[PATCH] Time: Clocksource Infrastructure

This introduces the clocksource management infrastructure.  A clocksource is a
driver-like architecture generic abstraction of a free-running counter.  This
code defines the clocksource structure, and provides management code for
registering, selecting, accessing and scaling clocksources.

Additionally, this includes the trivial jiffies clocksource, a lowest common
denominator clocksource, provided mainly for use as an example.

[hirofumi@mail.parknet.co.jp: Don't enable IRQ too early]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bca6f38..9686316 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -61,6 +61,7 @@
 	MTD	MTD support is enabled.
 	NET	Appropriate network support is enabled.
 	NUMA	NUMA support is enabled.
+	GENERIC_TIME The generic timeofday code is enabled.
 	NFS	Appropriate NFS support is enabled.
 	OSS	OSS sound support is enabled.
 	PARIDE	The ParIDE subsystem is enabled.
@@ -341,10 +342,11 @@
 			Value can be changed at runtime via
 				/selinux/checkreqprot.
 
- 	clock=		[BUGS=IA-32,HW] gettimeofday timesource override.
-			Forces specified timesource (if avaliable) to be used
-			when calculating gettimeofday(). If specicified
-			timesource is not avalible, it defaults to PIT.
+	clock=		[BUGS=IA-32, HW] gettimeofday clocksource override.
+			[Deprecated]
+			Forces specified clocksource (if avaliable) to be used
+			when calculating gettimeofday(). If specified
+			clocksource is not avalible, it defaults to PIT.
 			Format: { pit | tsc | cyclone | pmtmr }
 
 	disable_8254_timer
@@ -1617,6 +1619,10 @@
 
 	time		Show timing data prefixed to each printk message line
 
+	clocksource=	[GENERIC_TIME] Override the default clocksource
+			Override the default clocksource and use the clocksource
+			with the name specified.
+
 	tipar.timeout=	[HW,PPT]
 			Set communications timeout in tenths of a second
 			(default 15).