drm: dumb scanout create/mmap for intel/radeon (v3)

This is just an idea that might or might not be a good idea,
it basically adds two ioctls to create a dumb and map a dumb buffer
suitable for scanout. The handle can be passed to the KMS ioctls to create
a framebuffer.

It looks to me like it would be useful in the following cases:
a) in development drivers - we can always provide a shadowfb fallback.
b) libkms users - we can clean up libkms a lot and avoid linking
to libdrm_*.
c) plymouth via libkms is a lot easier.

Userspace bits would be just calls + mmaps. We could probably
mark these handles somehow as not being suitable for acceleartion
so as top stop people who are dumber than dumb.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h
index 0fc7397c8f1f..ae6b7a3dbec7 100644
--- a/include/drm/drm_mode.h
+++ b/include/drm/drm_mode.h
@@ -344,4 +344,33 @@ struct drm_mode_crtc_page_flip {
         __u64 user_data;
 };
 
+/* create a dumb scanout buffer */
+struct drm_mode_create_dumb {
+        uint32_t height;
+        uint32_t width;
+        uint32_t bpp;
+        uint32_t flags;
+        /* handle, pitch, size will be returned */
+        uint32_t handle;
+        uint32_t pitch;
+        uint64_t size;
+};
+
+/* set up for mmap of a dumb scanout buffer */
+struct drm_mode_map_dumb {
+        /** Handle for the object being mapped. */
+        __u32 handle;
+        __u32 pad;
+        /**
+         * Fake offset to use for subsequent mmap call
+         *
+         * This is a fixed-size type for 32/64 compatibility.
+         */
+        __u64 offset;
+};
+
+struct drm_mode_destroy_dumb {
+        uint32_t handle;
+};
+
 #endif