summaryrefslogtreecommitdiff
path: root/include/linux/rational.h
diff options
context:
space:
mode:
authorOskar Schirmer <os@emlix.com>2009-06-11 14:51:15 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-11 08:51:08 -0700
commit8759ef32d992fc6c0bcbe40fca7aa302190918a5 (patch)
tree316df64d3456597bf7f8ef7508654c82faf6a5fe /include/linux/rational.h
parent9f322ad064f9210e7d472dfe77e702274d5c9dba (diff)
downloadlinux-3.10-8759ef32d992fc6c0bcbe40fca7aa302190918a5.tar.gz
linux-3.10-8759ef32d992fc6c0bcbe40fca7aa302190918a5.tar.bz2
linux-3.10-8759ef32d992fc6c0bcbe40fca7aa302190918a5.zip
lib: isolate rational fractions helper function
Provide a helper function to determine optimum numerator denominator value pairs taking into account restricted register size. Useful especially with PLL and other clock configurations. Signed-off-by: Oskar Schirmer <os@emlix.com> Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/rational.h')
-rw-r--r--include/linux/rational.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/rational.h b/include/linux/rational.h
new file mode 100644
index 00000000000..4f532fcd9ee
--- /dev/null
+++ b/include/linux/rational.h
@@ -0,0 +1,19 @@
+/*
+ * rational fractions
+ *
+ * Copyright (C) 2009 emlix GmbH, Oskar Schirmer <os@emlix.com>
+ *
+ * helper functions when coping with rational numbers,
+ * e.g. when calculating optimum numerator/denominator pairs for
+ * pll configuration taking into account restricted register size
+ */
+
+#ifndef _LINUX_RATIONAL_H
+#define _LINUX_RATIONAL_H
+
+void rational_best_approximation(
+ unsigned long given_numerator, unsigned long given_denominator,
+ unsigned long max_numerator, unsigned long max_denominator,
+ unsigned long *best_numerator, unsigned long *best_denominator);
+
+#endif /* _LINUX_RATIONAL_H */