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authorDavid S. Miller <davem@davemloft.net>2013-10-23 16:28:39 -0400
committerDavid S. Miller <davem@davemloft.net>2013-10-23 16:49:34 -0400
commitc3fa32b9764dc45dcf8a2231b1c110abc4a63e0b (patch)
tree6cf2896a77b65bec64284681e1c3851eb3263e09 /include/linux/timex.h
parent34d92d5315b64a3e5292b7e9511c1bb617227fb6 (diff)
parent320437af954cbe66478f1f5e8b34cb5a8d072191 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts: drivers/net/usb/qmi_wwan.c include/net/dst.h Trivial merge conflicts, both were overlapping changes. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/timex.h')
-rw-r--r--include/linux/timex.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/timex.h b/include/linux/timex.h
index dd3edd7dfc94..9d3f1a5b6178 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -64,6 +64,20 @@
#include <asm/timex.h>
+#ifndef random_get_entropy
+/*
+ * The random_get_entropy() function is used by the /dev/random driver
+ * in order to extract entropy via the relative unpredictability of
+ * when an interrupt takes places versus a high speed, fine-grained
+ * timing source or cycle counter. Since it will be occurred on every
+ * single interrupt, it must have a very low cost/overhead.
+ *
+ * By default we use get_cycles() for this purpose, but individual
+ * architectures may override this in their asm/timex.h header file.
+ */
+#define random_get_entropy() get_cycles()
+#endif
+
/*
* SHIFT_PLL is used as a dampening factor to define how much we
* adjust the frequency correction for a given offset in PLL mode.