Kconfig

#
# u-dma-buf
#

menuconfig U_DMA_BUF
	tristate "u-dma-buf(User space mappable DMA Buffer)"
	depends on OF
	help
	  Enable this to allow the u-dma-buf to be built.
	  u-dma-buf is a linux device driver that allocates contiguous
	  memory blocks in the kernel space as DMA buffers and
	  makes them available from the user space.

	  If you don't know what to do here, say N.

config U_DMA_BUF_CONFIG
	bool "Configure u-dma-buf by Kconfig"
	depends on U_DMA_BUF
	default n
	help
	  If y, allows u-dma-buf configuration by Kconfig.
	  If n, build with
	    U_DMA_BUF_DEBUG=y
	    U_DMA_BUF_QUIRK_MMAP=y
	    U_DMA_BUF_IN_KERNEL_FUNCTIONS=y
	    U_DMA_BUF_IOCTL=y
	    U_DMA_BUF_EXPORT=y
	  
config U_DMA_BUF_DEBUG
	bool "u-dma-buf enable debug report"
	depends on U_DMA_BUF_CONFIG
	default y
	help
	  Enable debug report.

config U_DMA_BUF_QUIRK_MMAP
	bool "u-dma-buf enable quirk mmap"
	depends on U_DMA_BUF_CONFIG
	default y
	help
	  Enable quirk mmap.
	  The Linux Kernel mainline turns off caching when doing mmap() for architectures
	  such as ARM and ARM64 where cache aliasing problems can occur.
	  However, u-dma-buf provides quirk-mmap to enable caching in cases where the above
	  architecture does not cause cache alias problems.
	  The quirk-mmap is u-dma-buf's own mmap mechanism and does not utilize the 
	  dma_mmap_coherent() provided by the dma-mapping API in the linux kernel.
	  This may cause problems in some cases, so please be careful when using it.

config U_DMA_BUF_IN_KERNEL_FUNCTIONS
	bool "u-dma-buf enable in-kernel functions"
	depends on U_DMA_BUF_CONFIG
	default y
	help
	  Enable u-dma-buf in-kernel functions.
	  Setting this to y will EXPORT_SYMBOL the function to
	  manage u-dma-buf from inside the kernel.

config U_DMA_BUF_IOCTL
	bool "u-dma-buf enable ioctl"
	depends on U_DMA_BUF_CONFIG
	default y if U_DMA_BUF_EXPORT
	help
	  Enable ioctl.

config U_DMA_BUF_EXPORT
	bool "u-dma-buf enable prime dma-buf export"
	depends on U_DMA_BUF_CONFIG
	select CONFIG_DMA_SHARED_BUFFER
	default y
	help
	  Enable exporting u-dma-buf as PRIME DMA-BUFs.
	  PRIME DMA-BUFs is an abbreviation for the Linux kernel's internal
	  DMA buffer sharing API.
	  It provides a general mechanism for sharing DMA buffers among multiple
	  devices managed by different types of device drivers.
	  To use this option, ioctl must be enabled.