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, 4 insertions, 2 deletions

diff --git a/arch/cris/arch-v10/kernel/time.c b/arch/cris/arch-v10/kernel/time.c
index 162892f24a2..fce7c541d70 100644
--- a/arch/cris/arch-v10/kernel/time.c
+++ b/arch/cris/arch-v10/kernel/time.c
@@ -55,9 +55,9 @@ unsigned long get_ns_in_jiffie(void)
 	return ns;
 }
 
-unsigned long do_slow_gettimeoffset(void)
+static u32 cris_v10_gettimeoffset(void)
 {
-	unsigned long count;
+	u32 count;
 
 	/* The timer interrupt comes from Etrax timer 0. In order to get
 	 * better precision, we check the current value. It might have
@@ -191,6 +191,8 @@ static struct irqaction irq2  = {
 void __init
 time_init(void)
 {	
+	arch_gettimeoffset = cris_v10_gettimeoffset;
+
 	/* probe for the RTC and read it if it exists 
 	 * Before the RTC can be probed the loops_per_usec variable needs 
 	 * to be initialized to make usleep work. A better value for