u-boot/include/linux/kconfig.h
Rasmus Villemoes 7842749c35 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>
2020-07-09 12:33:24 +08:00

111 lines
3.8 KiB
C

#ifndef __LINUX_KCONFIG_H
#define __LINUX_KCONFIG_H
#include <generated/autoconf.h>
/*
* Helper macros to use CONFIG_ options in C/CPP expressions. Note that
* these only work with boolean and tristate options.
*/
/*
* Getting something that works in C and CPP for an arg that may or may
* not be defined is tricky. Here, if we have "#define CONFIG_BOOGER 1"
* we match on the placeholder define, insert the "0," for arg1 and generate
* the triplet (0, 1, 0). Then the last step cherry picks the 2nd arg (a one).
* 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) _config_enabled(cfg)
#define _config_enabled(value) __config_enabled(__ARG_PLACEHOLDER_##value)
#define __config_enabled(arg1_or_junk) ___config_enabled(arg1_or_junk 1, 0)
#define ___config_enabled(__ignored, val, ...) val
/*
* IS_ENABLED(CONFIG_FOO) evaluates to 1 if CONFIG_FOO is set to 'y',
* 0 otherwise.
*
*/
#define IS_ENABLED(option) \
(config_enabled(option))
/*
* U-Boot add-on: Helper macros to reference to different macros
* (CONFIG_ or CONFIG_SPL_ prefixed), depending on the build context.
*/
#if defined(CONFIG_TPL_BUILD)
#define _CONFIG_PREFIX TPL_
#elif defined(CONFIG_SPL_BUILD)
#define _CONFIG_PREFIX SPL_
#else
#define _CONFIG_PREFIX
#endif
#define config_val(cfg) _config_val(_CONFIG_PREFIX, cfg)
#define _config_val(pfx, cfg) __config_val(pfx, cfg)
#define __config_val(pfx, cfg) CONFIG_ ## pfx ## cfg
/*
* CONFIG_VAL(FOO) evaluates to the value of
* CONFIG_FOO if CONFIG_SPL_BUILD is undefined,
* CONFIG_SPL_FOO if CONFIG_SPL_BUILD is defined.
* CONFIG_TPL_FOO if CONFIG_TPL_BUILD is defined.
*/
#define CONFIG_VAL(option) config_val(option)
/*
* 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, ...) \
__concat(__CONFIG_IS_ENABLED_, __count_args(option, ##__VA_ARGS__)) (option, ##__VA_ARGS__)
#endif /* __LINUX_KCONFIG_H */