[PATCH] clocksource: Add verification (watchdog) helper

The TSC needs to be verified against another clocksource.  Instead of using
hardwired assumptions of available hardware, provide a generic verification
mechanism.  The verification uses the best available clocksource and handles
the usability for high resolution timers / dynticks of the clocksource which
needs to be verified.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 2 deletions

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index a585a29fe7c4..830a250ecf94 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -12,11 +12,13 @@
 #include <linux/timex.h>
 #include <linux/time.h>
 #include <linux/list.h>
+#include <linux/timer.h>
 #include <asm/div64.h>
 #include <asm/io.h>
 
 /* clocksource cycle base type */
 typedef u64 cycle_t;
+struct clocksource;
 
 /**
  * struct clocksource - hardware abstraction for a free running counter
@@ -62,13 +64,22 @@ struct clocksource {
         cycle_t cycle_last, cycle_interval;
         u64 xtime_nsec, xtime_interval;
         s64 error;
+
+#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
+        /* Watchdog related data, used by the framework */
+        struct list_head wd_list;
+        cycle_t wd_last;
+#endif
 };
 
 /*
  * Clock source flags bits::
  */
-#define CLOCK_SOURCE_IS_CONTINUOUS      0x01
-#define CLOCK_SOURCE_MUST_VERIFY        0x02
+#define CLOCK_SOURCE_IS_CONTINUOUS              0x01
+#define CLOCK_SOURCE_MUST_VERIFY                0x02
+
+#define CLOCK_SOURCE_WATCHDOG                   0x10
+#define CLOCK_SOURCE_VALID_FOR_HRES             0x20
 
 /* simplify initialization of mask field */
 #define CLOCKSOURCE_MASK(bits) (cycle_t)(bits<64 ? ((1ULL<<bits)-1) : -1)