[PATCH] x86/tsc: Fix -Wmissing-prototypes warning for calibrate_delay_is_known()

[Yi Wang]

We get a warning when building kernel with W=1:
arch/x86/kernel/tsc.c:1497:15: warning: no previous prototype for âcalibrate_delay_is_knownâ [-Wmissing-prototypes]
 unsigned long calibrate_delay_is_known(void)
               ^

Add the missing declaration in head file to fix this.

Signed-off-by: Yi Wang <wang.yi59@xxxxxxxxxx>
---
 arch/x86/include/asm/tsc.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index eb5bbfe..8a0c25c 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -35,6 +35,7 @@ static inline cycles_t get_cycles(void)
 
 extern void tsc_early_init(void);
 extern void tsc_init(void);
+extern unsigned long calibrate_delay_is_known(void);
 extern void mark_tsc_unstable(char *reason);
 extern int unsynchronized_tsc(void);
 extern int check_tsc_unstable(void);
-- 
1.8.3.1