u-boot/include/linux/kconfig.h
Simon Glass 097ff01fb9 kconfig: Add support for conditional values
At present if an optional Kconfig value needs to be used it must be
bracketed by #ifdef. For example, with this Kconfig setup:

config WIBBLE
	bool "Support wibbles, the world needs more wibbles"

config WIBBLE_ADDR
	hex "Address of the wibble"
	depends on WIBBLE

then the following code must be used:

 #ifdef CONFIG_WIBBLE
 static void handle_wibble(void)
 {
 	int val = CONFIG_WIBBLE_ADDR;

	...
 }
 #endif

 static void init_machine()
 {
 ...
 #ifdef CONFIG_WIBBLE
	handle_wibble();
 #endif
 }

Add a new IF_ENABLED_INT() to help with this. So now it is possible to
write, without #ifdefs:

 static void handle_wibble(void)
 {
        int val = IF_ENABLED_INT(CONFIG_WIBBLE, CONFIG_WIBBLE_ADDR);

	...
 }

 static void init_machine()
 {
 ...
 if (IS_ENABLED(CONFIG_WIBBLE))
	handle_wibble();
 }

The value will be CONFIG_WIBBLE_ADDR if CONFIG_WIBBLE is defined and will
produce a build error if not.. This allows us to reduce the use of #ifdef
in the code, ensuring that the compiler still checks the code even if it
is not ultimately used for a particular build.

Add a CONFIG_IF_ENABLED_INT() version as well.

If an attempt is made to use a value that does not exist (i.e. when the
conditional is not enabled), an error about a non-existing function is
generated, e.g.:

common/bloblist.c:447: undefined reference to `invalid_use_of_IF_ENABLED_INT'

Signed-off-by: Simon Glass <sjg@chromium.org>
2022-02-08 23:07:59 -05:00

155 lines
5.7 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, def_val) _config_enabled(cfg, def_val)
#define _config_enabled(value, def_val) __config_enabled(__ARG_PLACEHOLDER_##value, def_val)
#define __config_enabled(arg1_or_junk, def_val) ___config_enabled(arg1_or_junk 1, def_val)
#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, 0)
/*
* U-Boot add-on: Helper macros to reference to different macros (prefixed by
* CONFIG_, CONFIG_SPL_, CONFIG_TPL_ or CONFIG_TOOLS_), depending on the build
* context.
*/
#ifdef USE_HOSTCC
#define _CONFIG_PREFIX TOOLS_
#elif 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_TOOLS_FOO if USE_HOSTCC is defined,
* 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)
/*
* This uses a similar mechanism to config_enabled() above. If cfg is enabled,
* it resolves to the value of opt_cfg, otherwise it resolves to def_val
*/
#define config_opt_enabled(cfg, opt_cfg, def_val) _config_opt_enabled(cfg, opt_cfg, def_val)
#define _config_opt_enabled(cfg_val, opt_value, def_val) \
__config_opt_enabled(__ARG_PLACEHOLDER_##cfg_val, opt_value, def_val)
#define __config_opt_enabled(arg1_or_junk, arg2, def_val) \
___config_opt_enabled(arg1_or_junk arg2, def_val)
#define ___config_opt_enabled(__ignored, val, ...) val
#ifndef __ASSEMBLY__
/*
* Detect usage of a the value when the conditional is not enabled. When used
* in assembly context, this likely produces a assembly error, or hopefully at
* least something recognisable.
*/
long invalid_use_of_IF_ENABLED_INT(void);
#endif
/* Evaluates to int_option if option is defined, otherwise a build error */
#define IF_ENABLED_INT(option, int_option) \
config_opt_enabled(option, int_option, invalid_use_of_IF_ENABLED_INT())
/*
* 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), 0)) (case1, case0)
/*
* CONFIG_IS_ENABLED(FOO) expands to
* 1 if USE_HOSTCC is defined and CONFIG_TOOLS_FOO is set to 'y',
* 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 USE_HOSTCC is defined and CONFIG_TOOLS_FOO is set to 'y',
* 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 USE_HOSTCC is defined and CONFIG_TOOLS_FOO is set to 'y',
* 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__)
#ifndef __ASSEMBLY__
/*
* Detect usage of a the value when the conditional is not enabled. When used
* in assembly context, this likely produces a assembly error, or hopefully at
* least something recognisable.
*/
long invalid_use_of_CONFIG_IF_ENABLED_INT(void);
#endif
/*
* Evaluates to SPL_/TPL_int_option if SPL_/TPL_/option is not defined,
* otherwise build error
*/
#define CONFIG_IF_ENABLED_INT(option, int_option) \
CONFIG_IS_ENABLED(option, (CONFIG_VAL(int_option)), \
(invalid_use_of_CONFIG_IF_ENABLED_INT()))
#endif /* __LINUX_KCONFIG_H */