drm: base prime/dma-buf support (v5)

This adds the basic drm dma-buf interface layer, called PRIME. This
commit doesn't add any driver support, it is simply and agreed upon starting
point so we can work towards merging driver support for the next merge window.

Current drivers with work done are nouveau, i915, udl, exynos and omap.

The main APIs exposed to userspace allow translating a 32-bit object handle
to a file descriptor, and a file descriptor to a 32-bit object handle.

The flags value is currently limited to O_CLOEXEC.

Acknowledgements:
Daniel Vetter: lots of review
Rob Clark: cleaned up lots of the internals and did lifetime review.

v2: rename some functions after Chris preferred a green shed
fix IS_ERR_OR_NULL -> IS_ERR
v3: Fix Ville pointed out using buffer + kmalloc
v4: add locking as per ickle review
v5: allow re-exporting the original dma-buf (Daniel)

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Rob Clark <rob.clark@linaro.org>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: Inki Dae <inki.dae@samsung.com>
Acked-by: Ben Widawsky <benjamin.widawsky@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index cc1148837e24..e354bc0b052a 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -9,6 +9,7 @@ menuconfig DRM
         depends on (AGP || AGP=n) && !EMULATED_CMPXCHG && MMU
         select I2C
         select I2C_ALGOBIT
+        select DMA_SHARED_BUFFER
         help
           Kernel-level support for the Direct Rendering Infrastructure (DRI)
           introduced in XFree86 4.0. If you say Y here, you need to select