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>

4 files changed, 52 insertions, 0 deletions

diff --git a/include/drm/drm.h b/include/drm/drm.h
index e5f70617dec..8598cc94e16 100644
--- a/include/drm/drm.h
+++ b/include/drm/drm.h
@@ -701,6 +701,10 @@ struct drm_gem_open {
 #define DRM_IOCTL_MODE_PAGE_FLIP	DRM_IOWR(0xB0, struct drm_mode_crtc_page_flip)
 #define DRM_IOCTL_MODE_DIRTYFB		DRM_IOWR(0xB1, struct drm_mode_fb_dirty_cmd)
 
+#define DRM_IOCTL_MODE_CREATE_DUMB DRM_IOWR(0xB2, struct drm_mode_create_dumb)
+#define DRM_IOCTL_MODE_MAP_DUMB    DRM_IOWR(0xB3, struct drm_mode_map_dumb)
+#define DRM_IOCTL_MODE_DESTROY_DUMB    DRM_IOWR(0xB4, struct drm_mode_destroy_dumb)
+
 /**
  * Device specific ioctls should only be in their respective headers
  * The device specific ioctl range is from 0x40 to 0x99.
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index fe29aadb129..3cbe7a02d2a 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -880,6 +880,17 @@ struct drm_driver {
 	/* vga arb irq handler */
 	void (*vgaarb_irq)(struct drm_device *dev, bool state);
 
+	/* dumb alloc support */
+	int (*dumb_create)(struct drm_file *file_priv,
+			   struct drm_device *dev,
+			   struct drm_mode_create_dumb *args);
+	int (*dumb_map_offset)(struct drm_file *file_priv,
+			       struct drm_device *dev, uint32_t handle,
+			       uint64_t *offset);
+	int (*dumb_destroy)(struct drm_file *file_priv,
+			    struct drm_device *dev,
+			    uint32_t handle);
+
 	/* Driver private ops for this object */
 	struct vm_operations_struct *gem_vm_ops;
 
@@ -1544,6 +1555,7 @@ drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
 int drm_gem_handle_create(struct drm_file *file_priv,
 			  struct drm_gem_object *obj,
 			  u32 *handlep);
+int drm_gem_handle_delete(struct drm_file *filp, u32 handle);
 
 static inline void
 drm_gem_object_handle_reference(struct drm_gem_object *obj)
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 801be59f4f1..080a6e33470 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -798,4 +798,11 @@ extern int drm_add_modes_noedid(struct drm_connector *connector,
 extern bool drm_edid_is_valid(struct edid *edid);
 struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,
 					   int hsize, int vsize, int fresh);
+
+extern int drm_mode_create_dumb_ioctl(struct drm_device *dev,
+				      void *data, struct drm_file *file_priv);
+extern int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
+				    void *data, struct drm_file *file_priv);
+extern int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
+				      void *data, struct drm_file *file_priv);
 #endif /* __DRM_CRTC_H__ */
diff --git a/include/drm/drm_mode.h b/include/drm/drm_mode.h
index 0fc7397c8f1..ae6b7a3dbec 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