linux/kconfig.h: create two- and three-argument versions of CONFIG_IS_ENABLED
This adds a bunch of preprocessor magic to extend the capabilities of
CONFIG_IS_ENABLED. The existing semantics of
CONFIG_IS_ENABLED(FOO)
expanding to a 1 or 0 (depending on build context and the defined-ness
or not of the appropriate CONFIG_FOO/CONFIG_SPL_FOO/CONFIG_TPL_FOO)
are of course preserved. With this, one is also allowed a two-argument
form
CONFIG_IS_ENABLED(FOO, (something))
which expands to something precisely when CONFIG_IS_ENABLED(FOO) would
expand to 1, and expands to nothing otherwise. It is, in other words,
completely equivalent to the three lines
#if CONFIG_IS_ENABLED(FOO)
something
#endif
The second argument must be parenthesized in order to allow any
tokens, including a trailing comma, to appear - one use case for this
is precisely to make it a bit more ergonomic to build an array and
only include certain items depending on .config. That should increase
both readability and not least "git grep"ability.
A third variant is also introduced,
CONFIG_IS_ENABLED(FOO, (xxx), (yyy))
which corresponds to
#if CONFIG_IS_ENABLED(FOO)
xxx
#else
yyy
#endif
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h
index caea505..d109ed3 100644
--- a/include/linux/kconfig.h
+++ b/include/linux/kconfig.h
@@ -56,13 +56,55 @@
#define CONFIG_VAL(option) config_val(option)
/*
- * CONFIG_IS_ENABLED(FOO) evaluates to
+ * Count number of arguments to a variadic macro. Currently only need
+ * it for 1, 2 or 3 arguments.
+ */
+#define __arg6(a1, a2, a3, a4, a5, a6, ...) a6
+#define __count_args(...) __arg6(dummy, ##__VA_ARGS__, 4, 3, 2, 1, 0)
+
+#define __concat(a, b) ___concat(a, b)
+#define ___concat(a, b) a ## b
+
+#define __unwrap(...) __VA_ARGS__
+#define __unwrap1(case1, case0) __unwrap case1
+#define __unwrap0(case1, case0) __unwrap case0
+
+#define __CONFIG_IS_ENABLED_1(option) __CONFIG_IS_ENABLED_3(option, (1), (0))
+#define __CONFIG_IS_ENABLED_2(option, case1) __CONFIG_IS_ENABLED_3(option, case1, ())
+#define __CONFIG_IS_ENABLED_3(option, case1, case0) \
+ __concat(__unwrap, config_enabled(CONFIG_VAL(option))) (case1, case0)
+
+/*
+ * CONFIG_IS_ENABLED(FOO) expands to
* 1 if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y',
* 1 if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
* 1 if CONFIG_TPL_BUILD is defined and CONFIG_TPL_FOO is set to 'y',
* 0 otherwise.
+ *
+ * CONFIG_IS_ENABLED(FOO, (abc)) expands to
+ * abc if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y',
+ * abc if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
+ * abc if CONFIG_TPL_BUILD is defined and CONFIG_TPL_FOO is set to 'y',
+ * nothing otherwise.
+ *
+ * CONFIG_IS_ENABLED(FOO, (abc), (def)) expands to
+ * abc if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y',
+ * abc if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y',
+ * abc if CONFIG_TPL_BUILD is defined and CONFIG_TPL_FOO is set to 'y',
+ * def otherwise.
+ *
+ * The optional second and third arguments must be parenthesized; that
+ * allows one to include a trailing comma, e.g. for use in
+ *
+ * CONFIG_IS_ENABLED(ACME, ({.compatible = "acme,frobnozzle"},))
+ *
+ * which adds an entry to the array being defined if CONFIG_ACME (or
+ * CONFIG_SPL_ACME/CONFIG_TPL_ACME, depending on build context) is
+ * set, and nothing otherwise.
*/
-#define CONFIG_IS_ENABLED(option) \
- (config_enabled(CONFIG_VAL(option)))
+
+#define CONFIG_IS_ENABLED(option, ...) \
+ __concat(__CONFIG_IS_ENABLED_, __count_args(option, ##__VA_ARGS__)) (option, ##__VA_ARGS__)
+
#endif /* __LINUX_KCONFIG_H */