clocksource: SuperH MTU2 Timer driver

This patch adds a MTU2 driver for the SuperH architecture.

The MTU2 driver is a platform driver with early platform
support to allow using a MTU2 channel as only clockevent
during system bootup.

Clocksource on sh2a is currently unsupported due to code
generation issues with 64-bit math, so at this point only
periodic clockevent support is in place.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 6f91478..6d0dd37 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -113,6 +113,9 @@
 config SYS_SUPPORTS_CMT
 	bool
 
+config SYS_SUPPORTS_MTU2
+	bool
+
 config STACKTRACE_SUPPORT
 	def_bool y
 
@@ -478,6 +481,14 @@
 	help
 	  This enables the use of the MTU2 as the system timer.
 
+config SH_TIMER_MTU2
+	bool "MTU2 timer driver"
+	depends on SYS_SUPPORTS_MTU2 && !SH_MTU2
+	default y
+	select GENERIC_CLOCKEVENTS
+	help
+	  This enables build of the MTU2 timer driver.
+
 config SH_TIMER_IRQ
 	int
 	default "28" if CPU_SUBTYPE_SH7780 || CPU_SUBTYPE_SH7785 || \