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 --- include/linux/kconfig.h | 48 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 45 insertions(+), 3 deletions(-)
diff --git a/include/linux/kconfig.h b/include/linux/kconfig.h index caea505a0e..d109ed3119 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 */