[PATCH] math: Make RATIONAL tristate

[Geert Uytterhoeven]

All but one symbols that select RATIONAL are tristate, but RATIONAL
itself is bool.  Change it to tristate, so the rational fractions
support code can be modular if no builtin code relies on it.

While at it, add support for compile-testing and provide a help text.

Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
---
Exposed by commit b6c75c4afceb8bc0 ("lib/math/rational: add Kunit test
cases") and CONFIG_KUNIT_ALL_TESTS=m.

I'm not so happy RATIONAL_KUNIT_TEST selects RATIONAL, as test code
should depend on the presence of the feature to test.  Else enabling
a test may add unneeded code to a production kernel.
Perhaps the "if COMPILE_TEST" should be dropped, making RATIONAL
visible, so RATIONAL_KUNIT_TEST can depend on RATIONAL instead?
---
 lib/math/Kconfig    | 5 ++++-
 lib/math/rational.c | 3 +++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/lib/math/Kconfig b/lib/math/Kconfig
index f19bc9734fa7cc4b..14def252ea7db6e0 100644
--- a/lib/math/Kconfig
+++ b/lib/math/Kconfig
@@ -14,4 +14,7 @@ config PRIME_NUMBERS
 	  If unsure, say N.
 
 config RATIONAL
-	bool
+	tristate "Rational fractions support" if COMPILE_TEST
+	help
+	  This option provides support for rational fractions.
+	  This symbol should be selected automatically by drivers that need it.
diff --git a/lib/math/rational.c b/lib/math/rational.c
index c0ab51d8fbb98d17..ec59d426ea638b0f 100644
--- a/lib/math/rational.c
+++ b/lib/math/rational.c
@@ -13,6 +13,7 @@
 #include <linux/export.h>
 #include <linux/minmax.h>
 #include <linux/limits.h>
+#include <linux/module.h>
 
 /*
  * calculate best rational approximation for a given fraction
@@ -106,3 +107,5 @@ void rational_best_approximation(
 }
 
 EXPORT_SYMBOL(rational_best_approximation);
+
+MODULE_LICENSE("GPL v2");
-- 
2.25.1