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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-01-25 13:27:36 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-01-25 13:27:36 -0800
commit9f9cba810f36d16f4e64477e879a69f6c47b389d (patch)
treed787abcbead1439d3f82f0719efe520fd9689f79 /arch/s390/include/asm/timex.h
parentdbf5bef8da169b38db804996a661f8d634df8295 (diff)
parent949db153b6466c6f7cad5a427ecea94985927311 (diff)
downloadop-kernel-dev-9f9cba810f36d16f4e64477e879a69f6c47b389d.zip
op-kernel-dev-9f9cba810f36d16f4e64477e879a69f6c47b389d.tar.gz
Merge 3.8-rc5 into tty-next
This resolves a number of tty driver merge issues found in linux-next Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/s390/include/asm/timex.h')
-rw-r--r--arch/s390/include/asm/timex.h28
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index fba4d66..4c060bb 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
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