x86, olpc: Add XO-1 RTC driver

Add a driver to configure the XO-1 RTC via CS5536 MSRs, to be used as a
system wakeup source via olpc-xo1-pm.

Device detection is based on finding the relevant device tree node.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Link: http://lkml.kernel.org/r/1309019658-1712-11-git-send-email-dsd@laptop.org
Acked-by: Andres Salomon <dilinger@queued.net>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: devicetree-discuss@lists.ozlabs.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a6aefbb..0a9d573 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2080,6 +2080,13 @@
 	---help---
 	  Add support for poweroff and suspend of the OLPC XO-1 laptop.
 
+config OLPC_XO1_RTC
+	bool "OLPC XO-1 Real Time Clock"
+	depends on OLPC_XO1_PM && RTC_DRV_CMOS
+	---help---
+	  Add support for the XO-1 real time clock, which can be used as a
+	  programmable wakeup source.
+
 config OLPC_XO1_SCI
 	bool "OLPC XO-1 SCI extras"
 	depends on OLPC && OLPC_XO1_PM && POWER_SUPPLY