document clocksources

Document the available clocksources per platform and move clocksource= into
the correct (alpha) location in the file.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/kernel-parameters.txt

@@ -396,6 +396,26 @@ and is between 256 and 4096 characters. It is defined in the file
 			clocksource is not available, it defaults to PIT.
 			Format: { pit | tsc | cyclone | pmtmr }
 
+	clocksource=	[GENERIC_TIME] Override the default clocksource
+			Format: <string>
+			Override the default clocksource and use the clocksource
+			with the name specified.
+			Some clocksource names to choose from, depending on
+			the platform:
+			[all] jiffies (this is the base, fallback clocksource)
+			[ACPI] acpi_pm
+			[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
+				pxa_timer,timer3,32k_counter,timer0_1
+			[AVR32] avr32
+			[IA-32] pit,hpet,tsc,vmi-timer;
+				scx200_hrt on Geode; cyclone on IBM x440
+			[MIPS] MIPS
+			[PARISC] cr16
+			[S390] tod
+			[SH] SuperH
+			[SPARC64] tick
+			[X86-64] hpet,tsc
+
 	code_bytes	[IA32] How many bytes of object code to print in an
 			oops report.
 			Range: 0 - 8192
@@ -1807,10 +1827,6 @@ and is between 256 and 4096 characters. It is defined in the file
 
 	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).