clocksource: Replace vread with generic arch data

The vread field was bloating struct clocksource everywhere except
x86_64, and I want to change the way this works on x86_64, so let's
split it out into per-arch data.

Cc: x86@kernel.org
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: linux-ia64@vger.kernel.org
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/3ae5ec76a168eaaae63f08a2a1060b91aa0b7759.1310563276.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index d4646b4..0fb83c2 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -22,6 +22,8 @@
 typedef u64 cycle_t;
 struct clocksource;
 
+#include <asm/clocksource.h>
+
 /**
  * struct cyclecounter - hardware abstraction for a free running counter
  *	Provides completely state-free accessors to the underlying hardware.
@@ -153,7 +155,7 @@
  * @shift:		cycle to nanosecond divisor (power of two)
  * @max_idle_ns:	max idle time permitted by the clocksource (nsecs)
  * @flags:		flags describing special properties
- * @vread:		vsyscall based read
+ * @archdata:		arch-specific data
  * @suspend:		suspend function for the clocksource, if necessary
  * @resume:		resume function for the clocksource, if necessary
  */
@@ -175,10 +177,14 @@
 #else
 #define CLKSRC_FSYS_MMIO_SET(mmio, addr)      do { } while (0)
 #endif
+
+#ifdef __ARCH_HAS_CLOCKSOURCE_DATA
+	struct arch_clocksource_data archdata;
+#endif
+
 	const char *name;
 	struct list_head list;
 	int rating;
-	cycle_t (*vread)(void);
 	int (*enable)(struct clocksource *cs);
 	void (*disable)(struct clocksource *cs);
 	unsigned long flags;