time: convert arch_gettimeoffset to a pointer

Currently, whenever CONFIG_ARCH_USES_GETTIMEOFFSET is enabled, each
arch core provides a single implementation of arch_gettimeoffset(). In
many cases, different sub-architectures, different machines, or
different timer providers exist, and so the arch ends up implementing
arch_gettimeoffset() as a call-through-pointer anyway. Examples are
ARM, Cris, M68K, and it's arguable that the remaining architectures,
M32R and Blackfin, should be doing this anyway.

Modify arch_gettimeoffset so that it itself is a function pointer, which
the arch initializes. This will allow later changes to move the
initialization of this function into individual machine support or timer
drivers. This is particularly useful for code in drivers/clocksource
which should rely on an arch-independant mechanism to register their
implementation of arch_gettimeoffset().

This patch also converts the Cris architecture to set arch_gettimeoffset
directly to the final implementation in time_init(), because Cris already
had separate time_init() functions per sub-architecture. M68K and ARM
are converted to set arch_gettimeoffset to the final implementation in
later patches, because they already have function pointers in place for
this purpose.

Cc: Russell King <linux@arm.linux.org.uk>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>

1 files changed, 10 insertions, 6 deletions

diff --git a/arch/m68k/kernel/time.c b/arch/m68k/kernel/time.c
index 5d0bcaad2e55..c2994c8c30d5 100644
--- a/arch/m68k/kernel/time.c
+++ b/arch/m68k/kernel/time.c
@@ -80,14 +80,9 @@ void read_persistent_clock(struct timespec *ts)
 	}
 }
 
-void __init time_init(void)
-{
-	mach_sched_init(timer_interrupt);
-}
-
 #ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
 
-u32 arch_gettimeoffset(void)
+static u32 m68k_gettimeoffset(void)
 {
 	return mach_gettimeoffset() * 1000;
 }
@@ -106,3 +101,12 @@ static int __init rtc_init(void)
 module_init(rtc_init);
 
 #endif /* CONFIG_ARCH_USES_GETTIMEOFFSET */
+
+void __init time_init(void)
+{
+#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
+	arch_gettimeoffset = m68k_gettimeoffset;
+#endif
+
+	mach_sched_init(timer_interrupt);
+}