ARM: vexpress: refine dependencies for new code

The versatile express changes for 3.16 introduced a number of
build regressions for randconfig kernels by not tracking dependencies
between the components right.

This patch tries to rectify that:

* the mach-vexpress code cannot link without the syscfg driver,
  which in turn needs MFD_VEXPRESS_SYSREG
* various drivers call devm_regmap_init_vexpress_config(), which
  has to be exported so it can be used by loadable modules
* the configuration bus uses OF DT helper functions that are not
  available to platforms disable CONFIG_OF
* The sysreg driver exports GPIOs through gpiolib, which can
  be disabled on some platforms.
* The clocksource code cannot be built on platforms that don't
  use modern timekeeping but rely on gettimeoffset.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-vexpress/Kconfig

@@ -18,6 +18,8 @@ config ARCH_VEXPRESS
 	select POWER_SUPPLY
 	select REGULATOR_FIXED_VOLTAGE if REGULATOR
 	select VEXPRESS_CONFIG
+	select VEXPRESS_SYSCFG
+	select MFD_VEXPRESS_SYSREG
 	help
 	  This option enables support for systems using Cortex processor based
 	  ARM core and logic (FPGA) tiles on the Versatile Express motherboard,

drivers/bus/Kconfig

@@ -46,6 +46,7 @@ config VEXPRESS_CONFIG
 	bool "Versatile Express configuration bus"
 	default y if ARCH_VEXPRESS
 	depends on ARM || ARM64
+	depends on OF
 	select REGMAP
 	help
 	  Platform configuration infrastructure for the ARM Ltd.

drivers/bus/vexpress-config.c

@@ -118,7 +118,7 @@ struct regmap *devm_regmap_init_vexpress_config(struct device *dev)
 
 	return regmap;
 }
-
+EXPORT_SYMBOL_GPL(devm_regmap_init_vexpress_config);
 
 struct device *vexpress_config_bridge_register(struct device *parent,
 		struct vexpress_config_bridge_ops *ops, void *context)

drivers/clocksource/Kconfig

@@ -194,7 +194,7 @@ config CLKSRC_QCOM
 
 config CLKSRC_VERSATILE
 	bool "ARM Versatile (Express) reference platforms clock source"
-	depends on GENERIC_SCHED_CLOCK
+	depends on GENERIC_SCHED_CLOCK && !ARCH_USES_GETTIMEOFFSET
 	select CLKSRC_OF
 	default y if MFD_VEXPRESS_SYSREG
 	help

drivers/mfd/Kconfig

@@ -1229,7 +1229,7 @@ endmenu
 
 config MFD_VEXPRESS_SYSREG
 	bool "Versatile Express System Registers"
-	depends on VEXPRESS_CONFIG
+	depends on VEXPRESS_CONFIG && GPIOLIB
 	default y
 	select CLKSRC_MMIO
 	select GPIO_GENERIC_PLATFORM