arm float: Add Kconfig options

Adds Kconfig options CPU_HAS_FPU, FLOAT and FP_SHARING for the arm
architecture.

NOTE: All SOCs in the MK64F12 family have an FPU so that makes it a
convenient location to enable the hidden CPU_HAS_FPU option.

Change-Id: I71771d24f20f52079314bb8db9bf8a0aa827ab41
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>

arch/arm/core/Kconfig

@@ -31,6 +31,39 @@ config CPU_CORTEX_M
 	help
 	This option signifies the use of a CPU of the Cortex-M family.
 
+config CPU_HAS_FPU
+	# Hidden config selected by CPU family
+	bool
+	default n
+	help
+	This option is enabled when the CPU has a hardware floating point
+	unit.
+
+menu "Floating Point Options"
+depends on CPU_HAS_FPU
+
+config	FLOAT
+	bool
+	prompt "Floating point registers"
+	default n
+	help
+	This option allows tasks and fibers to use the floating point registers.
+	By default, only a single task or fiber may use the registers.
+
+	Disabling this option means that any task or fiber that uses a
+	floating point register will get a fatal exception.
+
+config	FP_SHARING
+	bool
+	prompt "Floating point register sharing"
+	depends on FLOAT
+	default n
+	help
+	This option allows multiple tasks and fibers to use the floating point
+	registers.
+
+endmenu
+
 if CPU_CORTEX_M
 source "arch/arm/core/cortex_m/Kconfig"
 endif

arch/arm/soc/nxp_kinetis/k6x/Kconfig.soc

@@ -22,6 +22,7 @@ depends on SOC_SERIES_KINETIS_K6X
 config SOC_MK64F12
 	bool "SOC_MK64F12"
 	select HAS_KSDK
+	select CPU_HAS_FPU
 
 endchoice