Pass clocksource pointer to the read() callback for clocksources.  This
allows us to share the callback between multiple instances.

[hugh@veritas.com: fix powerpc build of clocksource pass clocksource mods]
[akpm@linux-foundation.org: cleanup]
Signed-off-by: NMagnus Damm <damm@igel.co.jp>
Acked-by: NJohn Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

with this printk() and other sched_clock() user use the more precise
timestamps. The highly optimized math is from arch/x86/kernel/tsc_32.c.
Signed-off-by: NSebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Ungerer <gerg@uclinux.org>

This one could be used as a hrtimer.
Signed-off-by: NBenedikt Spranger <b.spranger@linutronix.de>
Signed-off-by: NSebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: NGreg Ungerer <gerg@uclinux.org>