Changelog v3:
- use __u64 instead of pointer in ioctl struct.

The G2D is a 2D graphic accelerator that supports Bit Block Transfer.
This G2D driver is exynos drm specific and supports only G2D(version
4.1) of later Exynos series from Exynos4X12 because supporting DMA.

The G2D is performed by two tasks simply.
1. Configures the rendering parameters, such as foreground color and
   coordinates data by setting the drawing context registers.
2. Start the rendering process by setting thre relevant command
   registers accordingly.

The G2D version 4.1 supports DMA mode as host interface. User can make
command list to reduce HOST(ARM) loads. The contents of The command list
is setted to relevant registers of G2D by DMA.

The command list is composed Header and command sets and Tail.
- Header: The number of command set(4Bytes)
- Command set: Register offset(4Bytes) + Register data(4Bytes)
- Tail: Pointer of base address of the other command list(4Bytes)

By Tail field, the G2D can process many command lists without halt at
one go.

The G2D has following the rendering pipeline.
--> Primitive Drawing --> Rotation --> Clipping --> Bilinear Sampling
--> Color Key --> ROP --> Mask Operation --> Alpha Blending -->
Dithering --> FrameBuffer

And supports various operations from the rendering pipeline.
- copy
- fast solid color fill
- window clipping
- rotation
- flip
- 4 operand raster operation(ROP4)
- masking operation
- alpha blending
- color key
- dithering
- etc

User should make the command list to data and registers needed by
operation to use. The Exynos G2D driver only manages the command lists
received from user. Some registers needs memory base address(physical
address) of image. User doesn't know its physical address, so fills the
gem handle of that memory than address to command sets, then G2D driver
converts it to memory base address.

We adds three ioctls and one event for Exynos G2D.

- ioctls
DRM_EXYNOS_G2D_GET_VER: get the G2D hardware version
DRM_EXYNOS_G2D_SET_CMDLIST: set the command list from user to driver
DRM_EXYNOS_G2D_EXEC: execute the command lists setted to driver

- event
DRM_EXYNOS_G2D_EVENT: event to give notification completion of the
		      command list to user
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>