nothing but + * constants and so are computed at compile time. SHIFT_HZ (computed in + * timex.h) adjusts the scaling for different HZ values. + */ +#define SEC_JIFFIE_SC (30 - SHIFT_HZ) +#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 30) +#define USEC_JIFFIE_SC (SEC_JIFFIE_SC + 20) +#define SEC_CONVERSION ((unsigned long)(((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) /\ + (u64)TICK_NSEC(TICK_USEC))) +#define NSEC_CONVERSION ((unsigned long)(((u64)1 << NSEC_JIFFIE_SC) / \ + (u64)TICK_NSEC(TICK_USEC))) +#define USEC_CONVERSION \ + ((unsigned long)(((u64)NSEC_PER_USEC << USEC_JIFFIE_SC)/ \ + (u64)TICK_NSEC(TICK_USEC))) +#define MAX_SEC_IN_JIFFIES \ + (u32)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC(TICK_USEC)) / NSEC_PER_SEC) static __inline__ unsigned long timespec_to_jiffies(struct timespec *value) { unsigned long sec = value->tv_sec; - long nsec = value->tv_nsec; + long nsec = value->tv_nsec + TICK_NSEC(TICK_USEC) - 1; - if (sec >= (MAX_JIFFY_OFFSET / HZ)) + if (sec >= MAX_SEC_IN_JIFFIES) return MAX_JIFFY_OFFSET; - nsec += 1000000000L / HZ - 1; - nsec /= 1000000000L / HZ; - return HZ * sec + nsec; + return (((u64)sec * SEC_CONVERSION) + + (((u64)nsec * NSEC_CONVERSION) >> + (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; + } static __inline__ void jiffies_to_timespec(unsigned long jiffies, struct timespec *value) { - value->tv_nsec = (jiffies % HZ) * (1000000000L / HZ); - value->tv_sec = jiffies / HZ; + /* + * Convert jiffies to nanoseconds and seperate with + * one divide. + */ + u64 nsec = (u64)jiffies * TICK_NSEC(TICK_USEC); + value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec); } /* Same for "timeval" */ @@ -85,20 +122,25 @@ static __inline__ unsigned long timeval_to_jiffies(struct timeval *value) { unsigned long sec = value->tv_sec; - long usec = value->tv_usec; + long usec = value->tv_usec + USEC_PER_SEC / HZ - 1; - if (sec >= (MAX_JIFFY_OFFSET / HZ)) + if (sec >= MAX_SEC_IN_JIFFIES) return MAX_JIFFY_OFFSET; - usec += 1000000L / HZ - 1; - usec /= 1000000L / HZ; - return HZ * sec + usec; + return (((u64)sec * SEC_CONVERSION) + + (((u64)usec * USEC_CONVERSION) >> + (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; } static __inline__ void jiffies_to_timeval(unsigned long jiffies, struct timeval *value) { - value->tv_usec = (jiffies % HZ) * (1000000L / HZ); - value->tv_sec = jiffies / HZ; + /* + * Convert jiffies to nanoseconds and seperate with + * one divide. + */ + u64 nsec = (u64)jiffies * TICK_NSEC(TICK_USEC); + value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_usec); + value->tv_usec /= NSEC_PER_USEC; } static __inline__ int timespec_equal(struct timespec *a, struct timespec *b) |