linux/kconfig.h: add CPP macros useful for per-image config options

The previous commit introduced a useful macro used in makefiles,
in order to reference to different variables (CONFIG_... or
CONFIG_SPL_...) depending on the build context.

Per-image config option control is a PITA in C sources, too.
Here are some macros useful in C/CPP expressions.

CONFIG_IS_ENABLED(FOO) can be used as a shorthand for

  (!defined(CONFIG_SPL_BUILD) && defined(CONFIG_FOO)) || \
   (defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_FOO))

For example, it is useful to describe C code as follows,

  #if CONFIG_IS_ENABLED(OF_CONTROL)
      (device tree code)
  #else
      (board file code)
  #endif

The ifdef conditional above is switched by CONFIG_OF_CONTROL during
the U-Boot proper building (CONFIG_SPL_BUILD is not defined), and by
CONFIG_SPL_OF_CONTROL during SPL building (CONFIG_SPL_BUILD is
defined).

The macro can be used in C context as well, so you can also write the
equivalent code as follows:

  if (CONFIG_IS_ENABLED(OF_CONTROL)) {
      (device tree code)
  } else {
      (board file code)
  }

Another useful macro is CONFIG_VALUE().
CONFIG_VALUE(FOO) is expanded into CONFIG_FOO if CONFIG_SPL_BUILD is
undefined, and into CONFIG_SPL_FOO if CONFIG_SPL_BUILD is defined.

You can write as follows:

  text_base = CONFIG_VALUE(TEXT_BASE);

instead of:

  #ifdef CONFIG_SPL_BUILD
      text_base = CONFIG_SPL_TEXT_BASE;
  #else
      text_base = CONFIG_TEXT_BASE;
  #endif

This commit also adds slight hacking on fixdep so that it can
output a correct list of fixed dependencies.

If the fixdep finds CONFIG_IS_ENABLED(FOO) in a source file,
we want
    $(wildcard include/config/foo.h)
in the U-boot proper building context, while we want
    $(wildcard include/config/spl/foo.h)
in the SPL build context.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/linux/kconfig.h

@@ -43,4 +43,52 @@
  */
 #define IS_MODULE(option) config_enabled(option##_MODULE)
 
+/*
+ * U-Boot add-on: Helper macros to reference to different macros
+ * (CONFIG_ or CONFIG_SPL_ prefixed), depending on the build context.
+ */
+#ifdef CONFIG_SPL_BUILD
+#define _IS_SPL 1
+#endif
+
+#define config_val(cfg) _config_val(_IS_SPL, cfg)
+#define _config_val(x, cfg) __config_val(x, cfg)
+#define __config_val(x, cfg) ___config_val(__ARG_PLACEHOLDER_##x, cfg)
+#define ___config_val(arg1_or_junk, cfg)  \
+	____config_val(arg1_or_junk CONFIG_SPL_##cfg, CONFIG_##cfg)
+#define ____config_val(__ignored, val, ...) val
+
+/*
+ * 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.
+ */
+#define CONFIG_VAL(option)  config_val(option)
+
+/*
+ * CONFIG_IS_ENABLED(FOO) evaluates to
+ *  1 if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'y' or 'm',
+ *  1 if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'y' or 'm',
+ *  0 otherwise.
+ */
+#define CONFIG_IS_ENABLED(option) \
+	(config_enabled(CONFIG_VAL(option)) ||		\
+	 config_enabled(CONFIG_VAL(option##_MODULE)))
+
+/*
+ * CONFIG_IS_BUILTIN(FOO) evaluates 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',
+ *  0 otherwise.
+ */
+#define CONFIG_IS_BUILTIN(option) config_enabled(CONFIG_VAL(option))
+
+/*
+ * CONFIG_IS_MODULE(FOO) evaluates to
+ *  1 if CONFIG_SPL_BUILD is undefined and CONFIG_FOO is set to 'm',
+ *  1 if CONFIG_SPL_BUILD is defined and CONFIG_SPL_FOO is set to 'm',
+ *  0 otherwise.
+ */
+#define CONFIG_IS_MODULE(option) config_enabled(CONFIG_VAL(option##_MODULE))
+
 #endif /* __LINUX_KCONFIG_H */

scripts/basic/fixdep.c

@@ -123,6 +123,7 @@
 char *target;
 char *depfile;
 char *cmdline;
+int is_spl_build = 0; /* hack for U-boot */
 
 static void usage(void)
 {
@@ -239,6 +240,7 @@ static void parse_config_file(const char *map, size_t len)
 	/* start at +1, so that p can never be < map */
 	const int *m   = (const int *) map + 1;
 	const char *p, *q;
+	char tmp_buf[256] = "SPL_"; /* hack for U-Boot */
 
 	for (; m < end; m++) {
 		if (*m == INT_CONF) { p = (char *) m  ; goto conf; }
@@ -263,6 +265,26 @@ static void parse_config_file(const char *map, size_t len)
 			q -= 7;
 		if (q - p < 0)
 			continue;
+
+		/* U-Boot also handles CONFIG_IS_{ENABLED/BUILTIN/MODULE} */
+		if ((q - p == 10 && !memcmp(p, "IS_ENABLED(", 11)) ||
+		    (q - p == 10 && !memcmp(p, "IS_BUILTIN(", 11)) ||
+		    (q - p == 9 && !memcmp(p, "IS_MODULE(", 10))) {
+			p = q + 1;
+			for (q = p; q < map + len; q++)
+				if (*q == ')')
+					goto found2;
+			continue;
+
+		found2:
+			if (is_spl_build) {
+				memcpy(tmp_buf + 4, p, q - p);
+				q = tmp_buf + 4 + (q - p);
+				p = tmp_buf;
+			}
+		}
+		/* end U-Boot hack */
+
 		use_config(p, q - p);
 	}
 }
@@ -456,6 +478,10 @@ int main(int argc, char *argv[])
 	target = argv[2];
 	cmdline = argv[3];
 
+	/* hack for U-boot */
+	if (!strncmp(target, "spl/", 4) || !strncmp(target, "tpl/", 4))
+		is_spl_build = 1;
+
 	print_cmdline();
 	print_deps();