clocksource/drivers/mxs: Add the COMPILE_TEST option

Change the Kconfig option logic to fullfil with the current approach.

A new Kconfig option is added, CONFIG_MXS_TIMER and is selected by the
platform. Then the clocksource's Kconfig is changed to make this option
selectable by the user if the COMPILE_TEST option is set. Otherwise, it is
up to the platform's Kconfig to select the timer.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

arch/arm/mach-mxs/Kconfig

@@ -16,7 +16,7 @@ config ARCH_MXS
 	bool "Freescale MXS (i.MX23, i.MX28) support"
 	depends on ARCH_MULTI_V5
 	select ARCH_REQUIRE_GPIOLIB
-	select CLKSRC_MMIO
+	select MXS_TIMER
 	select PINCTRL
 	select SOC_BUS
 	select SOC_IMX23

drivers/clocksource/Kconfig

@@ -176,6 +176,14 @@ config MOXART_TIMER
 	help
 	  Enables support for the Moxart timer.
 
+config MXS_TIMER
+	bool "Mxs timer driver" if COMPILE_TEST
+	depends on GENERIC_CLOCKEVENTS
+	select CLKSRC_MMIO
+	select STMP_DEVICE
+	help
+	  Enables support for the Mxs timer.
+
 config CLKSRC_DBX500_PRCMU_SCHED_CLOCK
 	bool "Clocksource PRCMU Timer sched_clock"
 	depends on (CLKSRC_DBX500_PRCMU && !CLKSRC_NOMADIK_MTU_SCHED_CLOCK)

drivers/clocksource/Makefile

@@ -23,7 +23,7 @@ obj-$(CONFIG_BCM2835_TIMER)	+= bcm2835_timer.o
 obj-$(CONFIG_CLPS711X_TIMER)	+= clps711x-timer.o
 obj-$(CONFIG_ATLAS7_TIMER)	+= timer-atlas7.o
 obj-$(CONFIG_MOXART_TIMER)	+= moxart_timer.o
-obj-$(CONFIG_ARCH_MXS)		+= mxs_timer.o
+obj-$(CONFIG_MXS_TIMER)		+= mxs_timer.o
 obj-$(CONFIG_CLKSRC_PXA)	+= pxa_timer.o
 obj-$(CONFIG_ARCH_PRIMA2)	+= timer-prima2.o
 obj-$(CONFIG_ARCH_U300)		+= timer-u300.o