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, 73 insertions, 30 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index cf4f74c7c6fb..bc7f06b8fbca 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -193,22 +193,20 @@ i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
         return 0;
 }
 
-/**
- * Creates a new mm object and returns a handle to it.
- */
-int
-i915_gem_create_ioctl(struct drm_device *dev, void *data,
-                      struct drm_file *file)
+static int
+i915_gem_create(struct drm_file *file,
+                struct drm_device *dev,
+                uint64_t size,
+                uint32_t *handle_p)
 {
-        struct drm_i915_gem_create *args = data;
         struct drm_i915_gem_object *obj;
         int ret;
         u32 handle;
 
-        args->size = roundup(args->size, PAGE_SIZE);
+        size = roundup(size, PAGE_SIZE);
 
         /* Allocate the new object */
-        obj = i915_gem_alloc_object(dev, args->size);
+        obj = i915_gem_alloc_object(dev, size);
         if (obj == NULL)
                 return -ENOMEM;
 
@@ -224,10 +222,41 @@ i915_gem_create_ioctl(struct drm_device *dev, void *data,
         drm_gem_object_unreference(&obj->base);
         trace_i915_gem_object_create(obj);
 
-        args->handle = handle;
+        *handle_p = handle;
         return 0;
 }
 
+int
+i915_gem_dumb_create(struct drm_file *file,
+                     struct drm_device *dev,
+                     struct drm_mode_create_dumb *args)
+{
+        /* have to work out size/pitch and return them */
+        args->pitch = ALIGN(args->width & ((args->bpp + 1) / 8), 64);
+        args->size = args->pitch * args->height;
+        return i915_gem_create(file, dev,
+                               args->size, &args->handle);
+}
+
+int i915_gem_dumb_destroy(struct drm_file *file,
+                          struct drm_device *dev,
+                          uint32_t handle)
+{
+        return drm_gem_handle_delete(file, handle);
+}
+
+/**
+ * Creates a new mm object and returns a handle to it.
+ */
+int
+i915_gem_create_ioctl(struct drm_device *dev, void *data,
+                      struct drm_file *file)
+{
+        struct drm_i915_gem_create *args = data;
+        return i915_gem_create(file, dev,
+                               args->size, &args->handle);
+}
+
 static int i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
 {
         drm_i915_private_t *dev_priv = obj->base.dev->dev_private;
@@ -1425,27 +1454,13 @@ i915_gem_get_unfenced_gtt_alignment(struct drm_i915_gem_object *obj)
         return tile_height * obj->stride * 2;
 }
 
-/**
- * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
- * @dev: DRM device
- * @data: GTT mapping ioctl data
- * @file: GEM object info
- *
- * Simply returns the fake offset to userspace so it can mmap it.
- * The mmap call will end up in drm_gem_mmap(), which will set things
- * up so we can get faults in the handler above.
- *
- * The fault handler will take care of binding the object into the GTT
- * (since it may have been evicted to make room for something), allocating
- * a fence register, and mapping the appropriate aperture address into
- * userspace.
- */
 int
-i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
-                        struct drm_file *file)
+i915_gem_mmap_gtt(struct drm_file *file,
+                  struct drm_device *dev,
+                  uint32_t handle,
+                  uint64_t *offset)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
-        struct drm_i915_gem_mmap_gtt *args = data;
         struct drm_i915_gem_object *obj;
         int ret;
 
@@ -1456,7 +1471,7 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
         if (ret)
                 return ret;
 
-        obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle));
+        obj = to_intel_bo(drm_gem_object_lookup(dev, file, handle));
         if (obj == NULL) {
                 ret = -ENOENT;
                 goto unlock;
@@ -1479,7 +1494,7 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                         goto out;
         }
 
-        args->offset = (u64)obj->base.map_list.hash.key << PAGE_SHIFT;
+        *offset = (u64)obj->base.map_list.hash.key << PAGE_SHIFT;
 
 out:
         drm_gem_object_unreference(&obj->base);
@@ -1488,6 +1503,34 @@ unlock:
         return ret;
 }
 
+/**
+ * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
+ * @dev: DRM device
+ * @data: GTT mapping ioctl data
+ * @file: GEM object info
+ *
+ * Simply returns the fake offset to userspace so it can mmap it.
+ * The mmap call will end up in drm_gem_mmap(), which will set things
+ * up so we can get faults in the handler above.
+ *
+ * The fault handler will take care of binding the object into the GTT
+ * (since it may have been evicted to make room for something), allocating
+ * a fence register, and mapping the appropriate aperture address into
+ * userspace.
+ */
+int
+i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
+                        struct drm_file *file)
+{
+        struct drm_i915_gem_mmap_gtt *args = data;
+
+        if (!(dev->driver->driver_features & DRIVER_GEM))
+                return -ENODEV;
+
+        return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
+}
+
+
 static int
 i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
                               gfp_t gfpmask)