diff options
author | David S. Miller <davem@davemloft.net> | 2013-01-29 15:32:13 -0500 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2013-01-29 15:32:13 -0500 |
commit | f1e7b73acc26e8908af783bcd3a9900fd80688f5 (patch) | |
tree | 9a9382fb7f12f1889020efb4bffa3f4a88589fc5 /arch/s390/include/asm/timex.h | |
parent | 218774dc341f219bfcf940304a081b121a0e8099 (diff) | |
parent | fc16e884a2320198b8cb7bc2fdcf6b4485e79709 (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Bring in the 'net' tree so that we can get some ipv4/ipv6 bug
fixes that some net-next work will build upon.
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch/s390/include/asm/timex.h')
-rw-r--r-- | arch/s390/include/asm/timex.h | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h index fba4d66788a..4c060bb5b8e 100644 --- a/arch/s390/include/asm/timex.h +++ b/arch/s390/include/asm/timex.h @@ -128,4 +128,32 @@ static inline unsigned long long get_clock_monotonic(void) return get_clock_xt() - sched_clock_base_cc; } +/** + * tod_to_ns - convert a TOD format value to nanoseconds + * @todval: to be converted TOD format value + * Returns: number of nanoseconds that correspond to the TOD format value + * + * Converting a 64 Bit TOD format value to nanoseconds means that the value + * must be divided by 4.096. In order to achieve that we multiply with 125 + * and divide by 512: + * + * ns = (todval * 125) >> 9; + * + * In order to avoid an overflow with the multiplication we can rewrite this. + * With a split todval == 2^32 * th + tl (th upper 32 bits, tl lower 32 bits) + * we end up with + * + * ns = ((2^32 * th + tl) * 125 ) >> 9; + * -> ns = (2^23 * th * 125) + ((tl * 125) >> 9); + * + */ +static inline unsigned long long tod_to_ns(unsigned long long todval) +{ + unsigned long long ns; + + ns = ((todval >> 32) << 23) * 125; + ns += ((todval & 0xffffffff) * 125) >> 9; + return ns; +} + #endif |