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kconfig.h: allow to use IS_{ENABLE,REACHABLE} in macro expansion

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The typical usage of IS_ENABLED() is

    if (IS_ENABLED(CONFIG_FOO)) {
            ...
    }

or

    #if IS_ENABLED(CONFIG_FOO)
            ...
    #endif

The current implementation of IS_ENABLED() includes "||" operator,
which works well in those expressions like above.

However, there is a case where we want to evaluate a config option
beyond those use cases.

For example, the OF_TABLE() in include/asm-generic/vmlinux.lds.h
needs to evaluate a config option in macro expansion:

  #define ___OF_TABLE(cfg, name)  _OF_TABLE_##cfg(name)
  #define __OF_TABLE(cfg, name)   ___OF_TABLE(cfg, name)
  #define OF_TABLE(cfg, name)     __OF_TABLE(config_enabled(cfg), name)
  #define _OF_TABLE_0(name)
  #define _OF_TABLE_1(name)  \
          ...

Here, we can not use IS_ENABLED() because of the "||" operator in
its define.  It is true config_enabled() works well, but it is a bit
ambiguous to be used against config options.

This commit makes IS_ENABLED() available in more generic context by
calculating "or" with macro expansion only.

Do likewise for IS_REACHABLE().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
This commit is contained in:
Masahiro Yamada 2016-06-14 14:58:57 +09:00 committed by Michal Marek
parent 05a25c8e2c
commit 5e8754fd80
1 changed files with 18 additions and 6 deletions
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24
include/linux/kconfig.h
View File

@ -3,6 +3,21 @@
#include <generated/autoconf.h>
#define __ARG_PLACEHOLDER_1 0,
#define __take_second_arg(__ignored, val, ...) val
/*
* The use of "&&" / "||" is limited in certain expressions.
* The followings enable to calculate "and" / "or" with macro expansion only.
*/
#define __and(x, y) ___and(x, y)
#define ___and(x, y) ____and(__ARG_PLACEHOLDER_##x, y)
#define ____and(arg1_or_junk, y) __take_second_arg(arg1_or_junk y, 0)
#define __or(x, y) ___or(x, y)
#define ___or(x, y) ____or(__ARG_PLACEHOLDER_##x, y)
#define ____or(arg1_or_junk, y) __take_second_arg(arg1_or_junk 1, y)
/*
* Helper macros to use CONFIG_ options in C/CPP expressions. Note that
* these only work with boolean and tristate options.
@ -16,12 +31,10 @@
* When CONFIG_BOOGER is not defined, we generate a (... 1, 0) pair, and when
* the last step cherry picks the 2nd arg, we get a zero.
*/
#define __ARG_PLACEHOLDER_1 0,
#define config_enabled(cfg) ___is_defined(cfg)
#define __is_defined(x) ___is_defined(x)
#define ___is_defined(val) ____is_defined(__ARG_PLACEHOLDER_##val)
#define ____is_defined(arg1_or_junk) __take_second_arg(arg1_or_junk 1, 0)
#define __take_second_arg(__ignored, val, ...) val
/*
* IS_BUILTIN(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y', 0
@ -42,14 +55,13 @@
* This is similar to IS_ENABLED(), but returns false when invoked from
* built-in code when CONFIG_FOO is set to 'm'.
*/
#define IS_REACHABLE(option) (IS_BUILTIN(option) || \
(IS_MODULE(option) && __is_defined(MODULE)))
#define IS_REACHABLE(option) __or(IS_BUILTIN(option), \
__and(IS_MODULE(option), __is_defined(MODULE)))
/*
* IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y' or 'm',
* 0 otherwise.
*/
#define IS_ENABLED(option) \
(IS_BUILTIN(option) || IS_MODULE(option))
#define IS_ENABLED(option) __or(IS_BUILTIN(option), IS_MODULE(option))
#endif /* __LINUX_KCONFIG_H */