Kbuild

KERNEL_LIMIT := 4.20.17
TEMP 	 := $(shell /bin/echo "$(KERNELVERSION)'\'n$(KERNEL_LIMIT)")
KERNEL := $(shell /bin/echo -e $(TEMP) | sed '/^$$/d' | sort -t. -k1,1nr -k2,2nr | head -1)

# If the user did not specify otherwise, use the in-kernel VME driver iff it was enabled
ifeq ($(VME_SOURCE),)
VME_SOURCE=external
ifeq ($(CONFIG_VME_BUS),y)
VME_SOURCE=inkernel
endif
ifeq ($(CONFIG_VME_BUS),m)
VME_SOURCE=inkernel
endif
endif

ifneq ($(VME_SOURCE),external)
ifneq ($(VME_SOURCE),inkernel)
$(error VME_SOURCE must be inkernel or external)
endif
endif

ifeq ($(VME_SOURCE),external)
ifneq ($(KERNEL),$(KERNEL_LIMIT))
$(warning Cannot build external VME driver with 3.10 - enable in-tree VME $(KERNEL) $(KERNEL_LIMIT))
VME_SOURCE=none
endif
endif

ifeq ($(VME_SOURCE),internal)
ifneq ($(CONFIG_VME_BUS),y)
ifneq ($(CONFIG_VME_BUS),m)
$(warning Kernel must have in-tree VME feature enabled)
endif
endif
endif

# Depend on wishbone.ko from pci-wb directory
KBUILD_EXTRA_SYMBOLS += $(M)/../pcie-wb/Module.symvers
ccflags-y += -I$(M)/../pcie-wb

# If using out-of-kernel VME, declare dependency
ifeq ($(VME_SOURCE),external)
ccflags-y += -I$(M)/../legacy-vme64x-core/drv/driver
obj-m += ../legacy-vme64x-core/drv/driver/
endif

# The actual driver!
ifneq ($(VME_SOURCE),none)
obj-m += vme_wb.o
vme_wb-objs := vme_wb_$(VME_SOURCE).o
endif