clocksource: em_sti: Emma Mobile STI driver

clocksource: em_sti: Emma Mobile STI driver

The STI hardware is based on a single 48-bit 32kHz
counter that together with two individual compare
registers can generate interrupts. There are no
timer operating modes selectable which means that
the timer can not clear on match.

This driver is providing clocksource support for the
48-bit counter. Clockevents are also supported using
the same timer in oneshot mode.

Signed-off-by: Magnus Damm <damm@opensource.se>
Cc: horms@verge.net.au
Cc: arnd@arndb.de
Cc: johnstul@us.ibm.com
Cc: rjw@sisk.pl
Cc: lethal@linux-sh.org
Cc: gregkh@linuxfoundation.org
Cc: olof@lixom.net
Link: http://lkml.kernel.org/r/20120525070344.23443.69756.sendpatchset@w520
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>