vtime: Describe overriden functions in dedicated arch headers

If the arch overrides some generic vtime APIs, let it describe
these on a dedicated and standalone header. This way it becomes
convenient to include it in vtime generic headers without irrelevant
stuff in such a low level header.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>

arch/ia64/include/asm/Kbuild

@@ -3,3 +3,4 @@ generic-y += clkdev.h
 generic-y += exec.h
 generic-y += kvm_para.h
 generic-y += trace_clock.h
+generic-y += vtime.h

arch/powerpc/include/asm/Kbuild

@@ -2,3 +2,4 @@
 generic-y += clkdev.h
 generic-y += rwsem.h
 generic-y += trace_clock.h
+generic-y += vtime.h

arch/s390/include/asm/cputime.h

@@ -13,9 +13,6 @@
 #include <asm/div64.h>
 
 
-#define __ARCH_HAS_VTIME_ACCOUNT
-#define __ARCH_HAS_VTIME_TASK_SWITCH
-
 /* We want to use full resolution of the CPU timer: 2**-12 micro-seconds. */
 
 typedef unsigned long long __nocast cputime_t;

arch/s390/include/asm/vtime.h

@@ -0,0 +1,7 @@
+#ifndef _S390_VTIME_H
+#define _S390_VTIME_H
+
+#define __ARCH_HAS_VTIME_ACCOUNT
+#define __ARCH_HAS_VTIME_TASK_SWITCH
+
+#endif /* _S390_VTIME_H */

arch/s390/kernel/vtime.c

@@ -19,6 +19,7 @@
 #include <asm/irq_regs.h>
 #include <asm/cputime.h>
 #include <asm/vtimer.h>
+#include <asm/vtime.h>
 #include <asm/irq.h>
 #include "entry.h"
 

include/linux/vtime.h

@@ -1,6 +1,10 @@
 #ifndef _LINUX_KERNEL_VTIME_H
 #define _LINUX_KERNEL_VTIME_H
 
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
+#include <asm/vtime.h>
+#endif
+
 struct task_struct;
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING