init.h: Add early_param_on_off()

At times all you need is a kconfig variable to enable a feature,
by default but you may want to also enable / disable it through
a kernel parameter. In such cases the parameter routines to turn
the thing on / off are really simple. Just use a wrapper for
this, it lets us generalize the code and makes it easier to
associate parameters with related kernel configuration options.

Signed-off-by: Luis R. Rodriguez <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Vrabel <[email protected]>
Cc: Dexuan Cui <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: [email protected]
Cc: Jan Beulich <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Pavel Machek <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xishi Qiu <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/init.h b/include/linux/init.h
index 2df8e8dd10a4..bc11ff96f336 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -268,6 +268,21 @@ struct obs_kernel_param {
 #define early_param(str, fn)					\
 	__setup_param(str, fn, fn, 1)
 
+#define early_param_on_off(str_on, str_off, var, config)			\
+	int var = IS_ENABLED(config);				\
+	static int __init parse_##var##_on(char *arg)		\
+	{							\
+		var = 1;					\
+		return 0;					\
+	}							\
+	static int __init parse_##var##_off(char *arg)		\
+	{							\
+		var = 0;					\
+		return 0;					\
+	}							\
+	__setup_param(str_on, parse_##var##_on, parse_##var##_on, 1); \
+	__setup_param(str_off, parse_##var##_off, parse_##var##_off, 1)
+
 /* Relies on boot_command_line being set */
 void __init parse_early_param(void);
 void __init parse_early_options(char *cmdline);